RhOME Prefab House - Simple, Durable and Sustainable

Architectural Concept
Engineering and Construction
Project participants

Rhome (A Home for Rome) is a part of a program of the city planning to regenerate the neighborhood of the Tor Fiscale, replacing in particular illegal settlements with efficient and ecological prefab housing. On these recovered spaces a small communities with neat aesthetics must set up. The ground floor consists of a reinforced concrete seating on which rest the four floors in wood frame, for a total of 12 apartments. These are distributed around a central column housing the technical services for kitchens, bathrooms, ventilation, etc. The peculiarity of Rhome is to integrate solar panels on the roof and in facade. Photovoltaic modules are also integrated into removable details of the main windows. The design team presented in Versailles a prefab house (one apartment of 60 sqm) which representes a part of the last level of the building.

Photovoltaic modules covers a continuous strip from the slope of the roof to the foot of the facade, on the south facade of the prototype. The chosen technology is Solbian's flexible monocrystalline modules because of their light weight and good resistance to hostile conditions (salt water, shocks, etc.). The photovoltaic facade panel can be raised by 15° to be placed in the extension of the roof modules, in order to increase the productivity of the system.

The new urban standard

The world is called to solve the challenge of the balance between development and resource consumption, and this change is entrusted to the city, which must be able to change the way they manage population growth, energy use and administration of the territory. Lately, news reports have highlighted the critical issues related to the city that governs itself through methodologies related to a society that is no longer there. New technologies, the different way of living social relations, new utilities, require a new way of enjoying the city and its spaces.

Historically, social changes were associated with a crisis of the cities, which had to change their way of being planned and lived, in order to solve the problems. Currently many such solutions have been proposed and implemented among difficulties and successes, but they need to be empowered in order to ensure that the planning and direction of the future towns are based on these values. The RhOME project accepts the challenge and takes the opportunity to define and propose new planning standards, adapted to the needs of a modern, multi-ethnic and different society.

For example, the current legislation ensures that 18 square meters per person will be dedicated to urban standards; 2.5 square meters of these are for parking. To encourage mobility slow this standard is too high and also exacerbates the problems of overbuilding. The process then starts from reviewing the current data to which add new features, like the ability for everyone to have an internet connection, to have clean energy and to re-use what it produces and consumes. Currently we are focusing on quantifying those standards.

RE-USE – Why “One thing leads to another”

The smart city is facing an environmental and economic sustainable reform of production processes and resource management, in an environmental and economic direction. This revolution feeds on concepts such as integration, interdependence and the “closed loop“. There is no waste, but resources. Eco- products that can be processed, consumed, abandoned and refed into the production cycle in other forms, in the logic that “ one thing leads to another.”

At the base of the crisis of consumptions, there is a “linear” model production, high waste of energy and natural resources. The products resulting from these resources, at the end of their life cycle become waste. The high cost required for their disposal, resource scarcity and price volatility have undermined this system. One response to this difficulty comes from the realization of an “circular” economy, based on reuse and regeneration values.

In order to become innovation, it must be the result of a new conception of the production process of goods, as well as their design. The basic conception of this innovation process is the will to reduce the production of waste by re-inserting the components of a product in production cycles, thereby limiting the dependence on natural resources. The beneficiaries of the assets are no longer seen as consumers, but as users. This means that unless a product has to be changed for its reuse, faster will be its reinstatement in the process. Also it can be reused several times, and its potential savings will be higher. Product innovation starts then by the choice of materials, which must be environmentally friendly and reusable.

The adoption of standardized and prefab modular components enables an easy implementation, making it possible to disassemble the product. Reducing the environmental footprint of the district means conceiving then closed cycles for food, water and waste. This principle must be accompanied by the creation of structures that make it possible to close the circle and on policies and actions capable of motivating and educating citizens in its implementation.

Therefore, in the neighborhood recovery disused industrial buildings has been designed to accommodate space craft fab lab, where old furniture, tools, objects, can find a new life thanks to the creativity of the people. The residential waste are managed by the capillarity of the “door-to-door” collection, also capable of creating jobs “socially useful”. The organic part produced from these wastes and catering services in the area, becomes a “compost” for growing urban gardens, which give rise to products sold in the market district, reducing the energy consumption related to the food chain.

The recovery system of rainwater and grey water must decrease the consumption of drinking water from the water mains. Rainwater and gray water coming from the apartments are then filtered with an innovative water purifier developed for the aerospace recycling of water. This purifier-used by the entire neighborhood-not only guarantees the reuse of water for irrigation, but for all domestic purposes. Part of the cleaning residue can then be used for fertilization of cultivated areas.

REDUCE - For a better life quality

There is a principle, almost more a consequence, that links all these aspects and is connected to the concept of reduction. Closely related, the actions of densification and redevelopment, put in place in order to regenerate urban fabric, leading to the compact city, with a consequent reduction in the consumption of ground and air pollutant emissions. The demolition of illegal buildings allows to recover a portion of the park, reconnecting to the Park of the system, expands its boundaries, creating an ecological corridor and a connection to the city system. The reconstruction of the volumes in the empty spaces in the part of the consolidated district along the ancient Via Latina, allows to generate an axis to reunite urban fabric, thanks to the structuring of a continuous space, and multifunctional services including residences and public spaces. The resulting rationalization of the movements and the stimulation of slow mobility reduce the use of private vehicles on road. The standardization of the production process and the use of dry construction technology, reduce the time of implementation of the project and therefore its costs. Certainty and ease in managing the process increases; a process which increases its attractiveness by allowing a large-scale deployment, further reducing costs and timing. The structuring of a circular economy, based on the principle of a closed cycle, reduces the waste of natural resources and production of waste, and creating a virtuous system for which each material can be fed back into the production process and become something else. Reduce, therefore, to improve the life quality for everyone.

Strategy to save costs

The real estate sector, in its most advanced form, is gearing up more and more towards new construction methods, giving priority, among all, to the prefab construction system.

The benefits of the prefab system are:

- quality controlled in the factory allowing a greater attention to the stages of assembly. A prefab house offers a better quality from the beginning of the work because of its assured performances, difficult to reach with other elements realized during the work.
- reduction of assembly time by providing, through the prefab system of dry construction, immediately after the outer casing , the realization of the cover and the laying of the frames and coming in a very short time to the plant works and internal finishing, this thanks to the use of prefabricated elements and a consequent standardization of the yard.
- limited relevance of meteorological phenomena during prefab construction thanks to the fact that the assembly moves from the yard to the factory.
- reduction of staff workers in site since the process is characterized by a greater number of machines than human resources.
- minimization of waste site because of the majority of the production takes place in the factory and the prefabricated product comes ready for installation.
- safety on site, the speed of prefab construction, assured by the dry shipyard, it reduces the duration of the work and therefore the exposure time of workers to risk factors.
- environmental sustainability of the process, the stratified prefab construction with dry wood elements is an high constructive solution on environmental sustainability, as it involves the reduction of the use of environmentally friendly materials and largely recyclable. In addition, the prefab system achieves a high thermal and acoustic isolation, saving energy and reducing emissions of harmful gases into the atmosphere, enhancing the relationship between the building, its operation and its disposal.

So the strategy for achieving our goal focuses on the maximum decrease of the costs of construction (about 70 %) of the aggregate, through a process of standardization which speeds up the time of completion of the work on site. This process allows to approach an economy of scale, for which bigger is more efficient: the unit cost decreases while the production increases.

Prefab building industry

In the past, in the building field, for the production of low-cost buildings is attempted the way of standardization. This led to the mass production of the prefab elements that made up the buildings, such as precast elements reinforced concrete (prefabricated “heavy”). This solution, with time, showed stronger limits, because it was associated with a production of low quality.

As part of our project was therefore decided to take the strengths of previous experience, adding new prefab elements and revisiting the concept of prefabrication. In particular, we decided to apply the prefabrication at the elements that make up the 3D Core (“solid heart of the house” because it contains within it the water plant, sanitary, electrical and air handling and integrates the body or bodies with the bath ‘kitchenette) making the production process more flexible.

This has been made possible by recent developments in computer science, which have allowed us to arrive at a finished product from a 3D design. So, through a three-dimensional drawing and CNC machines today you can get products that are highly industrialized and precise, but at the same time customized; all the more quickly as compared to a traditional building production, thanks to the materials used, such as wood. A wooden building, in fact, is best suited to become an industrial product.

These products can then be assembled in factories and then be transported as finished products directly on site. The advantages of this prefab manufacturing process can be summarized in the following points:

- Industrial product so cheap and rapid development, but at the same time adaptable to the type of accommodation.
- Reduction of the duration of the work.
- Reduced costs due to skilled labor.

Architectural Concept

It’s quite difficult to use a single portion to fully describe the logic of an entire building.

The RhOME dense aggregate is based on a system that lies at the basis of its structure, that dictates the laws of its articulation and variability thanks to the established flexibility of the plan and facades that allows plural solutions and a consequent richness of life, given by the plural possibilities offered.

We tried as much as possible to represent a small prefab apartment as significant part for the whole.

The model proposed in Versailles, a prefab prototype of an apartment of about 60 sqm, is just one of the different configuration options that can be achieved within the scheme - with the same square footage or with other dimensions- and thus favoring the rules imposed by this.

It’s a modest entity within a more extended complex: despite this -as much as possible- it contains all the elements necessary to describe the set. Good living is told here through a clear spatial, the result of a tectonic concept as logical and as straightforward as possible.

The space articulates itself around the 3d service core - bathroom, kitchen and technical room - which is also the main pillar of the house and building in the complex, too. This element hierarchizes and characterizes the space, defining the various areas, the kitchen, the living and the night rooms, of which the house is composed. The views open up to the south -south-west- and to the north -north-east-and are protected by loggias. This condition also allows to have a cross ventilation, which in summer is useful in order to cool the microclimate in a natural way.

The prefab prototype of Versailles represents the top floor of the complex described above. This choice derives from the intention to describe the architectural features and technological innovations that would not appear in a common floor or in the ground floor, where the focus is on the integration with the urban environment. The prototype inherits the distribution system from the aggregation: the access is located on its side as in the urban configuration there is a central distribution core, which serves the apartments on both sides. During the contest this distribution pattern is conjured up by the public tour which valorizes freedom of the plan. Our idea of good prefab house living is told here through a clear spatiality, the result of a tectonic concept. The space is articulated around the 3d core which is the plant and structural center of the prefab house. This element hierarchizes and characterizes the space, defining the various areas of which the house is composed: the kitchen, the living room and the bedroom. The views open up to the south-west and to the north-east and are protected by loggias. The presence of the loggias in the two opposite corners ensures an original and versatile plan scheme, of which the versailles prototype is only one possible configuration. Specifically, in the competition the two main areas of the prefab house relating to public life (living room) and the intimate life (bedroom) have direct contact with the outside world. In this way each one of these spaces receives the type of natural light suited to its function and in the phases of the day that compete to them. This condition also stands in terms of sustainability. In fact this result is not achieved exclusively working on the density (above all), on the use of solar and passive energy and on the optimal exposure to the sun and the wind. Attention has been paid to the choice of materials and of a technology that would reduce as much as possible.

Meeting the needs and the housing demand.

The building under consideration, of which the prototype of Versailles is just one of the prefab apartments -as has already been explained-, belongs to the type of the multi-storey building. The building is structured in four levels, in addition to the basement floor, each of which is divided into three units. These are served by the central spine to which belong all the facilities (bathrooms and kitchens and plants), in addition to the distribution system of the stairs and the elevator. Two of the prefab apartments are well exposed on three sides and one, ranging in size from 45 to 60 square meters, is monofacing, with a southern exposure (to south, south-east or south-west depending on the exact location of the building in the site).

This organization allows to maximize the space and meet the housing demand. Each four-storey building accommodates twelve prefab apartments of which 20% are one-bedroom apartments, 20% two-bedroom apartments, 30% three-bedroom apartments and 20% four-bedroom apartments. The surface of these units is also modifiable using a special system that allows you to scroll windows and close the lodges. These spaces, of which is equipped each accommodation, can thus be used both in the hot season such as open and shaded places, both in the cold season as glasshouses-like closed rooms, making them pleasant places to stay anytime. The layout includes the ability to have each floor, on the side facing north, a multipurpose space that can be shared, such as a reading or a playground room, or private, whether intended for a small studio, possibly communicating with one of the apartments of the plan. The building is enhanced accordingly also from the functional point of view: in addition to residences are located spaces for leisure and for work.

Construction and Materials

Prefab, modular and flexible, rigid in its rules, but articulated (articulable) and lively: these are the main features of the building as it has been intended. The modularity and the prefabrication of each element become qualities in terms of sustainability. This lens is not in fact achieved exclusively working on the density (above all), on the use of solar and passive energy, on the optimal exposure to the sun and the wind. Attention has been paid to the choice of materials and of a technology that would reduce as much as possible the impact on the environment of the prefab building. Sustainability is achieved through the adoption of a dry and lightweighted prefab construction system, which involves the use of prefabricated elements and, in some cases, preassembled elements. In this way, in fact, both the yard’s waste and the duration of the construction time itself are greatly reduced. Standardization and modularity offer the possibility to recycle some components and permit, in case of dismantling, the selective demolition and the subsequent reuse of the same elements, which are therefore released into a life cycle.

Summary of Reconfigurable Features

A crucial choice of the RhOME urban proposal is to locate solar active systems no longer just on roofs, but also on facades. Photovoltaic panels are installed and integrated in lightweight, mobile shading elements, that are designed to slide and protect, when the loggias are closed during the hot season, while allow, when open, thermal gains in winter.

The installation on the facades wants to promote the use of solar active systems in the dense urban environment, as a possible single-unit solution, to be installed in terraces, balconies and loggias: the open spaces which are typical architectural features of buildings in the Roman climate, so open space is usable for a great part of the year as an extension of the inner space.

Each prefab apartment could have one or more screens that provide energy directly to the apartment. This could be a great byproduct of the RhOME project, to be applied even to the existing building stock. The case of installation on an entire building, as in our new interventions, can allow a shared and intelligent energy management system organized for the building or even of the neighbourhood itself, that can distribute and eventually store production peaks and prevent losses. At the scale of the building the reconfigurable shading elements provide a great variability and variation to the building facade, that gains the ability to show the internal use of the space, adding a new layer to the already preset variation given by the changes to the interior layout (floor area, rooms, number of loggias, and so on) according to the family needs. The project therefore is articulated as a structural skeleton that allows two kinds of variations: a “hard” variation, based on the number and position of the loggias, a “light” variation, the reconfigurable one, that is provided by the sliding shading devices.

Inside the prefab house, reconfigurable features are furnishings that allow to have more functions in same square meters. In fact reconfigurable furnishings changes according to family’s needs and time of the day.

During the day the bedroom turns into an office, and that’s why it’s placed near the entrance.

During the night the living turns into a bedroom, too, in order to host three to four people.

In 60 square meters we have two bedrooms, living, office, kitchen and bathroom for two, three or four people.

Lighting Design


The main glass surfaces of the RhOME for denCity prefab house are located on the north and south loggias, allowing different but sufficient natural lighting respectively for sleeping and living spaces.

The loggias with large windows act as extensions of the prefab houses inner life. These are protected by fixed and mobile shields depending on the need of protection from solar radiation. In fact, we had to balance the contribution of windows and glass surfaces to natural lighting by paying a constant attention to the dangerous thermal gains during the hot season. Such protection is done with different devices depending on the location and orientation of the windows.

The south loggia, is protected by the mobile shading system. That system has two configurations: open and closed.

The north loggia does not need the same protection systems of the south loggia, but it is protected by the northwest wall of the building. After the evaluation of the contribution to natural lighting given by the loggias, additional windows have been located on South-West and North-West walls, and protected by some fixed shading system that follow the boundaries of the windows.

Artificial lighting

During the design of lighting system of the prefab house we have considered three different aspects:

- Energy efficiency
- Comfort
- Flexibility

Energy efficiency

We selected LED technology thanks to its benefits in terms of energy efficiency:

Lifetime: A LED has a lifetime of up to 50,000 hours of life against the 2,000 hours of an incandescent lamp, the 10.000 hours of a compact fluorescent and 30,000 hours of a linear fluorescent.

Low heat production: the reduction in heat loss allows the LED to have an excellent efficiency with a little heat loss, approximately 5% compared to the 90% of incandescent bulbs or 80% of compact fluorescent lamps.

Dimmering: The lighting system have the possibility to dimmer the luminous flux of light and for this reason we will have an energetical benefit.


The light quality of a room is one of the most important factors to give to inhabitants a pleasant or unpleasant experience. Light has an incredible influence in our ability and will to occupy a space.

We want the artificial light to contribute to this effect, and help to create the intimacy and quietness of feeling home. The intention in the project is to create different scenarios depending on the action that take place in each zone of the apartment, with a sharp-cut of style between the low ceiling zones and the pitched roof ones:

Low ceiling zones embed LED stripes into a recessed and concealed rails:

- The corridors will be characterized by a linear light mounted on the ceiling that run along the entire length of the environments and that will give a general light.
- The bathroom presents a linear light with the same structure of the devices of the corridors is also characterized by a finiture made of bright material.
- The kitchen, as well as having a general light, will also have a functional light for the work planes.
- The living room and the bedroom, with pitched roof, have a different design of the lighting system. These spaces will be illuminated by suspended, free-standing and spot fixtures that, as well as they making direct light, can also activate lights that will be directed upwards and that serve to illuminate spaces.

Daylighting and electrical lighting, are designed to have light from different directions in order to have a perfect balance of luminances on different surfaces, with particular attention on visual tasks and surrounding.


The areas with false ceiling presents a lighting system composed by linear elements (in which is inserted the Collego®) placed in the entry corridor, in the technical compartment, in the kitchen and in the bathroom.

For the other areas, with the pitched roof, we thought a lighting system which consists on an equipment of three different fixtures:

- In the living room it was chosen a ceiling lamp and a floor lamp.
- For the bedroom, we designed a lighting system which consists in a linear element joined to the “boundary cabinet”. On the lower side of this, there are four spots directed in order to provides functional enlightenment over both arrangement of the cabinet (bed and table); in the upper side, there are LED stripes that create an indirect and widespread light in the room. All these elements have various types of switches that can give direct, indirect or spot light, according to user needs.

Each lamps can support lights along the entire length of the elements, that can be inserted through a system of current flow called Collego®.

Collego® is an interconnection system that allows the direct connection between LED boards or LED circuits without employing welding tools. All compatible boards can be interconnected using a proprietary connector, and can be equipped with multiple accessories to ensure an effective versatility of use. In addition to all the accessories for power distribution, such as curves, junctions, junction terminals, flexible bridges, as well as mounting accessories, Collego® system also provides
various types of light controllers, which can be directly applied on the different compositions, everything in a simple and intuitive way.

In this way, we are able to install these LED bars wherever required and you can choose to activate the part of the lamp you need. In fact, the lamps have the opportunity to have this circuit on their whole length thanks to the milling of the lighting body ranging from the base to the top.

Outdoor lighting

For outdoor, we choose to use a stand-alone lights, the Sunflowers, which have their own solar panel that stores energy during the day and release it, as luminous flux, when the light sensor inside so requires.

We designed two types of supports for these lamps:

- The former, serves to fix the Sunflowers on the entrance ramps;
- The latter, hook-shaped, allows you to hang up the Sunflowers on appropriate cables placed in the loggias and in the hall, as the lanterns. These cables may have different lengths and can be positioned as needed, in order to achieve a high flexibility even in outdoor spaces. Furthermore, assembled on the contrary, the hook serves to place the Sunflowers on the handrail, where they receive a greater amount of solar energy.

Depending on the function, the color of the corolla is:

- Yellow, in the lamps fixed on the ramps.
- Grey, in the case of the lanterns.

Still in accordance with the Rules, we’ll have a minimum illuminance of 20 lux along the route of the public tour.

Natural lighting

Lighting Analysis: using the VELUX Daylight Visualizer Software.

With this software we wanted to verify that, the chosen distribution plan, can guarantee visual comfort, both in the case of the prototype and in the case of the aggregate. The target was to fit the lighting parameters required by italian law about the average factor of daylight FLDm, luminance and illuminance factors. So we made lighting simulations to modify some choices and to confirm others.

Our initial strategy was based on big large windows localized on the loggias, backward positioned from the facade, so to provide shading from direct radiation when needed. Some further analysis showed that this approach leads to an unbalanced distribution of daylight, configuring a high enlightened belt contrasting to some low enlightened ones.

We carried out the analysis using the software “VELUX Daylight Visualizer”, precisely analyzing each floor of the three typologies designed. We report here only one example of the various analysis carried out on a building floor.

Considering the conditions of natural light inside, it is necessary to take into account the worst case condition, that is one in which the main room is in absence of direct solar radiation.

The first analysis is carried out on the average factor of daylight FLDm that is a parameter introduced to assess the natural lighting within a confined environment.

In order not to limit the calculation of a single point, we use the average daylight factor FLDm, where average means averaged over several measurement points of the internal environment in relation with the outside world: in this way it is possible to better estimate the global illumination in a confined space.

In red we have highlighted all the problematic areas, or those areas of the apartment in which the FLDm did not respond to the comfort that we want to achieve, which is below 2% (the limit fixed by legislation).

This initial analysis shows how the opening of large windows on the sun loggias is not sufficient to ensure a good, homogeneous lighting in the whole area of the apartments. In fact, the daylight factor, which normally should not fall below 2%, is in some cases even 0.7% (bordered in red).

The need to investigate where to place new openings seemed like a pretty obvious choice.
It was therefore studied in the following ways:

- openings from 90cm to 120cm, full-height for the facades facing south-east / south-west, which alternate with large balconies
- openings from 90cm to 120cm, full-height for the facades oriented towards the north-east / north-west
- try to reduce the lodges oriented north-east / northwest, while leaving the angular ones
- skylight on the north slopes to facilitate the penetration of light into the space of the living room

To size the depth of the lodges we used the software Autodesk Ecotect: the tool “Shading Design Wizard” makes the program calculate the size needed to shade a window based on the orientation and the period in which it is most exposed to sunlight.

Acoustic Performance

We are working on the acoustic performance of our prefab house, with the objective to find the ideal solution also in terms of acoustic performance. The results of these analysis have been then used for developing further estimation of the circulation of sounds in the prefab house, considering the sonic surrounding of the dwelling in its local context.

Prototype Prefab House Acoustic Performance

For the Prototype’s Acoustic Performance we developed the following analysis: the estimate reverberation indoor time and the sound reduction index of facade. We intend to clarify that the following analysis represents a predictive estimation of the acoustic performance in the prototype prefab house.

Estimate indoor reverberation time

Reverberation is the persistence of sound in a particular space after the original sound is removed. A reverberation, or reverb, is created when a sound is produced in an enclosed space causing a large number of echoes to build up and then slowly decay as the sound is absorbed by the walls and air. This is most noticeable when the sound source stops but the reflections continue, decreasing in amplitude, until they can no longer be heard. To avoid those echoes we are analyzing separate area in the prototype prefab house to find some significant internal coating materials with as high as possible absorption coefficients.

Reverberation Time

In general basic factors that affect a room’s reverberation time include the size and shape of the enclosure as well as the materials used in the construction of the room. Every object placed within the enclosure can also affect this reverberation time, including people and their belongings. However in our case we can ignore nonfixed elements because of the small dimension of the affected area that we are taking in consideration.

For this deliverable we have done theoretical calculation of reverberation time, but for the next previous construction of the prefab house.

Our strategy for obtaining the optimal reverberation time is the use of vibrating panels: the coverings are porous absorbing material (larch wood panels made of three layers) which are distanced from the underlying layer (in Fiber Gypsum) with wooden muillions. The air gap has 6 cm thickness.

As stated in our acoustic standards, RT60 is the time required for reflections of a direct sound to decay by 60 dB below the level of the direct sound. Reverberation time is frequently stated as a single value. However, it can be measured as a wide band signal (20 Hz to 20kHz) or more precisely in narrow bands (one octave, 1/3 octave, 1/6 octave, etc.).

Typically, the reverb time measured in narrow bands will differ depending on the frequency band being measured. It is usually helpful to know what range of frequencies are being described by a reverberation time measurement.

Interior Design

In Rhome prefab house, interior design allows the flexibility, density and sustanibility that are in architectural concept and that represent the Italian talent, the “Made in Italy”. But we have chosen furnitures that do not want to be just a furnishing brand “Made in Italy”, where attention to detail, ergonomics, product quality and environmental protection are the basis of the design philosophy, but also the conviction that it is possible to redesign the future in a different way by rearranging and creating a new culture.

Simple, durable and sustainable

Re-use and re-think are our actions.

For kitchen and bedroom we have chosen Valcucine and Clei that represent our philosophy.
Demode Valcucine’s kitchen is durable and sustainable beacuse is eternal in all cycle of life. All components are recycable and reusable. Design is very simple and re-thinks the way of thinking the kitchen.

Clei’s Ulisse Dining allows flexibility and to have in same space two different functions as bedroom and office. But we can have many possible compositions. We rethink the way of thinking our prefab house: less space, more functions. So we have possibility to work in house.

For dining and living room we have re-used and refixed old furnitures that have 50-60 years but that are eternal and represent Italian tradition in the furnishing. Re-use to limit the increase and the consumerism and to valorize that we already have.

Engineering and Construction

Structural Design

Urban scale project

The structural behavior is systemic and its goodness depends on many factors, such as inner coherence, harmony between parts, responsiveness to consolidated typologies, quality of the constructive aspects, reliability of mahematical models for the mechanical prediction and safety quantification and so on.

The structural system of the urban aggregate consists of a reinforced concrete first floor that supports further four floors and the roof of a lightweight wooden building, made with frame-wall technology (Platform Frame). The first floor in reinforced concrete is formed by a central core constituted by structural walls to which a 3D structural lattice of reinforced concrete beams is stuck, that supports not only the first floor slab (made of horizontal panels of Platform frame system) but also the rest of the wooden building.

The foundation of the building consists of a grillage of reinforced concrete grade beams placed below the vertical walls that widen the contact section between the structure and the ground, in order to make the ground stress compatible with its compression strength. The geographical area of Tor Fiscale falls within the geological district of Alban hills, characterized widely by volcanic soils (tuff and similar soils), under which there are Pleistocene floods, often uncovered by erosion. In that area there are not deformable soils of recent origin, except for some very small local areas within some ditches. Generally speaking, ground compressive strength goes from 0,5 to 2 Mpa, and can support surface foundations, especially for moderately light buildings like those whose most structure is made of wood. Where the thickness of the tuff is consistent, sometimes you can find cavities for mining or preceding anthropic phenomena. However, a surface foundation does not interfere with archaeological heritage and preserves the soil around the building as much hydraulically permeable as possible.

The beams of the structural grillage of the first floor are characterized by sections of variable height, which allow the higher stresses due to vertical loads be moved to the core and meet the architectural principles of the project, limiting the height of the perimeter beams and defining a sort of structural “tray” that holds the building.

Aside from the first floor of reinforced concrete, whose choice is justified by architectural reasons, the choice of using the prefab Platform System wall technology is motivated by requirements of sustainability, lightness and quickness of installation. However, in Italy the prefab Platform System may be adopted only for buildings of limited height, usually not exceeding three storeys, especially for areas characterized by high seismicity. Since our building is located in Rome, we must take into account this limitation in height; so, we have decided to not lose the benefits of the Platform constructive system, strengthening it with another technology, the frame one, with in mind the idea of differentiating the structural tasks of the two different technologies. In practice, we have a hybrid technology, prefab wooden frame and prefab wall technologies, where the frames supports the vertical loads, increasing from upward to downward, while the walls, inserted within the spaces left empty by the frames and reinforced by St Andrew’s crosses where necessary, act as wind-bracings and support the horizontal forces, even increasing from top to bottom.

The structural system is based upon a grillage of reinforced concrete beams, supporting the rest of the construction, i.e. all upper floors. Most of these beams are cantilever ones and they have been subjected to a first dimensioning, by checking the maximum stress due to bending moments. These variable-section cantilever beams are almost all clamped in the vertical walls of reinforced concrete, or are part of a continuous beam on multiple supports. Obviously, their deformability has been also controlled at this stage of the preliminary draft, because if it were excessive, it would affect the
functionality of the building. This calculation was performed and produced a new dimensioning of some beams, whose height was increased, having as reference value of 1/250 of the span for the maximum vertical displacement. The load combination for this deformability check is obviously a service limit state combination load. The maximum displacement at the point indicated in the figure has been calculated as 28 mm.

Once made the first dimensioning based on the ultimate limit state combination for vertical loads, the behavior of structure under seismic action has been analized. Seismic analysis has been performed in the software environment SAP2000 in order to check some global properties, revealing whether the systemic behavior under horizontal action is good or not.

The prefab house prototype

The structural system adopted for the prototype uses diffusely the Platform wall technology, but with the peculiarity of putting inside of the walls, in addition to the simple standard studs, some larger pillars.

These pillars are placed precisely under the vertical constraints of the three large trusses (in the figure the trusses are over the red walls) supporting the doublepitched roof, so allowing sufficiently long main beams to be inserted, with the aim of having enough free space inside the house. Within the prefab house volume, in a nearly barycentric position, there is a prismatic core, which contains most of the technical equipment: water, tanks, heat pumps, heat exchanger, large appliances, plumbing, etc. This element, called “3D core” due to its complete realization in the factory, is sufficiently stiff because of its compact shape and, as a consequence, provides an appropriate contribution to the dissipation of the horizontal loads.

The double-pitched roof and the ceiling of the ground floor are also composed of prefab sandwich panels Platformtype, of the same technology as the prefab vertical walls, but composed of more resistant sheathing boards, made of an engineered wood, consisting of two external faces of wood fiber and a core of chipboard.

Both prefab panels of the roof and of the ground floor are firmly anchored to the underlying structural elements (walls and vertical trusses for roof panels, foundation beams for ground floor panels) with very ductile screws to transmit seismic shear forces. Moreover, these prefab panels are laterally constrained relative to each other through an almost continuous system of double crossed screws. In addition to that, for the roof of the prefab 3D core, which is at the same time the first floor ceiling under the roof, a Cross-lam full wood technology has been chosen. Of course, both on the vertical walls and on horizontal ones there are openings, but their locations and dimensions have been properly designed in order to maintain the resistance of the walls larger than definite values compatible with their structural function.

In accordance with the rules of SDE2014, the structural design fulfils the Building Code on the competition site; in addition, it has to satisfy the Italian technical codes and, in particular, the seismic regulations. In this regard, it is necessary to make a consideration: our prefab house, while being made of wood, is quite heavy because of the use of thermal mass inside the wall and this condition makes the structure seismically vulnerable. This happens in almost all regions bordering the Mediterranean Sea. Of course, the most challenging combination of horizontal forces is not the wind action in Versailles site, but the earthquake on Italian soil. For this reason, to require that mass center and stiffness center are the most close as possible is one of the requirements to be fulfilled by the structural design. This requirement has been satisfied by positioning in a nearly central position the prefab 3D core that, besides being very heavy is also very stiff due to its compact shape.

In addition, nearly all vertical walls are well connected each to other by the Cross-Lam ceiling of the first floor which, having very high membrane stiffness, ensures a good distribution of seismic forces between the walls. In contrast, the West wall is quite isolated from the rest of the building, because - due to the double-height living room - it is not linked to Cross-lam ceiling. Of course, it is connected to the building by the roof but this link is not sufficient to ensure its out-of-plane stability, because this wall is not monolithic but composed of three parts, two smaller walls - divided the window - and the west truss. In order to ensure out-of-plane stability of the west walls, we have placed two horizontal constraints for each of them, i.e. a full wood buttress and a horizontal beam at first floor height connecting it to the prefab 3D core.

Obviously, we add to the walls the shear anchorages and the hold-down which work, just to remember, as constraints in the average plane of the walls but not as out-of-plane constraints.

We have to spend some words about the three trusses (western, central and eastern ones) of the roof. They are composed of wooden GL24h and C24 elements, respectively used for upper and bottom chords and for vertical and diagonal bars; moreover, they are supported by the walls in the maximum number of points as possible, in order to redistribute at most the loads on the ground, given the low compressive strength of the foundation soil. Their geometry and their restraint conditions are different each from the other, depending on the architectural choices.

The upper chord elements are obviously subject to bending - because of the distributed loads - and compression. The chains are in tension, the vertical elements in compression, the diagonal ones in compression as well, because of their not standard orientation. In the joints there are different stresses conditions coming from every element, and for this reason each joint has been designed individually. The compression is transmitted by simple contact of the wooden elements, through rectangular hollows where a portion of the elements is inserted and fixed with a security bolt. This solution involves the very low perpendicular-to-fiber-compression strength of the wood elements and, therefore, is the main cause of the large contact area and, sometimes, also of the large dimensions of the elements.

The prefab house will be assembled, disassembled and transported several times, and its final location will be in Bolzano, at the enterprise site that has funded the construction. This means that hardest vertical loads acting on the structure are relative to Bolzano site, in relation especially to snow load, given its proximity to the Alps.

Relatively to the foundation system, we have to distinguish the permanent site from Versailles competition site. The foundation system in Versailles will consist of a prefab wooden frame: a wooden beam supports every vertical wall of the house and, frequently, other beams are put to have intermediate supports for the longest panels of the ground floor. By their turn, foundation beams are supported by a system of variable-height pallets, which have contact with the largest possible area. Our prefab house, being quite heavy for the addition of highdensity material as thermal mass in the walls, needs a considerable area of soil contact.

Structural behavior of Platform Frame walls

In the literature, there aren’t mathematical models universally accepted within scientific community for describing the mechanical behaviour of the panels used in the Platform Frame System and, in particolar, stiffness, strength and ductility. However, there exist many experimental tests from which we can obtain very useful information.

Some laboratory tests, conducted at the laboratories of Forintek Canada Corporation on nailed structural panels of plywood of thickness 9.5 mm, size of 4.80 m wide and 2.40 m high, showed a stiffness under horizontal forces of 1kN/mm per metre in width, while the same panels with plywood 12 mm thick and the same size in width and height have revealed a horizontal stiffness equivalent to 1.2 kN/mm per metre in width (see A. Ceccotti, E. Karakabeyli “Test results on the Lateral Resistance of Nailed Shear Walls”. International Wood Engineering Conference, New Orleans, USA, pp.V2, 179-186, 1996).

Further experimentation was performed at University of Trento, commissioned by the manufacturing company Rubner that built the prefab house in Versailles.

The wall has been tested under a displacemente controlled ciclyc loading hystory, whose experimental results are shown briefly in the following graph. The graphs evidences an obvious non linear behaviour, but for a linear analysis we need just to evaluate the tangent stiffness at the unstressed configuration.

The experimental evidence indicates an initial stiffness equal to 40 kN/12 mm = 3,33 kN/mm. To obtain a simple theoretical model in order to generalize the above value to walls of different width and height, we may assume that the wall stiffness under horizontal actions is directly proportional to its width B (A. Ceccotti, E. Karakabeyli “Test results on the Lateral Resistance of Nailed Shear Walls”. International Wood Engineering Conference, New Orleans, USA, pp.V2, 179-186, 1996) and inversely proportional to its height H, that is, Kt= K0 B/H=3,33 kN/mm for B=2500 mm and H= 2560 mm and where K0 is the horizontal stiffness of a square shake wall. From the simple formula given above, we derive K0= Kt H/B=3,41 kN/mm and so we are able to calculate the stiffness of a wall of any base B2 and heigth H2 dimensions:

Kt= K0 B2 /H2 =3,41 kN/mm * B2 (mm)/H2(mm)

Therefore, a wall of B2 = 2500 mm and H2 = 2850 mm will have stiffness Kt = 3,06 kN/mm.

Of course, the wall stiffness under horizontal loads is the most important parameter to evaluate the behavior of the prefab house under seismic actions. However, given the need to perform dynamic modal analysis for both the prototype and the urban-scale building, but also for the fact that the Platform panel has been used not only as a vertical wall but also for horizontal closure panels in the ground floor and for the roof, we had to generate a numerical model that takes into account its in-plane and out-of-plane behaviours.

For this purpose, each panel was modelled within SAP2000 as a plane thin shell, based on Kirchhoff plate model, with a given thickness and a homogeneous, elastic and anisotropic constitutive relationship. Some theoretical effort, based on standard homogenization methods, has been spent to determine the elastic coefficients of this “fictitious” material that takes into account the material inhomogeneities, the stiffness of the staples and the presence of voids.

Constructive Design

The interior space of the RhOME prefab house is the result of a search for the maximum continuity and fluidity of space around the “3D core” element. The core establishes the only effective constraint of the plan, that flows around it. It allows for the insertion of loggias and living spaces in a balance that can vary according to different apartment typologies.

The structural design has been developed integrating the spatial structure of the prefab house with the structural characteristics of the Platform Frame system. The walls are characterized by a good strength against forces in their mid-plan, but they need to be constrained out of their mid-plane to resist to out-of-plane horizontal forces. Another important feature of Platform Frame technology for our purpose is that walls can host a lot of insulation material. These walls are lightweight, especially if compared to other technologies such as Cross-Lam, for example, and therefore there is a great
saving in resources for transportation and assembly.

However, our thermal design is focused on adding mass to the walls, crucial for our energy strategy, after the installatin of walls on site, by adding a new layer of massive material. Therefore, the design proposal meets these structural prerequisites by merging synergistically architectural and energetic issues. The only exception within this set of two-dimensional wall elements is represented by the 3D core.

The volume is located in the center of the prefab house, and acts as a sort of pivot around which the distribution rotates, and constitutes the core of the constructive systems and also, but to a less extent, the core of the structural system. Its dimensions are 2.40m x 3.10m x 5.00m, so that it can be prefabricated and transported to the building site with standard transportation. It is partially composed of Cross-Lam materials (upper and bottom ceilings), and its the east-west oriented walls contribute strongly to the strength of the whole structure against horizontal actions.

The 3D core includes:

- Kitchen;
- Bathroom;
- Hydraulics core (external): HVAC main heat pump, thermodynamic heat pump, with a separate electrical panel;
- Electrical core (internal): electrical panel, Inverter 1 o 2 (depending on the photovoltaic panels), -tring Panel, Home Automation Server, Monitoring panel (SDE);
- Countertop: Manifold (water distribution), heat recovery;
- Radiant Panels in the floor (for the low temperature heating).

The first impact of the prefab 3D Core might suggest the idea of the “technical room”, but its constructive logic is opposite in some sense, since it becomes much close to an organic architecture, where the various components don’t entrust a single function, but on the contrary each of them is called to respond to different instances at the same time: structural, architectural and energetic, in this case. Systems are optimized, but not hidden, they are hosted in an element that lies at the very core of the dwelling space. And this is an important statement, for a building that puts energy, savings and sustainability at the core of its identity.

The walls along the perimeter of the prefab house are connected to each other by a roof that uses the same Platform Frame technology (while the 3D core structure is made of Platforme Frame walls collaborating with Cross-Lam ceilings), and largely satisfy the structural needs. In addition, they perform a fundamental energy function because they bound the mass which confers the appropriate properties of thermal inertia to the prefab house. Such “mass”, as already mentioned, is added to the walls once they are installed on site, in an additional layer, located towards the interior of the apartment in strategic locations (see images). The stratigraphy of these added vertical elements, in fact, requires the presence of aluminum tubes containing a material characterized by high mass density. They absorb the thermal energy produced inside the prefab house to release it within a strategy that could be effective in any season.

The Platform Frame System, moreover, allows to combine in a single thickness the supporting structure and the thermal casing: each panel contains a layer of 20cm of insulation, which is interrupted by vertical studs. Outside of the structural system a continuous coat runs that helps reducing the thermal transmittance, by protecting vertical and horizontal closures from any thermal bridges.

In addition to this, it should be noted that prefabrication and modularity reduce the construction time and costs, but, on the other hand, require attention in terms of reversibility of the structural joints.

Each wall is connected to the foundation system (a grid of foundation beams supported by a nearly continuous pallet system) by steel anchorages that prevent it from reversal in its middle plane (hold-down); additionally, appropriate steel plates, called shear anchorages, prevent wall from horizontal sliding. In the building site the walls are placed independently, anchored to the ground and then propped. Then they are fixed together in the edges with connections that serve only to ensure their verticality during the positioning of the other structural elements (trusses, horizontal beams, roof shells) which assure the stability of the building as a whole.

Many design features are due to the competition rules. For example, the fact that the walls are placed above the floor, and not vice versa, is not a structural choice but arises from the need to limit the height of the prefabricated walls and, therefore, decrease the difficulties related to transportation. The prefabricated elements allow extremely rapid assembly. The ease of assembly is also guaranteed by the lightness of the components, due to the fact that the heavy material - the inertial mass - will be added at wall installation completed on site. In particular, in the urban-scale building project, the plan is to re-use for this added layer of mass, the waste coming from demolitions done in the neighborhood to prepare the news interventions.

Horizontal components

The Platform Frame panels of both the floor and the roof structure are posed along East-West direction. They articulate the modularity of the structure through a step of 1.25m, that is the maximum width of the sheathing board sheets. The difference between the Platform panels that form the floors or the roof with respect to the Platform panels that form the vertical walls lies in the material of the sheathing boards. As for the vertical walls, the sheathing board material is fiber-gypsum (the industrial product is Fermacell), while for the horizontal panels the strongest superPan (FINSA brand). SuperPan is formed by outside faces of fibers and the interior made of wood particles. This unique composition differentiates it from chipboard and confers to it superior physical and mechanical properties.

There are some exceptions: the 3D core, for example, has an autonomous Cross-Lam prefab roof, necessary to allow its transportation. As a consequence of that, one of the two prefab modules of roof and of the ground floor - located next to the 3D core - will not have the same width of the standard ones. The remaining structure of the roof and o the ground floor starts from the 3D core with prefab modular elements until the northern and southern limits of the prefab house are reached. The floor stays on a series of foundation beams (placed under the walls and the 3D core). Each of these rests on different wooden foundation plinths (or pallets), which transmit the weight of the house to the ground.

Vertical components

The walls are fundamental both for the transmission of the vertical loads and for the dissipation of horizontal forces, i.e., seismic and wind forces. Since the walls don’t have any resistance out of their average mid-plans, the stability of the building is entrusted to mutual constraint that they offer to each other. For this reason, typically the corners of a building are key elements of its resistance to horizontal forces. In our case, however, the architectural choices have weakened the building’s corners with loggias and floor-to-ceiling windows, and thus the structural design has paid a moderately high price to these choices. In particular, the West wall has been somewhat isolated from the rest of the prefab house, also because the presence of the double-height living room prevented this wall from being directly linked to the ceiling of the 3D core. We put a posteriori an indirect link between the west wall and the 3D core, by means of two beams cutting through out the living room for the sole purpose of giving a out-of-plane constraint to the West wall. Further two supports to the West wall were placed inside the prefab house, agents on the wall as buttresses. To achieve the highest performance in minimum structural assembly time the walls are prefabricated and transported as unique blocks.

The pitched roof

The roof of the prefab house is geometrically composed of two differently inclined planes to the North and South. From the constructive point of view, it has the same technology as the panels on the ground floor, with joists oriented from East to West. These panels are supported by three trusses and they are mutually constrained by a system of crossed double screws which guarantee the structural continuity of the panels side by side. Each panel is joined to the trusses through high ductility ASSY screws, for the inertial force due to the earthquake be transmitted to the ground. On the roof, there is a light over structure with a purely energy function: it supports the photovoltaic systems and, over the loggias, a shielding system, which consists in adjustable vertical modular bands, allowing full handling of solar radiation.


The structural materials used are the following:
· Lamellar wood of strength class GL 24h (DIN 1052: 2000) for beams and upper/bottom rails pf prefab Platform system;
· Profiles DUO-LAM (mechanical properties equivalent to the class C24 (UNI EN 338)) for the studs of prefab Platform system;
· Fiber Gypsum (Fermacell brand) for the sheathing boards of Platform vertical walls;
· SuperPan (Finsa brand) for the sheathing boards of ceiling or roof panels;
· Staples BEA 155/45, fu=800 N/mmq for prefab Platform vertical walls;
· Flat head nails f 3/65, fu=600 N/mmq for ceiling or roof panels;
· Assy Wurth Combi 3.0 f 12/340 for connection of roof panels to the trusses, of the ground floor panels to the foundation system and of the trusses to the vertical walls;
· Self-drilling pins WS f8/200 for the inner joints of the trusses;
· Bolts KOS f12/200 Rothoblass, fu=800 N/mmq for the steel plates of the trusses and the for the steel plates connecting the horizontal beams of the living room to the chains of the west and central trusses;
· Plate Steel of strength class S235;
· Crossed screws VGS f 11/100 for lateral continuity of ground floor or roof panels.


The project must be developed in such a way as to meet various requirements, from which inevitably derive a series of limits. The adopted solution must allow rapid assembly and disassembly of the prefab house several times, without giving the impression to be ephemeral or provisional, but especially ensuring that the materials (from the structural one to thermal insulation, from plants to the coatings) maintain their properties, which are essential to give quality to the prefab house and to ensure their functioning.

In particular, from a structural point of view, we need to use a technology that provides reversible nodes between different structural elements: they have to preserve their integrity and their properties of constraint even after several cycles of assembly and disassembly. In turn, every component of the prefab house must match dimensional and mechanical criteria so that they can be transported with standard vehicles and easily moved in the building site with the fewest number of machines. These criteria are included in a logic of prefabrication strongly assisted by the chosen structural system, which allows to realize the prefab house in short time with the possibility of being extended.

The Prefab 3D Core

The so called “3D core” is the element that gives life to the prefab house. Its qualities are distributed on several domains and make it a resource at many levels.

Mechanical room and bathroom 
Mechanical room and kitchen

The 3D core is thought to be completely prefabricated and tested in the factory that produces it, in this way it is possible to reduce time and cost of installation, reducing the presence of qualified technicians on the assembly site and saving the related costs. The Core is very practical to manage on site, in fact, being equipped with all the systems that run the prefab house, and will allow us to perform only simple pipe and cable connections in input and output from the prefab 3D core. We are testing several solutions for smart plug and connections, for both thermal and electrical systems.

The block allows us to reduce the length of pipes in the system and being positioned in a barycenter within the prefab house leads to a better distribution of air through the ducts in three directions and allows us to effectively manage the return air of bathroom and kitchen. The 3D core is connected to photovoltaic and thermodynamic panels, providing electricity and domestic hot water. The hot water can be produced directly from the machine through the joint use of the pump Rotex and thermodynamic solar system. This latter system uses as alluminum panels as evaporators that, if exposed to the sun in an optimal manner, reach very high temperatures. Their coil, designed expressly by our team for our prefab house, hosts the refrigerant gas and is connected with felxible pipes to a heat pump, where a compressor with a heat exchanger produces hot water. The standard configuration of this system would send the hot water directly to a tank. In our case, the system is integrated with the Daikin/Rotex Heat Pump, to give a contribution to hot water production normally done by the pump with higher consumption. The overall efficiency of the system is therefore increased by the integration of the two systems, since them team decided not to use Solar Thermal because of its overheating in hot season, prevalent in the Rome climate. In addition, thermodynamic, that uses not only direct radiation but also exterior temperature, can give a contribution to hot water production also over night, at much lowe efficiency, of course.

The prefab 3D core is connected to the radiant panels, with cooling and heating function, and contains the heat exchanger that allows the heat recovery of the exchanged air. Using radiant panels is a static air conditioning, and through the combined use of heat recovery unit, is a controlled mechanical ventilation, which ensures the quality of the air, because the replacement is not activated with a timer programmed but depending on the concentration of CO2 and/ or other pollutants in the prefab house, detected by sensors. The system is activated by using the air from outside which is treated and inserted in environments.

The temperature is recovered from the exhaust air, hot or cold, allowing us to use less energy compared to a system that requires the use of only the external air. Then the external air will pass through the recuperator dynamic that is equipped with a small heat pump and a filter which purifies the air; the air pre-treated (almost neutral) will go through a condensing motion that will increase the volume of gas exchange (R314) refrigerating or heating depending on the season, humidifying or dehumidifying.

All engines used for mechanically controlled ventilation (provided by Eurotherm) and for the operation of the heat pump (by Daikin/Rotex) are brushless, in order to reduce energy dispersions and the degree of maintenance of the plant. The prefab 3D core contains all the control systems for air management as well as sensors, indicators, actuators, display control and the inverter that converts the continuous electricity (coming from the line of connection of the photovoltaic panels) into alternating current. The prefab house behaves structurally as a stiffening box being that the center of the masses is almost centered with the center of stiffness, also thanks to the presence of the core 3D in a central position, the dwelling can resist even more satisfactory to possible actions horizontal, such as wind or earthquake, helping to reduce the distance between the two centers.

Finally, our Cross-Lam block breaks in the light of the roof slab because the main beam, which divides the prefab house into two parts, based on the core 3D and on the walls of North and South, making possible a warping of the floors that lean on this beam, in the direction of East and West, but also allows us to have a space management of the prefab house very flexible.

Plumbing System Design

The plumbing system design follows the concept of prefab 3D CORE, the most efficient setting of pipes and tanks. The plumbing system is composed by: 3 tanks (clear water tank, rainwater tank, wastewater tank), 2 pumps (one taking the water from the clean water tank to the utilities, one taking the water from the rainwater tank to the irrigation system), relative pipes (for clean hot and cold water, rainwater and blackwater), filters and water meters.

Design criteria

Considering the particular location and terms of the project, it was mandatory to conceive a system that puts innovation and not conventional ideas to its core.

This means:

1) Water tanks are located underneath the outdoor deck, outside the prefab house, with appropriate dimensions that fit perfectly with the architectural design of the ramp, without the need for a dedicated space, caused by the use of off-the-shelf tanks with conventional shapes. Their location outside the prefab house makes it easy and fast to reach them for maintenance, through the exterior deck. The connections are also located in a limited and dedicated area, covered by a custom floor slab. The outdoor location of tanks, right above the ground, also contributes, in case of losses, to avoid damage to people or things inside the house.

2) The pumps are located as close as possible to the electrical cabinet, so as to save on electrical cables, and positioning of the Heat Pump the closest possible to the utilities that use it in order to minimize temperature losses of the hot water in the pipes between them.

Looking forward to have the most possible freedom about the pipes, the adduction pipes are made of crosslinked polyethylene called PEX-b, of 2 cm diameter and with an insulation of polyurethane of 1 cm. It is a crosslinked polyethylene obtained with silane method, starting from high density polyethylene. They are perfect for both hot and cold water and for the underfloor heating and they ensure ductility, flexibility, chemically and mechanically resistant, harmlessness, compatibility with the speed of the prefab house assembly and without the need of welding.

The discharge pipes are in Polyethylene terephthalate, called PET, and have instead a diameter of 4 cm, enjoying his main properties of high mechanical resistance, stiffness and sternness, dimensional stability and good resistance to acids. The Schematic diagram shows in synthesis the water cycle.

We have 3 tanks that can be filled from the opening (120 mm) located overhead: clean water tank (3,30m x 1,83m x 0,38m), wastewater tank (2,97m x 1,87m x 0,38m) and rain water tank (3,03m x 1,685m x 0,38m). The connectors (inlet and outlet) of each tank are located sideways and are 80 mm diameter. From the clean water tank the cold water circulates through the piping using a pump (DAB BOOSTER SILENT 4), and will reach the bathroom (bath sink, shower, bidet and clothes washer) and the kitchen (dishwasher and kitchen sink). The clear water reaches also the Daikin heat pump (placed in the 3D-core), where part of the water will be turned into hot water and placed in the pipes ready to use. Besides the clothes washer, chosen with a double input for the hot and cold water, is reached by a hot water pipe so as to avoid the activation of the resistance, in order to save electricity.

Black water related to the kitchen sink and dishwasher and grey water related to the clothes washer, shower, bath sink and bidet will reach the wastewater tank, as the condensate water from the HVAC System and from the hpsu Bi-Block Daikin Rotex. We provided a non-return valve located in the point of union between black water and grey water pipe.

For the Versailles contest the rain water coming from the north descendant, through gutters, will pass through a mechanical filter (a grating) in order to purify it by foliage and coarse elements, and will be collected in the rainwater tank. An overflow valve ensures ground dispersion in the case of overfilling of the tank. Then, through a system of automated irrigation, pushed towards the lodge and used as a source of irrigation water.

There are three flowmeters (two provided by team rhome and one provided by Sde) will be positioned between the pumps and the water distribution system, in order to measure the quantity of the output stream. We expect to have in sequence: upstream valve / Almaviva flowmeter / SDE flowmeter/ downstream valve. The two valves have the function to stop the flow in case of problems with the flowmeters.

Based on the amount of water needed for each activity performed during the day of the two weeks of competition, we can predefine our need of clear water at 2245,8 liters of water (to be charged in the tank). This water budget describes the worst scenario (total absence of rain) where the withdrawal of water for irrigation is from the clean water tank. However if we could have 20 l of rainwater per day, the amount of clear water necessary would decrease in 1995.6 liters (2235.6 minus the 240 liters for irrigation). The wastewater remaining in the tank at the end of the competition will be given by the amount between the total grey water accumulated (1690 liters) and the total black water (297,1) for an amount of 1987,1 liters.

Rainwater Recovery in Urban Scale

In the event that the sewer district is composed with two different pipes lines for sanitary water and the white water (that is rainwater without impurity) we imagine to realize a series of intermediate tanks for the first rain water. The purpose of these transit tanks is to capture oils and sedimentary substances, so to purify water which, through an ad hoc system of piping, will then be conveyed in the near ditches. The filtering is performed through the use of sand which acts as a sedimentation
tank. The sand normally needs to be replaced every 5-10 years.

Regarding the recovery of rainwater from the roof, we expect to send the water, through the descendants, from the roof of each of the new buildings in its own intermediate tank. The tanks will be sized to accommodate enough water to fulfill one of the purpose: district’s cleaning, irrigation of the park or irrigation of vegetable gardens. Through a lifting system the rainwater in the tank will be sent through a 10 cm x 10 cm conduit, placed over the other eventual networks of the neighborhood (sewerage, water adduction, electricity), in large storage tanks.

During the path from the single tank of one building to the common one, water will slowly pass through capture tanks (partitioned by septa able to block oils and sedimentary substances). Above the tanks there are plants and flowers, that look like simple and cheerful planters, however placed not just for a landscaping element of the neighborhood, being designed to filter the water passing underneath.

Grey water recovery in urban scale

In urban scale we propose an innovative system for the recovery of the domestic water.

It involves the placement, within the neighborhood, of a purification cabin whose purpose is to collect domestic waste water (gray and black) from the new settled buildings and to filter them through a particular system: the system of photo-ozonolysis, that combines the action of ultraviolet light with that of ozone. Ozone is a powerful oxidizing and electrophile agent, and the ultraviolet light presence enhances its action through a free-radical chemistry. To be effective, treatment with photo-ozonolysis requires a pre-treatment of the wastewater initially with a mechanical grinding and then with a series of filters (for example, sand and active carbon). The photo-ozonolytic action applies to both soluble organic matter, which is oxidized and mineralized, that even on the microbial load that is completely sterilized. Bacteria, viruses, and protozoa are removed from the aqueous phase without creating secondary toxic and harmful substances.

Chlorination is the classical technique for the disinfection of water and, in contrast to the photoozonolysis, always presents the negative aspect of creating organochlorines such as carbon tetrachloride and chloroform, which are toxic persistent in aqueous phases with potential carcinogens (cancer of the colonrectum).

The pilot plant that we have at our disposal is a batch system with recirculation and is able to treat up to 250 L / h of wastewater. Naturally, the reported value is only indicative since the treatment per unit of time can vary significantly depending on the load of pollutants present in the water.

With this system we will be able then to minimize at 9% the consumption of water from the aqueduct.

Electrical System Design

The electrical system will be concentrated in the prefab 3D core, a compartment that will be prebuilt and then tested on site. Having to serve areas that are not directly related to 3DCore we decided to add some branches of the electrical system on three channels:

- The first tange the 3D-core and passes through the entire length of the prefab house advantage of a channeling already designed to serve all the radiant panels of the prefab house;
- the second goes through a milling beams that divide the living area and which it serves to illuminate that area, as well as being the site where is some of wireless sensors;
- the third pass over the prefab 3D-core within the loft area to fall inside the cabinet that divides the entrance hallway from the bedroom area. This wardrobe will be the accommodation of a series of electrical devices and of the lights that illuminate the room.

The photovoltaic inverter and the string panel will be located in a technical compartment completely dedicated to the electrical systems. The battery rack and the battery inverter will be located inside an external ventilated covered compartment covered in the south loggia. The master electrical panel and the Monitoring Box will be located in the central hallway of the prefab house, near the technical compartment. The slave electrical panel will be located inside the technical compartment. In addition, the block is located in a central position, thus it will be possible to more easily manage all the electrical system of the prefab house, using a smaller amount of electrical wires. The system will be divided into different areas: the kitchen; the bathroom; the living area; the sleeping area; the entrance and the two loggias. Among these, the kitchen represents a singularity as it is provided with more electrical lines, as they will supply electric energy to the induction hob, the oven, the refrigerator, the dishwasher, the washing machine and the dryer, which are the appliances required for the contest. Each line will be provided with a switch and protected by a differential and an upstream circuit breaker.

The whole electrical system is designed so that each and every consumer energy production is read from the prefab house. Thus, there is an information system that helps the user to manage in the best possible way home to avoid unnecessary consumption of energy. The combination of various monitoring allows the prefab house to sense the amount of energy produced and the amount of energy consumed giving the user, for example, the specification of how the charging of batteries can affect the energy balance or giving advice regarding the management of the air or the use of radiant

General Description

The input for the electrical system is an IEC singlephase 230V-63A plug socket with pilot contact.

The most significant characteristics of the electrical systems are:

- TT grounding system classification according to CEI 64/8
- rated voltage 230V
- single-phase distribution
- short-circuit current protection (low voltage side) 6kA
- maximum power consumption 6,5kW

Electrical Panels

The system starting point is the Master Electrical Panel, fed by the IEC single-phase 230V-63A plug socket.

The proposed solution is conceived in order to limit wiring connections outside the Technical Room; the electrical power metering is obtained using some energy meters, provided by Energy Team, that can measure three power lines each, so to limit the number of electrical cables and, at the same time, to achieve enough detailed electrical consumption information. The PV and battery lines is protected in the slave panel, and then connected with the master electrical panel. The other lines exiting the slave panel feed the HVAC loads. All the other loads’ power lines branch off the master electrical panel.

The protection of the master and slave panel for legislation is guaranteed using on each main line a breaker 1P+N and for each branch line a differential breaker.

The four general breakers (Home general, PV general, Batteries General, Utilities general) are achieved through thermal, magnetic and differential protection actions, they are sized according to the rules.

Storage System

The storage system is powered by four GNB Industrial Sonnenschein S batteries. They will be used to power the fridge, the lightning system and the home automation loads during the night. The batteries are located inside a dedicated cabinet in a recess, along with the battery inverter.

The main technical characteristic of the batteries are:

- Type: S12/90A
- Nominal voltage: 12V
- Nominal voltage of the battery rank: 48V
- Nominal capacity: 90Ah
- Weight: 30Kg
- Dimensions: 330x171x236mm
- Brand and model: GBL Industrial Sonnenschein S

The battery inverter is provided by Schneider Electric.

The most significant characteristic of the inverter are:

- Model: Conext XW4548 230 50
- Nominal power: 4,5kW
- Weight: 55Kg
- Dimensions: 580x410x230 mm

Protection against direct and indirect contact

Since the DC side of the circuit is low voltage the objective of protection from direct contacts is achieved through the complete insulation of all the active parts of the circuit.

The unipolar cable connecting the batteries to the inverter (FG7) are class 5 and covered with an insulating termic sheath.

All the terminals and all the lugs have been insulated. On the AC side the protection against indirect contact is guaranteed through a differential breaker with a tripping current of 0,3 A.In order to guarantee the protection from indirect contacts a differential breaker with a tripping current of 0,3 A has been installed on the “AC-IN” side of the inverter so that the earth resistance according to the actual standard must be Rt <= 50 V / 0,3 A. The differential breaker with a tripping current of 0,3 A has been chosen in order to guarantee the safety requirements and to achieve the selectivity of the circuit through the current discrimination between the differential breaker protecting the inverter and the RCDs with a tripping current of 0,03 A protecting the loads downstream of the battery section. Grounding: system of hard wired battery bank and inverter In addition, further protection against indirect contact is provided by the system grounding, where the inverter, the battery pack and the negative cable are grounded as in the pattern shown in the figure and suggested by the inverter manufacturer. With reference to general standard rules, in order to ensure that protection against indirect contacts is promptly achieved, must be Rt <= 50V/Ig , where Ig is the tripping current of the circuit breaker(0,3 A). It means that must be Rt <= 166,7 Ω. The magnetothermic circuit breaker will be placed in a panel between the inverter and the battery rack.

Photovoltaic System Design 

 According to the rules, photovoltaic installation size connected to the prefab house is limited to 5 kWp. To this purpose it is selected a dc-ac power electronic converter (inverter) within the required power limit. However, in the energy saving perspective, it is also relevant the opportunity of self-generating as much as possible the electric power being require by the prefab house loads. As a result, the present project investigates different assembling options for the PV modules, as well the potential presence of a suitable battery storage unit is considered.

The considered PV modules are manufactured by SOLBIAN. Conceived to work well even in particularly difficult circumstances and under heavy mechanical stresses typical of extreme ocean racing, the photovoltaic module “SOLBIANFLEX” is a true revolution in the field for the high efficiency never achieved by a light and flexible panel and for the outstanding resistance to weather and degrading agents such as thermal shock, fog and salt water, solar radiation and mechanical shocks. For these reasons we decided to use these panels.

The modules utilized are the photovoltaic panels of SP 50L series, made using SunPower™ monocrystalline cells, with an efficiency than 20.5%, incorporated in polymers with high strength. The SunPower™ cells, thanks to their “backcontact” technology, have a very pleasant aesthetic appearance, furthermore, they make the Solbian panels at the top efficiency on the market.

First investigated solution has 24 rows of 3 PV modules each onto the roof, resulting in 72 modules being divided in 2 identical strings, and 10 rows of 3 PV modules each on the SUD side wall, resulting in 1 string of 30 modules. A 3-port input inverter is chosen, 2 inputs are supplied by half of the roof modules each, port 3 is supplied by the side wall PV modules.

In order to estimate the PV production we used the “pvWatt” web platform (the choice of method of calculation is be explained later). This site is a great tool for calculating the performance of a solar panel. By entering the data related to the city where you want to make the measurements, the inclination of the panels, nominal watts, their orientation with respect to the SUD and the appropriate coefficient of loss, the system will show the data related to energy production for an entire year cataloged hour by hour. 

Before proceeding to the calculation of PV production, however, we evaluated the reliability of the instrument by comparing the data obtained with the simulation made with pvWatt, with the data measured during the contest of the 2012 race in Madrid.

Having verified the reliability of the instrument we proceeded to the calculation of electricity production, setting the following parameters:

Panels on the roof:

City: Paris
DC rating: 3.672 kW
Derate factor: 0.77
Array tilt: 15°
Array azimuth: 200°

Panels on the south facade:

City: Paris
DC rating: 1.53 kW
Derate factor: 0.77
Array tilt: 90°
Array azimuth: 200°


Photovoltaic generator:

Each string is equipped with a disconnect switch, installed in the string combiner box. The strings are protected from over-voltage by grounded protectors, one for each pole.

Disconnectors and surge protectors are sized for the current and voltage of each group of strings to be connected to the inverters, and are installed in the field combiner boxes.

The PV module cabling is arranged with 6 sq mm section SOLAR HF 0.8/1.5kV cable, specific for photovoltaic systems.

The photovoltaic generator is managed as an IT system (i.e. no pole grounded to earth).

The support structures for the PV modules are grounded by a yellow/green-insulated conductor, not less than 16 mm2 in section.

PV Panels General Features:

Peak power (+/- 5%) – Pmax: 51 W
Nominal voltage: 9.0 V
Nominal current: 5.7 A
No load voltage– Voc: 10.9 V
Short.circuit current - Isc: 6 A
Temperature coefficient for Pmax: -0,38%/°C
Temperature coefficient for Voc: -0,27%/°C
Temperature coefficient for Isc: 0,05%/°C
No-load voltage variation with temperature - a: 10.9*0.27/100=0.0294 V/°C
Short-circuit current variation with temperature – β: 6*0.05/100=0.003 A/°C

DC/AC inverter:

The converter group consists of the inverter itself and a set of components (i.e. filters, diconnectors, protection and control equipment) that complete the system for transfer of generator power to the electrical grid, while meeting all relevant technical and safety norms.

One inverter is installed with single-phase 230V ACside connection, rated AC-side power 5 kW, and 2 MPPT. The model installed is SCHNEIDER Conext RL 5000 E, with nominal AC-side power 5Kw.

DC input parameters:

- Maximum power convertible to DC: 5.3kW;
- Allowed input voltage range: 90-550V DC
- Input voltage range for the maximum power tracker: 180–500V DC;
- Maximum input voltage: 550V DC;
- Number of trackers: 2
- Maximum input current for the tracker: 18A
- Maximum short-circuit current for the tracker: 25A

AC output parameters:

- Nominal AC power: 5 kW AC;
- Nominal output voltage: 230V single-phase AC, 50Hz;
- Nominal output frequency: 50 Hz;
- Power factor: 1;
- Maximum efficiency: 97.5%

Ambient and mechanical specifications:

- Operating temperature range: -20°C +65° C;
- Dimensions: 445 x 510 x 177 mm
- Weight: 24 Kg
- Protection rating: IP65

Inverter configuration:

Fixed at -10° C, the cell temperature in winter and 70°C in the summer, referring to the STC with TCell = 25° C we obtain the following temperature range:
∆C winter = -10 - 25 = -35°C
∆C summer = 70 - 25 = +45°C
Values of voltage and current in reference to these temperatures,
Reference expression no-load voltage: Uoc (T) = Uoc (STC) – α (Tcell-25)
Reference expression short-circuit currrent : Isc(T) = Isc (STC) – β (Tcell-25) 


Uoc (-10) = 10.9 – 0.0294*(-35)= 11.929V
Umpp (-10) = 9 – 0.0294*(-35)= 10.029V 


Umpp (70) = 9 – 0,0294*(45) = 7.677V
Isc (70) = 6 + 0,003*(45) = 6.135 A

Cell’s values

Isc max 6.135 A
Uoc max 11.929 V
Umpp max 10.029 V
Umpp min 7.677 V

Electrical Energy Balance Simulation 

The RhOME prefab house aims at maximizing the use of electricity while it’s produced, therefore reducing any need for storage, especially if made with non sustainable technologies, and even reducing the need of interaction with the grid. The first attempt for the team has been to design a passive strategy for the prefab house, extended to as much domains as possible, and reduce the need for active devices for thermal needs, through a careful tuning of the building envelope and the use of mass but also lighting, with an extensive use of natural sources and the introduction of photoluminescent tailing to store it naturally and use it during the night.

Once faced the side of lighting and systems, we had to define a strategy for appliances since their impact on the overall electricity consumption of a standard apartment is still very high, despite of the improvements of their performance coming from the industry. Our strategy in that sense is to select the most efficient ones available, but also to tune their use schedule in direct relationship with the production of the photovoltaic field, according to the above described strategy of “consuming while producing”. Of course in order to do this we would need the exact behavior in standard usage and not just the consumption for one cycle at optimal conditions: these calculations and their state of development are described extensively in the upcoming paragraph. But it’s important, for our team to involve the user in the definition of such schedule: we want the user to become “decathlete” of his own prefab house. The RhOME team believes, in that sense, in the active participation of the household to the house use strategy and the home automation system is all based on a high level of documentation to the user, by gathering all the data on the prefab house behavior.

In order to obtain this change, and involve our household as a “decathlete”, we believe that a direct relationship with production will help savings in consumption. We want to replicate what happens with cars where the drivers sees condensed in one number (liters per 100 Km) the consumption in real time: our household in a similar way sees the impact of its “driving attitude” to the prefab house behavior, through the realtionship production/consumption. In order to empower this effect of direct relationship between production and consumption we decided to introduce in the urban scenario a separation between PV fields: a “shared” PV field is located on the roof, and serves mainly the HVAC systems, while each apartment hosts a “personal” PV, embedded into a mobile shelter, that serves the appliances. In this way, there is a direct relationship between the “personal PV” and the “personal consumption”, done daily by people who live the house. And, last but not least, the “personal PV”, built as a mobile textile shelter, is thought as a urban and dense solution, to be installed in balconies and terraces even in the existing urban stock. The same concept of a “kit” of renewable energy devices for the dense city lies behind the thermodynamic baluster, to be installed in balconies, that provides domestic hot water to the same appliances, with a dedicated heat pump and tank.

Solar Thermal Design 

The team decided to foster innovation and substitute traditional solar thermal panels with a thermodynamic system, composed of an aluminum coil, fabricated by refrigeration industry leader CGA Tecnologies, connected to a heat pump fabricated by the portuguese company Energie, that is a longstanding player of the thermodynamic systems industry. While CGA core business is the refrigeration industry, Energie is currently selling and installing on the market the integrated systems to produce sanitary hot water. In the RhOME project the two companies accepted to experiment the architectural integration of these systems. A first choice was the selection of the right product to use.

Energie traditionally sells a complete system, composed of a tank, a heat pump, and the aluminum panel. Only recently, the company released a new simplified systems, called the “solar box” that features only the panel and the heat pump that can connected to already existing tanks. We opted for the Solar Box, with the idea of integrating it with the main heat pump of the HVAC system and increase the overall efficiency.

The thermodynamic solar panel will offer a perfect integration between the functional and the technological aspect: the panel, while being the balauster of the southern loggia, generates sanitary hot water for the house. It takes advantage of the difference of temperature between the gas inside the serpentine of the panel ( -30°C) and the external temperature of the air. 

The thermodynamic panel does not need direct solar irradiation, it constantly produces hot water even without the presence of the sun. When daylight hits the facade the functioning can be amplified positioning the photovoltaic frame in front of the thermodynamic panel, increasing the temperature difference. When the sun directly irradiates the southern loggia, the temperature of the air surrounding the panel will increase, allowing the panel to produce more energy and consequently more sanitary hot water to satisfy the requests of the prefab house. The panel uses a gaseous heattransfer fluid which guarantees the increase of energy efficiency.

In fact, heating of a volume of water requires more energy than the same volume of gas. Moreover, it resolves the well-known problems of the traditional solar thermal system, as the achievement of excessive pressures when the temperature of the heat-transfer fluid reaches the maximum operating level.

The thermodynamic panels reach their maximum production of thermal energy both when exposed to direct solar radiation and when the sky is cloudy but also if it is placed in a non-optimal orientation, with a non relevant loss of efficiency.

At night, the hot water production will no longer be entrusted only to the thermodynamic panels, but to the DAIKIN-ROTEX heat pump, with which the Solar ENERGIE-CGA box is connected. The Solar Box is connected to the HPSU Daikin - Rotex that is used by the heat pump of ENERGIE as external tank.

 Schematic working principle:

- the external temperature increases;
- the gas inside the thermodynamic panel begins to expand;
- the fluid reaches the Solar Box which converts and transfers energy to the HPSU Rotex Daikin;
- the HPSU Rotex Daikin that will provide suitably heated hot water.

The system configuration of the thermodynamic system is designed to obtain the maximum integration and closeness between the various machines which are used for heating, cooling and supplying hot water, to prevent the dispersion of energy.

The strategic and innovative positioning of the thermodynamic panel as finishing element provides many benefits. First of all it allows a perfect integration with architecture, playing a fundamental role in the research of the sobriety of building.

Operating Principle 

The SolarBox Thermodynamic Solar System is a piece of equipment based on the principle of cooling by compression – the Carnot principle – which we have named Thermodynamic Solar Systems: Solar Panel and a Heat Pump. The solar panel, which is the main component, placed outdoors, ensures the capture of energy from:

- direct and diffuse solar radiation;
- outdoor air, via natural convection;
- the effect of the wind (almost always existent);
- rainwater.

The temperature difference caused by the aforementioned external agents ensures the Klea (ecological refrigerant fluid) evaporates inside the solar panel. The absence of glass in the panel ensures increased heat exchange via convection.

After passing through the panel, the Klea is sucked in by the mechanical component of the system, the compressor (raising its temperature and pressure) and then the heat is transferred to water by means of the panel heat exchanger.

Before the Klea returns to the solar panel the pressure needs to be reduced to guarantee it attains its liquid state once again.

The ease with which we combine technology and the laws of nature (alteration of the state of a fluid), demonstrates the veracity and potential of SolarBox.

The Solar Thermal system is composed by a thermodynamic panel, a heat pump (Solar Box Energie - CGA) and an external storage tank (Hybrid Cube Daikin-Rotex). The basic system works independently and is electrically powered from the electrical panel.

The system runs 24 hours on 24 and works regardless of the weather conditions outside.

In our situation, however, for reasons of efficiency and energy savings the thermodynamic system will be alternated with the DHW from an external heat pump (Bi-Bloc Daikin-Rotex) with an external storage tank (Hybrid Cube Daikin-Rotex) that is put into system with the Solar box.

The heat pump (Bi-Bloc Daikin-Rotex) allows us to have another system to produce hot water with high efficiency, which will be used when the thermodynamic system will not have a high COP, in addition to fuel the heating/cooling system of the radiant panel. 

The dwell! system

Our prefab house will mostly rely on an efficient passive behaviour, and this would not work, without people. That’s why we want to recall the know-how that our Grandmothers had. They knew very well, from instinct, but mostly from tradition, if and how to open curtains, let the air pass through, and so on.

There is no more need to exclude users, in order to introduce technology and intelligence in these systems. The new digital consciousness can marry, in our approach, the environmental awareness. The behaviour should always be available, and people should be able to share it, or parts of it, in a social platform. We imagine the prefab house as a node of a network of homes, all connected between them. Social involvement today is crucial in technology, and energy saving systems have to become part of this scenario.

For these reasons, the prefab house is designed to hold a monitoring system called “dwell!” with a control unit located in the prefab 3D core. The purpose of these solutions is not to replace humans in the house management, but to provide exhaustive information to let the dweller have an aware and guided use of the environment where he lives. People should be let free to be wrong and make mistakes, but be in control of their life. The introduction, in cars, of the simple display showing instant and cumulative fuel consumption, had a demonstrated great impact on the driver savings, but there is no system that limitates directly their possibility to go fast if they want. Life is complex and rich, every attempt to de-humanize it, will definitely fail. Turning philosophy into reality We are designing a system constituted by three different interfaces meant to reach the widest number of dwellers, from the well-informed to the less aware ones:

1.Digital Mirror: this interface will be a user friendly door to a digital representation of the house, where intuitive dynamic graphics represent what is happening in the real world and let a non expert user understand e.g. the variation of comfort parameters in time and according to the factors that affect it. It’s meant to be social and entertaining, so that we can bring users to explore the house with growing interest, also in the other sections of the interface. It will be an interactive point-and-click model of the prefab house where the user can visualize what’s going on in real-time through simple animations (changing colors, point clouds, opening/closing windows and doors etc.) and popup windows. Also a child could interact and learn thanks to this intuitive solution.

 2. Dashboard: the contemporary prefab house is a complex, technological organism that needs to communicate in a real time, simple and direct way to the user, exactly like a car dashboard does. This is the aim of this interface section, where you can check, wherever you are, the current state of your house by simple counters that express the levels of energy consumption in relation with the data detected from the sensors installed in the house.

3. Discovery: the third layer is a presentation of the data collected in the course of time, exposed in an analytical way that can improve the environmental awareness and the comprehension of the connections between different physical events and between physical events and energy cost. The analysis of past behaviour is the ultimate and deeper step to personal awareness and responsibility.

Through these interfaces we are sure that every dweller will have the possibility to be aware of the consequences of his actions in the house. It will be easy to understand how to save energy identifying wrong and right behaviours but never being forced into a predefined conduct by the home automation.

Another important aspect of our approach is the social involvement. A part of data collected in the houses will be shared in a local network accessible by our social housing dwellers. This way we think the comparison between the comfort/consumption data of the single units could encourage the energy saving thanks to the virtuous competition which would arise. This dialogue should focus even more the attention of the whole community on these themes improving its knowledge and awareness.

This way the RhOME network of prefab houses, all monitored in the dwell! system, can become a green hub of energetic and environmental awareness that could spread through the whole urban context.

Passive design strategies 

A wooden building generally has low thermal inertia. In climates with alternating warm periods and cooler periods, the use of the mass can be very effective to reduce the use of active installations of air conditioning. The project strategy provides the insertion of a layer of sand, along the inner surface of the wall.

This provides not only a contribution in the transmittance value of the envelope and in the shifting phase of the thermal waves but, in this case, it is used strategically as a thermal shock absorber to adjust the internal temperature.

During the winter months the sand will absorb the internal heat gains of solar radiation during the day and drop them at night.

In summer the contrary, the sand will be used as absorber of the internal heat gains produced by the inhabitants and equipment, to be subsequently downloaded through the thermal night ventilation.

In summer, with the greatest height of the sun on the horizon our sliding/tilting screen system protects the entrance of solar radiations inside the prefab house. Given the heat production of the occupants and electrical appliances, we proposed the solution of thermal masses, with the function of thermal flywheel inwards, that absorb the heat excess. The layer of sand, along all the inner surface of the wall, provides not only a contribution in the transmittance value of the envelope and in the shifting phase of the thermal waves but is used strategically as a thermal shock absorber to adjust the internal temperature.

During the summer, the sand will be used as absorber of the internal heat gains produced by the inhabitants and equipment, to be subsequently downloaded through the night purge. At the same time the highly insulated and ventilated wall system in contact with the outside prevents overheating of the walls themselves and of the internal environments. The distance between the pitched roof and the sliding system containing the PV panels allows the induction of convective air movement so to cool down the panels. The facade section of this system (that in this climatic condition is moved over the south loggia) tilts open, shading the south loggia from the sun but letting the natural daylight get in. Loggias contribute to have more living space, ensuring continuity between interior and exterior spaces of the prefab house. In this situation, placing a loggia’s in the north which is not affected by a prolonged solar radiation is strategic and beneficial, and it becomes a cool and comfortable outdoor space. The permanent shading over the small south window and the west one are designed to protect from the solar radiation.

The energy absorbed during the day is released during the night. The wide openings connecting the north and south side of the prefab house promote a suitable crossventilation to ensure a night cooling and washing of inertial masses. The north side ceiling window provides an efficient “chimney effect” that improves the cross ventilation and the house cooling down. The sliding shading system is moved away from the loggia to guarantee the maximal cross ventilation. In winter, with the sun low on the horizon, the sliding PV shading systems is moved away from the south loggia to facilitate the penetration of sunlight deeply into the prefab house. Either the permanent shadings on the small windows on south and west are designed to allow the penetration in this part of the year. Occupants and electrical appliances and devices contribute to the natural heating.

During the winter this heat is stored by the accumulation walls and the sand will absorb the internal heat gains of solar radiation during the day and slowly release them during the night. The highly insulated parts of the system prevents the dispersion of the heat accumulated on the outside, protecting the interior from the cold. The air changes are guaranteed by the semi-passive (heat recovery systems), and through a heat exchange between incoming and outgoing air, avoiding this to affect the indoor thermal comfort. Even in this cold condition the PV array may need to be cooled down: the same convective air movement that was helpful in summer works now to make that possible. The heat accumulated in the day is released in the night and the insulating skin prevents the heat exchange with the outside.

Semi passive systems 

In order to save more energy, there are little energy intensive equipments used both in ventilation systems and air exchange and in the sanitary hot water production system. Such equipments, thanks to a heat exchange between the incoming fluid and the output one, can balance and reduce the temperature gap, ensuring a high energy saving in the heat pump operation and contributing to the indoor air quality improvement.

Project participants

Sapienza University of Rome

AddressPiazzale Aldo Moro, 5, 00185 Roma RM, Italy
Phone+39 06 49911

Faculty AdvisorChiara Tonelli+39 335 8432 560
Project ManagerStefano Converso+39 339 2251 213
Project ArchitectCristina Casadei+39 331 7186 790
Project EngineerUgo Carusi+39 380 5045 591
Structural EngineerGinevra Salerno+39 329 5045 591
Electrical EngineerLuca Solero+39 329 0572 362
Student Team LeaderMichele Caltabiano+39 339 1477 110
Health and Safety CoordinatorGiuliano Valeri+39 329 3552 946
Safety OfficersBarbara Cardone+39 333 3999 109
Matteo Persanti+39 329 6560 389
Site Operations CoordinatorsUgo Carusi+39 380 5045 591
Lorenzo Pirone+39 340 3897 034
Antonio Vellucci+39 377 1594 222
Contest CaptainGabriele Roselli+39 333 2496 935
Instrumental ContactAndrea Rastrello+39 333 5065 466
Communications CoordinatorNicola Moscheni+39 340 3573 319
Sponsorship ManagerElena Oetiker+39 338 6377 662

RhOME Prefab House - Simple, Durable and Sustainable