The Nuts and Bolts of our Home
For our row house with a skin to become a home, every technical aspect of the reconfiguration has been thought through. The engineering focuses mainly on the glasshouse but also covers the renovation of the existing climate systems and combining the old and new to work in harmony. The technical details of this are listed below. The resulting indoor quality can be viewed on the climate page.
The glass house is the primary focus of the structural design. The conceptual directions are translated in the structural design by the following criteria:
1) Spatial connection: No structure can block the transition between inside and outside, to achieve the maximum effect of extending the space to the garden.
2) Climate performance: Adaptability to the seasons – can open completely during summer.
3) Applicability: Simple and easy construction , minimizing weight and interventions while designing for wide adaptability for the different typologies of row-houses.
The final system comprises of a light steel skeleton supporting an aluminium frame system on which the PV panels are fixed. The aluminium structure follows the grid of the photo-voltaic panels, seamlessly integrating them into a single glasshouse structure, while keeping all the construction requirements like water and air-tightness. The Skin is simply connected to the house on its upper side and on surface foundations on its lower part, thus dividing the total load. Since the self-weight of the total added construction is minimal, the bearing capacity of both ground and the existing house is not exhausted.
The steel skeleton is designed for structural and construction efficiency to achieve minimum profile size and number of components. It is composed in the roof by a system of main and secondary beams and in the facade by a portal frame. For the roof, the grid of the secondary beams follow the one of the PV panels, minimizing the span of aluminium skeleton, while the main beams (rafters) are on a grid of 1.20m, following the functional grid of the row-house.The main beams distribute then the load to a ridge steel beam on the top and a steel portal frame on the bottom. The ridge beam is simply supported by the existing house through connections in the chimneys. The portal frame is used for many other functions than transferring the roof load. Structurally, it works as a beam element with adequate height to hold the heavy glass-house door and as a bracing for the side wind through welded diagonals. Additionally, vertical PV panels are installed upon it to produce more energy.
From the very conceptual beginning, Prêt-à-Loger team explored the idea of using a Building Integrated PhotoVoltaic (BIPV) system to power the house. The main criteria for the selection of this system is to combine seamlesslly efficiency, aesthetics and integration into an affordable package. This resulted in using a innovative BIPV system in relation with the Skin, to achieve transparency (around 35%), with the use of glass-glass modules and optimum Watt-peaks (Wp) to ensure that the structure is at least energy neutral for domestic use. The BIPVs’ selected technology is monocrys-talline Silicon (mono c-Si) with about 19.5% cell efficiency.The BIPV modules are of two types on the installation. The 20 roof BIPV modules (200Wp) and the 5 window PV modules (175Wp) offer an installed power of 4.875 kWp with an efficiency of 16.5%. The connection of the BIPVs with the inverter is done via Power Optimizers which track the maximum power point of the I-V curve. As the concept rep-resents the existing situation on Honselersdijk in the Neth-erlands, the orientation of the Prototype house is, by design, the same as of the original. That is 138 degrees azimuth (42 from the south) and 21 degrees inclination (window BIPVs – 23 degrees). As a consequence, the annual electricity gen-eration is estimated to be around 3,800 kWh (PVsyst simulation).
Considering the electrical installation of the house, the Prêt-à-Loger team seized the opportunity to implement many in-novative solutions while trying to represent the design of the house in Honselersdijk. Nevertheless, since safety and functionality are considered here the crucial factors, the de-sign provides maximum security without compromising the house’s functionality.For the above reason, four RCD’s were used for the house installation compared to one RCD that is normally used. Ev-ery one of those RCD’s is connected to either three or four electrical groups. This means that in the case of current leakage, the correspondent RCD will trip but partial func-tionality in the house will be maintained. The reason is that only a section of the electrical groups will be disconnected instead of the entire electrical installation.A second innovation is the plug and play cable installation. It enables newly added electrical elements to be implemented directly, by plugging them into the existing system without any major change to it. It is a simple process that allows for maintenance and replacement with minimal intervention, compared to the mainstream solutions. All the cables can be replaced by just removing the skirting board, while cable junctions are used to connect the various cables, promoting flexibility and achieving a swift and clean process. Another innovation can be found in the lighting design, where switches with RF emitters are used, along with RF adapters placed on the lights. This means that the lights can be turned on and off through RF (wireless) signaling and not by using the typical wired connection between the lights and the switches. This has two advantages. The first is the simplicity achieved in the electrical design, leading to mini-mum amount of required cables and a shorter time needed for design and installation of the system. The second is the level of control, since the lights can be turned on and off not only by the switches but by the domotica system as well.Continuing with the innovations in the light installation, a special reference should be made to the lights used. All the lights installed inside the House with a Skin are energy-effi-cient, solid state LED lights. Additionaly, Solatubes are used, which provide a combination of natural lighting through the roof during the day and artificial lighting when the illumi-nance is not enough. The combination of LED lights and Solatubes minimize the energy need to illuminate the house during both day and night.Apart from the lights used, every appliance installed is con-sidered as state-of-the-art in its consecutive field and it is chosen with the following three criteria: 1) lowest possible energy consumption 2) very high service standards 3) attractive designThe final major feature is the automation system for the climate control. Small scale motors are installed to control the glasshouse openings and the shading system. Addi-tionally, an air fan and a heat exchanger are installed in order to control the climate of the pavilion in combination with the PCM box. In total, the system aims to provide optimal climate conditions according to the residents’ needs and desires. All those components are coupled into two groups in the electrical box and they are controlled through the domotica system.
Following the main concept, the plumbing design relates to the usual solutions found in a dutch row house, except that instead of central connection, tanks are used for fresh and waste water. However, special fixtures and san-itary appliances are used, leading to reduction in water and energy losses. One of the most important is a heat recovery system in the shower, which allows for a max-imum of 50% reduction in energy used for heating the water. Furthermore, special plumbing installations are created to implement the solar water heating system of Solar Compleet, including connections between the boiler and a special energy panel on the roof. Additionally, it is noted that the main piping is using the free space inside the chimney for vertical transport, representing a possible solution in refurbishing the plumbing of an existing house and minimizing construction interventions. All the above enhancements of the plumbing system can be also used in the refurbishment in the Honselersdijk house.On the contrary, one of the major features that can be found only in the refurbishment concept but not in the prototype in Versailles is the rainwater use. Specifically the rainwater coming down from the glasshouse is gath-ered in a tank and is used for flushing the toilets, thus covering one of the most consuming uses of domestic water. Nevertheless, this system will be implemented in the relocation of the Prototype house in Delft. A more limited system will be used in the competition, to gather rainwater in a tank integrated in the glasshouse of the Skin system. This rainwater will be used solely for water-ing the plants of the garden.
Solar Decathlon competition, the starting points of this de-sign are high efficiency, affordability, wide applicability in existing Dutch row houses and being able to function all year long. Following the concept of the Skin refurbishment solution, the glasshouse can provide an integrated solution for the above goals. Because of the energy production of the PV panels and the transparent enclosed space, it can function as a solar thermal energy harvester that can be used for covering the hot water needs of the house.The system used to convert this energy source is Solar Compleet, a thermodynamic solar system. Both affordable and easily applied to existing houses and the glasshouse, Solar Compleet provides hot tap water during the whole year and heating for the radiators in the winter. In princi-ple, the system’s collectors extract heat from the PV panels, cooling them down and increasing their efficiency, while simultaneously generate hot water. These thermodynamic collectors are formed by a metallic panel which is directly exposed to the sun, acting as a heat pump circuit evapora-tor to collect heat from the sun and the environment. This is then passed on the water via a condenser, surrounding the outside of the boiler. The boiler is housing a heat pump of 4kW capacity with an average COP of 4, which is able to reach a reduction of 90% for hot water energy needs. The water has a maximum temperature of 55oC and is stored in
a 300 liter tank, integrated under the heat pump. This ca-pacity is sufficient for a family of 4 members, for more than a day. The system is also featuring a back-up heat pump, which uses the ambient air in the control room to continue the hot water generation even in the winter.