Architecture

Feasibility, Furniture and Fruit

When we try to make the existing more sustainable, one should always think from the perspective of the user: the common Dutch family. For the major part of this target group saving energy is not a sufficient motivation to renovate their house. The two most important aspects of a home according the Dutch are ‘space’ and ‘garden.’ By placing an adaptable glass house over the house we create extra space and make the garden usable year round, while also improving the sustainability. Taking into account Dutch weather conditions, the current garden can only be used 50% of the time. By applying the skin, the use of this space it optimized by it’s adaptability: the ‘space’ changes throughout the year related to the seasonal activities. In winter the skin will create a buffer zone, with temperatures suitable for a winter garden, while the living space remains the ‘warm core.’ This way inhabitants can even enjoy green and produce food during winter. When spring breaks, the temperatures in the skin become comfortably enough to function as an extension of the living room. The doors between living room and the skin will open: people can fully enjoy the sight of the first leaves and flowers. During summer the focus of activities is mainly on the outside. The skin adapts to this by opening up completely, so people can make fully use of their garden.

A Home with a Skin

Our House in Versailles

The House

To underline the fact that this is part of a row of houses, it is presented as if a slice has been taken to Versailles by including two parts of the neighboring houses. These neighbors present the original situation, without a Skin to experience the full effect of applying the Skin in the difference between the middle house and the two neighbors. However, this copy of the house in Honselersdijk is adapted to fit within the boundary conditions of the Solar Decathlon competition. The trade-off has been mainly regarding size, to fit within the Solar Envelope, and materialization, to make it constructible within the time set. Still in every design decision the house was imitated as realistically as possible. For example the exact same type of brick has been chosen as outer wall finishing and the thermal mass has been imitated using phase change materials. Even the exact orientation has been copied, even though this is not optimally North-South. This underlines the aspect that when dealing with an existing situation, orientation is part of the context.

The Interior

The most important aspect for representing the house in Honselersdijk is the quality and identity of a Dutch ‘home.’ This forms the main concept for the interior design: no hyper modernistic unfordable interior, but an existing home of a common Dutch family, in this case the family of Dennis. To present the aspect of an ‘existing home,’ a combination of second hand furniture of Dutch families and new furniture is used. Furthermore, elements that determine the identity of a home, such as pictures on the wall, shoes in the hallway, are implemented in the interior design. The interior concept is to recreate a real life dutch household, and generate a sensation of cosiness and intimacy of entering a well loved home. A fundamental characteristic that defines the typical Dutch environment is the mixture between old, familiar and meaningful elements and new, modern and efficient elements. New elements are of course easy to obtain. But the older elements are what makes a house a home; from the puckered cover on the couch to the used can of laundry soap over the washing machine, up to the smell of burned bread from the toaster. These items were acquired from donations from the Dutch public and members of the team. In order not to alter this sensation all the elements of the exposition are hidden within these items. For example posters will be printed in the newspapers left on the coffee table and blueprints can be shown on the back of the cereals boxes over the kitchen. Clarity, simplicity, high visibility are the three main elements that guided the project design and the interior organisation. In the second floor of the house, next to the bedroom, there lies the media room. This space is fundamental to show the connection between the new project and the existing neighbourhood and to demonstrate the possibility of a future expansion of this redesign to different household in the area.

The Garden

Integrating green in an urban environment has proven to have a positive effect of the wellbeing of inhabitants and the environment. The garden design contributes to water cycles and waste cycles of the house, by rainwater collection, food production and compost. By application of specific greenery, the garden also provides habitat for other organisms. In both the private garden and the greenhouse the design proposes space for growing herbs and fruits as this both offers food and activity, depending on the selection of green. In the design of the front garden, the street and the sense of community have been given meaning. Instead of focusing on the small territories in the form of tiny front yards the street is reconsidered as shared space, belonging to the community: the inhabitants of the street. In the design of the street/front garden fruit trees are main elements as this offers both shelter, room for social interaction with neighbors and food. In the garden design this is detailed by elements, such as the hedge which allows neighbors to share homegrown herbs and plants. Garden fences called ‘de Buurjongens’.

Engineering

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.

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.

Structural design

The glass house is the primary focus of the structural design. The conceptual directions are translated in the structural design by the following criteria:

Spatial connection: No structure can block the transition between inside and outside, to achieve the maximum effect of extending the space to the garden.

Climate performance: Adaptability to the seasons - can open completely during summer.

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.

PV panel design

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).

Electrical design

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.

Plumbing design

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 Thermal System Design

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.

Climate

Improving climate performance

"Our project is all about the home owner and so we have focused hard on providing them with the best quality internal environment."

Climate Design

The Skin consists of two sides: the cold side, the North-West in the case of Honselersdijk and the warm side, the South-East. On the North-West side an extra layer of insulation is added to the existing structure, diminishing heat losses during cold seasons. On the South-East side a smart glasshouse is added. These aspects are optimized further by the adaptability of the Skin. In winter the skin is closed, in spring and autumn the skin provides indirect natural ventilation for the house and in summer the skin is completely open to maximise natural ventilation using the stack effect, maintaining a comfortable temperature. The innovation in ‘Home with a Skin’ can be found in the adaptive characteristics of the Skin performing different in all four seasons, making the house energy neutral and adding quality to the home regarding health and comfort. Besides making the house energy efficient the ‘Home with a Skin’ also increase awareness of the inhabitant and try to improve its behaviour to a more energy efficient standard with help of the Comfilux system. But the most important statement in energy efficiency is that the ‘Home with a Skin’ improves the existing building stock rather than encourage demolishing houses and building new. The Skin make use of the existing building, improving it and adding decades to the live time of the Home. With help of the toolbox the Skin can be applied in different situations in The Netherlands and Europe.

Winter

By maximising the use of heat from the glasshouse, combined with active systems, such as the HRU and the Solar Compleet system. In the Netherlands one of the largest energy consumers is the heating of the house, especially for bad insulated row houses. The action to put an extra layer covering the house with a second Skin is similar to putting on an extra layer when you are getting cold. The southern Skin with the glasshouse, functioning as a buffer, already reducing the energy demand by 34%. Combined with replacing the windows with triple-E glazing, making the house more air tight, insulating the exterior walls and roofs result in a total energy reduction of 79% to yearly 1780 kWh. The heat for the heating and hot tap water is produced by the Solar Compleet system. Two energy panels extract the heat from the glasshouse and transport it towards two heat pumps which heat a 300 litres water tank to 55 °C. The system has a COP of 4,5 by average and has enough power to warm the 6 already existing radiators in the house. The radiators can be heated with a lower temperature since the energy demand is reduced (and only need 1900W instead of 8500W). Replacing the showerhead by a water saving one and adding a shower heat recovery pipe also reduces the need for hot water. The performance of the Solar Compleet system is upgraded by the pre-heated air in the closed glasshouse. The ventilation system also make use of the pre-heated air in the glasshouse and brings the temperature to the demanded level with the Heat Recovery Unit (96% efficiency). The balanced ventilation is CO2 driven and only ventilates when necessary to reduce energy usage. The ventilation system is applied to improve the health and comfort of the inhabitants and is mandatory after making the house airtight to prevent mould and unhealthy air.

Spring and Autumn

During the mild and wet seasons in the Netherlands the Skin shows other features, such as collecting water and solar heat. After a cold Winter it could be lovely to sit in the glasshouse heated by the sun to a comfortable temperature. At some point the windows and doors to the glasshouse can be opened to enable passive heating of the house. For this the domotica plays a major role in advising the inhabitants. The inhabitants have the possibility to control for example the sun shading with the domotica manually, but it also has an automatic system. The users can decides which temperatures are desired in the rooms and the Comfilux system will control the installations to reach this demand, by for example opening the windows of the glasshouse, heating the radiators, or deciding where to take the fresh air from. Besides that it can also advice to open or close the windows of the house to the glasshouse at certain temperatures. In addition, the Comfilux is a tool for improving the energy efficiency of the inhabitants behaviour. An energy efficient house is one, but an energy efficient user is another thing. The Comfilux screen can show the energy consumption and production. The user can compare and monitor the consumption and try to improve his behaviour. The Comfilux also gives the possibility to control the system form a distance, for example to switch off all the lights with one click or to control the heating to warm up the house just before you wake up or before you come home from work or vacation. This will reduce the waste of energy and improve the efficiency of the house. The Solatubes add value to the ‘Home with a Skin’ by improving visual comfort and by saving energy. The Solatubes illuminate the living room and bathroom with free solar light. The final characteristic of the Skin which is effective during the wet Spring and Autumn is the water collecting feature. The gutters are connected with a storage tank of 1,700 litres and the water is used to flush the toilets and water the plants, saving 29,500 litres water every year a reduction of almost 20%. The northern roof is covered with sedum which buffer water and improve the ecology. In conclusion the innovation of the Skin in Spring and Autumn is the re-use of rainwater, the use of solar energy and mainly the domotica Comfilux system which improves the energy efficiency of the house and the users behaviour.

Summer

In the Summer the function of the Skin is to retain comfortable temperatures in the house by blocking the solar heat and creating natural ventilation, mainly with passive systems. The Northern side protects the house with the extra isolation layer and with the green roof. The Southern Skin has a double function, on one hand it blocks the solar heat with the sun shading system and effectively remove the heat by opening the glasshouse in the top and at the façade. Calculations show that the temperature in the glasshouse will not exceed more than 2,5 °C of the outside temperature. And on the other hand the Southern Skin has a feature to harvest the energy of the sun with the PV panels of 4.9 Wp power, producing yearly over 3.700 kWh. The Skin opens op to the garden and adds the space to the outside while protecting the house against the sun and rain. The second step to retain comfortable temperatures in the house is partly a passive and active system. The HRU unit will take its fresh and cooled air from the PCM Box rather than from the warm glasshouse. The Phase Change Materials (PCM) will provide the prototype house in Versailles with extra thermal mass and functions as a passive system. The PCM will provide the house with cooling during the day and it can be recharged with cool air in the night. The cooled inlet air will bypass the heat recovery unit and the warm air from the house is discharged through the chimney. The PCM box will not be applied in the case study of Honselersdijk for the reason that the house has its own thermal mass in the concrete walls and floors to keep the house on temperature in the Summer. Also for the Summer the Comfilux domotica will give advice in opening or closing the windows to the greenhouse, showing figures of the production of the PV panels and give the forecast of the weather. This gives the possibility to use and charge the most energy demanding appliances during the midday when the PV’s produce the most power to improve the energy balance. For example turning on the washing machine, charging the electric bikes and heating the hot water tank during peak hours. In conclusion the innovation of the Skin in Summer is the possibility to open it fully and create natural ventilation and protect the house from solar heat, while harvesting the energy of the sun with the PV panels.

Light design

The main relevant light design aspect is daylight factors in the existing house and daylight comfort in the glass-house part of the Skin. Because Prêt-à-Loger is about an existing house, also the daylight factors inside this house are part of the existing context. By putting over the Skin it is assured that the existing daylight factor is at least maintained to comply with the Dutch law: the glasshouse hardly reduces the daylight inside the house. However, the daylight values asked by the Solar Decathlon competi-tion can never be achieved without touching the existing. To achieve higher interior daylight values in a way that is still in line with the concept, Solatubes are applied. These are highly reflective tubes suitable for renovations for increasing interior daylight factors. In the glasshouse visual comfort is achieved by integrating the PV-cells in the glass in such a way that still sufficient daylight enters the space below. This is done by leaving sufficient space in between these cells. Furthermore mov-able shading panels are added for controlling daylight. If there is a high level of brightness or glare, these panels can be moved down for maintaining visual comfort.

Acoustic design

Inside the glasshouse there is a risk of a poor acoustic comfort regarding reverberation time for it consist only of hard surface materials, such as single glazing. So the interior design of the glasshouse is essential for creating acoustic comfort. This has been accomplished by using a wooded floor, applying a lot of greenery and by the previously mentioned movable fabric shading pan-els. By for example adding edible green walls in the glass-house the absorption is increased.By applying the skin the facade airborne insulation, the capacity of the facade construction to limit the access of sound pressure of an external source inside a habit, has increased drastically. This is mainly a result of the extra in-sulation on the North-West side, limiting access, and the glasshouse, forming a cavity providing an extra acoustic insulation layer.Finally the acoustic comfort related to the noise levels of the installations is taken into account in the design. The critical aspect in this regard is the HVAC-unit. This unit would be placed on the attic in the original situation in Honselersdijk, however to comply with Solar Decathlon competition rules, this attic had to be removed to fit with-in the Solar Envelope. This resulted in placing the HVAC- unit on the first floor, next to the main bedroom against the exterior wall. Based on the design implementation mentioned above, the acoustic comfort of the part of the pavilion that rep-resents the existing house complies with the Solar De-cathlon rules, partly as a result of applying the Skin.

Urbanism

Our world is undergoing an unprecedented demographic shift of global urbanisation. Cities have been growing and projected to accommodate almost all of the world’s population in 2050. Apart from demographic increase the process of rapid urbanisation inevitably leads to spatial expansion e.g. urban sprawl. These two conditions pre-determine a constantly rising pressure on energy and mobility systems reflecting on the urban sustainability. Aiming to deal with these challenges the existing building stock and transportation networks, which serve the ever changing lifestyles of multiple generations of residents, demand certain adaptations. The urban concept is developed on the basis of the architectural / technological solution for energy self-sustaining unit (house) and a visionary design able to facilitate energy self-sustaining habitat on urban scale. The essence of the strategy relies on the promotion of distributed energy generation and shared consumption implemented simultaneously via top-down and bottom-up planning approaches. In order to enhance the transport network efficiency an integrated strategy, established on bicycling and shared vehicles, is elaborated linking Honselersdijk with the existing mobility nodes on metropolitan level. On urban level we aim to promote green mobility e.g. cycling and walking as major mode of movement circulation. For this purpose, a plan to pedestrianize numerous service streets within the urban area is executed. This urban mobility strategy seeks for establishment of walkable neighbourhoods contributing to lower vehicle travel and energy use; what is more, it provides new possibilities for extra utilisation of the street environment as community gardening and gathering space. In particular, our ambition is to develop an urban concept where sustainability is not just about creating energy efficient and comfortable spaces but it is fundamentally about promoting lifestyle balanced with the environment and based on shared communal responsibility and awareness regarding the performance of the urban energy and mobility systems. Related to the P-a-L toolbox an ‘urban toolbox’ is created. This comprises various solutions the municipalities can choose including urban gardening, waste and water management features, street light technologies, etc. The strength of this concept is the combined and enhanced performance of the various tools. The urban part of P-a-L project seeks for extension beyond the scope of the Solar Decathlon experimental architectural design by attempting to make a real difference on a larger scale from self-sustaining house through self-sustaining street to self-sustaining neighbourhood and town. In this sense, the urban concept does not only concern the physical adaptation and the connection of the house with the surrounding public space but rather than this it utilises the design of the house as a technological solution on the basis of which a comprehensive vision and strategy for achieving of self-sustaining habitat is projected.

Sustainability

Sustainability goes far beyond green-house gas emissions. Aspects on all three levels, environment, economy, and society have to be addressed to ensure that current and future needs of the planet and its inhabitants are met. Our solution strives for the preservation and reuse of materials and creates a positive impact on the energy performance, allowing the lifetime of the dwelling to extend by at least 50 years. The concept employs prefabricated elements in construction sections, which introduces two advantages. On the one hand, it increases the efficiency of material usage, especially when these are fabricated on a large scale, diminishing waste and saving energy at the same time. On the other hand, it reduces the construction time due to simplified handling, especially with the urban application. Prêt-à-Loger primarily utilises passive solutions such as insulation and the addition of the glasshouse to reach the goal of at least energy neutrality. Only when these are not sufficient, active systems are employed to assist in reaching the desired comfort levels. Consequently, the active and passive systems in the glasshouse and the existing dwelling complement each other, not only minimising energy losses, but also utilising solar energy (e.g. with the heat exchanger) alongside the photovoltaic panels. The sustainable built environment goes beyond that: It extends to the public spaces, which are incorporated and recaptured for the purpose of improving their sustainability performance and stimulating sustainable awareness. With this solution the focus is not on densifying the building stock, but on sustainable adaptation through the flexible densification of functions within the public space. When expanding and extrapolating the “Home with a Skin” to the urban level, the neighbourhoods will manage to reduce great amounts of energy and water. Over time, they will become self-sufficient through decentralised energy production in combination with a smart energy grid. Other changes will follow suit, such as the stimulation of sustainable awareness and shared interests, hopefully leading to a greater sense of community. These changes will be triggered by actively involving residents, fostering interaction and promoting a lifestyle in balance with the environment. Public transportation will contribute to this transition, facilitating not only the social network. It is also an inherent part of the energy network, where it helps to form a smart grid with the energy producing dwellings.

In Construction

Retrofitting of the house begins with selecting materials, before incorporating them through the construction system. Guided by the principle of preservation and reuse, Prêt-à-Loger chose a procurement strategy that would give preference to durable, recycled and recyclable materials. The three most relevant materials (in terms of weight) are glass (1,962 kg), steel (1,036.2 kg), and wood (818.13 kg), all of which meet the desired criteria. Besides these, three material highlights can be found in the house. The window and door frames in the house are made from 100% recycled plastic. For the insulation, old newspapers and wood shavings are reused and subjected to the so-called cascade use: the material and energy recovery - the most favourable use of materials in terms of resource efficiency. Lastly, a green roof is added on the house, which is not only ‘green’ regarding its materials, but also adds insulation, rainwater retention function and a small habitat for animals. What is less positive, but also essential to mention, is the toxicity that is caused. Human toxicity is the biggest impact category, accounting for 96%. The production of copper, and steel for the exterior joineries and façade are the largest contributors to toxicity, CO production and energy consumption. In total, the embodied energy of the materials amounts to 363,108.87 MJ, of which 76% was derived from fossil fuels. As a result, a total of 15,939.19 kg CO2 eq were emitted in the cradle to site phase. Since Prêt-à-Loger makes use of an existing building, the construction system is very limited, because fewer new materials are needed. This allows for a much faster construction, where efficiently prefabricated elements from mass production, both in individual houses and on urban scale, are installed. As a result, little energy is used and much resources are preserved, compared to demolishing and building a new house. Also, only a small amount of demolition rubble is generated. Most importantly from a residents’ perspective, the house is being renovated with the user remaining in the house, consequently avoiding this inconvenience in the user’s everyday life.

In use

After improving the house, it transitions into the use phase, where several systems are operated, resources such as water and energy are consumed and waste is produced. The three different energy systems present in the house and Skin are classified as passive, active or solar. The glasshouse part of the Skin on the south-west side of the house is the main contributor of passive climatic techniques. It provides a heat buffer in winter, induces cross and stack venti-lation throughout the year, catches rainwater and makes use of solar energy. Further passive techniques can be found in the insulation added to the north side and roof and the inherent heat retention of the brick structure of the existing house. Active systems are also present in the design, located mainly within the existing structure, which predominantly serve as complementary systems to the passive systems to maintain a constant comfortable environment. Active systems include a heat pump, heat recovery systems in the chimney, a water tank and active ventilation. Additionally, photovoltaic panels are present in the Skin to generate electricity, which are complemented by solar panels that simultaneously cool down the glasshouse and the panels and provide heat and hot water for the house. Especially the PV modules ensure that the house can be energy neutral, since they supply the house with a total of 161 MWh during 50 years of use. After accounting for the inherent energy of the modules that stems from manufacturing and transport, 143 MWh of the total amount is produced completely energy neutral.All climate systems in the glasshouse and the existing dwelling complement each other and work in close synchronisation to create a comfortable environment where not only energy use, but also material and water use is minimised. Freshwater use is limited by capturing and storing 2,000 litres of rainwater in the crawl space for use in the toilets, cleaning and irrigation, which results in 18% freshwater savings. In combination with the water saving sensors and devices in the house, the actual water use can even be reduced by more than 20% compared to the current situation. Waste is mainly prevented during the construction phase and by implementing a waste management system which facilitates recycling and composting of organic waste. Additionally, it is estimated that 80% of the materials used in the Skin can be reused or recycled at the end-of-life of the house, assuring waste prevention even after the use phase.Future FeasibilityIn order to demonstrate that the “Home with a Skin” positively contributes to the sustainable development, a Life-Cycle-Analysis (LCA) was carried out to quantify the environmental impacts. Furthermore, the consequences of scaling-up the product to an urban level were analysed.The LCA was carried out from cradle-to-grave, analysing the house in its local context for the lifetime of 50 years. The five main contributors (A, B, C, D, E) that form the main assembly ‘F’, the building, represent construction, transport of materials, materials, use phase, and transport of users, respectively.For the construction assembly, the engine, water and electrical consumption and the fall of materials and demolished matter were taken into account. It was estimated that 500 kg of water and 412.03 MJ of diesel (11.49 L) were consumed. Moreover, the old roof, outer layer of the north brick wall and windows and door that are demolished in the north made up the main share of the demolition waste.When analysing the transport of the materials needed during the construction and over the lifetime of the house, all trans-port modes, namely lorry, freight ship and aircraft were added up, amounting to 20,743.85 tkm. Here, the transportation of the photovoltaic panels via plane from China has the biggest share with about 86%. In the future, this value could be greatly reduced or even replaced when choosing a closer manufacturer or the common shipping method (freight ship).A highlight for the material evaluation concerns the above mentioned recycled window frames, which underwent a comparative study to determine if recycled window frames perform better than standard windows. The analysis verified that the recycled plastic frames are indeed more favourable in terms of environmental impact.To quantify the consumption of heating, cooling, lighting, sanitary hot water, ancillaries and specific electricity and the energy production, all the values were added up for one year and multiplied by 50, to account for the lifetime of the house. The total annual energy consumption and production values are 3184.9 kWh and 3753 kWh respectively, making the house energy positive, which even goes beyond the goal of energy neutrality. The transport of users entails the distances and transportation modes used by the family persona and occasional users who walk or take the bike, car, tram, train or bus measured in pkm per year.In order to quantify the impacts, the ‘ReCiPe Midpoint Method’, ‘Cumulative Energy Demand’ (CED) and ‘IPCC GWP 100a’ were employed. The ReCiPe Midpoint Method analyses a total of 18 indicators. For climate change, the indicator that is most prominently referred to, the largest contribution came from operating a personal car.Applying the Cumulative Energy Demand method resulted in the total energy demand value of 2,201,677.62 MJ eq. Here, the transport of users accounts for the biggest share with 80.6%, while the second largest contribution is made by the materi-als with 16.5%. The energy generation from the photovoltaic panels was represented in the negative value of -301,662.12 MJ eq, almost balancing out the energy needed to transport the needed materials.The IPCC GWP 100a served for the calculation of the CO2 eq emissions, which added up to 116,349.87 kg. Again, the great-est share was made up from the transportation of the users (81.56%).Conducting the LCA was extremely valuable for the impact eval-uation and the confirmation of design choices. Prêt-à-Loger at-tempted to strive for the best and most feasible solutions on all levels of sustainability, not only the environmental aspects. It turns out that while the project managed to maintain a bal-ance between these levels, there is still room for improvement. Even though it was surprising that transportation accounted for most of the negative environmental impact, it is a relatively easy problem to tackle. Fortunately, Prêt-à-Loger has already developed various transportation strategies aimed at mitigating the harmful impacts.These transportation strategies are an important part of the urban approach Prêt-à-Loger utilises, in which a lifestyle in bal-ance with the environment is endorsed inside and outside of the homes with a Skin. The aim of this approach is to promote optimal land-use, shared goods and public space, and maximised use of materials, energy and food in the neighbourhoods and towns where the Skin is utilised, using a flexible urban tool-box. Central to this strategy is the urban application and use of the Skin while retaining the basic urban structure, but also the creation of green spaces and the aforementioned transformation of the transportation strategy. The active involvement of residents and the municipality is important to achieve all this, since the incorporation of their needs and wishes will ensure the success and applicability of the urban transformation.For the urban application of the Skin, two main target groups are of importance, namely housing corporations and individual homeowners supported by external investor funds. For both parties the urban application is expected to be feasible within two to three years and the implementation is envisioned to take place in three steps between 2020 and 2035.Accompanying the application of the Skin is the transformation of the public space using the urban toolbox. It is a highly flexible process that is needed to ensure that the transformation is fully appropriated to the specific location and urban context. Options such as urban farming, green zones and water retention are all analysed and the most suitable options are utilised in the neighbourhoods and towns. For Honselersdijk, especially a transformation of the urban strategy forms an important part of the urban approach, with which the introduction of a shared electric car program lies at the centre. This program is introduced to stimulate sustainable travel and reduce CO2 emissions from short-distance travel by personal car. It will be integrated in the energy grid, containing the Skins and decentralised solar and wind energy facilities. This electric vehicle concept is further implemented by the introduc-tion of personal electric bicycles connected to the Skins, which allow residents to travel larger distances by bike in a sustainable manner.The use of sustainable modes of transportation is further en-couraged by transforming numerous service roads into green zones to better suit pedestrians and bicyclists, and by the in-tensification of the public transportation by green bus lines and light rail trains already planned by the Province of South Hol-land.InnovationThe approach that Prêt-à-Loger proposes, looks beyond creat-ing sustainable houses and instead focuses on transforming the existing and unsustainable building stock by using innovative interventions and materials. Preservation and improvement of existing structures is preferred over demolition and replace-ment and sustainable, economic and environmental potential of structures such as the post-war row house in Honselersdijk are analysed. This house is thereby adapted without undertak-ing major demolition works or implementing highly invasive interventions, directly saving on demolition and construction. This provides immediate benefits on a social, economic and en-vironmental level, since the construction time decreases dras-tically, less labour and materials are required and substantial amounts of waste and emissions related to construction works are prevented. The approach further introduces newly added living space and preserves the existing construction and lay-out of the dwelling, ensuring residents can improve and maintain not only their house, but also their home and their memories. The final product is an energy neutral, waste preventing and comfortable home resulting from a quick and economic inter-vention with a Skin that provides energy and extra living space.However, Prêt-à-Loger perceives sustainable improvement of the building stock as more than adjusting single dwellings and aims at improving the urban surroundings as well, even when the Skin is only applied to part of the building stock. To achieve this, a flexible urban toolbox is introduced which allows resi-dents and municipalities to be actively involved in the trans-formation, guaranteeing the interventions are highly adapted to the opportunities and needs of the specific location. This involvement of the local residents additionally supports sustain-able awareness and creates a shared feeling of responsibility for the neighbourhood and its public space. Even residents who didn’t implement the Skin will experience and profit from these interventions in their direct environment such as green car-free zones, urban farming and rainwater retention, which will sup-port environmental and social awareness throughout the neighbourhood and town.Related to the urban toolbox is the improvement of the transportation situation in Honselersdijk, which is currently predominated by short-distance travel by car. To reduce the emissions associated with personal and public transportation, a shared car program is introduced using electric cars powered by the Skins in combination with decentralised wind and solar energy. Additionally, electric bikes are introduced within this electricity network and the public space is redesigned to fit the needs of pedestrians and bicyclists better, making short distance travel by bike more attractive. This way, the foundation for a future smart energy grid is created and sustainable travel is encouraged.

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