Environment 

BUILT ENVIRONMENT: How ‘nanotowers’ will turn our cities into vertical gardens

As the Solar Decathlon 2012 revs up for a September start, hosted again at Madrid’s Villa Solar, Euroasia Industry takes a close look at one of the 20 entrants, which promises something a cut above the competition. ‘Canopea’, a Nanotower design from Team Rhône-Alpes, addresses the issues of providing low-energy, comfortable housing in a dense urban environment. Nick Charity learns more.

Originally started by the US Department of Energy, with its debut in Washington DC in 2002, the Solar Decathlon is a competition between universities from all over the world, to design and build a fully functioning prototype house that runs solely from solar power.

The contest, which came to Europe for the first time in 2010, was well received by 190,000 visitors over the 10-day duration. The competition now runs in alternate years as a counterpart to the US edition. The second edition of Solar Decathlon Europe (SDE), held at Villa Solar in Madrid from 14th to 30th September 2012, will feature 20 fully functional prototype houses, enduring a 10-day test of their functionality and energy efficiency, and scored for their all-round sustainability and suitability for the market.

The criteria for the contest are simple: the house must be self-sufficient and sustainable, and the winner will be chosen based on 10 strict criteria for a well engineered, sustainable and viable design. Producing an in-depth analysis of each house, the contest will members of the public and captains of industry alike to compare the energy balance of each design and observe new technologies in application.

Meeting an array of requirements

This year, the 20 teams come from 15 different countries, including universities from Germany, Spain, the UK, Norway, Hungary, China, Japan and Brazil.  Each design is unique and, having striven to incorporate influences from their native architectural traditions, many reflect the particular tastes of their own people. Producing an architectural concept that can be integrated into a specific market is an important part of the contest – making market viability and appeal central issues for the decathletes.

Med in Italy, for instance – the first entry into SDE from an Italian team – is introducing a design that fits into Mediterranean life in an aesthetic sense, but more importantly works into the lifestyle of the inhabitants, with an emphasis on the outside space for open community interaction and alfresco dining. The American University in Cairo has taken a similar route, producing a design which – on the outside, reflects both Ancient Egyptian aesthetics, while being organised into a domestic space that suits the customs of modern Arabic home life.

For the mutual good

Canopea, so named for the influences it draws from the canopy of a rainforest, is the project being delivered by Team Rhone-Alpes. Addressing a major problem in French culture, it seeks a solution to urban sprawl, which poses serious detrimental effects to many urban areas. The growth of low-density urban areas has been pandemic since the 1970s, and the problem has a particularly damaging effect in Rhone-Alpes. “Here, we are facing different ecological problems, because of the mountains and narrow valleys, which are already filled by urban development,” says Dr Pascal Rollet, Professor of Architecture at the National School of Architecture in Grenoble (ENSAG), and the Executive Advisor on the Canopea project.

He goes on to outline that, to meet the demands of growing cities, it has become necessary to develop areas of high quality, medium density housing, which gives people the same sense of ownership of their home as they desire from a stand-alone house. “The difficulty of the project is that we are facing in two opposite directions,” he continues. “Everybody in France wants to have a close relationship with nature, and everybody wants to have his own singular house, so the challenge we are facing is how can we design a collective building in which everybody can feel at home. The solution for us is the ‘nanotower’.”

The design has therefore taken a direction of its own and is different to every other entrant to SDE 2012, in that it is a nanotower: a building of 8-10 individual units stacked on top of each other. But the project extends further still from the design of a detached house, and incorporates a concept for constructing an efficient community. For the Solar Decathlon, Canopea will be realised as the top two floors of a nanotower, comprising a one-to-two-bedroom home and a communal roof terrace.

Comfortable and sustainable

Dr Rollet outlines that the nanotower project is designed to appeal to the potential resident’s need for an individual home. The units of a nanotower, therefore, bring together the spatial and architectural qualities of a single-family house. They have a 360-degree view with external extensions that can be vegetated. The concept also makes use of vertical farming to integrate garden features into the complex.

Equally important is the flexibility of the interior. Team Rhone-Alpes observes that open plan spaces have become ubiquitous in French houses, with private rooms becoming smaller and reception rooms becoming more prominent. “The idea is to create diversity and vertical connectivity,” he says. “On each slab you can create a different apartment.” Canopea offers the owners of the house the freedom to create their own home, with numerous possible configurations of the main construction blocks. The space can also adapt to the changing needs of the residents, such as the opening of the living area onto the balcony, and a mobile cabinet is manoeuvrable to produce an open space for entertaining guests, or for partitioning an enclosed area with a collapsible desk and bed.

Bearing in mind that the core intention of the project is to create a passive energy home, the Canopea project utilises a hybrid photovoltaic and thermal (PV/T) system, with 10 Kilowatt-peak, bi-glass solar panels. With full knowledge that central heating is the single largest energy expenditure in the home, the team’s use of a comprehensive thermal strategy has contributed greatly to the building’s overall efficiency, and has affected every aspect of its architectural design from materials used to layout and exterior.

To defend the building from solar incident radiation while providing natural ventilation, lamella blinds and adjustable louvres are used around the exterior walls, and the space under the solar canopy also protects the roof from direct exposure to the sun. For the interior, soil is being used as a coating to help balance temperature and humidity. Active heating and cooling is managed by compact water-water and air-air heat pumps, which are coupled with the PV/T system. Storage of water makes it possible to diphase the ambient temperature by reusing the water through the radiant walls, creating a thermal flywheel effect and flattening out temperature fluctuations throughout the day.

Integrating innovations

Many of the entries at the Solar Decathlon have incorporated natural techniques for thermal management. However the Rhone-Alpes team will be showcasing a revolutionary technology for regulating temperature. This new innovation, called the Thermal Phase-shifter (TPS), has been developed by the University of Geneva (UNIGE), and is being implemented into its first real-world scenario as part of the Canopea project.

The TPS is a passive cooling technique, which uses a packed-bed type of thermal storage to delay temperature oscillations by 12 hours. It can therefore ventilate cool air in the middle of the day without requiring any energy input, and similarly output warm air at the peak of night. Dr Pierre Hollmuller, a professor of thermodynamics at UNIGE, has been leading the team in the development of the TPS.

Outlining the importance of the development, Dr Hollmuller states: “It was a theoretical discovery of a physical phenomenon we were not previously aware of.” The presence of the phenomenon over a 12-hour period has now been proven theoretically and in practice, and Dr Hollmuller is now working on a phase-shifter module for the Canopea prototype, and over the course of the 10-day event, how the TPS behaves in a real-life scenario will e determined. “Canopea is so important to us, because up until now, we have not done any real demonstration,” he continues. “But now, we will be able to see if it really works.”

Meanwhile, the TPS will be a primary contributor to the ambience in the Canopea house, relieving some of the need for conventional heating and cooling. Dr Hollmuller is quick to outline that the contest presents an opportunity for the technology to be opened to a wider audience. “Being at this competition means that we will have the chance to see if there is any interest from potential industrial partners or other universities, who can help us to develop the technology as a product,” he remarks.

Integration into real-world scenarios

So far the team has completed the wood-steel structure and is presently installing interior walls, wiring and plumbing. Benjamin Le Naour, a student of ENSAG and the communications officer on the project, tells us: “The inauguration of the prototype will take place on 26th July, 2012, in front of our partners and the media,” he says. “Starting in mid-august, we will dismantle the construction to load it onto a dozen of trucks, leaving for the competition in Spain.” The building is being constructed with a modular construction programme, designed to be an efficient and cost effective process that can be carried into full commercialisation.

In fact, Mr Le Naour is able to tell us that the nanotower design has been proven as a viable format for the French market, and is on the path towards full commercialisation. “Some of our partners and sponsors have been so interested in the project that we will indeed be building nanotowers in the very near future,” he says. “Simultaneously to the competition, we are developing concrete constructions with our partners in Lyon and Grenoble.” On one such project, the team has been working with the Grenoble Innovations for Advanced Technologies (GIANT) campus in the Northwest of the city, to integrate nanotowers into the new residential areas of the city’s world-renowned centre for scientific research and hi-tech industries. As part of the EUR 1.5 billion project to rejuvenate the surrounding area of underdeveloped land, the nanotowers designed by Team Rhone-Alpes have been chosen as the appropriate housing format to be integrated into this dynamic new community.

Generating public awareness

Dr Rollet elaborates: “It is the main goal of the project is to be connected to a grid and to show that autonomy and energetic issues are not going to be solved at the scale of the building but at the scale of the neighbourhood and of the city,” he says. Building a strong agenda for communications is a fundamental point in the team’s approach. Due to the unorthodox nature of the Canopea project, the message they have been conveying does indeed show how new techniques and technologies can be integrated in the home, but they also intend to demonstrate the place of the nanotower within new, energy-mutualised districts. He continues: “We are going to really communicate that this is just a piece of a larger eco-system. The question is, how can we put this building in an urban network to exchange energy and information, and to use as little energy and material resources as possible?”

When visitors arrive at Villa Solar, in Madrid in September, they will be able to see how nanotowers work together with smart grids and shared thermal and electric distribution, low-emission mobility and mass-transit. The PV/T power generated by the nanotower will be just one resource in a more stable energy mix, mutualised throughout the community. In addition, the team will discuss the benefits of tackling urban sprawl as a means of reducing carbon emissions from commuter travel.

Canopea joins a line-up of revolutionary designs for the future. However, it is in a class of its own by offering an answer to the pressing need for urban redevelopment. It is also one of the only designs to appreciate that urban planning is essential to increased energy efficiency. Ultimately, the project’s ability to generate awareness is its greatest feat and Canopea shows the public that to achieve greater efficiency, autonomous, self-sufficient housing is not enough. Developments must be designed holistically.

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