International selection
The EU may be at the forefront of pushing energy efficient building, but innovative low energy construction is rarely recognised on a European scale. The Isover Energy Efficiency Awards are one exception, rewarding the continent’s best new build and renovation projects. We profiled buildings from the inaugural Irish awards in our last issue — here are nominations from across the continent that were celebrated at the European awards ceremony in Barcelona on 2 June
K3 House
Hörbranz, Austria
Architect: Hein-Troy Architecture
Renovation
Timber annexes
This project by Hein-Troy Architecture took a large 1960s single-family home and turned it into an energy-efficient, modern complex of three separate homes. The house was renovated to accommodate two young families who wanted to live on top of their parents’ house, while the basement now serves as a communal space for the families.
The first task for the architects was to remove the loft roof and the garage adjoining the house, then add timber annexes at the top and sides. The project presented some major challenges, such as doubling the living space while reducing the building’s energy use, and finishing the project while the parents were still living on the ground floor. Set at the foot of the Alps, the architects also aimed to maximise the house’s views over scenic Lake Constance.
Open plan split level interior
As part of the renovation, the building was wrapped with Isover façade insulation plates. It boasts excellent airtightness for a renovation — 0.80 m3/h/m2 — and excellent U-values of 0.22 W/m2K for walls and 0.13 W/m2K for the roof. The renovation slashed the building's energy use by 70%.
The award ceremony
Casa Capriata
Weissmatten, Gressoney Saint Jean, Italian Alps
Architect: Carlo Mollino (1954), Guido Callegari & team from Torino Polytechnic (2010)
New build
The experimental Casa Capriata — designed by prominent 20th-century Italian architect Carlo Mollino in 1954 — was never completed. Fifty years later, proposals were made to complete the project, and the tree-like building will be opened as an Alpine refuge dedicated to Mollino this summer. All architectural, structural, technological and plant engineering aspects have been designed to fit with Mollino’s original plans. The building was designed to have a space heating demand of less than 10kWh/m2/yr, achieving the CasaClima certification system’s class A gold standard. The walls, roof and floor have U-values under 0.1 W/m2K, and the building has an airtightness of 0.6 W/m2K.
A recent computer drawing shows the tree-like structure
Even Mollino’s original design aimed to minimise heat loss — essential for a building 2,100m high in the mountains. The Alps have become an experimental area in terms of the design of energy-efficient buildings — the region’s extreme climate and difficulty of access have prompted experiments with energy-autonomous buildings. The Casa Capriata project is based on Isover’s Multi Comfort House concept, using generous thermal insulation, high performance windows, super-airtightness and heat recovery ventilation to maximise comfort and energy performance. The hut’s main sources of heat are the sun and heat recovered from recycled air. Botanical engineering also plays a role in this experimental building, with wastewater treated with a photo-purification, plant-based system.
Originally designed by Italian architect Carlo Mollino in 1954, Casa Capriata building is finally set for completion this year
Noain City Hall, Noain, Spain
Architect: Zon-E Architects
New build
Noain City Hall in Spain features a double-skinned facade – the inner layer is translucent polycarbonate that lets natural light in, while the outer layer is a metal latticework that will support the Virgina Creeper vine, which will cover the facade and help prevent overheating inside during the summer, then turn red in Autumn, and finally shed its leaves and let sunlight in during the winter. Bound on one side by a desolate city square and on the other by a park, the building is designed to act as a mediating agent between these two contrasting urban landscapes
Noain City Hall was designed by Zon-E architects to be a “changing landscape” — one that follows the natural course of the days and seasons. The building was constructed in two layers — the inner layer is formed by a double translucent polycarbonate skin that lets natural light in, while the outer skin is a metal latticework over which vegetation can grow, altering the appearance and colours of the building throughout the year.
The Virginia Creeper vine will climb and cover the façade during the summer, protecting the building from solar radiation and acting as a cooling device. After turning spectacular shades of red in the autumn, it will drop its leaves in the winter, allowing sunlight to filter through and heat the double inner skin.
The building’s foundations are 70 metres deep to obtain sufficient geothermal energy, which meet heating and cooling requirements. The building also features a small gas boiler as back-up, while a suspended ceiling incorporates lighting, temperature and movement sensors that help minimise energy use.
St Leonhard’s School, Arnoldstein, Austria
Architect: Arch + More
Renovation
When St Leonhard's School in Austria decided to expand to accommodate a growing study body, it decided the renovated building should meet the passive house standard. But the refurb was about more than just energy efficiency — the building now includes a kindergarten, after-school club and public library too.
The project team focused on reducing thermal bridging. They added interior insulation to part of the building, while some of the façade was insulated externally with new pre-fabricated timber frame elements — this also helped to speed up construction and meet a tight deadline. Heat recovery ventilation was installed too, and new-triple-glazed windows also feature throughout.
The architects also chose to heat the sports hall with a wood pellet boiler. The building now boasts a superb airtightness of 0.4 m3/h.m2, while the walls and roof have superb U-values of 0.090 W/m2K and 0.065 W/m2K respectively. After renovation, the building’s heating costs are expected to be about 10% of the €17,000 they were previously. In total, the renovation reduced the building’s energy consumption by a massive 95%.
The refurbished building features a kindergarten and after school club
Apartment block
Zurich, Switzerland
Architect: Kaempfen Architecture
Renovation
Originally built in 1938, this apartment block in Zurich was renovated to add more living space and slash its energy consumption. The architects decided to enclose balconies on one side of the building, turning them into indoor alcoves. On the opposite side, the team used a timber frame structure to expand the size of the apartments and create new outdoor balconies.
Solar PV panels and solar thermal collectors were both installed. Surplus electricity from the PV system is exported to the city’s grid, while the collectors now contribute to the building’s space heating needs along with a gas boiler. Heat is distributed throughout by a new underfloor heating system. South-facing glass surfaces were expanded to maximise passive solar gain. The building envelope was extensively insulated as part of the project, and the roof and walls now have U-values of 0.09 W/m2K and 0.18 W/m2K respectively. The renovation slashed the building’s energy consumption by over 80%.
On the courtyard side existing balconies were enclosed in a timber frame structure to create new indoor alcoves
Passive house, Liguria, Italy
Architects: Alessandro Leardi & Rodolfo Solaroli
New build
The architects of Liguria’s first passive house aimed to a produce a building that would be self sufficient in terms of energy — and one that would fit neatly into its traditional setting too.
The building features a variety of energy recovery solutions, many of them inspired by the past. The underground heat exchanger — which aids summer cooling — is a modern version of the covoli system (ventilative ground-cooling system) used in several Venetian villas dating back to the 16th century. The two 5,000-litre underground rainwater tanks — used for domestic hot water — are modern versions of a similar solution used in many parts of southern Italy for generations, and provide 60% of the house’s water needs.
Excellent thermal and acoustic performance was achieved by heavily insulating the house — this includes 26 cm of high density Isover mineral wool for external insulation and triple-glazed windows. The house also boasts 24 solar photovoltaic panels that make it self sufficient in terms of electricity, and solar thermal collectors feature too.
Built with poroton (fired clay) block, the house was designed to have high thermal mass — this helps to keep indoor temperatures comfortable even when it’s scorching outside, as the structure absorbs heat and then releases it slowly over time.
This Ligurian passive house was designed to fit into its traditional Northern Italian coastal setting. The house was built with poroton block and Isover mineral wool external insulation