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Open doors in Thun
15. Nov 2021
Full house at the open house. Over 180 people wanted to see and feel the basement made of wood. The BMW15 apartment building in Thun is an innovative showcase project: It stands on the first basement made of wood in Switzerland, does not require heating and was built entirely without concrete.
The interest in our showcase project was enormous: On Saturday 13 November 2021, over 180 people visited Stefan Zöllig's new building. We are pleased about the large number of visitors and the coverage in the daily newspapers or 20 minutes online.
The visitors could see it for themselves: Comfortable temperatures prevail in the apartments - even without heating. The fact that modern houses can manage without any heating at all is proven in Thun. There are many sources of heat in buildings, such as kitchen appliances and computers. People also radiate heat constantly. If, in addition, the sun's rays are ideally used and the house is well insulated, there is no need for heating today if the design is good.
Advantage surface temperature
Well-insulated walls are important because the smaller the difference between the surface temperature of the walls, floors and ceilings to the air temperature, the room. That's why we feel comfortable in wooden buildings with good thermal insulation - even when the room temperature is slightly lower. This allows buildings to be more energy efficient. In addition, wood has a perceived higher surface temperature than concrete, steel or glass, which further increases the sense of well-being.
Efficient cooling durning the night
Global warming means that there will be more and warmer heat days in the future with temperatures above 30 degrees Celsius. Thermal insulation in summer is therefore becoming increasingly important. In order for us to feel comfortable even on hot summer days, buildings must be able to cool down during the night. Windows with adequate weather and burglar protection and insect screens or ventilation units with heat and enthalpy exchangers are important for this. Exterior shading and appropriate window size are equally important.
Mass equals stupidity
The important influencing variables for good summer thermal protection are adequate window areas, good solar shading and efficient night cooling. For a long time, the opinion was that summer thermal protection can only be achieved by installing a lot of mass. This is wrong. Old castles with their meter-thick walls may remain cool in summer. But this is due in particular to the small windows. Modern architecture often has large window areas. Once heated up, too much thermal mass can become a heat trap, especially in inner-city locations where buildings cannot cool down sufficiently at night.
The certificates prove the use of Swiss wood and the storage of a total of 222 tons of CO₂: Thomas Lüthi from the Initiative Holz BE and Stefan Zöllig handing over the certificate.
Houses without heating and without air conditioning make an important contribution to climate protection. An even greater potential for energy savings lies in the choice of building materials. Wood is already widely used in building construction. The next step is to avoid climate-damaging building materials such as steel and concrete - including in basements and floor slabs. In order for basements to be mass-produced from wood in the future, a number of research questions need to be answered. A research project of the Bern University of Applied Sciences together with Timbatec, TS3 and other business partners is currently addressing these questions. A start-up is to be founded from the group of research partners, which will be operationally active from 2023.