Energy saving in new mode: New Finnish technology cuts heating energy consumption in a block of flats to one-third

Technical Research Centre of Finland, VTT has supervised the development of building technology that cuts the amount of energy required for heating in a block of flats by 70 per cent. The first apartment constructed with this low-energy technology was completed in the city of Espoo Finland, in the summer. Building of an entire block of flats utilising the same technology is scheduled to begin next summer.

Research on low-energy building in Finland has mainly focused on single-family houses. VTT is now co-ordinating work aimed at creating the prerequisites for the productization of low-energy building. VTT has been supervising research and development activities in which the requirements set for apartments clearly exceeded the current living comfort and technical building (construction) standards. VTT and a network of several companies have designed exterior walls, sauna elements, balcony doors and windows with excellent thermal insulation properties, as well as an integrated ventilation-heat recovery system that removes the need for radiators in the apartment. Currently, the building product and construction industries mainly settle for meeting the minimum criteria set for the field.

Low-energy building only increases the construction cost by some two or three per cent, which will be soon covered by long-term savings in heating energy consumption. Compared with building construction according to current standards, the savings in heating costs achieved in one block of flats built with low-energy technology would total 50,000 euro in ten years, if energy prices continue to rise by three to six per cent annually. With the same price increase rate, the savings accrued in 50 years would total 400,000 to 1,000,000 euro. Low-energy buildings will receive the best energy classification when the European energy performance certificates for buildings are introduced next year.

Low-energy building with an inexpensive lifespan would also be extremely profitable in terms of national economy. If new residential buildings were constructed using the new low-energy technology, the savings achieved would correspond to the annual district heating consumption in the City of Helsinki (currently 7.2 TWh) by 2030. For an individual corporation producing thousands of apartments annually – such as SATO and VVO – low-energy building would become a highly profitable investment in less than ten years.

The low-energy apartment built in Espoo exploits the heat generated by the occupants and the household equipment. This heat is recovered with the new ventilation-heat recovery system. Thus external energy, produced with the same system, is only required for heating during two or three months a year; in the summer the apartment is kept cool as a combined result of structural solutions and ventilation.

The placement of the kitchen and wet areas in the low-energy apartment helps avoid the heat losses due to the customary long pipelines. The sauna was designed to be easily scalable and repairable. Particular care was taken during construction to make the joints between the building elements, windows and doors airtight and avoid thermal bridges. All these details contribute to the overall reduction in heating energy consumption.

The low-energy apartment was developed by VTT, Mikkeli Polytechnic, Rakennusliike Reponen Oy, Meptek Oy, Skaala Windows and Doors and Salon Sauna Oy. The project also received funding from the National Technology Agency of Finland (Tekes).