Energy Efficiency Calculations and Tightness of Buildings in Finland

From the year 2007 the buildings must have energy efficiency calculations, which requirements arenow part of Building Code Book. This is based on European Performance of Buildings Directive.This presentation will discuss about the results collected by VTT from multi-storey apartment housesand one-family houses mainly during 2008-2009. The biggest problem is how to improve the airtightness of existing building stock, because new building covers only 1-2 %/year/from the totalbuilding stock. The improvement of air tightness in general is a positive issue, also when it has carried also the systematic approach of better design. There are still lot of open questions, especially how to measure the air tightness of big and tall buildings, what is the real connection between air infiltration and air tightness number and what levels we will accept in the future. The results have also shown some problems in the measurement technology.