Dependence of measured specific air leakage rate (qE50) on envelope pressure differences and measurement position: a case study in an apartment building in winter conditions

Airtightness of the building envelope has become an important component in achieving ever stricter energy performance levels. However, airtightness measurements using blower door method are dependent on choices made by the specialist conducting the tests. One being the assessment of baseline pressure difference inside the building and position of the measurement equipment. Ideally, the test will be conducted without wind and stack effect which could disturb the envelope pressure measurements. Unfortunately, such conditions seldom exist, especially in colder climates. This increases the appeal of conducting apartment-wise measurements over whole-building measurements as it is far easier to comply with the ISO 9972. However, the apartment-wise method has a relatively random nature due to small share of actual building envelope. This paper investigates the effect of using different measurement positions and pressure levels on the airtightness measurement results. A 5-storey 15m tall residential building was used as a case study and measured as a whole and in select apartments. The results show that the variation caused by different choices of pressure levels, measurement positions etc caused relatively low variations and whole-building measurement should be preferred even if not all baseline and pressure level requirements are not met.

ANALYSIS OF THE AIRTIGHTNESS MEASUREMENT IN SINGLE OR DOUBLE APARTMENT HOUSE

The mandatory energy performance certification of new buildings or buildings for sale has been introduced in all Member States in order to achieve European Union’s energy efficiency goals. The certification of buildings sets mandatory requirements for higher energy efficiency buildings’ level of airtightness. However, a bigger problem lies in existing older residential buildings, which are energy inefficient and do not require certification. The unused potential for energy savings observed here is related to the airtightness of single and double apartment residential buildings and energy efficiency related to airtightness of them. Therefore, this work analyses the airtightness of energy class D and lower buildings based on actual airtightness measurements and evaluates the possible energy saving potential associated with the application of airtightness measures based on the example of one inefficient single apartment building. The results show that increase of the airtightness in such buildings to 3 h–1 enables to reduce the energy costs related to the airtightness in Lithuania over a period of 10 years by 0.17 TWh per year.