airtightness

There are three major ways to estimate this impact: - the simplest is to evaluate the infiltration losses based on a rule of thumb established by Drubul in 1988 (*) and suggested by Kronvall (**) in 1978. The rule says that the infiltration airflow rate in air changes per hour may be determined by dividing the n50 value by an empirical coefficient that lies between 10 and 30. In practice, the empirical coefficient is often set to 20 (i.e., the infiltration airflow rate is equal to the airtightness at 50 Pa divided by 20);
Post date: 12 Dec 2008
Type: Ask the Experts

Now in Europe, many countries have adopted the n50 value (i.e., the leakage flow divided by the volume) for their EP regulation while others (e.g., Belgium, France, UK) use the envelope area normalisation. The rationale behind this latter choice lies in the fact that the volume is not needed for an energy performance calculation. Using the n50-value should require a precise definition of the way the volume is calculated, which to our knowledge, is not the case in any European country. On the other hand, the envelope area is usually well-defined in regulations.
Post date: 12 Dec 2008
Type: Ask the Experts

There is no up-to-date document at this time. Anwered by: Rémi Carrié and Gaëlle Guyot (CETE de Lyon) Date: 2008/12/12
Post date: 12 Dec 2008
Type: Ask the Experts

The airtightness measurement of single apartments is usually performed the same way as in individual houses. Therefore, there is no specific protocol to balance the pressure between the apartment under test and other apartments. Different protocols may lead to very different results. Anwered by: Rémi Carrié and Gaëlle Guyot (CETE de Lyon) Date: 2008/12/12
Post date: 12 Dec 2008
Type: Ask the Experts

There is little information on the subject at the moment. A study referenced in a paper written by Erhorn et al. and presented at the 2008 AIVC conference shows airtightness values of 31 “Passivhaus” houses at commissioning and 2 years later. The average n50 at commissioning and 2 years later were 0.37 and 0.46 ach at 50 Pa, respectively.Anwered by: Rémi Carrié and Gaëlle Guyot (CETE de Lyon)Date: 2008/12/12
Post date: 12 Dec 2008
Type: Ask the Experts

Energy wastage due to envelope leakage has been estimated in various countries through numerical simulations: - in Belgium and in Germany, the energy impact has been calculated to be about 10% of the energy performance level for individual houses; - estimates based on simulations on 9 real buildings in France lie between 0.5 and 15 kWh-pe/m2 per year (depending on climate, ventilation system type, and building configuration), with an average of 6.6 kWh-pe/m2, between “default” and excellent airtightness
Post date: 12 Dec 2008
Type: Ask the Experts

To some extent yes. A collection and analysis of some data collected through the ASIEPI partners has been presented at the 2008 BlowerDoor conference (Papaglastra et al., 2008). However, caution should be exercised when comparing airtightness values : - the measurement methods are not necessarily the same. EN 13829 mentions two methods (A and B) that can lead to very different results e.g., depending on how combustion appliances are sealed; (*)
Post date: 12 Dec 2008
Type: Ask the Experts

To our knowledge, only two low-energy labels include a minimum requirement for low-energy buildings: - the PassivHaus standard (www.passivhaus.de) that requires an airtightness better than 0.6 air changes per hour at 50 Pa (n50 <= 0.6 ach); - the BBC-Effinergie standard (www.effinergie.org) that requires for an individual house an airtightness better than 0.6 m3/h per m2 of cold surface area at 4 Pa (this translates for an individual house to a n50 of about 2.5 ach).
Post date: 12 Dec 2008
Type: Ask the Experts

Measuring or evaluating the airtightness of multi-family buildings is challenging as there may be technical and practical difficulties that prevent from pressurizing the whole building. These difficulties include for instance building configuration (e.g., exterior hall ways that do not allow pressurisation from a single point), pressurisation fan size, stack effect, or cost. Therefore, the measurement of the whole envelope of multi-family buildings is rarely performed in practice. However, several countries use alternate schemes to overcome these problems, for instance:
Post date: 12 Dec 2008
Type: Ask the Experts

There exists a certification scheme in Germany which is not compulsory to perform tests. There exists a compulsory authorisation process in France for technicians who perform test on BBC-Effinergie buildings. To our knowledge, there is no other certification or authorisation scheme in European countries. Anwered by: Rémi Carrié and Gaëlle Guyot (CETE de Lyon) Date: 2008/12/12
Post date: 12 Dec 2008
Type: Ask the Experts