airtightness

In 1998, NIST published a review of commercial and institutional building airtightness data that found significant levels of air leakage and debunked the "myth" of the airtight commercial building (Persily, 1998). Since then, NIST has expanded and maintained a database of whole building envelope leakage measurements of U.S. commercial and institutional buildings.

The Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) recently developed design/construction strategies that improve the energy efficiency, reduce the potential for mould, and improve indoor air quality in newly constructed buildings and buildings undergoing major renovations. ERDC-CERL performed building envelope leakage tests on Army facilities to test their general integrity and the effect of increased airtightness on building energy consumption.

This paper presents results from whole building air leakage tests used to document the leakage reduction due to envelope sealing and assess the accuracy of contractor's estimates of the impact of their sealing. The measurements also compare the differences in envelope leakage reductions determined from depressurization versus pressurization tests and determine mechanical system leakage.

French authorities have launched an extensive thermal renovation program aiming at retrofitting 4M dwellings over 10 years, with priority given to the most energy consuming ones. Without specific focus on airtightness, retrofitting does not achieve very low airtightness levels, which means numerous leaks in the envelope. Added to the possibility of fungus development at the junction between ancient and new wall, the possibility of airflow conveying pollutants emitted in walls into indoor air is a major concern for public health.

As environmental issues are rapidly gaining more and more interest globally, various measures and standards are being set to minimize the use of energy in the architecture field, which consists about a fourth of the total use of energy. Korea, like other developed countries, is also aiming to make zero-energy buildings mandatory(by 2025) implementing various measures such as energy efficiency rating system and energy performance certification systems to gradually minimize energy consumption in buildings. 

The airtightness of the building envelope was studied in field measurements in recently constructed experimental small test buildings. Two types of research studies were carried out: the effect of special air tight sealing and the experimental determination of air exchange rate (h-1) under real operating conditions. In very small buildings with many joints between materials and construction the role of the air tight sealing is very important; the experiments show changes in measured air tightness.

CETE de Lyon gives support to French administration for thermal regulation definition and enforcement. They must therefore work on measurements in order to set appropriate requirements and give advice to professionals about building methods.

A large social housing retrofitting program was implemented in Porto, Portugal, a mild climate region. One of the features of that program was the upgrade of windows and ventilation systems. An increased airtightness was expected and mechanical extraction on kitchens and bathrooms was implemented. This work analyses the changes in building airtightness that resulted from that renovation.

The paper presents a calculation method for the combined standard uncertainty associated with the buildings airtightness measurement done in accordance with the ISO standard 9972:2006 (or EN 13829).

The method consists in an application of the law of propagation of uncertainty (JCGM 100:2008) combined with a linear regression (y = a x + b). It goes from the measured values to the air leakage rate and the air change rate.

Pushed at first by the labels backed onto the 2005 French energy performance (EP) regulation, and later on by the 2012 energy performance regulation, which imposes envelope airtightness requirements for any new dwellings, and pulled by a growing interest for low-energy labels, an important market transformation is observed in France on envelope airtightness measurement.