airtightness

We have developed a simple model to estimate ductwork leakage and heat conduction losses in steady-state conditions for a balanced ventilation system. Implemented in a spreadsheet, it allows us to calculate their impact on heat recovery efficiency consistently with EN 15241 without the need for a dynamic simulation tool. One case study shows that the global heat recovery of a balanced ventilation system with a nominal heat recovery of 80% can be reduced to less than 50% if the ductwork leakage and thermal resistance are poor.

Implementation of the European Energy Performance of Buildings Directive (EPBD) introduced the first legal airtightness regulations into the 2008 Polish Building Codes. Unfortunately these provisions are currently not sufficiently precise or developed in relation to testing procedures to ensure appropriate airtightness. Generally there is a low level of awareness, experience and knowledge among architects, designers, investors, contractors and there are no certification requirements imposed for measurement companies.

Although standards for single-zone air leakage tests are widely used, there are no existing standards for several multi-zone cases including: 1) testing air leakage between adjacent zones or 2) testing leakage to the outside from a single unit in a multi-zone building. While a range of test procedures have been used to determine inter-zone leakage using fan-pressurization, the accuracy of the methods can vary significantly. Using field measurements and simulations, we compared the uncertainty in the leakage between two adjacent zones for different measurement and calculation methods.

This paper describes two recent applications of aerosol sealing techniques in buildings for improving indoor air quality and reducing energy required for heating, cooling, and ventilation. One application applies a commercially-available duct sealing technology, which has typically been used in single-family applications, to large-building exhaust systems. The initial leakage rates, percent leakage sealed, and issues encountered are presented for several large buildings.

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.