fan pressurization test

Improving the knowledge on uncertainty for fan pressurization measurement is of first importance. It allows to assess the reliability of the measurement, which is essential when comparing the results with benchmarks or standards, but it also gives a better understanding, and thus a chance of improving, the measurement procedure. In this context, recent studies on alternative regression techniques highlights the importance of identifying and quantifying the sources of uncertainty.

Addressing the airtightness of the building envelope is key to achieve thermal comfort, good performance of ventilation systems and to avoid excessive energy consumption. Previous studies have estimated an energy impact on infiltration on the heating demand between 2 and 20 kWh/(m2·y) in regions with temperate climates. In Spain, this issue has not yet been addressed in depth. This study aims to assess the energy impact of uncontrolled air flows through the building envelope in residential buildings in Spain.

Uncertainties in airtightness measured using fan pressurization test should not be defined by the scattering of the points around the line defined using ordinary least square method anymore. Its definition requires first to know the uncertainties in pressure and airflow measurements. This works aims at quantifying one of the component of the envelope pressure uncertainty: the uncertainty in zero-flow pressure approximation due to short-term fluctuation of wind speed and direction.

The air leakage impact on energy performance in buildings has already been broadly studied in USA, Canada and most European countries. However, there is a lack of knowledge in Mediterranean countries regarding airtightness. An extensive study has been carried out in order to characterize the envelope of the existing housing stock in Spain. Preliminary results of more than 401 dwellings tested are shown. The sample includes different typologies, year of construction and climate zones. Blower door tests were performed and thermal imaging was used to locate leakage paths.   

It has already been proved that air leakage causes a great impact in the energy performance of buildings in cold climates. In recent years, many studies have been carried out in northern Europe, US and Canada. Regulations in these countries establish maximum air leakage rates for the construction of new dwellings and the refurbishment of the existing ones. However, there is a lack of knowledge relating to the housing stock in Spain.

This paper presents the new framework for the realization of reliable pressurization tests in Belgium and the provisions taken to widen the number of buildings where a valid pressurization test can be realized.

Airtightness becomes a more and more important parameter in the rationalization of the energy consumption.  The quality of the works during the construction process is essential. However, this particular step is on itself absolutely not sufficient to build airtight buildings. Airtightness has to be taken into account from the pre-project. For that, architects have to deal with a large bunch of items. Steps as the definition of the ambition level, the precise positioning of the airtightness barrier into the building are essential.

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.