infiltration

The most representative typology of residential buildings of Catalonia has been simulated in TRNSYS to evaluate the impact of both infiltration and natural ventilation. The typology is a block of apartments constructed during 1950-1980. 

Over three million subsidised dwellings were built in Spain between 1940 and 1980. Most of these buildings are now obsolete and fail to comply with thermal comfort and ventilation standards. A building's existing energy performance, including its airtightness, should be determined prior to conducting low-energy refurbishment, for those factors, particularly the latter, impact thermal comfort, energy demand and indoor air quality (IAQ) fairly heavily.

We have analysed the steady wind model error based on a simplified building model with one leak on the windward side and one on the leeward side of the building. Our model gives an analytical expression of this error that depends on the leakage distribution and pressure coefficients. Using a test pressure of 50 Pa in this model, standard measurement protocol constraints contain the steady wind model error within about 3% and 11% with wind speeds below 6 m s-1 and 10 m s-1, respectively. At 10 Pa, the error is in the range of 35% and 60% at 6 m s-1 and 10 m s-1, respectively.

Mechanical positive input and extract ventilation are common strategies employed in English houses, generally because they provide adequate indoor air quality and specifically because they are effective at minimizing mould growth and its associated negative health consequences. Air is either exclusively supplied or extracted (never both) by a mechanical system at a prescribed airflow rate designed to ensure adequate indoor air quality.

The mixing of a tracer gas with zonal air was compared between two zones in an unoccupied test building in both the horizontal and vertical direction. A constant injection of sulphur hexafluoride (SF6) tracer gas was released into each zone separately and its concentration was measured at different positions within the zone. Variations in concentration were observed for different horizontal positions in the southern zone indicating incomplete mixing.

The aim of the project was to evaluate how the air tightness of buildings changes over time and how the sealing materials are affected during the expected life length of 50 years. The project was divided into two parts were one was laboratory tests of different products with accelerated ageing, and the other part were evaluation of older existing buildings. The laboratory test was conducted in a temporary room with lightweight construction in wood and different sealing products. The room was then heated to 80 °C and had changing relative moisture content in the air.

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.

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.

Air quality in the office room areas, as well as their energy demands for heating and cooling are directly depended on the ventilation levels in those rooms. Specifically, high internal air quality requires high levels of ventilation and therefore high energy demands. On the other hand, high energy savings can be accomplished by full building impermeability, which means low to none ventilation and at the same time low air quality.

The importance of adventitious air leakage under normal operational conditions and its reduction in order to save energy is highlighted by the relvant building standards of many countries. This operational leakage is often inferred via the measurement of air permeability, a physical property of a building that indicates the resistance of its fabric to airflow. A building’s permeability is the measure of airflow rate through its envelope at a constant pressure differential of 50 Pascals.