air tightness

The developing trend that Building Regulations in the future will be applied to buildings in use rather than to their design intent on paper has many important implications. It will lead to pressure testing of new buildings to ensure air tightness, low energy bills and the associated absence of draughts. Importantly, it means that for the first time, the ventilation air will enter the building through the air inlet ductwork. This offers the designers the opportunity to control the indoor environment to create refreshing comfortable climate while retaining low energy use.

As heat exchanges through building envelopes and undesirable internal gains have been reduced in the last years due to energy conservation efforts, the importance of the energy needed to heat, cool and move outdoor air for ventilation has increased in relative tem1s. This study, developed within the European project TIP-VENT (JOULE) aims to study the impact of ventilation air flow rates upon the energy needs of typical buildings. Five real buildings were selected as case-studies: A hotel, an auditorium, an office building, a single-family residence and an apartment building.

This paper summarizes the most recent results from an ongoing, multi-year research program to monitor the long-term performance of residential air barrier systems. Airtightness tests were conducted on I 7 houses, located in Winnipeg, Canada, ranging in age from 8 to I I years, for which there was extensive historical data. Eight of the houses used polyethylene air barrier systems and nine used an early version of the airtight drywall approach (ADA). The latest tests were conducted in 1997.

Whole-house tests were developed to compare the airflow resistance of several different materials used to seal the walls of a house at the outer surface. These airflow resistances were measured infield installations and include the effects of interactions with adjacent materials and assemblies. The materials tested were housewrap over fiberboard and foam sheathings, extruded polystyrene foam sheathing with the edges taped, extruded polystyrene sheathing with the edges untaped, and caulking and foaming the inside of the wall cavity.

The purpose of this project was to devise a simple, experimentally validated method for quantifying the energy impacts of exterior envelope air leakage. Four full-size exterior envelope test specimens, two opaque wall systems and two fenestration systems, were built for determining simultaneous conductive and convective heat loss. The two opaque clear wall sections were metal-faced sandwich panel and cold formed steel frame.

The methodology of risk analysis and assessment is reviewed and applied to study the reliability of condensation control measures in lightweight building envelopes. It is generally recognized that airtight construction is an essential part of condensation control. Nowadays, different air barrier systems are developed and documented to prevent air leakage and moisture accumulation in the envelope. But does this mean that the condensation risk is sufficiently minimized and that the protective system is reliable?

A field measurement study of the airtightness of 73 - less than 5 year old - French dwellingswas led between 1999 and 2000. Buildings have been selected and classified according to theconstruction structure, the thermal insulation and the occupancy mode. Using a fandepressurizationtechnique, we assessed the air leakage rate of each dwelling with twodepressurization tests. Meanwhile quantifying air leakage rates, we observed qualitatively themost frequent locations of air leakage paths using a smoke detection method and infraredthermography.