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Knowledge of the amount of air leaking into a building through the various building components is important for a wide variety of reasons. Initially the interest in these values was so that estimates could be made on the amount of energy to be added or removed to heat or cool air that was infiltrating into the structure. Selection of new and replacement building materials was done partially on the amount of energy costs that would be saved by the selection of that component.
More recently however as structures are being built to tighter standards in order to conserve energy, there has been an increasing interest in determining the air flow though building components in order to predict the amount of outside air entering the structure through the building envelope. There is a need to be able to estimate the air leakage in a building envelope in order to estimate the forced ventilation which might be required in the structure. These values are also used by designers as they locate the leakage for ventilation purposes. Rather than sealing the structure airtight and going back and installing openings at the desired locations, if we were able to accurately predict the leakage it would be possible to design the envelope with sufficient (but not excessive) leakage.
As more locations have energy and indoor air quality codes and standards being applied to buildings in their jurisdiction, it will be even more critical to have good estimation methods to predict the amount of leakage in a structure. This will be important not only for the code enforcement official who might be applying a performance based code but also for designers and builders attempting to meet performance requirements. It is even more important for those developing prescriptive codes and standards since they must know a-priori that their specifications will meet or exceed the desired leakage recommendations.
The establishment of the appropriate air leakage value to use for the various components is not an easy task. There has been much discussion about testing techniques, values to be used and the accuracy of the data. The problem is confounded even further when it is considered that many of the air leakage components or sites are manufactured on the construction site and not on an assembly line where quality control can be maintained.
Therefore the goal of this research was to evaluate the existing data of component leakage and determine an appropriate technique to enable the estimation of potential rates of air leakage through various building components.