Air infiltration typically accounts for a third of the energy loss in a heated building. The driving forces for natural air infiltration are wind and temperature differences. For a given combination of weather conditions the amount of air infiltration is determined by the character of the building envelope, mainly its airtightness. A useful technique in characterizing this housing quality is to measure air leakage. An air leakage standard for new construction has been in effect in Sweden since 1975.
The relation between air infiltration rate and indoor concentrations of radon gas, radon daughters, and formaldehyde has been investigated for both summer and winter conditions in a number of Toronto houses with low rates of natural ventilation.
ASHRAE is preparing a standard which addresses the maximum air leakage associated with good construction. This standard, 119P, links Standard 90, which addresses energy conservation in new residential construction, and Standard 62, which specifies the minimum acceptable ventilation to achieve adequate indoor air quality. Within Standard 119P there is currently a classification scheme that groups building tightness into categories depending on envelope leakage, floor area and building height.
This paper compares the conventional exhaust system with a supply-exhaust system with regard to the possible degree of control of the air exchange in the individual rooms. Ventilation efficiency and air exchange efficiency are defined and some examples show the local concentration, mean ventilation efficiency and mean air exchange efficiency for some simple ventilation schemes. Exhaust systems require a very tight building with small make up air openings. The ability of the different systems to avoid leakage out from the building of indoor air is also compared.
In this paper, an empirical method is proposed which qualifies the thermal performance of buildings through the entire year. The thermal quality parameter (BTPI) is intended to be an instrument for the implementation of new energy regulations for buildings, especially for those that are located in areas with mild climate and no heating or air conditioning systems. Portuguese climatic zones are typified for summer and winter and predominance factors for seasonal loads are defined.
One option of reducing residential energy consumption is to improve air tightness but adequate ventilation must be provided for health reasons. Sources of infiltration and factors affecting infiltration rates are described, with methods for quantifying and comparing rates. The relationship with air quality is explained and the effect that air quality has on respiration and health. Typical indoor pollutants are carbon monoxide, carbon dioxide, nitrogen oxides, radon and radon progeny, formaldehyde gas, particulates, tobacco smoke and odours.
In discussion of air infiltration, we must consider air leakage flow, air change, air changes per hour at 50Pa, the surface permeability coefficient, the component permeability coefficient and equivalent leakage area. Air change and air leakage data are given for multiple family houses, single family houses, offices, industrial buildings and single cell elements.
Briefly notes the significance of ventilation heat losses for energy consumption. Notes the main sources of air pollutants in indoor air and the recommended fresh air rates per person for housing, for smokers and non-smokers. Notes the need for a well-sealed facade with mechanical ventilation and for judicious facade leakiness in the absence of mechanical ventilation. Notes the long-term need is for improved control of air infiltration. Notes briefly the AIC publication "Air infiltration control in housing".
Login