Reports investigation of air change rates in two residences using helium as a tracer gas. Gives results of measured air change rates, wind speed and direction and internal to external temperature difference. Uses statistical method to compare results from the two residences and concludes that temperature coefficients were statistically different but that wind coefficients were not. Finds high dependence of infiltration rates on indoor to outdoor temperature difference and that values for air leakage obtained from current methods of estimation were lower than those actually experienced.
Describes experiments made to determine the air infiltration rate through revolving doors. Estimates infiltration by combining air leakage past the door seals with infiltration caused by the revolving of the door. Finds that air exchange depends on door speed and temperature differential and somewhat on wind and indoor air velocities. Gives flow past the door seals as function of indoor -outdoor pressure differential and flow related to door movement for a motor- driven revolving door and for a manually operated door for traffic rates up to 2000 people per hour.
Gives measurements of air infiltration made in ten houses in Indiana using helium as a tracer gas. Assumes linear dependence of infiltration rate on temperature difference and wind velocity and calculates infiltration rate per unit crack length. Change rates ranged from about 0.6 to 1.5 changes per hour.
Reviews methods of measuring infiltration rates. Describes tests made on a mobile home using carbon monoxide as a tracer gas and measuring the rate of decay. Concludes that infiltration rates depend primarily on whether or not the blowers for air conditioning or heating are turned on. Without blower the infiltration rate was of the order of 0.8 changes per hour, with the blowers it was 1.2 to 1.7. Reported linear dependence of infiltration rate on temperature difference but did not identifya dependable trend on the effects of wind.
Describes how ventilation rates in two houses with recirculating air distribution systems were monitored by injecting CO2 tracer gas into the supply and measuring its concentration in the return air. In one house with solid concrete floor, normal windows and air bricks, ventilation rates were mainly dependent on wind speed. In the other with suspended timber floor and weatherstripped windows ventilation rates were much lower and mainly dependent on internal to external temperature difference.
Developes mathematical model of air infiltration based on crack flow equations. Describes measurements made on test house. Shows that actual pressure distributions in walls deviate considerably from values in guidebooks. Finds background leakage area of house by pressurizing house with electric fan and measuring pressures. Suggests two distributions for leakage areas. Measures infiltration rate using helium tracer gas, recording temperature and pressure differences. Concludes that comparison between prediction and experimental results is encouraging.
Measurements of the dynamic heat transfer in a four-bedroom townhouse were made under controlled conditions in a large environmental chamber to explore the viability of a computer program developed at N.B.S. labelled NBSLD for predicting heating and cooling loads and inside temperatures. Test house was factory-produced, of modular design and lightweight (wood) construction. Tests were performed with simulated outside summer, winter and autumn diurnal temperature cycles. Inside temperature was maintained at 75 f and the activities of a six-member family were simulated.
Reports pressurization tests on eleven schools both with the air handling system on and with it off. Obtains air leakage through components of the building by comparing overall leakage rates before and after sealing each component. Uses leakage rates to calculate air infiltration using a simplified model of a school building. Finds that infiltration caused by stack effect is significant even for a single-storey building.
Reports theoretical and experimental calculations of heat balance of 5 houses. Discusses the extent of air leakage and various factors contributing to heat losses, particularly effects of wind and winter temperatures. Normal air leakage is 0. 5-0.7 air changes/h, mainly through chimneys, air outlets, window, and door cracks. Air leakage of floor, door, and roofs is 0.1-0.2 air changes/h. in winter, temperature differences have the same influence on ventilation as wind velocity. Measurements in attics show 3 air changes/h. This is largely dependent on wind velocity.
Points out that difficulty in calculating fortuitous ventilation in buildings caused by infiltration means that energy demand of a building contributed by it is scarcely ever known. Provides equations describing infiltration due to pressure differences, which in turn are caused by wind conditions, inside/ outdoor temperature differences and possible influence of mechanical ventilation systems. Describes computer program developed in Finland to calculate air infiltration. Demonstrates infiltration rates in houses.
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