air leakage

Describes results of computer study of behaviour of 2 better insulated houses, one of rationalised traditional and one of timber frame construction. Compares their performance with a contemporary house. Provides most important results regarding mode of operation and effects of air leakage. Concludes that better insulation is effective energy conservation measure but heavyweight characteristic of insulated structures result in intermittent heating being a less attractive means of reducing heat demand. Air leakage, if not controlled, becomes animportant component of the total heat loss.

Presents method for establishing conditions and an acceptance criterion for window air-tightness testing in relation to average energy (heating) saving per winter. Uses wind velocity data from israeli meteorological station of Ashdod to demonstrate difference between various methods of evaluating design wind velocity. Uses 41 different typical dwellings to determine unique criterion for acceptable air leakage under test conditions which ensures average of 1 air change per hour in most Israeli dwellings.

Points worthy of consideration regarding air leakage, i.e. the causes, identification, problems and remedies are briefly discussed generally without technical details and some illustrations are given of problems. Air leakage is common in most buildings, but with increasing standards of performance and the trend to taller buildings, it is becoming less tolerable. Reference is made to other CBD reports in which details are specified. The positive control of air leakage can only be achieved by careful attention in design and adequate inspection during construction.

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.

Describes experimental method of determining air leakage characteristics of exterior walls of a building. Method involves pressurising the building with the supply air system and measuring flow rates of outside supply air and resultant pressure differentials across building enclosure. Uses results to obtain flow coefficient and exponent for exterior walls. Checks method by results of computer simulation of a building, finding good agreement.

Reports results of series of tests on 6 single-family houses to determine rates of overall leakage through windows, doors, walls and ceilings. Uses vane- axial fan to reduce pressures inside house and measure flowrate and resultant pressure differences across house enclosure. Purpose of tests was to assist in eliminating rates of air infiltration in houses.

Summarises results of research project comprising survey of air tightness and natural air change rates in various types of residential building. Briefly describes equipment for pressurization tests and tracer gas measurements. Compares properties, range of measurement and cost of 5 different tracer gases. Provides some results from measurements in 53 single family houses and 28 flats. 9 of tested dwellings had their tightness improved and supplementary measurements made.

Describes pressurization method of measuring air leakage using a fan installed through an open window. Gives results of survey of 24 houses. Humidity, meteorological parameters, indoor particulate levels, measured equivalent leakage areas and other information were recorded. Finds that tight houses tend to havehigher humidity, that leaky houses require more heating energy and that houses where smoking takes place have higher air pollution levels than others.