English

Reports conclusions from projects investigating the tightness of buildings sponsored by the Ministry of Trade and Industry. Describes factors influencing ventilation such as size and shape of building, location, distribution of leakage points, interior air flow paths and the design and control of ventilation. Wind condition and temperature difference are the only driving forces in natural ventilation, in mechanical ventilation the temperature has only a limited influence but the wind may cause considerable draught in an untight building.

Reviews the energy conservation features employed in most low energy houses in the Prairie region including airtightness (by application of a vapour barrier), increased thickness of insulation, air-to-air heat exchangers and south-facing windows. Discusses the performance of low energy houses in Saskatoon, and the cost of energy conservation features.

Discusses the possible effects of wind, stack effect, vents and fans on air leakage, and the influence of air leakage openings and the location on the pattern of air flow through buildings. Considers the possible extent and location of condensation in relation to these patterns, as well as methods of controlling moisture entry and removal of accumulated moisture.

Studies the effects of permeability on the wind loading on a building. Compares experimental results from wind-tunnel tests with theoretical methods for estimating the mean and fluctuating internal pressures for various permeability. Observations show that the internal pressure can be estimated from known external conditions in terms of mean RMS and spectral values to a reasonable level of accuracy for the case where the permeability consists of circular apertures. Effects on the external pressure distribution due to permeability are found to be significant under certain circumstances.

Describes a series of experiments performed on a residential attic under controlled laboratory experiments to obtain a better understanding of attics and attic insulation. Studies type and level of ceiling insulation, mean temperature and heat flow direction (summer v winter) and ventilation rate Describes the experimental set-up and the weather conditions simulated. Gives details of the mathematical models of thermal performance that are developed from finite difference analyses of the ceiling-insulation system. Compares experimental results with the predictions of these models.

During winter experiments in central Pennsylvania a windbreak, 61 metres long and composed of a single row of white pine trees, significantly reduced air infiltration rates and space heating energy needs in a small mobile home by upto 54% and 18% respectively. Greatest reductions in air infiltration rates occurred with the home at one windbreak height (1H) downwind, even though maximum reductions in wind velocity occurred at 2H or 4H downwind. Space heating energy savings were less sensitive to downwind position, with maximum energy savings measured at both 1H and 2H.

Reviews the mechanism of air infiltration as a background for introducing a procedure that yields more reliable estimates of average infiltration rates through a window unit than do methods currently employed.The procedure is applied to estimating the average winter heat losses through windows in low-rise residential buildings variously located through out the US. Concludes that, regardless of climate, the heat loss attributable to infiltration through the window unit is small compared with that incurred as a result of direct transmission of heat through the window.

Reports on some current projects in the UK using a certain type of CO2-controlled ventilation system, the "Builiding Breathaliser". This system has been installed in lecture theatres at the University of Kent, BHS department stores and cinemas owned by Rank leisure.

Grab sampling of a tracer gas/air mixture in conjunction with the tracer gas decay technique is a convenient method for conducting a survey of air infiltration rates in homes. Examines such a method, using SF6 as the tracer gas and storing the concentration in evacuated glass tubes.

A wind-tunnel model study of the experimental building at Aylesbury, England has been conducted at scales of of 1:25, 1:50 and 1:100. Compares model results with those obtained in other wind-tunnel studies and with full-scale values obtained by the Building Research Establishment at Aylesbury.