English

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.

After discussing briefly the principles of natural ventilation, goes on to describe tracer gas techniques, air movement measurements, and various model techniques including analogues. Advantages and disadvantages of each method are indicated, andtheir suitability for particular applications.

Assuming higher than probable cd values for crack length openings on calculation of infiltration rates results in excessive allowances for heating and cooling capacity. Using a given cd graph, proposes equation to determine infiltration rates and reduce internal pressurization requirements to offset wind impingement.

A number of cases of water and frost damage in masonry and non loadbearing walls have been examined. This damage could not have resulted from vapour diffusion or rain penetration and is primarily caused by condensation due to exfiltration of air. Air exfiltrates through the many cracks and joints and in this connection the result of chimney action and wind is explained in some detail, including the pattern and magnitude of building pressure differences that induce ex-filtration together with a discussion regarding the moisture that is transferred.

Using nitrous oxide as a tracer, the author made 390 measurements of ventilation rates in seven closed rooms of six houses, in Melbourne, Australia. Half of the observations were taken when the wall ventilators were sealed, in order to explore their influence on room ventilation. Results for each room, grouped in ranges of wind direction and according to whether ventilators were open or closed, are shown as regression curveson plots of ventilation rate against wind speed. The ventilators are shown to have only a slight effect on ventilation.

Outlines the development of current ideas of effective ventilation from early 19th century when official (U.S.) requirements were unduly high due to misconceptions in health requirements. Examines current requirement.

Gives survey of humidity in Canadian homes indicating that humidity depends primarily on outside conditions but is influenced by the ventilation habits of the occupants and moisture storage by hygroscopic material. The difference between indoor and outdoor humidity ratios gave an estimated ventilation rate of 0.44 charges per hour. Resultant indoor relative humidity level is between 25 and 30% on average and approaches the maximum humidity attainable without condensation on double-glazed windows.

Analyses wind pressure records, taken during 5 different windstorms on 2 levels in a 400ft (122m) high office building in downtown Montreal March 1964 pressure fluctuations on an actual building. Preliminary work done to compare full-scale measurements with wind tunnel measurements indicates that simulation of basic statistical properties of wind pressure fluctuations can be successful when carried out in a boundary layer type of wind tunnel.