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.
Wind pressure measurements made over a 4 years period on a 34-storey building in downtown Montreal were used to obtain data for checking and improving wind tunnel techniques of modelling flow characteristics of wind and aerodynamic behaviour of buildings. Specifies the major problems involved in making field measurements and in comparing them with wind tunnel measurements. Comparisons with model measurements are made. Examples have been found of excellent agreements, but for some wind directions the comparisons gave unsatisfactory correlation.
Discusses current knowledge concerning wind-induced ventilation in buildings. states major difficulty in estimating ventilation and infiltration rates in a building is ignorance of wind pressure distributions around structures. Examines properties of wind with special reference to mean velocity profiles, characteristics of turbulence and wind energy spectrum. Reviews internal and external pressure distributions on an isolated building. Studies effect of grouping of buildings on pressure distribution around a house by considering results of wind tunnel tests.
Reports a theoretical study of natural ventilation made jointly by HVRA (UK) and Institute for Public Health Engineering TNO (Netherlands). Uses analogue and digital computers, and results so derived were used to produce a design method suitable for rapid assessment of the natural ventilation of projected buildings. Shows this method to be quicker, cheaper, and more accurate than the crack method (measured leakage at windows and doors) or the air change method.
Treats measurements of air infiltration rate in 2 mobile homes - one treated with caulking, the other with continuous sheathing board - over entire heating and cooling season. Concentrates on summertime data. Summarises results in graphs and tables. Analyses results to find general parabolic dependence on wind and linear dependence on temperature difference. In addition data exhibit marked reduction of infiltration attributed to use of continous sheathing board.
Presents a review of the problem area relating to unintentional ventilation, with special reference to the significance of this phenomenon with regard to the heat balance of buildings. It also contains a list of research tasks which the authors consider to be urgent. Factors which affect unintentional ventilation are discussed, such as wind and temperature conditions outdoors, permeability of the climate envelope of buildings, flow conditions on rooms with known rates of air supply and known temperature conditions, air movements in a flat and in the entire building.