Ventilation rates in two test home were measured using helium as a tracer gas. Pressure differences across the exterior walls of the house were recorded using pressure taps. Gives results for air infiltration tests and the calculated air infiltration. Finds that during summer air infiltration rates varied approximately linearly with wind velocity. During the winter, the pattern and extent of air infiltration were influenced by both house stack action and furnace operation.
Gives theoretical discussion of the neutral zone in ventilation. Shows that the pressure difference tending to cause flow at any opening is proportional to the vertical distance of that opening from the neutral zone and that the amount of air that may be passed by a given opening is proportional to the square root of the vertical distance of that opening from the neutral zone.Discusses the position of the neutral zone in a building which is governed by the relative amount of opening at top and bottom and by the inside to outside temperature difference at different levels.
Explains forces causing stack effect in multi-storey buildings and suggests ways of reducing air leakage. Mentions that stack effect makes the operation of doors difficult and interferes with the operation of dampers.
Gives method for calculating infiltration of a building due to wind and stack effect. Uses equations from ASHRAE guide of 1958, but resolves wind vector into horizontal and vertical components and takes the angle between wind and ground into effect. Method is used to calculate infiltration due to wind for a given building of height h at a distance d from the nearest building with height c and a sample calculation is given
Discusses theoretical pattern of pressure differences inside a tall building and describes measurement of pressure made on anine-storey building in Ottawa. Pressure differences were measured across external walls, vertical shafts, stairwell doors and elevator doors with the mechanical ventilation system both on and off. Concludes that pressure differences across external walls depend on the distribution of openings in the exterior wall and of the ratio of resistance to air flow inside the building to that across the exterior wall.
Describes measurements made of wind speed and direction and pressure differences across the exterior walls of two multi-storey buildings in Montreal. Regression coefficients are obtained and show better correlation for higher levels than forlower ones and for the taller building "A" than building "B", indicating that shielding by adjacent buildings has an important effect. The variation in wind velocity between the site and a meteorological station was recorded.
Describes a method of analysing the stack effect on a multi-storey building. The building is divided into zones and a computer programme calculates air-flow and pressure for each zone. Analysis is given for an example hypothetical building under different temperature, wind and air leakage conditions. Shows that the method can be used to evaluate the difficulty in opening doors due to pressure differentials and the noise resulting from air flowing through cracks around doors.
Discusses the factors affecting air change rates in multi-storey buildings and derives expressions for the air infiltration through walls, windows and doors; air flow through gravity ventilation ducts; pressure pattern on the outside walls of the building and the "chimney draught" in the staircase. Derives mathematical model for calculating the air balance for a building with gravity ventilation ducts. Concludes that chimney draught (stack effect) has a large effect and that proper design of the extraction gravity ventilation system is very important.
Describes measurements of heat flow taken in three rooms at different heights in a multi-storey office building. Heat supply, internal to external temperature pressure differences, wind velocity and sunshine were recorded. Gives result that it needs more heat to maintain the same room temperature on lower floors than on upper floors. Difference is that heat needed on 32nd floor is approximately 40% less than that on 8th floor.
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.
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