States direct observations of wind effects on real buildings are necessary for the development of reliable information for wind load estimation. Their essential role is to provide data for the guidance of systematic wind-tunnel investigations. Briefly reviews instrumentation used in a particular tall building and the methods employed to interpret the measurements. The review illustrates the potential, as well as some of the problems of field measurements in providing practical information about wind loading phenomena. Summarizes results and discusses their implications for design.
Reports on the air leakage characteristics of the exterior walls of eight multi-storey office buildings in Ottawa. Results of the measurements taken are given and a method for calculating infiltration rates caused by stack action has been developed andis applied to heat loss calculations using the measured wall leakage values.
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.
Describes method for simulating natural wind boundary layer in a conventional, short working section, aeronautical wind tunnel. Boundary layers, which may be as thick as one-half of the working section height are generated by spires at the working section inlet. This approach is used to measure mean wind pressures and pressure spectra on a model of a tall building in downtown Montreal. Measurements are repeated using the long roughness fetch technique for boundary layer generation and results from the two methods compared.
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.
States that to calculate the ventilation characteristics of a building it is necessary to know the shape, planning and dimensions of the building, air leakage characteristics of all elements of the building, aerodynamic coefficients, wind velocity and internal and external air temperatures.
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.
Login