modelling

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.

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.

Reviews the main mechanisms giving rise to natural ventilation of spaces with openings to outside air on one wall only. These are temperature difference, pressure fluctuation, mean pressure difference, turbulent diffusion and the "vane" effect. Derives expressions for the magnitude of the ventilation rates caused by each of these mechanisms. Reports wind tunnel studies of the ventilation rate in a small test chamber ventilated through one opening only. Air change rates were measured using a tracer gas.

Conducts series of tunnel tests to examine ways in which wind influence air infiltration energy losses in housing. Develops qualitative model for air infiltration based upon a linear relationship between air flow and pressure difference across walls and roof surfaces. Tests a variety of wind-house orientations with the model. Assesses and compares sheltering effects provided by solid fences, adjacent houses and tall evergreen trees. NOTES See also later study by Mattingly et al. abstract no.187

Points out that ventilation heat loss can account for 50% of total loss in a well-ventilated house. Presents analysis of mechanics of natural ventilation. Describes computer-based model developed by British Gas Corporation for predicting ventilation patterns in houses. Uses calculations applying the method to illustrate basic reasons why natural ventilation is likely to cause problems in heating well-insulated dwellings. Discusses these problems in detail. Treats how ventilation could affect sizing of appliances and indoor thermal environment.

Reviews mechanism of natural ventilation. Provides mathematical expressions for wind pressure distribution, stack effect, and air flows. Treats air leakage component's characteristics, both individually and connected in series or parallel. Employs model simplification to 1 and 2 Junctions. Illustrates a 1-Junction model calculation. Finds calculated and measured values agreed well for a large factory hall.

Presents documentative report of findings of research into effect of weather on internal environment in buildings. Presents results to promote their further application. Defines problem as that of applied meteorology and illustrates its distinguishing features. Evaluates physical assumptions made in establishing mathematical model. Notes limitations of results. Presents worked solutions for numerous locations in USSR and discusses way of improving calculation methods. Indicates direction of further research.