Discusses how building ventilation is affected both by steady mean effect of air pressures and temperatures around and within the building and turbulent nature of the wind causing air diffusion through openings and cracks in the building envelope. Studies ventilation of an enclosure with a single opening subjected to turbulent impinging airstream. Derives simple theoretical models to assist understanding of physical phenomena causing air-flow through the opening. Compares these with results of experiments on a large-scale model, states need forfurther work on this problem.
A survey of current methods of calculating natural ventilation and infiltration rates showed that most design recommendations are based on the results of digital analogue studies. As the natural ventilation rate calculation methods reriewed make a number of simplfying assumptions, which have not been experimentally verified, studies have been carried out, using scale model buildings in a wind tunnel, to investigate the validity of these methods. Calculated ventilation rates were found to be up to 30% higher than the model ventilation rates.
Gives series of maps and a chart used to specify performance requirements for windows in the United Kingdom in a simple way. Gives maps for the design wind pressure and exposure grades.
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
Outlines basic requirements for a fresh air supply to a dwelling, which include health, comfort and air for combustion appliances. Discusses feasibility of achieving these requirements by natural and mechanical means.
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.
Claims procedures for design of ventilation and air flow systems are energy wasteful. Cause lies in their methods and technical bases and influence of other factors entering into final systems choice (particularly economics). Discusses outside air requirements. Concludes ventilation rate can be lowered 45% to 50% if higher humidities are used. Proposes new standards based on fact that ventilation rate is independent of air space per person. Analyses air distribution systems and sub-systems in terms of minimum energy requirements.
Reconsiders semi-empirical equations derived from earlier laboratory investigation of flow through cracks. Proposes revised method of application. States equations offer improved technique for estimating open areas of room components. Presents supportive experimental results. Demonstrates implications of the equations regarding scale effect for full-scale and model-scale situations. Presents some results of ventilation rate measurements at model scale to illustrate effects of scale and wind turbulence, flow characteristics of scale model windows and of simple circular holes.
Treats 4 mechanisms of building heat exchange with the environment and their effect on overall energy consumption: 1) air infiltration and exfiltration, pressure distributions and gradients and resulting mass transfer at building surfaces; 2) influence on surface heat transmission of turbulent mixing of air close to building surface and mechanisms causing this mixing; 3) how air circulation around buildings strongly affects air conditioning cooling towers and how incorrect location of ventilation inlets and exhausts can reduce thermal efficiencies of cooling equipment and increase fan power
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