Natural ventilation of buildings

Reports model scale experiments to investigate the validity of digital analogue methods of predicting natural ventilation. Finds calculated ventilation rates up to 30% higher than observed model ventilation rates. Shows differences between observed and computed results caused by operating efficiency of ventilation openings being less than calibrated efficiencies. Corrected ventilation rates, allowing for changes in efficiency due to pressure fluctuations and lateral air flows over model surfaces showed close agreement with observed results.

Air leakage in buildings

Examines ways in which air leakage affects building performance. Heating load and building relative humidity in winter are affected by over-all air infiltration and ventilation rates. Windows and doors usually represent the major source of air leakage in buildings. Condensation problems occur when exfiltrating air deposits moisture on surfaces such as atticsand inside double windows. Discusses ways of reducing condensation. Finds that air tightness in inside of enclosure must always be many times greater than that of the outer cladding.

Air infiltration in buildings due to wind pressures including some neighbouring body effects.

Developes procedure for calculating air infiltration rates due to wind pressures on the exterior walls of buildings, assuming no chimney and mechanical ventilation effects. Assumes resistance to internal air flow is small. Using results of wind tunnel test, presents calculations showing the significant effects a single neighbouring building can have on the infiltration rates. Relative building heights, distance between buildings and wind direction are varied, and both uniform and shear flows are considered.

Joints in building-method of test for the resistance of joints to air penetration.

Gives standard test method for air leakage of joints between components used in the exterior walls of buildings. Outlines basic apparatus and test method. Resistance to air penetration shall be recorded expressed as cubic metres of air per hour.

Model simulation of wind effects on structures

Sets out the similarity requirements which must be observed so that results of wind tunnel tests may be used to predict behaviour of full-scale prototypes in the natural wind. Discusses rigid models, suspension bridges, models of slender towers. Outlines problems of representing natural wind and the effect of wind tunnel-wall interference. Introduces correction procedure for wake blockage which permits the use of larger wind-tunnel models than would otherwise be possible without serious errors.

The application of the boundary layer wind tunnel to the prediction of wind loading.

Discusses use of long boundary layer wind tunnel to produce a more realistic model of natural wind than that obtained in conventional aeronautical wind tunnel. Reports tests made tofind wind velocity profile and model tests to find dynamic response to wind loads and local pressures on buildings. Finds aeroelastic model response in turbulent flow is markedly different from that in smooth uniform velocity. Concludes that adequate simulation of natural wind has been obtained. Finds comparison between model and full-scale tests is encouraging.

Some effects of shelter-belts and wind-breaks.

Reviews work done on the physical and biological effects of wind-breaks and shelter-belts, outlining main results. Discusses reduction in mean speed of wind, turbulence produced by shelter-belt, shading and humidity. Outlines some biological consequences of shelter-belts. Gives bibliography containing forty-seven references.

Air leakage characteristics of low-income housing and the effectiveness of weatherization techniques for reducing air infiltration

Reports measurements of air change rates made on approximately 250 dwellings, occupied by low income households in 14 cities, in all major climatic zones of the United States. Two types of measurements were used : a tracer-gas decay technique using air sample bags and a fan depressurization test that measures induced air exchange rates. Shows that for this group of dwellings natural air infiltration rates have an approximate lognormal distribution.

The dependence of wind loads on meteorological parameters.

Discusses problem of assessing wind loads on buildings. Describes general properties of the wind and suggests wind can be described by its mean velocity with superimposed gusts. Suggests averaging period of 10-15 minutes for the mean velocity. Gives empirical expression for wind spectra. Considers relationship between extreme value of wind speed and the parent distribution. Suggests influence of gusts is not best determined by maximum gust speeds. Finds mean wind speed profile and turbulent structure are strongly dependent on terrain.

Model law and experimental technique for determination of wind loads on buildings.

Describes experimental techniques used to produce turbulent boundary layers in a wind tunnel. Gives model law for velocity profile in a turbulent flow over a rough surface. Describes wind tunnel, five tunnel coatings used to generate turbulence, themodels and instrumentation. Gives as an example the test results from a model of house with desk roof.

Pages