English

Outlines projects at the Division of Building Research to carry out extensive field observations and studies of loads particularly snow loads on roofs and wind pressures and suctions on walls of high-rise buildings. Describes major features of this work including observation methods and some of the results.

Reports an indoor/outdoor sampling program for NO, NO2 and CO in four private houses which had gas stoves. Pollutant gases were measured essentially simultaneously at three indoor locations and one outdoor location. Shows that indoor levels of NO and NO2are directly related to stove use. In some instances levels of NO2 and CO in the kitchen exceeded the air quality standards for these pollutants if data for the sampling periods were typicalof an entire year.

Describes method of estimating ventilation rate using organic vapours as tracer gases and ultra-violet absorption to measure concentration. Gives table of absorption of different vapours. Suggests estimation using a test paper. This method is less precise but requires a minimum of apparatus.

Briefly reviews methods of estimating infiltration rates in dwellings. Describes tracer gas method using methane. Gives results of measurements of air change rate made in houses in Minneapolis, Kansas and Denver. Concludes that technique works well for measuring residential infiltration.

Reports some results of field measurements of radon levels in apartments and houses and shows that summer measurements with high natural ventilation rates are generally lower than winter measurements. Suggests exhalation of radon from building materials can be studied by placing samples of material in closed vessels and following the growth of activity in the vessels. Shows that a ventilation rate of one air change per hour will lower the theoretical maximum level to 0.008 of the unventilated maximum value.

Radon is a radioactive gas which diffuses naturally from all mineral based building materials. States for most homes, concentration of radon is approximately inversely proportional to the ventilation, although this is not valid for very low or very high air change rates. Gives brief results of measurements of concentration of radon in dwellings. Outlines health risks from radon and daughters. Reviews norms laid down in some countries for specific situations. Discusses ways of reducing radon concentrations.

Describes a photo-electric technique for instant determination of contaminant concentration in wind tunnel studies of stack gas dispersion. A roving sensor is used to measure the light scattered by the particles of oily aerosol representing theprototype stack effluent. The minature probe has a noise level of only one hundred thousandth of the full linear range of the output signal for a time constant of 5s. Device is also suitablefor measurement of fluctuating flow properties, such as turbulence, where a high frequency response is required.

Reports investigation of the relative effectiveness of wall gratings and flues as means of naturally ventilating unheated closed rooms. Ventilation rates of several rooms were measured using carbon dioxide as tracer gas and wind speed and direction were recorded. Presents results and finds for the flue, ventilation increased with wind speed irrespective of direction. For grating, ventilation rate increases slowly with size of grating and is dependent on both wind speed and direction. Concludes flue with base opening of 15 sq.ins. is as efficacious as grating having 50 sq.ins.

Reports measurement of wind pressures on Royex House, a multi-storey building in London. Reports that suction loads on cladding are more severe than had been indicated by wind tunnel tests. Face-on winds produce the maximum structural loading with whole of peak load on windward face.

Reports tests using a natural exposure rig on a number of designs of horizontal and vertical joints employing labyrinths to separate the air and water entering the joint. Results obtained under a limited range of conditions show that it is possible, with suitable designs, to prevent penetration of water without necessarily making a joint airtight. Puts forward a number of potential applications, including a prototype window.