Practical measurement has shown that gasoil and candle flames provide constant tracer gas sources. Suggests their use for meaSuring ventilation. suggests application in temporary dwellings such as caravans, using candle as simulated "people" consuming oxygen and producing heat and carbon dioxide. Describes measurement methods using natural decay exponential equation. Graph illustrates sequence when air change rate fulfills requirements in swedish building code 1975 of 0.5 change/hour.
When attempting to determine heating/cooling requirement of a home a difference in infiltration can drastically affect heating/cooling requirement imposed on air conditioning system. Describes "the super sucker" machine designed to depressurise homes so that infiltration can be measured under simulated windconditions and each area of leakage isolated. Illustrates machine photographically. Gives method of determining air change rates. Summarises test data for several homes which indicatethat infiltration could be effectively reduced by use of various caulking compounds.
Describes different types of weatherstrips and reports ageing and deformation test on strips and tests on air tightness and closing force. Concludes that tubular strips provided the highest degree of airtightness in both windows and doors, while angle strips were only slightly inferior in performance. Air leakage was considerably greater for strips of expanded and foam plastics and fibre strips. Tests on ageing properties indicated that special rubber mixtures such as silicone rubber and epdm were preferable to p.v.c.
Reports measurements of ventilation rate in specially designed low energy office building. Air change rates were measured using sulphur hexafluoride as a tracer gas and air samples were analyzed for carbon dioxide. Gives tables of results. Discusses analysis of ventilation from CO2 data. Concludes that most of the spaces in the building were operating at or above recommended levels.
Treats measurements of ventilation rates in a model building and wind tunnel. 2 types of opening, circular holes and model windows were tested under 2 wind cOnditions. one wind condition was selected to give maximum flow through the model; with theother, ventilation was mainly due to turbulent pressure fluctuations. Illustrates different characteristics of theopenings. Draws comparisons between measurements and theoretical predictions. Discusses use of wind tunnels for ventilation studies. NOTES: A further comment on this paper was published in Building and Environment vol.15 no.141.
States that application of further thermal insulation to house structures increases importance of ventilation heat loss, from around 20% to nearly 50% of total design heat requirement. Any further energy savings will be by minimising ventilation components. On basis of British Gas research results and others, illustrates sources and mechanisms of infiltration to give an insight into problems it may cause in future housing. Treatseffect of weather, ventilation rates. Among conclusions states increasing attention will have to be paid in future toinfiltration.
Notes principle of air change rate measurement using natural growth exponential equation to measure concentration of tracer gas. Experience shows that period required for satisfactory measurement is often periodicity of air change rate. Diagram relates linear and logarithmic scales used in air change equation. Describes use of pre-programmed gas analysis equipment allowing extrapolation to forecast results. Uses microprocessor for evaluation. Also discusses importance of instrument calibration.
Describes sealing houses against air infiltration to allow controlled ventilation. Notes inherent risks in poor ventilation such as high radon content and its associated decay products, poor air quality, moisture, condensation, mould and allergy-producing dust particles. Treats requirements in swedish building code and stipulated minimum air change rate. Comprehensive series of graphs illustrates air change rate as function of wind speed and different grades of building air tightness.
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.
Using nitrous oxide as a tracer, the author made 390 measurements of ventilation rates in seven closed rooms of six houses, in Melbourne, Australia. Half of the observations were taken when the wall ventilators were sealed, in order to explore their influence on room ventilation. Results for each room, grouped in ranges of wind direction and according to whether ventilators were open or closed, are shown as regression curveson plots of ventilation rate against wind speed. The ventilators are shown to have only a slight effect on ventilation.
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