Air change rate is often reported as a single number, with no attention paid to different values of air change rate in different zones of a building. This may affect air quality evaluation as there may be undetected zones where air change rate is too small, resulting in localized pollutant concentrations. Describes a multi-point tracer gas technique used to quantify air change ratein different zones of various residential buildings. Defines and calculates zonal ventilation efficiency terms, and proposes a criterion for analysis of the results for indoor air quality evaluation.
Investigates the reliability of the single-room infiltration model used in the computer program ENCORE. Compares calculated air change rates with tracer gas (N2O) measurements in 25 identical one and a half storey detached houses. Describes the infiltration model, the parameters and some results. Thecomparison shows good correlation at low wind speeds (< 3m/sec) but the model's values at higher wind speeds are too high.
States that the dependence between the energy consumption to maintain a comfortable indoor climate and the average outdoor temperature is close to being linear (at least in the absence of significant passive solar gains). Calls the slope of the graph the energy signature of the building. Such an analysis yields a powerful tool to monitor the energy consumption of a building and thereafter to evaluate the effectiveness of a set of retrofits. Suggests that the energy signature be expressed in units of hourly air change rate.
Describes a simple, inexpensive sampling technique for infiltration measurement using SF6 tracer gas. Uses pre-evacuated blood collecting test tubes with rubber stoppers for sampling. This is controlled by a micro-processor driven automatic sampler, which drives a hypodermic needle through the rubber stopper to fill the tube with an air sample. Analyzes samples using a gas chromatograph. Releases SF6 at ground level in a high-rise cold store and collects samples of air at different heights to see if stratification is present.
Measures air exchange across open cold store doors using an anemometer and by tracer decay methods. Anemometer results show that an empirical factor of 0.68 should be applied to the predictive equation by Tamm. Observes a further reduction in air change rate (about 47% reduction) due to imperfect mixing of the air. Air curtains reduce infiltration by about 75-80% and plastic curtains by approx. 93%. Forklift traffic and internal circulation fans also affect air change rate.
Explains possibilities of saving energy in the area of ventilation. Summarises fundamental theories for calculating air flow through building leaks, ventilators and fan systems which are put in their total context - wind, temperature, air leakage, intentional ventilation, building technology, energy requirements. Treats factors which influence ventilation requirements. Compares results from field studies of actual air change rates with the requirements of Swedish Building Standard 1980.
Uses a two-region model to predict infiltration, to take into account non-ideal mixing of tracer gas in a building. Considers versions of this model:< 1. Fluid flows between the 2 regions and the environment in any manner provided steady state and mass balance are maintained.< 2. There is limited interchange between the regions< 3 Air flows into the first region and out of the second with (unbalanced) interchange between the two.< 4. The second region is a "dead-water" zone, which is not directly connected with the outside.<5.
Describes air leakage and tracer gas (SF6) measurements made in 42 Scottish houses. Finds that leakage in the "test" (better insulated) houses are on average 10% higher than that in the "control" houses. About 40% of the total leakage rate (at a pressure difference of 50 Pa) flows into houses through thefloor boards and the air-bricks under the crawl spaces. Tracer gas measurements indicate that average leakage rates with closed windows lie between 0.52-1.65 air changes per hour. Opening a window can increase the number of air changes by a factor of 2 to 5.
Describes investigations into the air change rate in dwellings with very air-tight windows carried out by the West German Institute for Water Earth and Air Hygiene under a contract from the Federal Building Ministry. Treats the 80rooms investigated in 20 different buildings and in some office type rooms in Berlin. Notes the measurement method and the procedure of evaluating the results. Gives some results in graphs. Summarises the findings of the analysis of the results.
Lists in a table and discusses the chief sources of indoor air pollution. Distinguishes between short term and long term pollution. Provides advice for reducing pollution from various sources. Discusses the minimum permissible fresh air supply rates. Gives recommended humidity values and when, how often and for how long should ventilation be carried out. Recommends 12-15 m3 fresh air per person per hour, with double this rate for physical activity or smoking. States fresh air supply should be monitored to ensure the carbon-dioxide content does not exceed 0.15%.
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