ASHRAE's first ventilation standard, published in 1973, has been used in many building codes in the USA. The 1981 revision of this standard has been criticised for its approach to indoor air quality. A comparison of the '73 and '81 standard, currently underway, is expected to better explain the rationale and provide new support for controversial parts of the standard.
Ventilation is widely used to help maintain acceptable indoor pollutant concentrations. In this paper, the relationships between ventilation rate and indoor concentration are examined by the use of mass balance models and measured data. It is shown that the pollutant source strength and pollutant removal by processes other than ventilation can have a large impact on the indoor concentration and that maintenance of a typical ventilation rate does not ensure an acceptable indoor concentration.
The paper proposes a methodology for evaluating and ranking specific alternatives for control of indoor air quality in existing buildings, based on comparative costs and benefits. The method avoids the difficulties of assigning a monetary value to a change in air quality by adjusting the air exchange rate in each alternative until equivalent indoor air quality is achieved. The difference in air exchange rates between alternatives allows calculation of energy savings, which can be compared to capital cost savings,which can be compared to capital cost using the payback period method.
When indoor air concentrations from indoor combustion processes are estimated, source strengths and ventilation rates are usually considered. Recent studies, conducted in the Energy Research House at Iowa State University, indicate that seve
Based on the age concept, the performance of the following three principle ventilation schemes have been monitored (supply air terminal - extract air terminal), ceiling-ceiling, ceiling-floor, floor-ceiling. All systems used only air for both heating and cooling. Contaminants with both greater, less and approximately the same density as air were released at a point source. The tests were both carried out in an empty room and with a person (heated mannekin) in the room.
The paper shows that age analysing techniques are an excellent tool to assess ventilation effectiveness. It is important to differentiate between air exchange effectiveness and contaminant removal effectiveness, having continuous generation of contaminants. Only when a source is homogeneous andpassive, are the age of the air and the contaminants in the room equal. However, the air exchange effectiveness accounts for the removal effectiveness of the contaminant left in the room when the generation stops.
Examines evidence for relating sickness to the office environment. Notes research into the office building syndrome (obs) in various countries. Notes that although air conditioning goes back to the 1920s, obs has been in the news only during the last five years or so. Notes the contribution to this of energy saving regulations. Notes the complex nature of indoor air contamination. Points to obvious factors such as air conditioning systems unserviced for 30 years, occupational psychology, indoor architecture, climatic constance and air ionisation.
A general multi-chamber model is presented and explored from the viewpoint of air quality studies. The model involves the following key concepts: purging flow rate and age distribution of both air and contaminants. From the physical and mathematical properties of the model, are deduced estimates of themagnitude of, and the relations between, the key concepts. The practical use of the model is illustrated.
Complaints related to moisture problems in houses which had been air sealed, led to a study of indoor air quality in 20 weatherized demonstration homes in the Cambridge, Ontario area.
Indoor radon concentrations have been measured in a 13 year old two story concrete building of the University of Texas at Dallas. Variations of the radon concentration from the basement to the second floor in offices, classrooms, laboratories, storage rooms, corridors and other locations have been measured. Dependence of the above concentrations on the location and ventilation rates have been studied.
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