Introductory talk on the indoor air quality problem. Compares risk of radon pollution in houses to the risks of smoking tobacco, and gives a definition of levels of concern. Mentions filtering of indoor air by means of an air-to-air heat exchanger, the interaction between ventilation and sources, e.g. unvented combustion heaters and carbon dioxide emissions; measurements of nitrogen dioxide are compared, and formaldehyde concentrations in 28 different commercial buildings.
In order to save energy, i.e. ventilation heat losses, the fresh air change rate should be adapted to the prevailing need. Even though it is a fact that reducing the fresh air change rate will result in a ventilation heat gain, the fresh air flow rate should not be kept too low, so that pollutants, humidity and body odour can accumulate. The results of measurements in a climatic chamber and in a lecture theatre show a significant relationship between the concentration of carbon dioxide and body odour of the indoor air under nonsmoking conditions.
Commercial buildings require mechanical ventilating systems, the specifications for which are included in the building codes. These codes specify the amount of outdoor air to be supplied per person for designed occupancy conditions. Many buildings such as retail establishments operate much of the time at occupancy loads well below the design. Thus, they are generally over ventilated and waste energy when operated according to the codes. A control system based on measurement of the carbon dioxide generated by the occupants was tested in a small bank in Pasco, Washington.
Good indoor air quality and thermal comfort and good energy-efficiency can be achieved simultaneously only if the amount of ventilation can be demand-controlled. Two approaches are discussed in the article: CO2- control and use of so-called air quality sensors. The first experiments have been promising but further development of equipment is still needed, in order to improve the reliability and economy of demand-controlled ventilation.
Air qulaity measurements along with airflow rate measurements of air conditioning system were conducted in an office building occupied by workers with clerical activities. Contaminamts measured were CO2, SPM (suspended particulate matters) NOx and airborne bacteria. Indoor CO2 and SPM levels were found to be quite high, 1,600 ppm (CO2) and 0.25mg/ m3 (SPM), respectively, at their maximum and exceeded Japanese Standards The cause of the high concentration was found to be air leakage in the outdoor air intake duct. The air leakage rate was estimated applying mass-balance model of CO2.
The Energy Division is working toward development of ventilation systems capable of providing acceptable levels of indoor air quality in superinsulated houses. The research was designed to analyze and improve the indoor air quality of a superinsulated retrofit house located in St. Paul, Minnesota. The occupants had encountered 'stuffy air' problems after their house was superinsulated and weatherized to reduce heat loss, and uncontrolled air infiltration. High levels of CO2 build up were revealed indoors, despite the presence of a continuously operating air-to-air heat exchanger.
Discusses the natural ventilation of the Paintings Room of Altamira Cave, in Spain. The radon-222 concentration was measured by scintillation cells of capacity 500 cm3. From the mean monthly Radon-222 concentration the natural ventilation was calculated using Wilkening's method. Compares the variations in ventilation rate (monthly) with the temperature differences between the Paintings Room and the Hall Chamber. Natural ventilation is the major factor affecting changes in the carbon dioxide concentration.
Too high a concentration of certain gases (e.g. water vapour, carbon dioxide, tobacco smoke, alcohol, etc.) in public buildings can damage the health. Even low concentrations can cause discomfort and make the room air seem unpleasant. This paper describes this subjective perception of air qulaity. It is shown that installation of an appropriate sensor can make substantial energy savings.
Effectiveness of ventilation as a major means of controlling indoor air quality was evaluated by correlating concentrations of gaseous (CO and CO2) and particulate (total) pollutants with two ventilation parameters. Pollutants are differently af
Tracer gas techniques, used for routine ventilation checks or trouble shooting are outlined with emphasis on their applicability in a variety of situations.
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