A major cooperative study of the effect of ventilation of timber flat (cold) roofs on combatting condensation and moisture accumulation has been undertaken in Denmark. Field measurements of moisture content in a number of test roofs over long periods and under different conditions are evaluated and conclusions drawn. They include the advice that, where moisture accumulation is a problem, it can be aggravated if roof vents are installed.
A subcommittee of the Nordic Committee for Building Codes has released guidelines for building regulations regarding indoor air quality, especially concerning ventilation. The main features of the guidelines, such as acceptable outdoor air quality for ventilation and minimum outdoor air flows for dwellings and offices, are presented and discussed. Mechanical ventilation is, in principle, required in all buildings including dwellings, due to therequirement of a minimum outdoor air change of 0.5 h-1 and the normal highly airtight nature of new buildings.
Discusses the nature of the problem of indoor air pollution, limitations in the authority of established health agencies in the US to control the problem, research needs and some control options. Indoor pollutants of current concern include radon, tobacco smoke, emissions from unvented indoor combustion appliances, aeropathogens, formaldehyde and pesticides.
A control program for a natural ventilation system for agricultural buildings is described which calculates a required ventilation rate, then adjusts vent openings to achieve this ventilation rate with equally distributed flows.
Efforts to reduce the energy needs to heat or cool dwellings have the potential to create new health hazards. Increases in indoor levels of radon and its progeny from the reduction in air exchange rates add a substantial radioactive burden to the general population. Other indoor pollutants reaching critical concentrations in homes with low air exchange rates are CO and NO2 from unvented combustion in gas stoves and heaters, tobacco smoke, and asbestos fibres.
The total air infiltration rates can be determined by the tracer gas decay method, but to measure the influence of inhabitants or convective exchanges between rooms, the constant concentration method is more suitable. In order tomeasure these effects, the Compact Equipment for Survey of Air Renewal (CESAR), developed at the LESO, was used to perform an air exchange analysis on data recorded at regular intervals in up to 10 locations simultaneously. Three tracer gas methods were implemented: decay, constant concentration and continuous flow.
A Compact Equipment for Air Renewal Survey (CESAR) has been developed by the Ecole Polytechnique Federale de Lausanne. The device has been designed for simultaneous analysis of up to 10 different inhabited rooms over extended periods of time (days or weeks). The constant concentration tracer gastechnique was used for the first survey done in the South rooms of the LESO building. Mean outdoor to room flow rates of between 1 and 40 m3/h were found.The mean building to room air flow was found to be 5 m3/h for rooms with only one communicating door with the rest of the building.
An increasing incidence of 'building illness' is being noted among white-collar workers due to the high pollutant content of air in modern energy-efficient office buildings.
This investigation looks at sensory (odour, irritation) and physical criteria for ventilation requirements, paying particular attention to the difference between smoking and nonsmoking occupancy in a well-controlled environmental chamber.
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