air quality

In order to reduce heating energy consumption, single glazed windows are commonly replaced by double glazing and joints tightened in Danish dwellings. Reports investigation of the influence of such tightening of dwellings on the indoor climate. 25 tightened and 25 not-tightened identical flats were investigated. Finds an improvement in thermal climate and a significant reduction in heat consumption in the retrofitted flats. Finds absolute humidity of indoor air was significantly higher in improved flats, probably due to reduced ventilation.

Tests carried out during the sixties and seventies showed that there was a correlation between lung cancer and the existence of radon gas in mines and that there was radon gas in homes built of aerated concrete based on slate. This led to political activity with regulations for limits on emanation in new, re-built and existing buildings. Provisions were also made for grants to help house owners finance the improvements specified.< In the new bye-laws, SBN 80, gamma radiation is not to exceed 50 mu.R/h, the radon content is not to exceed an annual mean of 70 Bq/cu.m.

Discusses acceptable levels of CO2 contamination in occupied rooms. Describes measurements in a classroom over 3 days using an infra-red analyser with natural ventilation via the windows. Illustrates curves for CO2 concentrations in 8 graphs for closed windows. Notes that limiting value of 0.1% by volume CO2 (1000ppm) is reached in from 5 to 15 minutes. Repeated sudden ventilation by opening windows is not practicable. Evaluates air change rate. Concludes energy saving for ventilation in heavily populated rooms is only attainable by mechanical ventilation with heat recovery.

Reviews ventilation criteria for occupied buildings. Considers minimum ventilation for the control of carbon dioxide, odours, cigarette smoke, moisture and radon. Discusses future work to improve ventilation routes.

Reports investigation of the air quality in a sound-insulated dwelling house. Measurements of ventilation rate and concentrations of CO, CO2, and NO2 were measured in a tight sound-insulated dining-kitchen, with and without the operation of a gas range, instantaneous hot-water heater and ventilation fan. Finds that natural ventilation was inadequate when the gas appliances were operating and recommends that an instantaneous gas hot-water heater should be provided with an exclusive air exhauster.

The air-tightness of various houses is revealed by testing with the pressurization method, and the equivalent open area of air infiltration per floor area is proposed as the index of air-tightness of a house.< Then the heating system, indoor air quality, indoor temperature and humidity and house planning which affect the ventilation design are discussed in connection with the air-tightness of a house.

The reduction of ventilation in buildings as an energy saving measure may result in a deterioration in indoor air quality. Suggests use of contaminant control devices and summarises devices available. These are filters, electrostatic precipitators, mechanical dust collectors, scrubbers, and contaminant combustors Suggests five areas where further research is necessary.

Indoor air quality in an air conditioned California high school has been measured over a variety of ventilation rates ranging from 13.3 cubic feet of outside air per minute for each classroom occupant to approximately 1.5 cfm per occupant.< Parameters measured include outside air supply rate, the occupants' subjective perception of indoor air quality, airborne microbes, carbon dioxide, carbon monoxide, nitrogen oxide, sulphur dioxide and ozone in two classrooms, a halland outdoors.

Working men's clubs are commercially thriving organisations catering for a wide range of social activities commonly held in a single room holding 300-400 people. Packaged air conditioning is being introduced into Working Men's Clubs to provide air recirculation and cleaning when the buildings are occupied. Air cooling and dehumidification is also available. One club was dissatisfied and an investigation was started to investigate the difference. Measurements showed that the unsatisfactory installation was unusual in two ways.

Discusses indoor air quality in residences with low ventilation rates. Reports investigation of indoor air pollutant levels in a test kitchen with a gas stove under various air change rates. Results indicate that gas stoves generate high emissions of carbon monoxide, nitric oxide, nitrogen dioxide, formaldehyde and respirable aerosols. Recommends a kitchen ventilation rate of at least 170 cu.m.&h.< Also reports study of CO and NO2 emissions from gas appliances in an energy- efficient research house.