The problem of radon emission in buildings first came to light at the end of the 1970s, when a report by the Swedish National Institute of Radiation Protection revealed high radon daughter concentrations in some houses. Temporary limits on permitted concentrations in different types of dwellings were imposed in Sweden. They were related to the age of dwellings, due to the known historical use of alum shale in lightweight concrete.

Notes that moisture problems could arise with improvements to thermal insulation of buildings. In addition indoor radon levels could rise. Considers the choice of heating system. Compares total costs of alternative systems. Treats the effects of increased insulation on internal environments. Identifies moisture sources. Stresses this should be regarded as only a limited guideline and that there is a need to ascertain the heat and mass transfer behaviours of building materials, particularly those that affect prediction of the transient behaviour.

Summarises in tables the energy consumptions of a block of flats and a single house demonstrating how the share of energy consumed for fresh air heating and domestic hot water supply increases significantly in line with improved thermal insulation.

Notes that the Department of the Environment is considering the implications of imposing limits for the maximum annual dose of radiation to which occupants of existing and new homes should be exposed, as recommended by the Royal Commission on Environmental Pollution in its report of 1984. Describes radon's properties and origins in buildings, where levels are at least ten times higher than outdoors. The occupants of some homes, chiefly on granitic soils, receive up to 100 times the national average dose from radon. Explains the units used when discussing radon.

Describes the pollutant burdens on indoor air. Notes heat exchanges by air renewal and associated heat losses. Examines how to determine the required air change rate. Lists the minimum air changes for various types of building with and without smoking. Treats air infiltration. Considers how to reduce losses with air renewal by weather stripping, special air inlets, reduction of the indoor air temperature, heat recovery with controlled mechanical ventilation, heat pumps and heat pipes.

The U.S. EPA initiated an indoor air monitoring program in 1982, concentrating on commercial or public-access buildings (homes for the elderly, schools, and office buildings). Several buildings from each category are sampled over 2-3 day peri

Notes the considerable savings in heating energy that could be made if ventilation rates could be modulated so that only the requirements of the actual number of occupants was supplied. Explains how this can be done by ventilating to maintain a constant concentration of carbon dioxide. Describes carbon dioxide monitoring system based on infrared absorptiometry. Illustrates diagrammatically the layout of a cinema ventilation system which monitors carbon dioxide levels and explains its operation. Notes other buildings where the system is used.

Examines the most important sources of indoor air pollution in dwellings. These include pollutants introduced with the outside air, pollutants generated by human activity, emissions from building materials, furnishings, cleaning and polishing materials and disinfectants. Notes the importance of keeping formaldehyde and carbon dioxide down to safe levels. Discusses the consequences for the minimum room air change rate.

Describes a novel modification of stroboscopic illumination used to give an unambiguous record of the direction of the flow in an otherwise conventional visualisation of a complex three dimensional air flow. The flow was seeded with small soap bubbles which were viewed by scattered light. Each flash of light was split into two periods of unequal length, separated by a short extinction, thereby marking the direction of flow on the photographs. The technique allows a more complete determination of the velocity field than can be obtained by the usual stroboscopic method.

Within the last ten years, energy shortages, economic pressures, and changes in indoor environmental requirements have resulted in buildings that are more energy efficient but less forgiving, environmentally. These results indicate that energ