Finnish

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.

Describes laboratory tests to find correct operative conditions for a controlled outside air intake through the air space in the window to provide efficient ventilation without creating draughts. 

Measurements were made in the PIKO low-rise pilot building project to study air tightness, interior air quality, and air heating in 15-30 residences in various seasons. Exterior wall air tightness was measured in 70 units and repeated in 10.

Notes the contaminants which may be contained in room air - radon, solvents, tobacco smoke, formaldehyde, dust mites etc. Points out that no definitive threshold values have been established for contaminants representing health hazards. Points out that the reactions of various individuals to them differ widely, determined by a number of factors.

Presents a study to improve knowledge of the air tightness of the building envelope. The airtightness of buildings was measured by the pressure method and a literature study was carried out of corresponding measurements inScandinavia. The air tightness was measured mainly in timber frame detached houses,in some detached houses of masonry as well as flats. Notes that minorsealing techniques can improve Finnish dwellings, which are leaky compared to Swedish requirements. States that ventilation, heating and air infiltration must be considered together.

Measurements made in Finland have shown that the airtightness of many small houses is lower then the level of requirements specified in Sweden. States that the most important areas for sealing up external walls in concrete structures are the joints in the internal shell, the joints between concrete and timber structures, and the joints between door and window frames. All these areas can be made airtight by using appropriate materials and construction methods. In general, the air tightness of small concrete houseshas been found to be good and to comply with the specified requirements.

The radon contents in the two wings of a university building in Tampere were measured. Outside air was supplied to the corridors where it flowed to the rooms via ceiling ducts. Lower radon values were obtained in the rooms located close to the air supply end of the corridor. Radon content was also higher on the first floor then on higher floors, probably because of radon emission from the gravel layer in the foundation. Notes that the main source of radon in a wooden building is the ground, and the tightness of the floor construction is therefore very important.

The air tightness of buildings is part of an investigation performed by the State Research Centre of Finland. Regulations are being developed in Finland for the maximum allowable leakage in buildings. These can be stated as 0.2 ach/hr for residences, 0.1 ach/hr for low apartment buildings, and 0.2 ach/hr for high rise buildings. Tightness can be measured using a suitable fan connected to a board in a window or door opening, or by thermography.

Investigations in Denmark show that there are as many as 75 different compounds in indoor air in tight houses including toluene, xylene, and radon. The dust in homes contains a large number of allergically active ingredients, the most important being the dust mite, which occurs in bed clothes.< States that good air quality is therefore difficult to maintain with natural ventilation in new tight houses. If the hygienic demands of this decade increase the need for ventilation, mechanical ventilation seems to stand a good chance.

In dwellings and similar spaces with limited volume, dilution of indoor air contaminants may be insufficient. The concentration of contaminants in the inside air depends partly on the rate of emission into the room, partly on the ventilation and the concentration of impurities in the outside air. Sulphur dioxide, hydrocarbons, ozone and lead compounds occur in higher concentrations in the outside air, whereas nitrogen oxides, carbon monoxide, benzpyrene (from tobacco smoke), formaldehyde and dust have higher concentrations indoors.