ageing

The influence of air change and ageing on emissions from 5 different building materials were studied. It was concluded that increasing the air change rate in a rather leaky house was of practically no importance in preventing problems caused by emissions. It was also assumed that a reduction of the air change rate in a tight house may result in a considerable increase in the concentration of substances in the room air. For all 5 materials, the emission rate decreases with time.

The paper shows that age analysing techniques are an excellent tool to assess ventilation effectiveness. It is important to differentiate between air exchange effectiveness and contaminant removal effectiveness, having continuous generation of contaminants. Only when a source is homogeneous andpassive, are the age of the air and the contaminants in the room equal. However, the air exchange effectiveness accounts for the removal effectiveness of the contaminant left in the room when the generation stops.

Subjects 11 private dwellings at Taby and 5 at Brunna (all 2-3 yrs old) to repeated airtightness tests over a period of two years. Finds the largest leakage is 2.5 ach and the mean leakage is 1.6 ach. Immediately after its completion, the air tightness of a building undergoes a certain deterioration, after which it stabilizes. Over the 2yr. measuring period the changes are small, and could all be attributed to occupancy effects. Leakage paths occurat the junctions of wall and ceiling and wall and floor, and at service entries.

Outlines factors influencing natural ventilation rates. Discusses techniques for measuring natural ventilation. Gives results of pressure measurements, made by the Building Research Establishment, of the leakage of houses and of tracer gas measurement of room ventilation rates. Discusses variation in air leakage rates with time. Gives results of measurements of the distribution of air leakage between components of the building shell.

Reports study of indoor climate-primarily air quality-and energy consumption in a number of detached houses in a group housing area. All the houses were pressure-tested over three years; 1977-1980 and a relatively larger increase in air leakage was measured after the houses had been occupied for approximately one year. Suggests this is due to the drying out of timber, producing cracks. Two types of houses, a and b were investigated when studying indoor climate. both were mechanically ventilated.

Describes tests made on fifty different weatherstrips. Tests were made in the laboratory of airtightness, rigidity, ageing, load tests, freeze tests and wear tests. Strips mounted in windows were tested for ageing and resistance to driving rain. Gives test methods and results and discusses the characteristics of eight main types of strip.

Reports tests made to determine the air leakage characteristics of various types of walls. Describes apparatus and method and gives results of tests on brick, wood frame, stucco and brick and tile walls, with and without plaster, paint and caulking. Finds that air leakage characteristics alter with the age of the wall, that paint alone did not greatly reduce the leakage of the brick wall, but that plaster was very effective. Also gives data for leakage between plaster or stucco and wood frame.