condensation

Defines types of condensation occurring in houses and describes practical ways for the householder to control surface and concealed condensation. Gives instructions to builders for installing air/vapour barriers to meet the required standards, and shows ways in which ventilation can control condensation.

Investigates the effect of energy-saving measures by selecting a large number of multi-family and single-family swedish houses where such measures have been carried out. Energy saving methods include insulation of external walls and attics, triple glazing windows, and installation of radiator thermostatic valves. Concludes that these modifications have, in average, led to anticipated savings when they have been modified individually. Also considers moisture problems arising in retrofitted houses, and the effectiveness of different types of weatherstrips in energy conservation.

Reviews results of tests carried out during a joint industry/university project. Discusses characteristics of single and two-component foam, airtightness, condensation and safety regulations since polyurethane foam contains isocyanates. Diagram illustrates typical cross-section through window frame under normal conditions and when conditioned at 15 deg. C and 65% R.H.

Treats drawbacks of current methods used in East Germany of calculating vapour barriers used to protect building elements from condensation. Notes building materials for which moisture absorbed in winter is sufficient to cause condensation damage before it has diffused in summer. Develops method based on calculation model of determining direct relation between any period of condensation and requisite vapour barriers. In addition amount of wateraccumulated during condensation period can also be determined.

This sixteen-page digest provides a guide to why condensation occurs in buildings and how to avoid it. Outlines causes of condensation problems in buildings.Gives 9 case studies. Discusses physical principles of moisture transfer. Describes vapour sources in buildings. Outlines ways of reducing thecondensation risk in buildings. Gives methods for predicting when condensation will occur.

Describes the thermal and ventilative properties of some older dwellings and the latest test dwelling in Hokkaido. Results include the following.< 1) The above mentioned older dwellings suffer a great heat loss by ventilation and conduction. Therefore such dwellings must be retrofitted.< 2) The airtight dwelling is in danger of condensation due to high humidity.< 3) In the future, the heat recovery system should be used in the airtight dwelling to get rid of high humidity and to increase the supply of fresh air.

Presents a long term calculation method for indoor air temperature and moisture variation related to the water vapour condensation problem in a detached residence. In this method, the multi-room infiltration calculation is developed. Furthermore the effect of sorption and description of a room, which is evaluated by means of a short term experiment, is introduced.

States condensation caused by high humidity is a major problem in British homes. Describes a conventional heat pump dehumidifier for removing moisture from the air. Describes the advanced dehumidifier developed by the Electricity Council Research Centre which is designed to work in cold damp conditions typical of British winters. Gives details of the design and reports that tests of a prototype show that the design is more than twice as effective in terms of litres of water extracted per unit energy than conventional designs.

Discusses condensation within dwellings. Treats conditions conducive to reducing risk of condensation, factors which control concentration of water vapour in the air in a building and temperature of building fabric. Distinguishes between those under control of occupier and those controlled by design of building fabric. Considers in particular effect of ventilation on dewpoint of the air in bedrooms and humidity and temperature conditions in a bedroom during the day. Provides several case histories which illustrate relationship between ventilation and condensation.

Discusses the problems of sealing double glazing to reduce condensation between the panes. Describes sealed glazing unit and sealants used. Discusses causes of failures. Reports tests for seal leakage made by lowering air pressure surrounding theunit and observing glass deflection. Windows were also tested by weathering in the laboratory and by exposure to actual weather conditions. Discusses results and finds extreme difficulty in providing and maintaining an effective sealing system.