The current German Standard specifies a minimum thermal insulation. However even with excellent insulation, if the air change rate is too low, condensation can form. High humidity emissions in dwellings can require air change rates of more than 2/hour. The use of mechanical ventilation, possibly humidity-controlled and with a heat recovery system, is suggested to minimize ventilation heat losses. The user has to be educated to provide adequate ventilation in spring and autumn, but during the cold season the ventilation rate can be reduced to two thirds of the minimum value.

Outlines some of the principles behind air driven aspects of moisture in buildings and illustrates how calculation methods and mathematical modelling techniques may be used to both predict and remedy associated problems. Primary remedies include a reduction in the generation of moisture, ensuring thermal integrity of the building and providing adequate ventilation. The use of dehumidification may also have a role to play. Mathematical models offer an inexpensive method for assessing design ideas at an early stage of development.

Discusses case histories of rehabilitation work in flats and maisonettes in London, UK. It is clear from the results of these that the ventilation rate is inadequate for the lifestyle in the dwellings considered. Discusses provision of adequate ventilation by use of fans, vents and windows and use of thermal insulation.

The determining parameters for the formation of condensation are 1) the surface temperature of the building section and 2) the dew point temperature of the air in the room. Thermal bridges in intensively insulated outside walls and decreased ventilation due to tighter windows both increase the risk of condensation. Mechanical ventilation reduces the risk, but natural ventilation is dependent on occupant behaviour.

Discusses ventilation efficiency and production rates of water vapour in residential buildings, using a three person flat of 100 m2 living area as amodel. The cold outer surfaces of a building are the critical ones regarding condensation. To avoid surface condensation, the ventilation requirement is that the air change rate must reduce the vapour content in the room air at least so far as to reduce the dew point temperature below the lowest surface temperature.

Sixty houses built with widely different construction practices and located in different areas in upstate New York were monitored for airtightness (using fan pressurization) and integrated radon concentrations in indoor air, household water,

Presents a compact control system of modular construction, developed in the Netherlands, which incorporates in one unit the functions of air circulation and ventilation, heat recovery and heating. It conforms to the German health and building regulations and operates with any fuel. In 1983 it was installed in 6000 new, highly-insulated Dutch dwellings and in another 10000 dwellings in 1984. Operating costs are 700-800 florins/year for heating a living area of 110m2. Future models may include water heating.

Describes four ventilation options for a 3-4 person dwelling of 100-140 m2 living area. These are: a simple transverse system conforming to State (Land) building regulations, a shaft system conforming to Standard DIN 18017 (old design), a central heat recovery based system conforming to Standard VDI 2088, and a central heat recovery/heat pump system. Presents the energy balances of the four systems with the aid of energy flow diagrams.

Discusses the problems arising from inappropriate ventilation in highly-insulated flats and houses: outlines the advantages of ventilating systems with heat recovery as a possible solution. Deals with the advantages of combined ventilating and space heating installations including those which can blow air directly into bedrooms.

Discusses the various measures used to achieve the energy-conservation aims of the Federal Republic of Germany thermal insulation regulations of 1 January 1984 and to counter the health problems that arose as a result of higher fuel prices leading to reduced domestic fuel consumption in conjunction with poor ventilation. Discusses the advantages of installing heat recovery based central air conditioning systems with filters which are eligible for tax relief.