ventilation needs

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 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.

There are three general categories of techniques for the control of radon and radon progeny concentrations in indoor air - restriction of radon entry, reduction of indoor radon concentrations by ventilation or air cleaning, and removal of airborne radon progeny.

The bacterial content of the air and physical environment of two crated veal calf units were monitored over the growing period of 16 weeks. The rate of release of bacteria colony forming particles (BCFP) from the calves was rapid.

Notes that the trend to airtight window constructions has upset the balance in buildings between moisture generation and its removal. Treats the factors which combine to determine whether a building will have moisture problems. Presents a procedure for the straightforward determination of the specific minimum air flow required in a particular building to prevent condensation on the inner surface of corners formed by two dimensional external walls. Determines the base air flow and the supplementary air flow for four models of representative apartments.

Tests were conducted in Ottawa during the winter of 1982/83 to investigate the effects of a gas cooking stove in the kitchen of an energy-efficient two-storey test house. Products of combustion: NO, NO2, CO and CO2, were measured in the kitchen, living room and bedroom in order to relate theinfluence of air infiltration and kitchen hood exhaust operation to the levels of air contaminants. Tests were also conducted, using the enclosed kitchen as a test chamber, to establish the values of emission rate for CO, NO and NO2and of reactivity for NO and NO2.

Measures of a number of ventilation parameters and of a number of pollutants from 21 locations furnished data for evaluating interrelations among commonly used descriptors of ventilation as well as their relation to frequently measured indoor gaseous and particulate pollutants.

A subcommittee of the Nordic Committee for Building Codes has released guidelines for building regulations regarding indoor air quality, especially concerning ventilation. The main features of the guidelines, such as acceptable outdoor air quality for ventilation and minimum outdoor air flows for dwellings and offices, are presented and discussed. Mechanical ventilation is, in principle, required in all buildings including dwellings, due to therequirement of a minimum outdoor air change of 0.5 h-1 and the normal highly airtight nature of new buildings.

This investigation looks at sensory (odour, irritation) and physical criteria for ventilation requirements, paying particular attention to the difference between smoking and nonsmoking occupancy in a well-controlled environmental chamber.