For controlling and for setting ventilation standards to maintain acceptable indoor air quality, it would appear to be of greatest importance to determine the strength of relationships between contaminant concentrations on one hand and different rates of ventilation and how these rates are expressed on the other.
A major cooperative study of the effect of ventilation of timber flat (cold) roofs on combatting condensation and moisture accumulation has been undertaken in Denmark. Field measurements of moisture content in a number of test roofs over long periods and under different conditions are evaluated and conclusions drawn. They include the advice that, where moisture accumulation is a problem, it can be aggravated if roof vents are installed.
Airtightness measurements were carried out in ten typical Dutch dwelling complexes. In each complex four homes were measured. The IMG calculation model was used to calculate expected ventilation for these dwellings. Results of a survey of 1500 occupants on use of ventilation are given. The ventilating behaviour in 610 homes was studied in greater detail. 210 of these had some form of mechanical ventilation. Ventilation requirements are given for individual rooms.
In this paper ventilation of attics and crawl-spaces is investigated theoretically. Ventilation rates and temperatures of the spaces are calculated by means of flow balance procedures. Flow characteristics of ventilators and openings for attics and crawl-spaces are far from well known, so a laboratory investigation on pressure drops across such devices was undertaken and reported in the paper. As convective flows from the heated part of a houseinto a colder, ventilated space can create moisture problems this situation has been investigated extensively.
The performance of whole-house mechanical ventilation systems was explored in an full-scale indoor test house (volume 176 m³ ) . A range of parameters were monitored: * The pressure distribution * The inflow of outdoor air to each room, the mean age of air in each room and the air-exchange effectiveness * The spread of a 'contaminant' released respectively in the kitchen and in the bedroom. The tests were undertaken both with the internal doors closed and with the internal doors open. Both mechanical extract system and balanced (combined) systems were tested.
Ventilation can be advantageous as opposed to adventitious and, with careful building design, can eliminate the need for air conditioning in summer. This paper discusses the general principles of design for ventilation, inparticular the removal of excess heat, and presents two examples of buildings designed to eliminate air conditioning. One is a deep plan office block, the other an exhibition hall. In both cases ventilation models featured strongly in the design.
The increasing awareness that indoor air quality aspects may restrict energy conservation by infiltration and ventilation measures has led to extensive investigations of different ventilation strategies. Aiming at a reduction o f energy consumption air infiltration and ventilation rates have t o be minimized. But in order to maintain healthy, safe and comfortable conditions for the inhabitants and to avoid damages to the building fabric the outdoor a i r supply should not remain under minimum ventilation rates.
A passive ventilation system has been installed in four new houses: it comprises simple ducts which lead up from the kitchen and bathroom to outside near the house ridge and utilise the wind and the temperature difference between inside and outside (the stack effect) as driving forces. During occupation the system provided a consistent background ventilation rate: the flows dropped only when it was warm and calm outside (when other ventilation measures might be taken by the occupier); when it was very cold and windy outside the system did not over extract but appeared to self-throttle.
Various ventilation systems have been examined in unoccupied test houses under natural climatic conditions. Two identical test houses were used to enable comparison of the effects of different ventilating systems on the air change rate and heat consumption. The systems examined were natural ventilating devices placed in the window area and centralized and decentralized mechanical systems. With the decentralized systems, draughts were generally unavoidable. Heat recovery from exhaust air at an air change rate of 1.0 h-1 gave a measured heat consumption saving of about 16 per cent.
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