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.

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.

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.

It is often stated that advanced ventilation or air conditioning is expensive or energy-wasting. There are, however, several examples of highly energy-efficient air conditioning systems in industrial, commercial and public buildings. Energy-efficiency can be achieved by - optimizing air flows or demand-controlled ventilation - avoiding simultaneous heating and cooling (except if "free") - advanced automatic control system - good operation and maintenance The performance of ventilation and air-conditioning depends on several factors in the building process.

A Compact Equipment for Survey of Air Renewal (CESAR) was developed at the Ecole Polytechnique Federale de Lausanne in Switzerland. Controlled by a microcomputer, this apparatus uses tracer gas methods ( decay, continuous flow or constant concentration). Up to ten different locations in inhabited rooms can be monitored simultaneously over extended periods of time, using mainly the "constant concentration" technique. Several air renewal surveys were carried out on different inhabited buildings.

The multiple tracer gas technique developed at UMIST has been applied to the measurement of roof-space ventilation rates and house to roof-space air movement, for various types and combinations of roof-space ventilation. It has been shown that ridge tile ventilators, whilst increasing roofspace ventilation rates at low wind speeds, also significantly increase house to roof-space airflows over the whole range of wind speeds. This has implications not only in terms of energy wastage, but, more significantly , in terms of increased moisture rates to the roof-space.

For more than two years a series of detailed air infiltration measurements have been conducted over the complete yearly weather cycle on two identical side-by-side test houses in Gaithersburg, Maryland, USA. These measurements have been part of a broad study of the interaction of air infiltration , indoor air quality and energy in tightly constructed, well-insulated homes. The standard method of collecting air infiltration data throughout the study has been tracer gas decay. Operation of the duct air circulation fans has transformed each house into a single well-mixed cell .

The effects of operating unvented appl i ances and opening windows on indoor pollutant levels and air exchange rates are being studied under the sponsorship of the Gas Research Institute. The study is being conducted i n an instrumented, well-characterized bilevel house located near Washington, D.C. Air leakage due to window openings is characterized by pressurization measurements and the air exchange increment is characterized through tracer gas measurements. Two unvented space heaters, one radiant and the other convective, are operated singly and in combination with a gas cooking range.

Natural ventilation rates in bedrooms at night have been measured in retrofitted apartments. The measurements indicate clearly that air quality in bedrooms may be unacceptable in dwellings with an energy-efficient minimal ventilation rate. The air supply rates may be as low as 1 l/s/person in themedian case of bedroom size, ventilation rate and two occupants. The carbon dioxide concentration will reach a level of 4000-4500 ppm in the morning depending on the length of sleeping time in a closed room.

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.