English

Discusses minimum ventilation necessary for occupied buildings and finds that occupiers minimum needs are based on dilution of body odours and that in Britain a high ventilation rate is necessary to reduce humidity. Describes two electrical solutions to the ventilation problem. The first is a combined ozone and ultra violet irradiation to oxidize the malodours. The second is the application of a heat pump dehumidifier to remove excess moisture in mild weather.

Treats measurements of ventilation rates in a model building and wind tunnel. 2 types of opening, circular holes and model windows were tested under 2 wind cOnditions. one wind condition was selected to give maximum flow through the model; with theother, ventilation was mainly due to turbulent pressure fluctuations. Illustrates different characteristics of theopenings. Draws comparisons between measurements and theoretical predictions. Discusses use of wind tunnels for ventilation studies. NOTES: A further comment on this paper was published in Building and Environment vol.15 no.141.

Reports pressurization tests on eleven schools both with the air handling system on and with it off. Obtains air leakage through components of the building by comparing overall leakage rates before and after sealing each component. Uses leakage rates to calculate air infiltration using a simplified model of a school building. Finds that infiltration caused by stack effect is significant even for a single-storey building.

States that application of further thermal insulation to house structures increases importance of ventilation heat loss, from around 20% to nearly 50% of total design heat requirement. Any further energy savings will be by minimising ventilation components. On basis of British Gas research results and others, illustrates sources and mechanisms of infiltration to give an insight into problems it may cause in future housing. Treatseffect of weather, ventilation rates. Among conclusions states increasing attention will have to be paid in future toinfiltration.

There is at present no analytical step-by-step procedure for calculating air infiltration into houses. Extracts useful house air infiltration data from almost 20 years of scattered research work. 1) Highlights important conclusions of these papers andgives some selected notes on the many variables involved. 2) Reduces this information and summarises it in 2 tables. sets out 2 worked problems using these tables to demonstrate their application.

Describes results of computer study of behaviour of 2 better insulated houses, one of rationalised traditional and one of timber frame construction. Compares their performance with a contemporary house. Provides most important results regarding mode of operation and effects of air leakage. Concludes that better insulation is effective energy conservation measure but heavyweight characteristic of insulated structures result in intermittent heating being a less attractive means of reducing heat demand. Air leakage, if not controlled, becomes animportant component of the total heat loss.

Presents method for establishing conditions and an acceptance criterion for window air-tightness testing in relation to average energy (heating) saving per winter. Uses wind velocity data from israeli meteorological station of Ashdod to demonstrate difference between various methods of evaluating design wind velocity. Uses 41 different typical dwellings to determine unique criterion for acceptable air leakage under test conditions which ensures average of 1 air change per hour in most Israeli dwellings.

Points worthy of consideration regarding air leakage, i.e. the causes, identification, problems and remedies are briefly discussed generally without technical details and some illustrations are given of problems. Air leakage is common in most buildings, but with increasing standards of performance and the trend to taller buildings, it is becoming less tolerable. Reference is made to other CBD reports in which details are specified. The positive control of air leakage can only be achieved by careful attention in design and adequate inspection during construction.

After discussing briefly the principles of natural ventilation, goes on to describe tracer gas techniques, air movement measurements, and various model techniques including analogues. Advantages and disadvantages of each method are indicated, andtheir suitability for particular applications.

Assuming higher than probable cd values for crack length openings on calculation of infiltration rates results in excessive allowances for heating and cooling capacity. Using a given cd graph, proposes equation to determine infiltration rates and reduce internal pressurization requirements to offset wind impingement.