Perera MDAES, Powell G, Walker R R, Jones P J
Bibliographic info:
11th AIVC Conference "Ventilation system performance" Belgirate, Italy, 18-21 September 1990

A single whole building pressurisation test using robust and easy to use equipment can, in a very short time, quantify the air-leakiness of the building envelope. However, such measurements do not give a direct measure of the ventilation characteristics of the building which normally requires timeconsuming and specialist tracer gas tests. This paper provides a model which makes the link between leakage measurements and ventilation characteristics and applies it to a large, industrial building constructed according to 1979 UK Building Regulations. Air leakage measurements with the building 'as found' and then with its loading doors sealed showed a 14% reduction at an insideloutside pressure differential of 25 Pa. Using these leakage characteristics, the model predicted ventilation rates which corresponded well with measured values. Meteorological data at the site for the heating season were combined with the ventilation characteristics of the building (given by the model) to predict the ventilation performance of the building over that period. The results indicated that the building 'as-found' would have, on average, an air change rate of 0.5 h^-1 during the heating season. Sealing the loading doors would reduce this rate by 24%, i.e. to 0.38 h^-1. This paper shows that space heating energy requirements for the heating season can be assessed using either the combined hourly-predicted ventilation rates and meteorological data for the site or using the mean predicted ventilation rate with existing design guidance. The two approaches agreed to within 10% of each other. The results also indicated that ventilation heat losses accounted for 44% of the total required energy. Calculations also show that replacing the loading doors with ones which are more air tight and better insulated will reduce by 25% the energy required for ventilation losses and by 5% the losses through the building fabric. This results in an overall reduction of 14% of the total requirement.