English

Attic ventilation is compared with other means of ceiling heat flux reduction in low cost housing. A simple steady state mathematical model has been run with climatic data for a summer day of Porto Alegre, Brazil. The increase inceiling thermal resistance has proved to be the best improvement, but it is expensive. The greatest proportion in ceiling heat flux reduction is in the natural ventilation range and forced ventilation adds little to it. As natural ventilation does not imply extra cost, it is very important in low cost housing and should be optimised.

This paper examines the excess ventilation losses arising from window opening behaviour by occupants and using data from a number of sources relates these losses to the outside air temperature. These excess ventilation losses alter the shape of the total heat loss predictions and bring these more into line with the energy consumptions measured. Excessive ventilation by open windows is shown to negate the benefits of increased fabric insulation.

The passive perfluorocarbon tracer (PFT) technique for determining air infiltration rates into homes and buildings was evaluated in an environmental chamber. 

Multizone infiltration requires extensive and complex information about the flow characteristics and pressure distribution inside the building, and thus has been too difficult to develop and to validate. By relying on lumped parameters for the description of air flow distribution in a building, a simplified model is produced. This paper describes the parameters and considerations involved in the development of the multizone infiltration model.

Buildings in cold climates must provide an indoor environment that is markedly different from that outdoors. The materials and components of the exterior envelope are subjected to large variations in conditions and greater demands are placed on the indoor environmental control system. Air pressure differences across building elements are augmented by buoyancy forces that influence air movement and indoor air quality. The potential for moisture condensation on and within the envelope is increased as is the danger of freezing in liquid systems.

Describes a reasonably accurate method for estimating air infiltration for engineers or energy auditors who are not specially trained in infiltration research. The method requires two steps: field measurement of the building properties, and calculation of the infiltration from weather data and themeasured properties. Fan pressurization techniques are described and how to use them to measure the air tightness of the building envelope, and the procedures required to make infiltration predictions with the Lawrence Berkeley Laboratory infiltration model.

This paper presents a simple method for estimating the total air change rate of a house with or without mechanical ventilation. The proposed method can be used to assess the effect of a mechanical ventilation system on total air change rates. It can also be included in existing simple computer programs forestimating heating requirements for houses. A calculation procedure is also presented for sizing mechanical ventilation systems for houses. This procedure can be used to estimate the forced ventilation rate required to achieve the desired total air change rate.

Measurement of air exchange rates, ages of air, and nominal and local ventilation efficiencies in large buildings is often complicated by the building size and compartmentalization, and by the presence of multiple ventilation systems. To allow characterization of the ventilation process in such buildings, a unique experimental system, that employs multiple tracer gases, is being developed at Lawrence Berkeley Laboratory. The tracer gases are sulfur hexafluoride and five halocarbons. The system is designed to be non-obtrusive, highly automated, and relatively easy to ins tall in buildings.

If the energy losses due to ventilation have obviously become an important problem since the energy crisis, there is still a lot to be done with respect to the behaviours. Previous research has given results about the share of venti lation losses i n the energy balance, and the rational reasons to introduce fresh air into the house. Annex VIII is specialized in the attitudes of the inhabitants, in their habits with regard to ventilation and even in their apparent irrationality.

Although infiltration of outside air across the envelope of a building has been considered of prime interest in relation to energy conservation and indoor air quality, it also important to understand the way in which air moves between zones within a building. A knowledge of the air movement pattern enables the transfer of pollutants or heat to be determined. In order to achieve this, a number of experimental methods have recently been developed, using either single or multiple tracer gases. (See, for instance, references 1,2,6,7,9) .