English

A supply of fresh air is necessary in any dwelling to ensure a comfortable, safe and hygienic environment, but the heat loss to this air, during the heating season, may represent a substantial proportion of the total heat loss. This points to the need forgreater control of domestic ventilation, either by using a mechanical system or by better design for natural ventilation. This paper touches upon both of these possibilities. Gives simple method for assessing approximately the possible reduction in heat loss achieved by the use of a mechanical ventilation system.

Describes detailed study of infiltration rates measured with a tracer gas and air leakage rates obtained from fan pressurization in small, 3 - bedroom California house as part of a larger study. Finds surface pressure measurements are an essential step in process of finding a correlation between natural air infiltration and air leakage by pressurization. Measurements also show significant duct leakage and air flow between attic, living space and crawl space.

With improved thermal protection of buildings proportion of ventilation heat loss has grown until it now accounts for 50% and more of total building heat losses. Since ventilation cannot be reduced below certain limits for comfort and hygenic reasons, selection of appropriate type of ventilation system is increasingly important to control heat losses. Describes characteristics and consequences for heat energy consumption and hygiene of constant ventilation and abruptly increased ventilation such as window opening etc.

Treats development of generalised model of hourly air infiltration in residences. Describes its testing. Uses tracer gas measurements of infiltration in 9 research residences inColumbus, Ohio, under widely varying weather conditions. Estimates various linear and physical models against 7000 measurements. Measures and correlates weather parameters. Correlation coefficients ranged around 0.9 with an error between 0.1 to 0.36 air changes. presents Fortran algorithm.

Known principles for the prevention of rain penetration and air leakage are not being applied in practice. States that rain penetration requires the simultaneous presence of water, openings and a force ; the two-stage weathertightening or "open rain screen" separates the control of these factors and allows the production of a weathertight joint under practical conditions. Outlines the causes of air infiltration and gives brief case histories to illustrate the serious problems that can arise from air leakage.

States that current methods of estimating heat demand of buildings are very inaccurate, and so large safety margins are used which usually result in overestimating the necessary heating plant capacity. Describes computer program developed to improve the accuracy of heat demand calculations. Gives formulae used in the program for calculating heat demand, pressure conditions and air flow within the building. Gives example of the use of the program to calculate the effect of wind on an eight-storey residential building.

Derives equations for the calculation of air-change-rate in a room where carbon dioxide is being produced at a known rate using the measured initial and final concentrations of CO2. Also derives expression for the calculation of air-change-rate with no source of CO2 but a high initial concentration

Describes research project which aimed to quantify the difference between actual dynamic ventilation rates and natural ventilation rates predicted using a steady state model. 

Explains why house external shell and ventilation system must be treated as integral elements of a total system. Explains, using an analogous water system, why air leakage through shell is greater using push-pull ventilation than when using extract ventilation and why houses should be airtight.

Reports the investigation of the natural ventilation of three test houses. Describes the houses which were of standard design. Natural ventilation rates were measured using sulphur hexafluoride as a tracer gas. An energy audit was also performed using a fan to pressurize and depressurize the house and an infrared scanner to detect the leakage paths. The tracer gas measurements were converted to a format similar to thepressurization results by using a previously developed model. Gives results in the form of graphs.