modelling

Looks at the requirements for computer model validation, especially in regard to predicting energy usage in buildings. Discusses the IEA project for comparing and validating several computer programs in this context. Describes the Glasgow commercial building monitoring project, which includes detailed measurement of temperature and air flow rates to provide data for model validation. States what type of data is needed for validation.

Describes the application of a model that relates infiltration to a quantity called the effective leakage area. This quantity scales the infiltration to local weather conditions and major design features of the house. The model isused to calculate the ratio of infiltration to leakage area averaged over the heating season, for a large number of sites in the US. It provides an effective tool for builders and designers who need a rational basis for assessing compliance with construction quality standards in ventilation.

Proposes a simple equation derived using a more complex theoretical model for use in the prediction of the infiltration performances of houses over a range of meteorological conditions. Initial comparisons have been made with the results from field measurements in a range of typical modern UK house types.

Briefly reviews the study of wind flow around buildings. Shows that fundamental theoretical and experimental studies are beginning to produce simple descriptive and mathematical models of flows round buildings. These should enable designers to predict the general features of wind around a proposed building or group of buildings at an early stage in the design. Gives some examples of these models.

The results of a prediction method for calculating ventilation rates in a detached house are compared with experimental measurements described in aprevious paper. The method is capable of giving good agreement for a wide range of ventilation conditions. The need is demonstrated for further work in two important areas - the spatial distribution of background areas and the effect of turbulence.

Describes LBL's Mobile Infiltration Test Unit (MITU) which spent the 1980-1981 winter in the field collecting the data required for infiltration modelling. Data included measured infiltration rates, surface pressures, wind velocities, indoor and outdoor temperatures, leakage area and leakage distribution. Comparisons of measured infiltration rates with values calculated from surface pressures (using MITU) have shown no decrease in accuracy when a square-root flow model is used instead of the general power-fit model of leakage.

Presents the results of an investigation carried out on behalf of the Swiss Ministry for Environmental Protection. The main aims were to find acalculation method for the annual energy demand of a building which takes into account solar heat gain and which generates data permitting the effect of thermal protection regulations on energy consumption to be evaluated. Treats the effect on transmission heat loss of outside walls of absorbed solar radiation, the specific heat loss of typical dwellings, reference years based on weather data for energy consumption calculations.

Reviews a research project which has the objective of establishing:< 1. Expressions for ventilation efficiency< 2. Methods for measuring ventilation efficiency< 3. Rules for acheiving efficient ventilation.< Derives expressions for ventilati

Measures air infiltration and tightness of Swedish houses using the tracer gas technique and the fan pressurisation technique. Uses a previously developed model correlating air tightness and infiltration to evaluate the performance of Swedish homes. Shows that it is difficult to achieve the recommended minimum ventilation rate according to the Swedish Building Code by relying on natural air infiltration. Most new homes do, however meet the Code's stringent air tightness requirements. A comparison with American houses show that Swedish homes are very tight.

An experimental investigation of wind-induced pressure loads acting on two square-plan flat-roofed model structures (50ft and 225ft high in full scale) is described. Measurements of mean, peak and root mean square pressures acting on points and over larger roof areas have been made in turbulent boundary layer flow simulating wind over urban and open country terrains. Area loads on the roofs have been measured both by a pneumatic-averaging technique, and by using a large flush-diaphragm transducer.