modelling

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.

Describes a new method, termed Minisystem Analysis (MSA) developed for the calculation of the energy conservation potential of an individual building in which a number of energy conservation measures interact. In this method, account is taken of the fact that effects cannot at all times be added, and that certain measures must always be combined in order that the full effect may be obtained.

Discusses difficulties inherent in multiplexity of full-scale trials and the use of EDP simulation in models. Considers the measurement of low air movement velocities using different types of anemometers and field trials in lecture rooms and open-plan offices. Reports on studies into ventilation efficiency and full scale trials. Reviews International Institute of Refrigeration Congress held in Essen September 1981.

At present, there are many design and investigatory methods(often supported by computer programs)that take account of the reaction of the building and its heating and cooling systems to outdoor conditions as they vary with time. This makes it desirable to have some agreed sample of weather to allow contrast and comparison between various methods
for predicting building and system behaviour, and between individual design cases to be on a common basis.
The proposals below although evolved from work in the authors' establishments have been discussed more widely and