modelling

A number of studies have reported comparisons of building energy simulations to measured building performance. This paper summarizes results of studies of occupied buildings in which monitoring varied from very detailed tonon-existent, the comparison interval from hourly to yearly and the number of buildings from one to 200 plus. These results are briefly compared to results from unoccupied buildings and preliminary conclusions are presented about the use of building energy models for different types of field application.

Uses the building energy program DOE 2.1A with the objective of validating it for use with single-family dwellings. Carries out four studies, each with a different set of conditions. The first involves a single-story house with full basement, while the second involves a single-story house on a slab. Runsblower door tests to estimate infiltration. On a bimonthly basis, simulated heating energy differs from the measured value by up to 11%. The third study, using 75 similar houses with electrical resistance heating, shows an agreement of within 5% between simulated and actual measurements.

Commercial building energy analyses may be used for new building design, energy end use forecasting and energy audit calculations. Many building simulation programs, such as DOE 2.1A or BLAST, are quite complex and must berun by specialists on main frame computers. A simplified method of commercial building energy analysis has been developed and utilises a database of previous DOE 2.1A simulations to predict the outcome of other simulations. Applies this method to an office building in one climate region and finds that it predicts heating, cooling, and total energy use very accurately.

The model of moisture concentrations in a building cavity containing hygroscopic material presented in earlier works is extended to allow for evaporating surfaces within the cavity (eg soil, water tanks) and fluctuating external climatic conditions. Linearized coupled differential equations are solved for three cases - 1. Steady state 2. Step function 3. Periodic climate driving forces. The third case gives formulae predicting the cavity moisture contents at any time of day or year, and shows that the steady state approximation is adequate for all but the tightest cavities.

Discusses the mechanisms available for "single-sided" ventilation - ie when ventilation is achieved by the exchange of air through windows on one side of a space rather than by cross-ventilation. Describes a simple approach to its prediction based upon a combination of theoretical modelling, wind tunnel testing and tracer gas measurements made in full-scale buildings. Describes wind tunnel and full scale measurements which show the effect of degree of opening, window type and combinations of windows on the magnitude of ventilation rate.

Assesses energy saving as a function of window air tightness, and transforms value into a corresponding U-value. Uses a single-cell infiltration model, and shows that using the U-value is a convenient way of comparing different energy saving methods. As an example, computes the U-value for the windows in a detached single-family house in an urban area and for Gothenburg weather conditions.

Presents a review of work carried out by SCBR concerned with airtightness of buildings and ventilation up to January 1982. Describes important features of building systems and mechanics, ventilation systems and immediate surroundings of importance to ventilation process. Assesses the building physics aspects of ventilation systems for various building categories. Discusses a number of ventilation case studies for detached houses and apartment buildings, and presents existing computer programs for single-cell and multi-cell models.

Leakage measurements of houses are common practice in many countries, partly because they are needed for predicting ventilation rates. To use the measurements in this way it is usually necessary to fit an equation to the measured leakage data, so that the data can be extended into the region of interest. At present, the power-law equation is generally chosen for the curve fit. Considers a new approach using a quadratic equation. Shows that there can be large differences between the 2 equations, so the choice of equation is important.

Discusses the ASHRAE Standard 62-1981 "Ventilation for Acceptable Indoor AIr Quality", and extensive field measurements of ventilation. Presents apredictive model for indoor air contaminant concentrations in residences andits verification, along with the effects of several variables. Additional research on the indoor emanation rates of contaminants which are health hazards would enable the prediction of indoor contaminant levels with various control options.

Investigates the energy performance of a two storey occupied gas heated house in Ontario Canada by means of steady state and dynamic analyses of measured data. Experimental results were obtained from a monitoring study done on an hourly basis.