heat loss

Outlines two techniques for estimating ventilation heat losses in houses. The first is a tracer gas technique using a constant concentration of gas and the second a theoretical prediction method. The theoretical technique treats the building as a multi-cell model with specified wind pressure, leakage openings and background leakage area. Reports use of the method for simulating the natural ventilation of a house in London and the effectiveness of sealing the windows and floor.

Compares annual fuel consumptions of seven large factories against calculated requirements to illustrate seasonal thermal efficiencies of 7.7 to 49.7%. Shows that ineffective and uncontrolled ventilation is by far the most significant factor in excess fuel consumption. Illustrates savings of 38 to 80% in fuel which have been achieved. Shows that fuel savings of 20 to80% are possible in the factories studied, with 35 to 95% savings possible when heat recovery is provided in addition to other improvements.

Examines the influence of air movement on the thermal performance of the building envelope by identifying and discussing the mechanisms of 8 distinctive air movement paths. These are; convection from interior air to interior surface ; convecti

Provides table showing that annual heat loss through windows in U.S. accounts for about 5% of total energy consumption, or around 1.5 times energy derived from oil transported by alaskan pipeline, costing $30 billion annually. Describes relatively simple window treatment to eliminate substantial portion of thisloss which involves tightly sealed, interior-applied insulating panels. Demonstrates how performance of several such systems was predicted and verified by standard test methods.

Reports measurements made in six blocks of flats of energy consumption and wind speed. Gives graphs of results. Concludes that a moderate wind (of 30m/s) increases energy consumption by12% and a strong wind (60m/s) by 25%. Suggests heat loss can be reduced by tightening windows and controlling ventilation.

Briefly discusses wind-pressure on buildings. Derives equations for air-flow in a building without internal walls caused by wind pressure from perpendicular and oblique wind. Gives simplified method for calculating air flows inside a building with internal walls. Gives tables showing results of calculation of air flows for a building with two and three rooms. Discusses more complicated building types and gives results of calculation. Outlines determination of ventilation heat loss, air leakage of windows and doors.

Reports model scale experiments to investigate the validity of digital analogue methods of predicting natural ventilation. Finds calculated ventilation rates up to 30% higher than observed model ventilation rates. Shows differences between observed and computed results caused by operating efficiency of ventilation openings being less than calibrated efficiencies. Corrected ventilation rates, allowing for changes in efficiency due to pressure fluctuations and lateral air flows over model surfaces showed close agreement with observed results.

Outlines the problem of assessing the rate of heat loss from dwellings due to ventilation. Discusses the mechanisms and pathways of ventilation and ways of controlling air infiltration. Reviews methods of measuring ventilation using tracer gases. Discusses qualities of ideal tracer gas and three automated measuring systems. Reviews some experimental results obtained from the SEGAS test house. Describes house and measurement method. Finds sealing house reduced ventilation rates by between 30 and 45 per cent.

Studies influence on energy loss of an air curtain installed at building entrance. The energy loss consists of transmission loss and ventilation losses caused by stack effect, pressure difference due to wind, direct wind on the entrance and differences in the specific gravity of inside and outside air. Gives an example of calculated energy loss at the entrance of a simulated department store. Outlines principles and types of air curtain.

Describes experimental studies of the natural ventilation of four similar houses with different ventilating systems. Describes houses and gives experimental procedure and results of measurements of air-change-rates using hydrogen as a tracer gas.Shows variation in air-change-rates are due mainly to changes in wind speed and that wind direction and temperature difference are secondary factors. Estimates rate of heat loss as a functionof wind speed. Discusses relationship between measured pressure differences and wind speed and direction.