thermography

Retrofitting for air infiltration is undertaken for two principal reasons, to provide greater comfort and to save energy. Qualitative and quantitative measurement of air penetration is an essential prerequisite for planning anefficient retrofit for air infiltration. Describes methods of measurement with two examples of single family houses in sheltered and exposed locations.

Defines air change and air penetration. Describes the differential pressure method, the infrasound method, qualitative judgement methods, and acoustic measurement devices for determining air penetration. Explains procedures todetermine air change - the rate of decay method, the constant concentration method, and the constant emission method.

Reviews the literature on techniques of air infiltration measurement, including pressurization methods, use of tracer gas and thermography.

Provides a brief introduction to infrared theory and its application in building analysis, and describes some typical building faults that may be identified by thermographic inspection.

Reports on measurements carried out by energy consultants at a national test centre using thermography to determine any improvements in insulation and airtightness through the injection of mineral wool in Dormer houses. Measurements show results which are much better than expected. States costs and payback period of approx 6 years.

Discusses the mechanics of thermography, the type of instrument used and its application in building surveys. This includes the location and extent of any insulation deficiencies such as cold bridging or air leakage, and the quantification of existing thermal deficiencies.

Reports air tightness measures and variations in 14 low-energy houses in Heimdal, plus testing of energy saving measures for exposed detached houses. The air tightness should be considerably improved according to the regulations. Treats principles of air tightness, pressure measurement, thermography tracer gas measurements and heat loss measurements.

Describes the retrofitting of a 14-storey office block in Oslo, done as part of an energy conservation project carried out in Norway 1979-82. The main reduction in energy consumption was achieved by tightening air leaks between concrete wall elements and windows by the application of sealing compound in 2 critical types of joint in the facade. Measures the energy consumption one year before and one year after retrofitting, using thermography to find the air leaks and to verify the tightening afterwards. Also carries out pressurization tests using the building's ventilation system.

Describes the testing of 8 federal office buildings (size from 3000 sq.m. - 45000 sq.m.) for their air infiltration characteristics, as part of the NBS program to develop diagnostic test methods for evaluating the thermal integrity of federal office buildings. Performs tracer gas tests in the autumn, winter and spring to evaluate both the ventilation of these buildings during occupied periods and the natural air leakage under various weather conditions.

Presents various measurement and inspection techniques for assessing the thermal performance of the exterior envelopes of buildings. Inspection techniques include the use of ground-based infra-red thermographic surveys, aerial infra-red surveys, tracer gas air infiltration measurements, pressurization tests for measuring the tightness of the building envelope, and spot radiometer surveys for detecting gross defects. Also considers heat flow meters, a portable calorimeter and a microprocessor-driven envelope testing unit. Provides recommended procedures for each technique.