English

Subjects 11 private dwellings at Taby and 5 at Brunna (all 2-3 yrs old) to repeated airtightness tests over a period of two years. Finds the largest leakage is 2.5 ach and the mean leakage is 1.6 ach. Immediately after its completion, the air tightness of a building undergoes a certain deterioration, after which it stabilizes. Over the 2yr. measuring period the changes are small, and could all be attributed to occupancy effects. Leakage paths occurat the junctions of wall and ceiling and wall and floor, and at service entries.

Measures air change rates in a 2-storey detached house with operation of various types of mechanical fresh air ventilation systems. Studies 4 systems, including 2 balanced systems and 2 exhaust-only systems. The forced ventilation rate is controlled at 0.15, 0.25, 0.4, or 0.5 ach. Develops expressions for the test house relating the house air change rate under winter conditions to the forced ventilation rate and the infiltration rate due to wind and temperature difference.

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.

Discusses the Hjortekar project of 6 low energy houses, built as part of the Danish Energy Research and Development Programme. Explains some of the construction details to avoid cold bridges and ensure airtightness. Test results of infiltration air change rates range from 0.02 to 0.12 ach, while other tests show less than 15% difference between calculated and measured transmission heat losses, which range from 70-155 w/degree C.

Examines and tests a number of commercial air-to-air heat exchangers to determine their performance as installed in each house. Results show that although some heat exchangers indicate a high performance level, there are many installation and operational faults. A number of recommendations are made on the selection, installation and operation of air-to-air heat exchangers in houses.

Proposes a new experimental technique for investigating the natural ventilation potential of new building designs. The method tests scale models of ventilated buildings outdoors in the natural wind. Results from this method agree closely with data from a similar full-scale building. Discusses use of this method by building designers.

One limiting factor in achieving optimum thermal performance in shutters is air leakage around the shutter edges. Describes a motor driven shutter using multilayer curtains employing a magnetic type edge seal. Measures the thermal performance of 2-layer and 4-layer shutters using a controlled environment chamber. The 2-layer shutter performs as well as a similarly sized unit in which the layers ar permanently sealed. The 4-layer unit does not perform as well as expected because of air leakage between cells at the top of theshutter.

Tests a room-size, residential air-to-air heat exchanger for effectiveness of heat recovery. Conducts experiments in a small wood frame building, the Test Chamber, on the roof of the lab building. Determines heat recovery efficiency by comparing actual heat loss to that expected due to mechanically induced ventilation. The heat exchanger recovers almost 50% of the heat contained in the outgoing air flow. Additional experiments quantify effects of fan power consumption and heat conduction through the case of the device.

Uses wind tunnel model studies of houses to determine how best to reduce the surface pressure variations from wind and the associated air infiltration emphasizing the correct placement of suitably modelled coniferous trees. Finds that tree crowns convert the directed kinetic energy of approaching wind into random turbulent energy, which reduces pressure gradients on the windward walls, a prime region for air infiltration.

Presents a review of the main methods used for the study of air movement. Includes sections on physical modelling (wind tunnel modelling etc), analogue (water and electrical) models of air movement, mathematical models and digital computer analogues, and full scale investigations including pressurization andtracer gas techniques.