Describes experiments carried out in 4 low energy electrically heated houses incorporating extra thermal insulation and heat recovery mechanical ventilation systems. Airtightness was made an objective so that the ventilation system would provide as much of the required fresh air as possible. Instrumentation was installed during construction to monitor the performance of the houses, with the cooperation of eventual purchasers. The houses were leak tested and sealed where necessary.
Notes initial airtightness requirements in SBN 1980 and discusses various forms of ventilation. Discusses how tightness testing can reveal location and magnitude of leaks. Gives theoretical method of calculating air leakage flow and relates this to practical measurement. Considers different alternatives such as pressurising the building and combining tightness testing with thermography. Discusses 1980 building regulations and what buildings ought to be tested. Lists critical points of a building and measures which can contribute to good airtightness.
Notes job losses in prefabricated timber housing industry in Sweden and Hjaltevad's endeavours to produce a large series popular house with low-energy characteristics. House is on one and a half floors and has an occupied area of 150 sq.m. Heating economy is strongest sales argument with estimated annual consumption of 8000 Kwh. Low energy consumption results from electric boiler and heat pump. The heat pump assumes a mechanical exhaust air system and heat extracted is added to hot water system. Notes strict control of tightness before external cladding is nailed in position.
Notes the high heat loss in Canadian houses due to air leakage and condensation problems caused by uncontrolled moisture movement into the exterior wall structure. Recommends the installation of an air-vapour barrier to form a completely sealed envelope around the house structure except at doors, windows, vents and other obstacles. The recommended thickness for the polyethylene sheet of the air vapour barrier is 6mm, which is continually sealed at all joints. Details the recommended installation procedures for realising an air-vapour barrier.
The Heimdal project concludes that airtight houses can be built. Measurement results from 11 detached houses indicate an average leakage factor of 0.9. Building regulations in Norway require a value below 4 and NBI's field investigations indicate that there have been problems in complying with this requirement. The results from the trial houses have been achieved through the implementation of available methods but construction on site has been carefully planned and executed.
Describes a programme of ventilation measurements performed on a group of energy efficient houses built in the mid-1970's and situated in Abertridwr, S.Wales. Pressurization, tracer decay and British Gas autovent techniques were employed. Results show satisfactory whole-house ventilation rates (0.5 ac/h), but the living room and bedrooms had very low ventilation rates. Some cases showed serious condensation. "Trickle" ventilation installed in 18 of the houses improved internal ventilation patterns and condensation levels were substantially reduced.
Describes a simple method of controlled ventilation comprising an extract system and air inlets. The extract system is effectively a flue connecting to vents in the kitchen and bathroom and relying on thermal differences and the wind to create air flow, air enters the house via slot vents over windows. Theproposed system has been installed in a timber framed house.
Examines several ventilation strategies in tight houses for both impact on the total ventilation and effect on the energy balance of the system. Uses the single-zone infiltration model developed at LBL as part of the calculation of total ventilation load. Strategies covered include natural systems such as ventilation stacks as well as mechanical systems such such as air-to-air heat exchangers and exhaust fans with and without heat pumps.
Describes project on experimental housing of a new type built by Swedish manufacturers employing light, timber construction. Good airtightness and careful work results in the lowest total cost. Investigation shows results of profitability of various investments. Illustrates energy balance for housing discussed.