heat pump

This report examines three devices (exhaust fan, air-to-air heat exchanger and exhaust air heat recovery heat pump) which could be used to increase the ventilation rate of a tightly constructed house to a level sufficient to keep indoor air pollutants and moisture to acceptable concentrations.

Provides a brief summary of Swedish energy policy. Covers current knowledge and research in Sweden concerning low-energy buildings and building services, energy supply, the built environment and heat pumps.

Describes the main energy R and D projects in the building sector which are financed by the Finnish Ministry of Trade and Industry. Projects in the 1970's included improving the air tightness of buildings, and balancing and controlling ventilation systems. Projects started in the 1980's include energy-economic improvement of ventilation and the building envelope, and development of heat pumps.

Considers the options which could be described as heat recovery and which are open to building services designers and operators. Treats fundementals for heat recovery, inadvertent heat recovery, deliberate heat recovery, air recirculation, passive heat exchangers, active heat exchangers, heat pump systems, heat recovery systems, incremental systems, heat distribution in central plant heat recovery systems, controls, heat recovery in air conditioning systems, bivalent heating, the actual application process of heat recovery.

Makes general suggestions for future buildings and their ventilation methods with the aim of creating improvements to avoid the faulty design of the 1960's with their high energy consumption. Considers the characteristics of natural ventilation and mechanical ventilation with respect to ventilation heat loss. Recommends the use of `ventilation on demand' for bathrooms, w.c.'s and kitchens using individual extract ventilation units for each room.

In order to investigate the possibilities of installing heat recovery equipment in old apartment houses, a large project has been started. There are 30,000 to 35,000 apartment houses in Finland with an average volume of6000-7000 cu.m. Possible savings from heat recovery in houses with mechanical exhaust are the transfer of heat to supply air using standard equipment and heat recovery from exhaust air using heat pumps.

Reports measurements of air leakage rates in the four energy-conservation research houses using the fan pressurization method. One of the houses is standard for the area and the other three houses have added insulation and vapour barriers. One house has a heat pump and one an air-to-air solar heating system. Air infiltration rates were measured in two of the houses using CO2 as a tracer gas. Discusses results and compares tracer gas with pressurization tests.

States condensation caused by high humidity is a major problem in British homes. Describes a conventional heat pump dehumidifier for removing moisture from the air. Describes the advanced dehumidifier developed by the Electricity Council Research Centre which is designed to work in cold damp conditions typical of British winters. Gives details of the design and reports that tests of a prototype show that the design is more than twice as effective in terms of litres of water extracted per unit energy than conventional designs.

Energy lost through ventilation becomes increasingly important as building insulation levels improve. Describes application to this problem of heat pump dehumidifier which transduces latent heat of moisture in cool damp air into sensible heat of warm drier air. Describes laboratory prototypes which combine sensible heat from counter flow heat exchangers with heat transfer properties of a heat pump. Claims such systems perform twice as effectively as conventional equipment and offer a new approach to ventilation losses.

Ventilation is a key factor in low energy housing and in temperate maritime climates such as Britain's moisture is a major factor in determining ventilation needs. Outlines necessary levels of humidity for both people and buildings. Summarises sources of moisture. Discusses control of humidity by either mechanical ventilation or heat pump dehumidification.