In a way most heat pumps recover or reclaim heat energy for space heating and cooling, water heating or process heating. In the building sector, the natural heat sources which heat pumps transfer to useful heat, such as outside air, the ground, ground water and sea/lake/river water are in fact all heat sources that consist of solar heat and cannot be directly used for heating due to their temperature. Hence, one can argue that heat pumps which use these sources are (solar) heat-recovery devices.

Demand controlled ventilation systems can be used to minimise energy consumption whilst maintaining satisfactory levels of indoor air quality (IAQ). As an alternative to C02 sensors IAQ sensors (based on Taguchi mixed gas sensors) can be used to infer levels of IAQ. This Technical Note provides details of a series of laboratory and site tests to determine the performance of a range of IAQ sensors.

To investigate the effect of ventilation on indoor radon (222Rn), simultaneous measurements of radon concentrations and air change rates were made in 117 Danish naturally ventilated slab-on-grade houses built during the period 1984-1989. Radon measurements (based on CR-39 alpha-track detectors) and air change rate measurements (based on the perfluorocarbon tracer technique; PFT) were in the ranges 12-620 Bq m-3 and 0.16--0.96 h-1, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated uncertainty is discussed.

An extensive survey has been carried out in 52 underground car parks in Hong Kong focusing on carbon monoxide concentrations in the air. So far as short term health effects are concerned this compound is generally regarded as the most important chemical species from car exhausts. Its presence can be used to quantify air pollution, and give an indicator of the air quality in car parks. The sites were sampled during peak hours. This report presents the results and analysis of the carbon monoxide levels measured.

A publicly-owned office building in Eskilstuna, Sweden, has been retrofitted with high-frequency with self-regulating controls for the lighting and ventilation systems. The building has a total floor area of 19,000 m2 and contains more than 3 00 offices, a conference room, lunch rooms, and a recreation hall. Before retrofitting the total annual electricity consumption was 1/300 MWh and the district(heat consumption was 950 MWh. The total annual energy consumption was reduced by 20% as a result of the new installlations.