To build houses and flats with an energy saving of 40% for heating and domestic hot water in comparison with equivalent housing built according to Danish regulations (br 77) which came into force in 1979. This means an annual energy consumption of between 84 and 96 kwh/m2 of floor space.
- a thermographic survey of the housing showed that apart from some localised defects, the thermal insulation was successful.
- the natural ventilation rates were 0.1-0.5 renewals per hour of the volume of the new housing, and up to 1.5 renewals per hour for the modernized house.
Furthermore the overall rates for natural and mechanical ventilation in the new housing were between 0.3 and 1.0 renewals per hour, with the exception of one house which achieved 1.7 renewals per hour.
- the measurements revealed a wide diversity of figures for energy consumption for heating and domestic hot water. This diversity is due especially to the differing life-styles of the occupants.
The annual consumption figures for the 52 new houses and flats range from 38 to 82 kwh/m2 of floor space; thus the project has achieved its aim.
The annual consumption figure for the modernized house is 115 kwh/m2, which significantly exceeds the target, although it is still very acceptable in absolute terms.
- it was noted that the flats clearly consumed more energy than the houses; this was caused by the fact that the heating was not shut down in the summer and by greater losses in the preparation and centralized distribution of domestic hot water.
- the coefficients of the average annual performance of the heat pumps
(including electricity form the pumps and electrical resistance heaters for supplementary heating) were as follows:
- heat pumps for heating the flats: 2.58
- heat pumps for heating the houses: 1.2-2.0
- heat pumps for the water for the houses: 0.8-0.9
- the contribution of useful energy from the solar collectors was smaller than had been expected:
- 9 identical houses: 154 kwh/yr/m2 of collector.
-Flats:134 kwh/yr/m2 of collector.
- The project has further provided some interesting information regarding the automatic regulation of the systems and the need for good insulation on heating and hot-water units.
The savings have exceededexpectations:50% instead of 40% have been reached.
The construction of the following 53 low-energy-consumption houses and flats, in Skive, Denmark : - 9 identical one-family houses, each with an area of 116 m2
- 9 different one-family houses, with areas ranging from 130 to 206 m2
- 34 flats in two or three-storey buildings, with an area of 80 m2 per flat
- 1 old house (1912) for modernization.
The work was carried out in 1979 by different concerns, and the houses were equipped with different energy-saving means that were commercially available in Denmark at that time. The following energy-saving methods were used according to the different types of housing : - increased thermal insulation. The minimum coefficients of heat transmission through surfaces were :
Exterior walls: 0.17 w/m2k (0.40)
Floors: 0.18 w/m2k (0.30)
Roofs: 0.14 w/m2k (0.20)
Windows: 1.60 w/m2k (3.00)
(BR 77 requirements in brackets)
- increased air-tightness.
- heating and domestic hot water provided by heat pumps with underground pipes (using a horizontal reservoir) or by heat pumps using water pumped from the soil.
- water-type solar collectors, with anti-freeze, for domestic hot water and, in some cases, for supplementary heating of the building.
The other heating systems used in the project were:
- topping-up electrical resistance heaters
- oil-fired boilers
- district heating
- back-up wood-fired stoves
The heat pump using water pumped from the soil had to be modified following the blockage of the water-return system. The external heat is now provided by underground vertical exchangers.
