Objective
Economical justification of superinsulation in northern countries of the EEC and finding fair solution for design, construction and usage of such houses in cold and wet climates. The extra-cost is expected to be 1865 UKL (1983 prices) and fuel savings for space heating should be 4,500 Kwh/house/year.
1. A prefabricated timber frame system was chosen to build the superinsulated houses because it was one of the best to get an airtight construction with good levels of insulation. The same insulation and airtight qualities should be performed with a house built in masonery but the construction duration should have been longer.
2. Air change rates were measured and the results showed infiltration rates lower than 0,1 a.c./h when the ventilation system was off and equal to 0,9 a.c./h when the ventilation system was on. This shows the airtight quality of the superinsulated houses.
3. The ground floor heat loss were also measured in the superinsulated houses. This showed that the ground floor heat loss has to be related to the ground temperature rather than to the external air temperature because there is a time bag between the variation of external temperature and ground temperature.
4. The fabric heat loss was evaluated be using thermography. This measurement gave results of 62 to 68 W/K for the specific heat loss rate compared to the predicted value of 58 W/K for the calculated fabric loss. The difference (4 to 10 W/K) corresponds to the heat loss due to a background air leakage of 0,06 to 0,16 a.c./h. This also shows the good thermal performance of the superinsulated houses.
5. The opinion of the superinsulated householders was that the houses are very comfortable because of the lower tempeature difference between inside air and walls or floor in winter and because of relatively low overheating in summer.
6. A complete absence of condensation was reported by all the householders showing the efficiency of the insulation and of the ventilation system used as heating system.
7. The consumption measurements showed a fuel saving for space heating and sanitary hot water of arund 6000 kWh per year for the superinsulated house compared to the control one.
8. The efficiency at the boiler used in the project was very poor (between 25 and 37 %), this efficiency is calculated by the ratio between the measured usefull heat for space heating and sanitary hot water and the gas usage.
But, if the efficiency is evaluated by comparing the measured flue losses and the gas usage, it varies between 66 and 71 % the difference is called the heat loss to the house which contribuuted to space heating and sanitory hot water preparation. Fortunately, these losses which were not controlable, didn't lead to overheating in the houses.
Two sets of houses (84 m2; 3 bedrooms; semi-detached houses) are built.
The first set includes superinsulated houses and the second set includes houses built according to the thermal requirements of the 1981 Building Regulation.
2. The superinsulated houses have the following thermal characteristics (U-values in w/m2 deg K) :
walls : u = 0,18 (150 mm glass fibre insulation, timber frame)
roofs : u = 0,12 (300 mm glass fibre insulation, timber frame)
floors : u = 0,20 (100 mm rigid insulation beneath the concrete floor slab)
windows : u = 1,20 (triple glazing and low emissivity coating)
For comparison, the reference houses are insulated as follows :
walls : u = 0,40 (90 mm glass fibre insulation)
roofs : u = 0,35 (100 mm glass fibre insulation)
floors : u = 0,60 (no insulation under slab)
windows : u = 5,60 (single glazing)
3. Heat is supplied for both type of houses by a gas boiler of the "Cormorant" type. The principle of this boiler is to keep a thermal storage of water at a constant temperature of 80 deg.C.
Domestic hot water is prepared in a heat exchanger placed in the storage and space heating is performed by circulating water of the storage in radiators (reference houses) or in a coil to heat the air of ventilation (superinsulated houses).
The reference houses are ventilated by means of window frame ventilators and a cooker extract system in the kitchen; a double flow ventilation system with heat recovery is installed in the superinsulated houses.
4. A monitoring system is used to record temperatures and consumption during all the year.
The heating consumption of both types of houses has been predetermined by use of a simulation program of building behaviour and measured by the monitoring system.
Programme(s)
Topic(s)
Call for proposal
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DEM - Demonstration contractsCoordinator
BA1 6AA Bath
United Kingdom