The project is in two parts:

1. Retrofitting of three Victorian style houses and conversion into 15 low energy flats.

2. Construction of 18 new low energy single-family houses.

The aim is to achieve an annual energy consumption for heating and domestic hot water of 11630 kWh per flat (retrofitting) and 6288 kWh per single-family house (new construction).

This means a saving of 59% and 61% respectively over houses corresponding to standard retrofitting or to the 1985 Building Regulation Thermal Standard ("85 BRTS").

CALCULATION OF PREDICTIONS:

1. Assumptions made for calculating the predictions were modified during the monitoring period. A new calculation of predictions has thus been done using the modified assumptions. These assumptions were about:

- the mean temperature in dwellings

- the occupancy of dwellings

- the number of month in the year without heating

- the correction factor that takes the inertia of the building into account in the simulation program. This factor has been chosen to get, as calculated value with the program, the measured mean consumption of energy efficient houses. This value of the correction factor has then been used to calculate the heating consumption of houses corresponding to the standard retrofitting or to the "85 BRTS" and to deduce savings.

2. Payback periods have been calculated assuming a gas price of 0.11 UKL/kWh.

RETROFITTING OF EXISTING HOUSES

3. The initial prediction was a consumption of 11633 kWh/yr per dwelling i.e. a saving of 59% over the standard retrofitting.

4. The monitoring showed that the consumption is 14813 kWh/yr but assumptions are different.

5. Using the measured assumption to calculate the consumption gives a value of 30616 kWh/yr for a flat corresponding to a standard retrofitting and 15803 kWh/yr for a flat corresponding to efficient retrofitting i.e. a saving of 52%. This saving is very close to the first estimate of 59%.

6. The additional capital cost was 955 UKL per flat giving a payback period of 5.5 years.

NEW HOUSES

7. The initial prediction was a consumption of 6288 kWh/yr per house corresponding to a saving of 61% over the same house built to the "85 BRTS".

8. The measured consumption is 8366 kWh/yr per house.

9. Using the measured assumption to calculate the consumptions gives a value of 8240 kWh/yr for an efficient new house and 64% more for a house corresponding to the "85 BRTS". The results are thus a little better than predicted.

10. The additional capital cost was 674 UKL per housegiving a payback period of 4.9 years.

RESULTS OF THE DEMONSTRATION SUITE

11. The aim of the "demonstration suite" was to show the interest of the project to the public. The visitors were invited to fullfill a questionnaire and give their opinion. The main results are:

- a significant increasing of awareness and a changing of attitude of people,

- a big proportion of designers (58%) intend to give a higher priority to energy efficiency in their future designs.

THE "ENERGY CERTIFICATE"

12. The four boroughs of SLC (Greenwich, Lambeth, Lewisham & Southwark) have set up a procedure whereby a retrofitted or a new build house can get a "Design Energy Consumption Certificate". This certificate has been very successful and from January 1985 to February 1988, 1122 certificates have been issued covering 6805 dwellings. The corresponding saving in fuel cost is evaluated to 1,225,000 UKL/yr. This procedure is now continuing.

The site of the project is Lawrie Park road, London SE 26.

Retrofitting of three existing houses. This involves major structural changes inside the houses. The means of energy-saving are:

(a) increase of heat insulation in the roof (insulation: 200 mm), the outside walls (insulation on the inside: 100 mm) and the floor (insulation: 100 mm)

(b) improved draught-proofing in the houses by means of closed weather porch and door and window seals. In principle ventilation with outside air is limited to one air change per hour. Ventilation is provided by the hot-air heating system. (c) supply of domestic hot water by one direct gas heater per flat. New single-family houses. Houses face north-south.

The means of energy-saving are:

(a) good heat insulation of the opaque partitions and double glazing

(b) good draught-proofing (closed weather porch and door and window seals).

(c) glasshouse on the ground floor along the entire south-facing side of the houses.

(d) supply of hot water by thermosyphon-operated solar heat collectors.

A second hot water circuit is supplied by a gas storage device. The houses are heated by a hot-air system combined with outside air ventilation.