As an example we’ve taken a pretty standard 3 bedroom Victorian end of terrace in London (85m2 floor area), surveyed and then modelled it and then analysed the predicted effect of upgrading the boiler – an annual saving of £495 from an initial annual fuel bill of £1,766.Background on the house:
Solid brick, no loft insulation, uninsulated solid and suspended floors
Single sash windows in good condition
Old boiler with permanent pilot light providing heating and hot water
Programmable heating on twice during the week and most of the day at weekends, thermostat set at 19 degrees throughout.What we did next was to hypothetically move it around the country and carry out exactly the same boiler upgrade for the house in each location.

The image below shows where the different locations we chose and the graphs and figures show the £ sum of the variance from London over a 20 year timescale – chosen to represent a Green Deal style loan although it is expected that these may be up to 25 years.

These results are for single measures only and with everything else about the house and its use being kept constant.

We believe that the figures are large enough to make taking regional climate into account if accurate predictions are going to be made – especially if they have a financial implication.