Assume you cook with gas which accounts for residual summer usage?
Cooking is with electricity. The residual summer usage is caused by one, and sometimes 2, members of the "3.5" adults in this house using far more than their fare share of hot water. e.g. 1 (power) shower can be up to 14 minutes = total of 120 litres of blended water. Sometimes 2 of them commit this sin on the same day. So even in summer the hot water sometimes has to be topped up from the C/H boiler. I won't go into detail about other hot water extravagances - such as always turning on the hot tap for the smallest need of water but due to the dead leg no hot reaches the tap before the tap is turned off - it just cools in the pipe work. Rinsing dishes under the hot tap before putting them into the dishwasher (a particularly heinous crime). And filling used cooking pans with hot water leaving them to soak for a while and then pouring away the water before putting the pans into the dishwasher – which usually fails to clean the used pans properly, hence leading to further usage of hot water to do a post-dishwasher manual job!
Is there Any way you could play with the data to show how much of the overall improvement was due to each development? It would be very useful for convincing people.
Not really. The new boiler & 216 litre cylinder were fitted 2 weeks before the solar panel - so too close together. The additional loft insulation difference can be detected because it was fitted just about 1 year before the new boiler. I checked back in the older records to see the difference made by adding the cavity wall insulation in mid-May 2000. But even that is difficult to be exact because it was done only 6 months after the double glazing was fitted in Dec 1999. However on the basis that the DG made about a 5% difference, then the cavity wall insulation was about 15%.
