A Season of Smart Heating

Last October I mentioned that I had been fitting programmable radiator valves to my central heating system to try to reduce my astronomical gas bill. Generally, these have worked quite well although the noise of the motors in one child’s bedroom was too disturbing so I have had to revert to a manual TRV. Other than that they have been an improvement as it makes it much easier to accurately turn the temperature up and down. The only other issue I have had has been in the last few weeks: once the AA batteries go flat the radiator defaults to an “on” setting. Fortunately, replacing the batteries is very easy.

I’ve kept monthly records of my gas and electric usage since moving in to the house so I have been able to plot out how much I have been using in the November through to April period which covers the heaviest heating use. This week, I received the energy bill covering the last of the Winter months so I have been able to assess how effective or otherwise they have been. The good news is that the gas usage per day has gone down compared to previous years as you can see on this graph (although it should be borne in mind that the radiator valves were only fully operational from the end of October):

The year refers to when January falls. On the face of it, it would appear that the gas use has gone down year on year. However, it is worth bearing in mind that we did get some extra roof insulation added in the summer of 2012 so it isn’t an exact comparison and, of course, the biggest variable factor is the weather. I have been told that a ballpark figure for switching the central heating down by 1 degree is a 10% reduction. That may be optimistic but the flipside is that a 1 degree reduction in the outside temperature will result in a 10% increase in heating requirements. To try and work out how much of an effect this would have I have managed to get average minimum temperature figures for Eastern Scotland from the Met Office:

It seems to indicate that this past Winter was, for the most part, more severe than the previous year but not quite as severe as 2013 (although that was more a case of a very cold early spring). The other thing that is difficult to assess is what the house occupancy has been like and the number of times the heating has been on in the daytime due to various people suffering from colds or flu this year will skew things.

So what has been the total effect of fitting the valves. Well, my gas use has been the lowest over the last year since we moved in and this translates to a 17% reduction on the previous year and a 29% reduction on 2012/13 (with its cold spring). Averaging out I’d say that would be something like a 23% reduction in gas use which is not at all bad and easily covers the cost of the radiator valves. Of course this is no substitution for proper external wall insulation but given that is neither cheap nor easy on a solid walled house it is a fairly quick win.