- Energy Saving
- Heat Pumps
- Electricity Generation
Energy efficiency is not just low-hanging fruit; it is fruit on the ground.Stephen Chu, US Secretary of Energy
The clocks have changed as normal ... but what a difference compared to last year
Last week (Week 43), the average temperature in the south of England was 15°C. This compares with 10.5°C in Week 43 last year.
Now, 5°C might not seem like a lot — but, when you use degree day analysis to determine the impact it had on heating requirement, it is ‘marked’ to say the least.
Using degree day analysis tells us that, in Week 43 2012, the degree day heating requirement in the south of England was 65.34. This compares to 36.05 in 2013, based on a 20°C heating temperature. Check out the graphs.
Put more simply, if your heat demand was 100% driven by the need to maintain a set temperature (i.e. no humidity control), you should have used 45% less fuel last week than in the same week the year before. Although not quite as marked, the pattern is similar in the north — 38% less.
Looking at when the clocks changed to BST in Week 13, it was the opposite. Degree day analysis shows that you should have used 86% more heat in 2013 than in 2012.
You might wonder what the point of all this is — after all, none of us can yet control the weather.
This is best explained with two examples:
- If you installed thermal screens 12 months ago, there may not be much difference between your gas bill for March 2012 with your bill for March 2013, and you could be forgiven for wondering if the screens had ‘done the business’. But, once the impact of the weather is taken into account, you can be pretty sure the answer is very positive indeed.
- If you look at last week in isolation, you may feel like giving yourself a ‘pat on the back’ — surely your energy efficiency drive is paying off? It may well be, but it isn’t the only reason your energy use was so low.