Gas CH bill sky high - Help is needed...

Cardew

There is so much thermal mass in a house that it would be unusual for a house with reasonable insulation to drop more than 5 or 6 degrees overnight.

Even during that really cold weather last winter(-19C here) we still kept to our normal pattern of heating off at bedtime and on about 30 mins before getting up.

becksfaz

Thanks guys. In that case, it will remian OFF!
I had a new programmable digital thermostat fitted last week (foc! Bargain!) and have functions on it to set temperatures at different times of the days over 7 days (old stat was just a dial) so will do what you do Happy MJ and programme it to be on 24/7 and set in to 7 at night. Thanks.
Now another thing I'd like help with if anyone can shed any light on this (I'm baffled).... last week I was ill (flu - never want that again!) so heating was on from 6am right through to 9.30pm and we used the following metric units Weds = 7, Thurs = 8, Fri & Sat = 10) Having it on timer with old stat (2 hrs AM & 3 hrs PM) over the past few weeks has been costing us 8-10 units per day. I initially thought this was as a result of my new stat (fitted last Tues) which is possibly more accurate(?) but then Sunday we were out for the whole day so set the heating to timer again for only 2 hrs AM and 3 hrs PM and used 10 units! Why do we use so many units having it timed?

macman

Only a wild guess-because it was much colder?

becksfaz

macman wrote: »

Only a wild guess-because it was much colder?

Just pulled up tempertures for last week for my area - and Sunday was colder but not significantly.
Weds was a high of 9 degrees which explains only using 7 units, Thurs is was highs of 7 degrees when we used 8.
Now Fri and Sat it was high of 5 degrees and we used 10 with 15.5 hrs of heating.
Sunday it was high of 2 degrees and we used 10 with 5 hrs of heating - would 3 degrees have this much impact?

HappyMJ

becksfaz wrote: »

Just pulled up tempertures for last week for my area - and Sunday was colder but not significantly.
Weds was a high of 9 degrees which explains only using 7 units, Thurs is was highs of 7 degrees when we used 8.
Now Fri and Sat it was high of 5 degrees and we used 10 with 15.5 hrs of heating.
Sunday it was high of 2 degrees and we used 10 with 5 hrs of heating - would 3 degrees have this much impact?

Yes it is possible. You really need to know the average temperature for the day.

I look at a local weather station and it tells me Wednesday the 25th average temperature was 9.3C ranging from 8.4C to 10.2C and Sunday the 29th the average temperature was 0.8C ranging from -1.4C to 3.0C. So it's not just 3 degrees difference it's 8.5 degrees difference over the 24 hours. The difference in temperature will easily cause your consumption to double.

The number of "degree days" required to heat the house to an average temperature of 15.5C on the 25th would have been 7.1 and the number required on the 29th would have been 14.7. My house uses about 2kWh per degree day so my usage would have doubled.

I get a lot of this information from http://ebico.imeasure.org.uk and entering in my weekly meter readings and looking at the "energy against heating degree days" chart.

becksfaz

Thanks Happy MJ. I think you have sent me that before and I started filling it all in but when I had to select 'local weather station', none were my region so I couldn't register. I know Jalexa has mentioned 'degree days' before but I wasn't sure what he/she meant. How do I find out more about degree days and, like you, gain the knowledge of what my house uses per degree day??

HappyMJ

becksfaz wrote: »

Thanks Happy MJ. I think you have sent me that before and I started filling it all in but when I had to select 'local weather station', none were my region so I couldn't register. I know Jalexa has mentioned 'degree days' before but I wasn't sure what he/she meant. How do I find out more about degree days and, like you, gain the knowledge of what my house uses per degree day??

Lots of spreadsheets and charting that's why the imeasure site is so useful. Just select any weather station. The one I selected is in Coleshill which is 28 miles away. The one I use to know what the temperature was on a particular day is 2 miles away but isn't linked to the imeasure site. Just pick a site which you think would be similar to the weather in your area. It won't be 100% accurate but it will give you an idea. It's hard to actually measure what your house uses per degree day accurately. You need to take the meter reading at exactly midnight every night which is extremely difficult. I just take it at the same time every week. If you were to do it manually you need to find the average temperature of that day then you just need to calculate the difference between the average temperature and 15.5C. Most people don't use the heating at all if the average outside temperature over 24 hours is 15.5C or above as the house will just about always be 3 or 4 degrees warmer than outside and feel warm enough. You then need to find the base usage of your house. Just use a summer week when the heating is off for a week. An average house would be about 15kWh per day for electric and gas hot water. Then you would have to figure out by deducting the base usage and dividing by the degree days that you have figured out to get the amount used per degree day. The figure that you get should be about the same. It's pretty complex so just use the imeasure site and let them do it. I would guess that an average house uses about 8kWh per degree day each day but it could be anything depending on your house.

macman

It's said that turning down your heating 1C can knock 10% off your bill. So a 1C decrease in the ambient temp will (in theory) add 10% to your bill.

becksfaz

macman wrote: »

It's said that turning down your heating 1C can knock 10% off your bill. So a 1C decrease in the ambient temp will (in theory) add 10% to your bill.

I understand the 1st part but not sure what you mean by 'a 1c decrease in ambient temp will add 10% to your bill'. (Sorry if I'm being stupid!)

HappyMJ

Average temperature in Edinburgh is 8.5 degrees over the year average bill is about 20,000kWh
Average temperature in London is 10.5 degrees over the year and the average bill is about 16,200kWh

20,000kWh muliplied by 90% then multiplied by 90% again equals 16,200kWh. Very approximate figures and a bit of guessing but it's close enough to give you an idea. Figures are available for average usage on the internet depending on region. The further south someone is the less they use in gas as it's generally warmer.