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

becksfaz

HappyMJ wrote: »

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.

Wow this is rather complex but I like a puzzle so gunna give it a whirl at working it out (roughly)! Thanks for taking the time to explain everything.
Just grabbed my final bills from my account with BG and based on those bills my average useage is 19kwh in the summer (so slightly higher than the average house).
So let's say the average temp today in my area is 2.5c. 15.5-2.5c = 13c difference.
I read my meter at 9.30pm as this is when heating goes off. So let's say I read my meter at 9.30pm and I've used 14 units. 14 x 11.36 = 159.04kwh - 19 kwh = 140.04kwh / 13.5 = 10.37kwh per degree day. Is this formula corrcet??? (If yes, my old maths teacher would be proud!) haha.

becksfaz

HappyMJ wrote: »

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.

Oh this is much lower than the figure I found. I found that for a 4 bed house the average kwh is 28,000 and then it said add 2,500 for extra bedrooms so I added that as we have 4 beds and an office to get 31,0000. That's almost double your figures! I thought I was doing OK (comparing with the figures I found), turns out I'm not with your figures!!!! I will use yours from now on! Thanks.

HappyMJ

becksfaz wrote: »

Wow this is rather complex but I like a puzzle so gunna give it a whirl at working it out (roughly)! Thanks for taking the time to explain everything.
Just grabbed my final bills from my account with BG and based on those bills my average useage is 19kwh in the summer (so slightly higher than the average house).
So let's say the average temp today in my area is 2.5c. 15.5-2.5c = 13c difference.
I read my meter at 9.30pm as this is when heating goes off. So let's say I read my meter at 9.30pm and I've used 14 units. 14 x 11.36 = 159.04kwh - 19 kwh = 140.04kwh / 13.5 = 10.37kwh per degree day. Is this formula corrcet??? (If yes, my old maths teacher would be proud!) haha.

That's correct. Thanks for understanding my explanation. It is a puzzle. You might have a bigger house than average or a less insulated house or a more occupants or more electrical stuff than normal so a base usage of 19kWh per day and 10kWh per degree day might just be normal for your house. Keep reading at the exact same time every day and it should be near to 10kWh most of the time. Knock the temperature down 1 degree and it should drop to 9kWh per degree day.

HappyMJ

becksfaz wrote: »

Oh this is much lower than the figure I found. I found that for a 4 bed house the average kwh is 28,000 and then it said add 2,500 for extra bedrooms so I added that as we have 4 beds and an office to get 31,0000. That's almost double your figures! I thought I was doing OK (comparing with the figures I found), turns out I'm not with your figures!!!! I will use yours from now on! Thanks.

You need to add something onto my figures for hot water and 2,500kWh per occupant per year for hot water is about right.

becksfaz

HappyMJ wrote: »

That's correct. Thanks for understanding my explanation. It is a puzzle. You might have a bigger house than average or a less insulated house or a more occupants or more electrical stuff than normal so a base usage of 19kWh per day and 10kWh per degree day might just be normal for your house. Keep reading at the exact same time every day and it should be near to 10kWh most of the time. Knock the temperature down 1 degree and it should drop to 9kWh per degree day.

It is a pretty big house so I think my figures are larger due to the size and insulation wise we have cavity wall and loft insulation and double glazing throughout. I'm home most of the day and with having a pre-schooler and a baby washer is always on, sterliser gets used every day etc. Do you mean knock the temperature down by 1c on my stat? Thanks for the suggestion but not doing this - it's only set at 17c as it is! I think that's pretty low - lower than all my friends.

macman

becksfaz wrote: »

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!)

OK, let me put it this way. It requires x kWh to raise the temp of your house from say 16C to 20C. 16C is the ambient temperature. When it's colder outside, and the heating is not on, the ambient temp inside is also less. Let's say it's 15C. To warm your house from 15C to 20C then requires x kWh and some extra kWh as well.
So your heating bill goes up in cold weather. Not because the house is warmer, but because the differential is greater, and so a greater energy input is required.

becksfaz

HappyMJ wrote: »

You need to add something onto my figures for hot water and 2,500kWh per occupant per year for hot water is about right.

Oh right! Well in that case if the 2,500 is per occupant then I'm incorrect adding 2,5000 on for our office. (My mistake). So taking your figures my average should be between 26,000-30,000. I will try go with the 26,000. From Sept to last week I'd used 11,000ish and bearing in mind I over-used hugely at the start of the winter/late autumn with the way I'd set the heating and my old stat so I'm just focussing on getting through this year then can start a fresh next year! This is our 1st winter in this house and it's taken quite a bit of trial and error working out what works best in this house for us.... I've learnt so much about heating, costs, degree days etc etc. Thank god it's been pmild whilst I've been experiementing and I'm prepared now for this cold snap but bring on the spring!!!!

becksfaz

macman wrote: »

OK, let me put it this way. It requires x kWh to raise the temp of your house from say 16C to 20C. 16C is the ambient temperature. When it's colder outside, and the heating is not on, the ambient temp inside is also less. Let's say it's 15C. To warm your house from 15C to 20C then requires x kWh and some extra kWh as well.
So your heating bill goes up in cold weather. Not because the house is warmer, but because the differential is greater, and so a greater energy input is required.

Got it!