Excessive gas use?

2013yearofthehouse

A family friend has asked me to look into her gas and electricity usage as her gas in particular looks to be quite high.

Comparing her bills with my family's as both houses are similar sized, in the same area and have same amount of insulation and same boiler installed for central heating.


House 1:
1-2 people
very old secondary glazing with timber windows and doors
electric cooker
gas used to heat hot water on daily basis
winter heating left on in daytime (thermostat 18-22C) and turned off at night


House 2:
1 person
fairly old double glazing (not ideal but not as bad as house 1)
gas cooker
shower water heated by electric
hot water only heated by gas when occasionally using washing machine (washing up done with kettle, all other water is used cold)
tumble dryer
winter heating left on 24/7 (thermostat 15-16C)


House 1 vs House 2
Aug-Feb
elec 1300 vs 700 kwh
gas 4000 vs 6500 kwh
Feb-Aug
elec 1000 vs 650 kwh
gas 2000 vs 3600 kwh
year total
elec 2300 vs 1350 kwh
gas 6000 vs 10100 kwh


I'm not sure if one house is lower than expected or one is higher than expected or a bit of both? House 1 should surely use a lot more gas for heating/hot water than house 2, but house 2's total is so much higher. The heating is left on for longer hours but at a lower temperature. I wouldn't have thought a gas cooker could make such a difference? It isn't used excessively, not even every day, especially in summer.

Anyone have any figures of their own they could compare with?

rogerblack

A large slice of this will be due to leaving the heating on overnight.
Let's say 19C*16h for one, and 15C*24 for the other.

It takes so much energy to heat a house a given number of degrees over the outside temperature for an hour.

If we assume an average outside temperature of 8C, the total heating-degree-hours for each is (19-8)C*16h = 176 for the first house, and 192 for the latter.
But, it's not that good, as for 8 hours that the first houses heating is off it's perhaps 3C colder, taking the total heating needs up to about 220.

220/176=1.25 - the 24 hour house will take about a quarter more gas.

Windows are largely irrelevant, unless they are leaking serious amounts of air.

If you assume that the heating is on for a bit longer in the winter, then that goes a long way to covering it.
South facing windows can make a big difference.

Without knowing in detail the structure, it can be hard to compare.
Is the structure square or a more elongated construction?
Does that floor slab the floor is laid on have no insulation, or 6"?
Is the insulation missing over half of the attic?
Are the windows draughty?
Does the person keep the house at 16C, but run a gas fire in the lounge a lot when they get chilly?
Gas cooking will use gas, but probably not more than 2-3kWh a day.

In short - it's not obviously an incorrect amount of gas.

2013yearofthehouse

Thanks for your reply.

It was the plumber who installed the boiler that said leaving the heating on all the time was more efficient (same guy for both houses, 1 ignored him and 1 followed his suggestion!). Despite house 1 turning the heating off at night, the temperature by morning has rarely dropped below 16C (having been turned off at 20-22C), so I guess I just figured House 2's heating would rarely need to "kick in", but I guess it does as it's always on "the cusp" anyway. Also, with these different approaches it's hard to tell which house is actually better at keeping heat in. Both houses are roughly the same square shape, detached but with houses about 2m on the north and south sides (windows all on the east and west facades), windows/doors a bit draughty, suspended floors, cavity wall insulation and loft insulation same over whole of attic. Neither house has a gas fire, house 2 does have a chimney though - the fireplace isn't used and there is a board in front of the opening to stop draughts, not sure how effective that is though. Could this be responsible for quite a bit of loss or would it be minimal? Perhaps a chimney balloon would be a good suggestion for them?

Cardew

2013yearofthehouse wrote: »

House 1 vs House 2
Aug-Feb
elec 1300 vs 700 kwh
gas 4000 vs 6500 kwh
Feb-Aug
elec 1000 vs 650 kwh
gas 2000 vs 3600 kwh
year total
elec 2300 vs 1350 kwh
gas 6000 vs 10100 kwh

Are you sure that these figure are correct?(especially gas)

If they are correct then they are at odds with the title of this thread(excessive gas use)

The annual average UK consumption is 16,500kWh gas and 3,500kWh electricity.

2013yearofthehouse

Cardew wrote: »

Are you sure that these figure are correct?(especially gas)

If they are correct then they are at odds with the title of this thread(excessive gas use)

The annual average UK consumption is 16,500kWh gas and 3,500kWh electricity.

Was wondering if one was excessive in comparison to the other (or in fact if one was just a lot lower than expected which seems to be the case) - title is written with a "?"

Guessing comparison to UK average depends more on size of house and number of people who live there. In these cases 100 square metres and only 1 or 2 people - but maybe they are still lower than average for that size and number?

macman

2013yearofthehouse wrote: »

Thanks for your reply.

It was the plumber who installed the boiler that said leaving the heating on all the time was more efficient (same guy for both houses, 1 ignored him and 1 followed his suggestion!). Despite house 1 turning the heating off at night, the temperature by morning has rarely dropped below 16C (having been turned off at 20-22C), so I guess I just figured House 2's heating would rarely need to "kick in", but I guess it does as it's always on "the cusp" anyway. Also, with these different approaches it's hard to tell which house is actually better at keeping heat in. Both houses are roughly the same square shape, detached but with houses about 2m on the north and south sides (windows all on the east and west facades), windows/doors a bit draughty, suspended floors, cavity wall insulation and loft insulation same over whole of attic. Neither house has a gas fire, house 2 does have a chimney though - the fireplace isn't used and there is a board in front of the opening to stop draughts, not sure how effective that is though. Could this be responsible for quite a bit of loss or would it be minimal? Perhaps a chimney balloon would be a good suggestion for them?

Time to get a new plumber then...
It will be more comfortable; it most certainly will not be more efficient, and it will cost much more.
As Cardew points out, the annual consumption is extremely low.

2013yearofthehouse

macman wrote: »

Time to get a new plumber then...
It will be more comfortable; it most certainly will not be more efficient, and it will cost much more.
As Cardew points out, the annual consumption is extremely low.

Sadly there's no chance she'll get a new plumber as she's used him 25+ years, but he must be 60-65 years old so maybe he'll retire soon!

Turns out I was over generous on her thermostat being constantly on 15-16C, it's actually 14C! How that can be comfortable I'll never know, but each to their own I suppose! I'm much happier (and never cold) with it high in the day and off at night, so it's nice to know it's also cheaper

Thanks again

Wywth

2013yearofthehouse wrote: »

Sadly there's no chance she'll get a new plumber as she's used him 25+ years, but he must be 60-65 years old so maybe he'll retire soon!

What will she do then??? :eek:

Presumably you've booked her in on a good plumbing course ... :cool:

2013yearofthehouse

Wywth wrote: »

What will she do then??? :eek:

Presumably you've booked her in on a good plumbing course ... :cool:

haha I could've worded that better when forced to, she'll get a new plumber, but she wouldn't do out of choice, while he's still working

2013yearofthehouse

I asked what the plumber had said exactly (luckily she doesn't entirely follow his instructions), apparently he leaves his heating on permanently all year round, but turns it down to the lowest setting in summer. He thinks that if you keep the house at a constant temp then it shouldn't keep turning on/off too many times.

What would be the point of having it turned on in summer? Our lowest setting is 10C and I can't imagine the central heating would ever need to kick in, far from it. Maybe the plumber just has an abnormally cold house?! Still, he shouldn't be telling customers to do the same, very odd.

Fire_Fox

Are you comparing like with like, actual reading to actual reading, the correct calculation of cubic metres or cubic feet to KWH for each property?