New build air source heat pump advise please

GreatApe

Can anyone advise how good or bad these are?

I am considering purchasing a new build and the options are LPG or ASHP. Builder was unable or unwilling to put in Nat Gas I believe due to very high cost of a new line.

AFAIK you don't get renewable heat incentives on new builds so that's out.

Are these low maintenance and long life?

What is the COP generally like in the UK?

How hot can it get a tank I am a little concerned if it doesn't get the tank over 60 centigrade that could be bad for health. Or even if it stays below 60 for long periods of time it could be bad for health. Would it be wiser to do the hot water on a simple immersion tank (or perhaps even just an electric shower so no standing losses from a tank) and the central heating on the ASHP?

I am also considering just asking the developer to reduce the price by £10k and don't bother with the heat pump and underfloor heating. Could then use that to install a 4KWp solar PV system and still have £5k left over to install immersion and electric heaters. Is that a bad idea?

Any idea how much heating a new build needs? No EPC yet and I'm not so sure how accurate/realistic an EPC is. I spent an hour hours trying to find info on heating needs of a new home built to current spec without any luck

Also attic room has four windows two facing south two facing north all at a angle of about 40degrees. Would it be silly to request that the north windows not be built and have it just a roof on the north side. The south facing windows should be zero heat loss or even a net solar gain. Is that a stupid idea eg would it be a negligible energy saving and loss of worthwhile natural lighting?

Have to say I am a little disappointed we are not yet near passive house standards for new builds. A passive house could potentially do away with the central heating systems and use that saving to spend on more insulation or PVs etc.

tacpot12

I can't help with any direct experience of ASHPs but your health concern with the hot water temperature could be addressed by having an immersion heater in the hot water cylinder on a timer to boost the temperature to 60 degrees C every 7 days. This temperature is more than hot enough to kill legionella bacteria.

Crowmann

GreatApe wrote: »

Can anyone advise how good or bad these are?

I am considering purchasing a new build and the options are LPG or ASHP. Builder was unable or unwilling to put in Nat Gas I believe due to very high cost of a new line.

AFAIK you don't get renewable heat incentives on new builds so that's out.

Are these low maintenance and long life?

What is the COP generally like in the UK?

How hot can it get a tank I am a little concerned if it doesn't get the tank over 60 centigrade that could be bad for health. Or even if it stays below 60 for long periods of time it could be bad for health. Would it be wiser to do the hot water on a simple immersion tank (or perhaps even just an electric shower so no standing losses from a tank) and the central heating on the ASHP?

I am also considering just asking the developer to reduce the price by £10k and don't bother with the heat pump and underfloor heating. Could then use that to install a 4KWp solar PV system and still have £5k left over to install immersion and electric heaters. Is that a bad idea?

Any idea how much heating a new build needs? No EPC yet and I'm not so sure how accurate/realistic an EPC is. I spent an hour hours trying to find info on heating needs of a new home built to current spec without any luck

Also attic room has four windows two facing south two facing north all at a angle of about 40degrees. Would it be silly to request that the north windows not be built and have it just a roof on the north side. The south facing windows should be zero heat loss or even a net solar gain. Is that a stupid idea eg would it be a negligible energy saving and loss of worthwhile natural lighting?

Have to say I am a little disappointed we are not yet near passive house standards for new builds. A passive house could potentially do away with the central heating systems and use that saving to spend on more insulation or PVs etc.

Interesting questions, my thoughts....
Yes new builds exempt unless its you doing a self build
Tank gas - very expensive with low competition. Avoid at all costs
ASHP have mixed responses from end users - I would only consider if I understood the thermal value of the house. In a Passiv House sure in a EPC C UK house it will cost.

Have you considered oil? Not cheap at the moment but my choice if roof too small/wrongly sited for a big PV array.
Electric - storage - Expensive if fitting Dimplex Quantums but controllable. Expensive to run.
PV generation in the colder months - ie when you want it to be running ASHP or storage not viable - simply not enough generation.
Typical 4 bed EPC D/C will call for at least 15,000 kw's of heating IMO.

GreatApe

Crowmann wrote: »

Interesting questions, my thoughts....
Yes new builds exempt unless its you doing a self build
Tank gas - very expensive with low competition. Avoid at all costs
ASHP have mixed responses from end users - I would only consider if I understood the thermal value of the house. In a Passiv House sure in a EPC C UK house it will cost.

Have you considered oil? Not cheap at the moment but my choice if roof too small/wrongly sited for a big PV array.
Electric - storage - Expensive if fitting Dimplex Quantums but controllable. Expensive to run.
PV generation in the colder months - ie when you want it to be running ASHP or storage not viable - simply not enough generation.
Typical 4 bed EPC D/C will call for at least 15,000 kw's of heating IMO.

The developer says he has already sold 70% of the plots and almost everyone went for gas. I am assuming most the buyers have no idea what he or the agents were talking about when they were telling the buyers to choose ASHP or Tank Gas. Most probably assumed tank gas means nat gas but it's actually LPG in a big tank buried in the garden. I suspect some of the new buyers will sue once they figure out what they purchase isn't what they expected. And yes I didn't even consider the LPG I mean how the hell am I meant to repair the underground tank at reasonable cost if it developed a fault which everything given enough time will. And as you mention LPG is multiples the price of grid nat gas

Anyone any idea what a new build 100sqm home would use?
I've searched for a couple of hours but I can't seem to find any data on new build heating needs.
Someone here must live in a house built 5 or fewer years ago. What's your gas bill say?

My guess which is just that a total guess is that it would be around 10,000kwh nat gas or 8,000 electric for heating as electric is a little more efficient. Putting the figures into a comparison site I figure an electric only house is going to be £750 more per year than the same property with nat gas. I would also assume as tines goes on electricity is going to get even more expensive vs gas as the greening if electricity costs start to balloon.

If the home is £20k cheaper than comparable local properties that would pay for the additional energy costs in lower mortgage payments. But I wonder how hard or easy it would be to sell on in the future to other buyers?

Martyn1981

GreatApe wrote: »

My guess which is just that a total guess is that it would be around 10,000kwh nat gas or 8,000 electric for heating as electric is a little more efficient.

If you have a heat pump, then the COP will reduce the leccy consumption. In the UK average COP for ASHP is 2.9, so the 8,000kWh's of heat that a gas boiler would consume aprox 10,000kWh's of gas to produce, would take approx 2,750kWh's of leccy.

GreatApe

To try and answer my earlier question regarding how much energy a new build uses. I managed to find some new builds in the local area built about 5 years ago and looking on their EPCs it says aprox 1,700 KWh for space heating and 1,600 KWh for water heating.

This seems very suspect to me, for a start why would their water heating needs be half of a typical home? Maybe 10% less due to super duper efficient boiler but not 50% less. So I think that is wrong and if the water heating is that massively wrong then its hard to trust the space heating.

Anyone here have a new build? If so what is your actual space heating usage is it similar to what your EPC says or much more ?

GreatApe

Martyn1981 wrote: »

If you have a heat pump, then the COP will reduce the leccy consumption. In the UK average COP for ASHP is 2.9, so the 8,000kWh's of heat that a gas boiler would consume aprox 10,000kWh's of gas to produce, would take approx 2,750kWh's of leccy.

Yes I get that it will use less electricity vs joul heaters but I am concerned about how reliable they are.

I suppose the biggest question is what is the space heating needs of new builds. After spending hours searching I am no closer to a reliable answer to that. If it is indeed just 1,700 units a year for space heating that would be affordable just to use joul heaters and an immersion tank

Martyn1981

GreatApe wrote: »

Yes I get that it will use less electricity vs joul heaters but I am concerned about how reliable they are.

I suppose the biggest question is what is the space heating needs of new builds. After spending hours searching I am no closer to a reliable answer to that. If it is indeed just 1,700 units a year for space heating that would be affordable just to use joul heaters and an immersion tank

Yes, i suspect you'll get differing answerrs.

I don't know the correct figures, but for two of us, non hearting gas is around 100kWh pm based on the summer months. That's hot water and gas oven, but leccy hob.

BTW total gas consumption ia 7-8,000kWh pa, for a 3bed 1930's semi, that's had all the stuff done to it, that you should, apart from a modern boiler, ours is about 20yrs old. Gas might now reduce due to install of a small (3.5kW) ASHP.

lstar337

GreatApe wrote: »

Anyone here have a new build? If so what is your actual space heating usage is it similar to what your EPC says or much more ?

EPC: A
Space Heating Demand: 1743 kWh/year
Water Heating Demand: 2161 kWh/year
Combined Heating Demand: 3904kWh/year

Actual Gas Usage pa
2014-2015: 4330kWh
2015-2016: 3417kWh
2016-2017: 3338kWh
2017-Now: 3046kWh

We have a gas hob, but that usage is probably negligible.
Hot water used as and when needed.
Heating set to keep lounge at 21C and rest of house at 18C with simple hallway mounted room stat and good balancing of radiators.

GreatApe

lstar337 wrote: »

EPC: A
Space Heating Demand: 1743 kWh/year
Water Heating Demand: 2161 kWh/year
Combined Heating Demand: 3904kWh/year

Actual Gas Usage pa
2014-2015: 4330kWh
2015-2016: 3417kWh
2016-2017: 3338kWh
2017-Now: 3046kWh

We have a gas hob, but that usage is probably negligible.
Hot water used as and when needed.
Heating set to keep lounge at 21C and rest of house at 18C with simple hallway mounted room stat and good balancing of radiators.

Thanks. It looks like you use very little for space heating maybe just 1000 units a year! How big is the property?

I think we will be closer to 3,500 units for water and I have no idea about space heating but I can't image it was be as low as you seem to manage. If I assume 3,000 for space heating to make it 6,500 units and knock 10% off for the added efficiency of electric it goes down towards 6,000 units of electric for heating. Add 3,000 for electrical gets towards 9MWh a year total electricity

GreatApe

Can someone give me some advise on solar for new builds. What is the fit on PV if any on new builds?
I assume it would cost about £4,000 for a 4KWp system the scaffolding is already in place.
How much roof area is needed for 4KWp? Thanks