Heat Pump for a new build holiday home

WildWestWorld

Hi.
The most recent posts on this topic are a bit old I am hoping some of you have new information after using. I am researching the various options for heating these days and this Heat Pump seems popular.

My question is for a new build holiday home (starting planning) on the north west coast (~250sq/m, big open plan, lots of glass) - does the system need to be “on” all the time? I only intend to be in the house no more than 3 months per year but a lot in winter. So some of the requirements is to be very cost effective and reliable when I want it “off” (rules out geothermal?). Also if it is turned off then how long to get back to warm mode for the house?

Bonus points for any recommendation on additional heat sources for winter e.g. closed log fires to boost the cosiness index..
Thanks

air

I'd recommend going with an LPG boiler for a holiday home. If you're only there 3 months a year it will take longer to amortise the capital cost of a heat pump than normal and it may never pay for itself. Oil would be vulnerable to theft when you're not there.
If you want to future proof the house put in tightly spaced underfloor heating pipes so that it can use a heat pump efficiently if it ever ends up being occupied on a full time basis.

antoinolachtnai

The OP is going to have to put in some measure or other anyway for Part L though? Solar PV would be a total waste of money.

It sounds like this is going to be a very high spec home. It seems to make sense to me to Not hold back on the heating system.

The cost of putting in a geothermal loop can be amortized over the entire life of the building (as opposed to boiler equipment or the heat pump itself, which have to be amortized over a much shorter life). So financially it might make sense.

The three month cold season is really when most heating is needed anyway.

UFH definitely makes sense for this sort of house.

The architect needs to really work this out. It depends on the building’s heat requirement more than anything else. Cost may also be a factor.

It might take a day or two to heat up the house with a heat pump, but if the windows are properly positioned and the house is well insulated and it isn’t the coldest day of winter it will probably take less. You can start the heat by remote control when you leave for your holiday home. It will be ok by the time you get there. You can always turn on a few fan heaters to get some quick heat. It need not be that big a consideration. But again the architect needs to work this out and factor it in.

Log fires and all the rest of it are a nice idea but they are really a lot of work.

Water John

Very good points there. I'd probably go with A2W and the UFH. It will bring the building up, in a few hours.

WildWestWorld

Thanks for the help. I can clarify a few things:
- I want the house to be as green as possible. I am looking into wind/solar and ideally a small personal hydro (I have a small supply of water but I have some steep gradient I can possibly use) to power whatever pump I need.
- I will be on the grid. I won’t go LPG. I don’t mind investing in a multi-faceted energy supply approach I assume the wind/solar etc could all contribute to “fuelling” the pump for ATW or Geothermal or at least making the shower water hotter
- Yes the house will be high spec (insulation, triple glaze where necessary) . Investment is not the biggest issue but all within reason I figure at this stage these types of products are mainstream and they pay for themselves over time.
- I will definitely go under floor heating
- Yes there is the potential the family will spend more time there in about 10/15 years (would act as primary residence)
- yes it will have to be remote control


It is interesting that antoinolachtna you mention the Geothermal might be a good option for the longer term so that is now back on my radar.


My uncle has the UFH and the Geothermal pump but his house isn’t as warm as I would like. So I feel I need another better heat source. Agree the log fire is hard work but the wife needs flames. Also I feel the warm water delivered by Geothermal or the ATW pump wouldn’t be sufficient.


Thank you and look forward to any more advice.

BryanF

WildWestWorld wrote: »

I want the house to be as green as possible.

Ok then
half the footprint from 250 to 125m2. Don’t use concrete. Build beyond the passive standard. Don’t connect to grid.

Water John

If you have a good flow of water passing by the house, you could harvest that to heat your house using W2W. Extremely efficient up towards 6:1.

KCross

WildWestWorld wrote: »

My uncle has the UFH and the Geothermal pump but his house isn’t as warm as I would like. So I feel I need another better heat source. Agree the log fire is hard work but the wife needs flames. Also I feel the warm water delivered by Geothermal or the ATW pump wouldn’t be sufficient.

No reason why Geo or A2W wont be hot enough. Just because your Uncle's isn't doesn't mean anything other than his isn't working right or spec'd right or configured right or his house is draughty etc. My house is 21C all year round. I could put it up or down as I see fit.

Also, there is no issue with warm water. Geo will deliver all the hot water you could possibly need. Mine has a 300L tank heated to 45-50C everyday with a boost every 2 weeks to kill legionella. Hot water wont be an issue nor will space heating as long as you use UFH and the house is reasonably airtight.

antoinolachtnai

You can’t really gauge this off someone else’s house or off your ‘feeling’. This just has to be worked out mathematically by the architect or engineer.

The cheapest, greenest energy is always the energy you don’t use. So the main thing is always going to be how well insulated the house is. This is the thing you need to educate yourself most about. If your architect isn’t interested in this part of it, I would suggest you find another.

Another thing to do is to see if you can reduce the size of the house a bit. This is going to be a really comfy house. You will be able to use every inch comfortably. So you might not need as much space.

As has been suggested - If there is a way to utilize the water flow for geothermal then that would be your best project to do if you want to do a really ‘green’ project. The reason is simply that even on a very cold day, the stream will be warmer than everything else and you can utilize that warmth with a heat pump.

Wind or PV are going to do very little for you except cost you money. PV won’t give you much during the winter. If you really want to own a wind turbine or a hydroelectric turbine the best thing might be to put the fifty grand into SSE shares.

If you want an actual open flame you need to talk to the architect about this. You need to think carefully about ventilating it. It will give you very little heat. If you really need a flame, maybe LPG is an option? Worth suggesting.

looksee

KCross wrote: »

Also, there is no issue with warm water. Geo will deliver all the hot water you could possibly need. Mine has a 300L tank heated to 45-50C everyday with a boost every 2 weeks to kill legionella. Hot water wont be an issue nor will space heating as long as you use UFH and the house is reasonably airtight.

I am also heading in the direction of AtoW. Heating sounds fine but am concerned about water heating. Is the boost you mention for legionella electric?

Water John

Well a wood stove, with its own external air feed, if you want something like that. Its more a feature and comfy thing rather than a necessity. As said above, insulate and seal, most important.

KCross

looksee wrote: »

I am also heading in the direction of AtoW. Heating sounds fine but am concerned about water heating. Is the boost you mention for legionella electric?

No, its just normal operation.
If its very cold outside the heat pump can call on an electrical element to help with space and water heating but it rarely comes on on my system but I am Geo, not A2W. It will be used more in A2W systems as they are less efficient at lower temps and will need more help but it still all depends on the overall heat demand of the house.

Bottomline, don't worry about the system being able to generate enough space heat or hot water. Just ensure the system is sized correctly and installed by a competent company.

gooner99

BryanF wrote: »

Ok then
half the footprint from 250 to 125m2. Don’t use concrete. Build beyond the passive standard. Don’t connect to grid.

But how would he satisfy part L is the question.

WildWestWorld

test - I am getting error 502 bad gateway

WildWestWorld

sorry I have been slow to respond I think my response it too long so I will break it up. I was getting the error above.
Thanks again I appreciate I am getting in early with some basic questions so thank you for your patience. This is early stage for me I have not started conversations with the contractors or professionals. At this stage my research is based on what could be but I know costs will play into it later and some trade offs may have to be made.
Given the input to date I have learned a few things on this thread and reading through some older threads - some very obvious:

• New insulation requirements reduce the need for heating these days
• Downsize the house - I will definitely look at this but I have a good size modern day family of 3 children and some family dependants
• What I meant by flames is not an open fire but something like a closed wood stove.
• You are right my uncle retrofit and his house is probably not as well insulated as modern day houses.

WildWestWorld

- If not using concrete then what are good alternatives that would stand the test of time? I am exposed to the sea air as the site overlooks a beach.
- I am now leaning more towards geothermal given some of the input. Can anyone comment on whether turning off the geothermal pump for large periods of time e.g. weeks/month is a bad idea (e.g. subject to freezing of the pump or the UFH, energy required to restart)? I can deal with restarting it remotely a day or two in advance but I am more worried about any other possible negatives of this solution and the local salty air.

WildWestWorld

- Going off the grid - as per the legionella issue how can you boost without being there and not on the grid e.g. cannot start a wood stove remotely.
- Going off the grid - I initially researched https://www.tesla.com/en_IE/powerwall but it seems it is more for a back up.

- Solar - I am surprised that the input is PV is a “waste of money” (is this more a longer RoI you mean or it’s really a waste due to lack of sun in Ireland)? I have a good aspect. Does anyone know any data sources that would give me a sample solar output for a geographic location in Ireland? I am interested in Tesla’s Solar Roof  https://www.tesla.com/en_IE/solarroof?redirect=no but it seems this probably wouldn’t be a good idea

KCross

WildWestWorld wrote: »

Can anyone comment on whether turning off the geothermal pump for large periods of time e.g. weeks/month is a bad idea (e.g. subject to freezing of the pump or the UFH, energy required to restart)? I can deal with restarting it remotely a day or two in advance but I am more worried about any other possible negatives of this solution and the local salty air.

Shouldn't be an issue for Geo because the unit is inside the house unlike A2W where, part at least, of the system is outdoors.

Now that you mention you are on a beach, it gives you another reason to look closer at Geo because an A2W system next to a beach will suffer from the salty air more since it is sucking in that air.

WildWestWorld wrote: »

- Going off the grid - as per the legionella issue how can you boost without being there and not on the grid e.g. cannot start a wood stove remotely.

The legionella program is usually on a timer where it boosts once a fortnight. I guess each system will be slightly different here. I don't have first hand knowledge of whether you can activate that remotely.

WildWestWorld wrote: »

- Going off the grid - I initially researched https://www.tesla.com/en_IE/powerwall but it seems it is more for a back up.

Tesla powerwall is useful for shifting your usage from expensive daytime electricity to half price night time electricity. That is its main benefit along with short term backup during electricity outages. It also fits well with Solar PV to soak up that free electricity from the Solar and allow you to use it later in the day.

Its still too expensive though at €6k just to buy it.

WildWestWorld wrote: »

- Solar - I am surprised that the input is PV is a “waste of money” (is this more a longer RoI you mean or it’s really a waste due to lack of sun in Ireland)? I have a good aspect. Does anyone know any data sources that would give me a sample solar output for a geographic location in Ireland? I am interested in Tesla’s Solar Roof https://www.tesla.com/en_IE/solarroof?redirect=no but it seems this probably wouldn’t be a good idea

The ROI is too long rather than lack of sun and it will be even longer for you since you wont be in the house for many months of the year.

antoinolachtnai

PV is a waste of money for you in particular, because you won't be in the house for the warm months when there is a significant amount of sun.

An environmentally friendly, off-grid luxury one-off house is not really going to be a flyer with today's technology (or anything we can see in the next five to ten years). An off-grid house can be done, for sure, but you would have to use a diesel generator (not very environmentally friendly at all).

The electricity grid is in many ways a very environmentally friendly thing. There are no special prizes for being off-grid unless armageddon comes and the grid completely fails.

In terms of humdrum practicality, an off-grid house may not be marketable, or might have to be sold at a great discount. You might have difficulty obtaining mortgage finance if that were ever needed.

unkel

WildWestWorld wrote: »

I am surprised that the input is PV is a “waste of money” (is this more a longer RoI you mean or it’s really a waste due to lack of sun in Ireland)?

Ireland is actually quite good for solar PV, some areas are on a par with Austria (which is far further south than Ireland)

The problem here is that we do not get any subsidy for a solar PV install. And we do not get paid anything for electricity we generate that we feed back to the grid

This makes the payback time extremely long, in your case (a not permanently occupied holiday home) even longer

A great shame as feed in tariff micro solar electricity generation would be the easiest, cheapest solution with the least responsibility for the government (and tax payer) to meet up with the up and coming increase in demand for electricity (think EVs) and in relation to the penalties we are paying for our higher than agreed emissions

antoinolachtnai

[QUOTE=unkel;105939409A great shame as feed in tariff micro solar electricity generation would be the easiest, cheapest solution with the least responsibility for the government (and tax payer) to meet up with the up and coming increase in demand for electricity (think EVs) and in relation to the penalties we are paying for our higher than agreed emissions[/QUOTE]

We are heading off-topic here:

Utility scale solar electricity is about half the price per kilowatt of retrofitting domestic rooftop solar. Solar doesn't seem to be a good match for EVs because cars will be out and about during the day, not at home. And there just isn't much electricity from PV during the winter when a lot of driving is done.

The single most important thing for reducing domestic emissions would seem to be replacing oil central heating systems with heat pumps. Heat pumps might or might not work out to be a good match for heat pumps. Whether that will make it worthwhile putting panels on domestic roofs is a separate question.

Water John

Certainly, as said above, look at Geo rather than A2W because of the sea air.
Insulate ans seal, resulting in very low space heating cost. Don't forget the orientation of the house, and maybe less glass on the northern walls than the southern. A porch to the door facing the wind.
Reducing the overall size will improve your build, carbon footprint, but shouldn't make a big difference to you annual carbon footprint.

Howlin

Just to throw in my two cents,

As far as im aware, all heat pumps come with frost protection (but best ask the supplier), and the system in theory could be set up so the heating would come on to ensure the house is kept to a minimum of say 10 degrees during the winter.

If the house is built with a low air permeability, and a heat recovery system is installed, it can help reduce the the cost of heating and increase the BER rating.

Another area to look at might be the thermal bridging elements in the house. The lower the thermal bridging factor, the less the heat loss (to an extent).


In relation to the off the grid, as far as I'm aware, legally every house has to be connect to the grid.

Water John

Some of the cheaper A2W units were unable to defrost themselves at low temps, in the past.

TomOnBoard

You say you have a small supply of water that might give you hydro power. Is that a stream on your property? if so, can you check its temperature and flow rate to help figure out if it would be practical to use the water temperature (probably higher and certainly more constant than air in the winter) as an input to a heat recovery unit for the house?

air

Howlin wrote: »

In relation to the off the grid, as far as I'm aware, legally every house has to be connect to the grid.

I'd be interested to hear more about this law.

Water John

Tom, those W2W systems are really efficient. Up around 5/6:1.

antoinolachtnai

air wrote: »

Howlin wrote: »

In relation to the off the grid, as far as I'm aware, legally every house has to be connect to the grid.

I'd be interested to hear more about this law.

I don’t think it’s a legal requirement but I can’t imagine any bank agreeing to finance a house without an electricity connection.

antoinolachtnai

Water John wrote: »

Tom, those W2W systems are really efficient. Up around 5/6:1.

The issue is really going to be whether it is cost effective for a relatively small heat demand. A well insulated modern home just doesn’t need that much heat. It may not be worthwhile carrying out the required earthworks and works on river bed and obtaining a suitable coil.

Water John

Correct, but OP has sort of indicated that finance isn't a major deciding factor. Certainly electricity gen from a stream would be very capital intensive, for example.

Haven't heard of any bank, looking for proof of ESB connection. Shush, they probably presume it. Only thing you would be short of is an MPRN, which is needed for paying your LPT, for example.

antoinolachtnai

An mprn? Don’t think you need it to pay LPT. It is expected for the BER certainly. You won’t get an MPRN if there is no application for a grid connection.

It is an item in the standard requisitions on title when a house is sold. I think it would be drawn to purchaser’s bank’s attention that there is no electricity connection. I think this would make lenders very reticent (because the property would be difficult to sell or rent as a result) but I do not know of this actually happening.

Water John

Off grid is extremely rare and in effect, sort of wishful thinking by most that discuss it.
But a person should have no difficulty getting planning and a loan. As you say, renting or selling would be different.

samdeluxjones

If you build your house airtight with passive raft slab which is cheaper than traditional, wrap it in Styrofoam and put all your big windows south facing with sun shades it shouldn't drop below 15 degrees in the wintertime.

Because its airtight you will need a heat recovery ventilation. I would recommend a Zenhder comfoair q with LAN Module fully controllable from your phone with all temp readings indoor and out.

Fit a Nibe air to water heat pump which is also fully controllable from your phone and in our house it can heat UFH from 15 degrees to 22 in about 2 days so turn off holiday mode 2 days before you need it.

Airtight is the hardest, majority of builders and architects still don't get it unfortunately.

WildWestWorld

Thanks this thread has been very informative and useful for me. Sorry for the delay I’ve somehow missed the alerts.
Here’s my outlook:

• insulation beyond the standards and make airtight
• maximise the southern aspect for light in with shades, limit the north facing windowing (ouch best view)
• Geothermal UFH over A2W due to salt air. So I will assess first for this option. But W2W might be interesting to research next (thanks Tom)
• I will probably go Solar PV because I just think why waste the solar energy available. I can use for electric vehicle at least
• Closed wood stove is a lot of work, so I will look for alternatives.
• heat recovery ventilation installed
• Agreed this will be connected to the grid.

It is early in my planning process so let’s see what happens after I discuss with my architect. I may revisit this thread for input and advice.
Thank you.

samdeluxjones

Maximize your views man in your main living area not your bathrooms, bedroom and hallways.

Plan your house around your view and the suns orientation, if your architect cannot do this fire him. He should know all this stuff we are telling you anyway.

Make sure your builder has previously built an airtight house 0.6ac/h or better at least.

I have just finished an all of the above house and am part of the nzeb open doors in the South East where you are welcome to visit on organised days.

A previous visit to another guys passive house through nzeb persuaded me to build this way.

Water John

I think you can still have a view. Glass windows have upped there u value over the last 10 years. Not as much heat loss, as before.

samdeluxjones

BryanF wrote: »

Ok then
half the footprint from 250 to 125m2. Don’t use concrete. Build beyond the passive standard. Don’t connect to grid.

Why not concrete?

air

samdeluxjones wrote: »

Why not concrete?

He said it within the context of being as green as possible with the build.
Every cubic metre of concrete represents about 410 kg of CO2 emmissions, equivalent to 3000km of driving in a diesel car, plus all the environmental destruction from quarrying, transport etc.

samdeluxjones

Ah ok, for thermal retention in a well insulated house concrete seems to be the best at the moment..

BryanF

samdeluxjones wrote: »

Ah ok, for thermal retention in a well insulated house concrete seems to be the best at the moment..

Not necessarily, Ive cellulose in my timber extension, floor is concrete that’s enough thermal mass for me.

gooner99

samdeluxjones wrote: »

Maximize your views man in your main living area not your bathrooms, bedroom and hallways.

Plan your house around your view and the suns orientation, if your architect cannot do this fire him. He should know all this stuff we are telling you anyway.

Make sure your builder has previously built an airtight house 0.6ac/h or better at least.

I have just finished an all of the above house and am part of the nzeb open doors in the South East where you are welcome to visit on organised days.

A previous visit to another guys passive house through nzeb persuaded me to build this way.

Sorry to go slightly off topic. Doesn't seem to be much info on the NZEB website about 2018 open days. Anyone know when and where they will be?

air

Where did you source cellulose from in Ireland if you don't mind me asking?

samdeluxjones

gooner99 wrote: »

Sorry to go slightly off topic. Doesn't seem to be much info on the NZEB website about 2018 open days. Anyone know when and where they will be?

They are gonna be late this year, normally November gone this year April or may I think.