Heating - PH vs near PH

just do it

My understanding of the magic figure of 15kw for passive house heating demand is it does negate the need for a central heating system. At this heating demand it is possible to maintain a constant temperature by heating the incoming air to the MVHR via a heating loop coming from the hot water tank. I state this because I've seen it said on here that PH's still need a central heating system.

Now one of the issues I have with this form of heating is I don't like it. For example this is how the heater in the car works and I hate that. There is a PH near me (which I haven't visited, yet) and the comment I've heard on it is that it feels "airless" after being in it for a few hours. Having said that I've been in a PH in connemara for ~3 hours and found that very comfortable and didn't have any issue with the freshness of the air.

Currently I'm veering towards a target heating demand of 18-20kW with MVHR and UFH, bathroom towel rails and possibly a feature radiator in a central position in the main living area. We won't have an open fireplace or stove but the feature rad will be nice to warm one's butt when coming in a bit frozen from being outside on the farm.

A few more reasons for this are:
- seems to be the most cost effective option
- not as critical if build doesn't achieve it's targets
- intend to achieve a PH standard of airtightness but I'm not confident enough that this will last 20, 30 or even 40 years
- same lack of confidence that u-values won't deteriorate over the long term
- saleable in the future as will have a central heating system
- thermal store provided by large hot water tank being heated by solar panels and a yet to be decided back-up
- it's an excellent site for a wind turbine so set up will suit this when it becomes a financially viable option.

Critical feedback on this is welcome as I'll be breaking ground soon:-)

fclauson

just do it wrote: »

My understanding of the magic figure of 15kw for passive house heating demand is it does negate the need for a central heating system. At this heating demand it is possible to maintain a constant temperature by heating the incoming air to the MVHR via a heating loop coming from the hot water tank. I state this because I've seen it said on here that PH's still need a central heating system.

Now one of the issues I have with this form of heating is I don't like it. For example this is how the heater in the car works and I hate that. There is a PH near me (which I haven't visited, yet) and the comment I've heard on it is that it feels "airless" after being in it for a few hours. Having said that I've been in a PH in connemara for ~3 hours and found that very comfortable and didn't have any issue with the freshness of the air.

Currently I'm veering towards a target heating demand of 18-20kW with MVHR and UFH, bathroom towel rails and possibly a feature radiator in a central position in the main living area. We won't have an open fireplace or stove but the feature rad will be nice to warm one's butt when coming in a bit frozen from being outside on the farm.

A few more reasons for this are:
- seems to be the most cost effective option
- not as critical if build doesn't achieve it's targets
- intend to achieve a PH standard of airtightness but I'm not confident enough that this will last 20, 30 or even 40 years
- same lack of confidence that u-values won't deteriorate over the long term
- saleable in the future as will have a central heating system
- thermal store provided by large hot water tank being heated by solar panels and a yet to be decided back-up
- it's an excellent site for a wind turbine so set up will suit this when it becomes a financially viable option.

Critical feedback on this is welcome as I'll be breaking ground soon:-)

You cannot sit around UFH or a rad and have a wee dram - so I would definatly put in a stove

If the electric fails for 24hrs (which is might if it snowed) - your knacked

You are relying on the MVHR to deliver you heat - alothough indirectly as you are using the bathrooms to provide the heat

I would put in UFH - no need to put in the pumps etc - but its cheap to put in the pipe work (for the sake of a very expensive refit later)

I would put in a stove - you might just burn for effect (e.g. pallets etc) but then its there if you need to burn to warm the place

I was in a PH recently - they have a big stove which will be used to duct the heat around the house - and now due to some calcs (they did not fit UFH) they are putting up wall embedded heating panles to back up the heat - they have a concerete floor and despite all the above I suspect you might be "challenged" to walk around in bear feet stepping off the warm bedroom carpet onto the cooler concerete floor without a "ohh :eek:" I wish I had UFH
Good luck

sinnerboy

Technically , it is not the 15kW/hr/m2/year demand figure that is crucial but maintaining the 10w/m2 heat load figure .

Head load equates to the battery size of the torch and heat demand equates to the amount of light you get over a period of time. When it's really cold you need to need only a small battery.

The PHI spreadsheet provides a sub-calculation taking into account certain specifics unique to your house and climate region i.e. the efficiency of the heat recovery of your MVHR , your house volume and the lowest ambient temperature where your site is to determine if the house may be heated via the internal air only.

So the Passive house in the next field ( making 10w/m2 max load ) may not need a back up system - but your house also making 10w/m2 load may do.

There is no ready reckoner. ( That I know of )

Non technically - if you don't like it don't do it. And the fact remains that what you have is what you sell. I think PH is fantastic but I speak to enough people , some of them smart well educated and otherwise knowing , who simply reject the whole concept.

Add into the mix that this is Ireland meaning there are bound to be enough badly executed attempts at DIY passive house to further discredit it. " I was in a PH once and it was cold and stuffy" . I've actually heard that.

So if you are inclined to do it - put a boiler in. It will have the easiest life in Ireland and you will have a very comfortable saleable house.

Do-more

+1 on fitting the UFH pipes in the slab when you have the chance.

I'm putting in the pipes in a very basic configuration and will treat the entire ground floor as one zone, although I have arranged the four loops so that I could split it into two or four zones in the future if necessary but I am told that I shouldn't need to.

The pipework, fixings, manifold, thermostat etc. and labour comes to €2,050 + VAT. The only additional cost is for the mixing valve but that is included with the air to water heat pump I'm getting.

fclauson

sinnerboy wrote: »

Technically , it is not the 15kW/hr/m2/year demand figure that is crucial but maintaining the 10w/m2 heat load figure .

Head load equates to the battery size of the torch and heat demand equates to the amount of light you get over a period of time. When it's really cold you need to need only a small battery.

...

Good description

also remember that the 10w/m2 is an average based on the best fit between two different weather sets - cold but sunny and warm but cloudy

See the attached graphic - worked with John Morehead - it shows a single passive house being moved around the country and the associated heat demand.

Although the PH model is very good - if you look at this graphic it shows just how much the deamnd may vary just by moving a house a few miles

Also he produced a "peak demand" data set - this allowed me to look at my own house
Normal PHPP data set = 14.2 Kwh/M2/Annum
Peak Data set 19.8 Kwh/M2/Annum

also note that the house went from not overheating at all to overheating 12% of the time - so in the summer windows will need to be opened to keep the house cool

So PH is good - but you have to build in reserve to your systems to make sure you can handle the peak

BarneyMc

If you live on a farm I think you should have a (room sealed) wood burning stove... it would have a very cheap running cost and somewhere to sit around with a wee dram!

beyondpassive

BarneyMc wrote: »

If you live on a farm I think you should have a (room sealed) wood burning stove... it would have a very cheap running cost and somewhere to sit around with a wee dram!

If you live on a farm, you should have a pig in the parlour, Thats a free 500W constant heat and you'll never run out of rachers, #sweet.

BarneyMc

beyondpassive wrote: »

If you live on a farm, you should have a pig in the parlour, Thats a free 500W constant heat and you'll never run out of rachers, #sweet.

Absolutely but if pigs get swine flu again then the logs are still good :-)

just do it

fclauson wrote: »

You cannot sit around UFH or a rad and have a wee dram - so I would definatly put in a stove

If the electric fails for 24hrs (which is might if it snowed) - your knacked

You are relying on the MVHR to deliver you heat - alothough indirectly as you are using the bathrooms to provide the heat

I would put in UFH - no need to put in the pumps etc - but its cheap to put in the pipe work (for the sake of a very expensive refit later)

I would put in a stove - you might just burn for effect (e.g. pallets etc) but then its there if you need to burn to warm the place

I was in a PH recently - they have a big stove which will be used to duct the heat around the house - and now due to some calcs (they did not fit UFH) they are putting up wall embedded heating panles to back up the heat - they have a concerete floor and despite all the above I suspect you might be "challenged" to walk around in bear feet stepping off the warm bedroom carpet onto the cooler concerete floor without a "ohh :eek:" I wish I had UFH
Good luck

Stove
Yes I get the point of the stove and it is nice to have one the sitting room. But having put one in the house I'm currently in this winter, I can't be arsed with having to set it and empty the ashes. It's ideal my current house as it's a standard celtic tiger dormer build and it both blocks the chimney and gives a constant heat source to the house. Having grown up with a Rayburn in the kitchen and open hearth in the sitting room, having lived years without either, and now having a stove, I'm happy to forgo the stove and keep the mortgage to the minimum. (Having said that I may yet change my mind on it!) Any with a few drams in the belly there is no need for another heat source:D;).

Reliance on Electricity
Over the last 39 years there was only one occassion that I can recall where the electricity was continuously out for greater than 2 days. I hope with having a near passive house it would retain enough heat to maintain a comfortable temperature for 1-2 days.

UFH
Yes I think this will be going in even if it is rarely/ never used. In the overall scheme of things it is a cheap contingency plan. Anyway with a decision to go near passive the heating will get used a certain amount every winter. Also if we're away for a few days it will be nice to have the place warmed up when we get home, rather than in the truly passive house where you have to wait for the passive heat to build.

PH
Is the passive house you visited being lived in? It's only after a winter you'd know how well it's working. I'm interested to hear more about the wall embedded heating panels. I'd imagine a long payback period on those?!

just do it

sinnerboy wrote: »

Technically , it is not the 15kW/hr/m2/year demand figure that is crucial but maintaining the 10w/m2 heat load figure .

Head load equates to the battery size of the torch and heat demand equates to the amount of light you get over a period of time.

And is this not one of the difficulties with PH in Ireland vs Germany? Potentially the house can be unoccuppied for a large number of hours and hours of sunlight in winter are shorter. Both factors mean less passive heat available than desirable. Also we tend to build much bigger houses (mine being 235m2) thus the total passive heat available has a much larger volume to heat.

sinnerboy wrote: »

When it's really cold you need to need only a small battery.

I'm not sure if I'm understanding you correctly here. Do you mean with a PH when it is really cold you still only need a small battery to heat it?

sinnerboy wrote: »

The PHI spreadsheet provides a sub-calculation taking into account certain specifics unique to your house and climate region i.e. the efficiency of the heat recovery of your MVHR , your house volume and the lowest ambient temperature where your site is to determine if the house may be heated via the internal air only.

So the Passive house in the next field ( making 10w/m2 max load ) may not need a back up system - but your house also making 10w/m2 load may do.

So to negate the need for a back-up system, depending on the specifics of your build, you may need to reduce the heat demand figure to something <15kW/hr/m2/yr to ensure it can be heated solely by internal air.

sinnerboy wrote: »

Non technically - if you don't like it don't do it. And the fact remains that what you have is what you sell.

sinnerboy wrote: »

So if you are inclined to do it - put a boiler in. It will have the easiest life in Ireland and you will have a very comfortable saleable house.

Yes and this comes down to personal preferences. Hence I'm tending towards this route, even though I hope to live out my days in the house (or at least downsize in time and hand it over to the offspring;)).

fclauson

just do it wrote: »

...
UFH
Yes I think this will be going in even if it is rarely/ never used. In the overall scheme of things it is a cheap contingency plan. Anyway with a decision to go near passive the heating will get used a certain amount every winter. Also if we're away for a few days it will be nice to have the place warmed up when we get home, rather than in the truly passive house where you have to wait for the passive heat to build.

You've got it - if a passive house with a normal heating system goes cold it take a very very long time to heat up

PH
Is the passive house you visited being lived in? It's only after a winter you'd know how well it's working. I'm interested to hear more about the wall embedded heating panels. I'd imagine a long payback period on those?!

no not lived in yet
heated panels - they are like UFH but looped though the back of a pre-cut plaster board type thing and plastered into the wall - no idea on payback - but not the route I would go

just do it

Do-more wrote: »

+1 on fitting the UFH pipes in the slab when you have the chance.

I'm putting in the pipes in a very basic configuration and will treat the entire ground floor as one zone, although I have arranged the four loops so that I could split it into two or four zones in the future if necessary but I am told that I shouldn't need to.

The pipework, fixings, manifold, thermostat etc. and labour comes to €2,050 + VAT. The only additional cost is for the mixing valve but that is included with the air to water heat pump I'm getting.

Sound advice and thanks for the prices. In general how're you finding prices compare to here?

just do it

fclauson wrote: »

See the attached graphic - worked with John Morehead - it shows a single passive house being moved around the country and the associated heat demand.

Although the PH model is very good - if you look at this graphic it shows just how much the deamnd may vary just by moving a house a few miles

Is it easy to get planning on Garnish Island?;)

Interesting to see the differences alright. As I'm 800m from the sea it looks like this is in my favour. And it stands to reason. During cold spells here the local roads are usually fine and then as you move a few miles inland the ice starts appearing.

just do it

fclauson wrote: »

Also he produced a "peak demand" data set - this allowed me to look at my own house
Normal PHPP data set = 14.2 Kwh/M2/Annum
Peak Data set 19.8 Kwh/M2/Annum

also note that the house went from not overheating at all to overheating 12% of the time - so in the summer windows will need to be opened to keep the house cool

So PH is good - but you have to build in reserve to your systems to make sure you can handle the peak

That's interesting stats about the peak data set.

Is the 14.2kWh finalised and matching the spec you've decided on? And what back up system are you settling on?

just do it

BarneyMc wrote: »

If you live on a farm I think you should have a (room sealed) wood burning stove... it would have a very cheap running cost and somewhere to sit around with a wee dram!

I know Barney, and when the decision time comes on the stove I may well go for one despite all I've written so far!

just do it

beyondpassive wrote: »

If you live on a farm, you should have a pig in the parlour, Thats a free 500W constant heat and you'll never run out of rachers, #sweet.

:D

I'll just run that one by the missus;)

fclauson

just do it wrote: »

That's interesting stats about the peak data set.

Is the 14.2kWh finalised and matching the spec you've decided on? And what back up system are you settling on?

Yup - thats about the figure - bit of window tweaking to be done, and some cold bridges but 14 to 16 is about it

backup heat NO SUCH THING
Primary heat source for h/w and heating will be a 8kw GS Heatpump
Plus a stove in the sitting room (cannot sit around UFH)

just do it

fclauson wrote: »

Yup - thats about the figure - bit of window tweaking to be done, and some cold bridges but 14 to 16 is about it

backup heat NO SUCH THING
Primary heat source for h/w and heating will be a 8kw GS Heatpump
Plus a stove in the sitting room (cannot sit around UFH)

No solar panels? GS heatpump seems an expensive option given your heat demand, particularly if you'll be lighting your stove regularly?

Do-more

just do it wrote: »

Sound advice and thanks for the prices. In general how're you finding prices compare to here?

It's swings and roundabouts, on a general level the pricing is pretty much like for like but anything that is labour intensive tends to be dearer here than in Ireland.

We are very much in the minority here in building direct labour, most people would use a main contractor and the majority would purchase a turnkey house from one of the major suppliers.

We have contracts signed for almost all our major expenses at this stage so I have a good idea of the final cost of the house so from the bare site to walking in the door to finished floors, painted walls, bathrooms and fitted kitchen we are looking at between €250,000 - €260,000 including all fees for design, planning permission, water, sewer and electric connections, insurance, bonds etc. for a straight forward 215m2 dormer bungalow achieving 22kW/m2/a on paper.

That appears to be near the bottom of the price range here, when we were getting our 10 year house bond (which you purchase here yourself more like a normal insurance policy) one company quoting us said that the average build cost for a house of that size here would be €485K :eek:

Regarding the radiant wall heating, I looked at it as the passive house heating guy I used to do various calculations for me was pushing it as a solution.

As fclauson says it is 12mm ufh pipe set in the wall rather than the floor, there are systems for both wet plastered walls and for plasterboard.

The system I looked at was for use with plasterboard and was EPS sheet routed with pipe runs. To achieve the heat output we needed it could have been installed on just one or two walls in most rooms up to a height of 1m.

But the eps sheet was pretty expensive (about €35/m2) and whilst minimised fitting at less than 1m high, there is always the danger of someone sticking a screw or nail through a pipe in the future. I suppose you could stick an aluminium spreader plate between the pipes and the plasterboard to minimize the risk further but that just keeps adding to the cost.

The heating guy was particularly keen on it as it gives a fast reacting heating system so you don't overheat the house when you light a stove or have intermittent solar gains for example, but you could do the same with ufh in a thin screed for the same money or less if you were inclined.

We won't have a stove (although I have put an air supply in the slab just in case and have provision to easily add a flue in the future if we change our mind) and I have gone back to having a bio ethanol fire place as a centre piece so the opportunities for overheating are limited.

Regarding heat pumps and back up heating options during a power cut, the same can be said of almost every system as almost all rely on some electricity input for ignition, circulation pumps etc. so for back up heating in a power cut you are looking at some form of stove or fireplace to provide direct heat to the house so in this case a Super Ser stored in the garage is as good an insurance policy as any and doesn't entail any cold bridge!

fclauson

just do it wrote: »

No solar panels? GS heatpump seems an expensive option given your heat demand, particularly if you'll be lighting your stove regularly?

So this is the big discusion

SP cost say 4 to 5k - plus a thermal store plus a back up heat source e.g. gas or oil

so you are in for say 10 to 12K (very conservative)
my HP is similarly priced - in actual fact my costs for HP is considerably cheaper that Solar + thermal store + Oil + controls

then check out the attached -

So - Why would I want to spend money on solar ??

just do it

Do-more wrote: »

We have contracts signed for almost all our major expenses at this stage so I have a good idea of the final cost of the house so from the bare site to walking in the door to finished floors, painted walls, bathrooms and fitted kitchen we are looking at between €250,000 - €260,000 including all fees for design, planning permission, water, sewer and electric connections, insurance, bonds etc. for a straight forward 215m2 dormer bungalow achieving 22kW/m2/a on paper.

That seems a great price and on a par with here considering you've adding all the costs, not just a builder's finsh.

Do-more wrote: »

a Super Ser stored in the garage is as good an insurance policy as any and doesn't entail any cold bridge!

:D. My God, I'd forgotten about the good auld Super Ser!! It's a pity the canester for the BBQ is of a different type;)

just do it

fclauson wrote: »

So this is the big discusion

SP cost say 4 to 5k - plus a thermal store plus a back up heat source e.g. gas or oil

so you are in for say 10 to 12K (very conservative)
my HP is similarly priced - in actual fact my costs for HP is considerably cheaper that Solar + thermal store + Oil + controls

then check out the attached -

So - Why would I want to spend money on solar ??

I haven't gotten to this element of my build yet but thanks for blowing that preconception I had on cost out of the water! I'll come back to you after your first year in the house to see what your actual heat demand turns out to be. It will hopefully be decision time for me at that point in time as to what the heating system is going to be;).

Now that I think of it, geotherm maybe more suitable as my site/ farm is ideal for wind energy and having everything electricity based makes a better fit for when ever a wind turbine becomes a realistic investment (if ever?!).

fclauson

just do it wrote: »

.... I'll come back to you after your first year in the house to see what your actual heat demand turns out to be. It will hopefully be decision time for me at that point in time as to what the heating system is going to be;)....

It will cost you to get that info - directly proportional to the amount of money I will save you if you go this route