Green Building Forum - A Frame House

A Frame House

renewablejohn — Wed, 16 Feb 2022 22:03:43 +0000

Looking to build an A frame house. Anybody any experience, looking to be 6mtr sides and 6 mtr length alithough will have an added 1mtr upright as I intend to sit the A frame on precast concrete panels for atability.

A Frame House

Nick Parsons — Wed, 16 Feb 2022 22:19:53 +0000

Isn't this what Ed Davies is building? I think he has a blog on Buildhub.

A Frame House

renewablejohn — Wed, 16 Feb 2022 22:35:14 +0000

Posted By: Nick ParsonsIsn't this what Ed Davies is building? I think he has a blog on Buildhub.

Just had a quick look on buildhub and cannot find it. Do you know what section it is filed under as I have tried a search.

A Frame House

Ed Davies — Wed, 16 Feb 2022 22:49:16 +0000

My blog's on my own site. Pages about the house: https://edavies.me.uk/blog/tag/perihelion/

Mine's post and beam (on concrete pads) - sort of Segal. Roof slopes at 60Â° so it's an equilateral triangle viewed from the ends, about 7.6 metres on the triangular dimensions, 17.2 metres long east-west + a porch/greenhouse sticking off the west end.

Starting from scratch, I'm not sure I'd go with A-frame again. It's high for the amount of loft space it gives. The original idea was to have a large area steep enough for decent solar exposure in the winter but maybe I'd give more thought to just putting PV panels on ground mounts.

https://edavies.me.uk/2021/12/north-roof/img_3904-medium.jpg
https://edavies.me.uk/2021/12/corrugation-round-velux/img_3876-medium.jpg
https://edavies.me.uk/2020/09/bob/img_2723-medium.jpg

A Frame House

renewablejohn — Wed, 16 Feb 2022 23:25:06 +0000

Thanks Ed for coming back to us. I am looking to convert a Dutch barn into an A frame with Scandinavian glasshouse. Sounds complicated until you realise its just 2 x 6.15 x 2.2 roof trusses joined at the apex to give the sides of the A frame (6.15). Width at the bottom is 8mtr to pull the height down then lifted by 1 mtr on both sides to allow height for 2 floors. Other 2 sides of each roof truss covered in glass or polycarb sheet dependant on planners. Solar will be priority with one side of the A south facing.
Am I just being mad as retained as a Dutch barn it would give me far more room and the trusses would then become a room feature

A Frame House

Ed Davies — Thu, 17 Feb 2022 10:22:01 +0000

Posted By: renewablejohnScandinavian glasshouse

Do you mean a greenhouse built over the top of the existing?

A Frame House

renewablejohn — Thu, 17 Feb 2022 14:44:11 +0000

Posted By: Ed Davies
Posted By: renewablejohnScandinavian glasshouse
Do you mean a greenhouse built over the top of the existing?

In effect yes that is what I will end up with. The two long sides of the trusses will form the A frame and the shorter sides of the truss will be covered in glass to form the greenhouses one on each side.

A Frame House

Ed Davies — Thu, 17 Feb 2022 16:37:14 +0000

I think we need a picture.

A Frame House

Peter_in_Hungary — Thu, 17 Feb 2022 18:18:39 +0000

Posted By: renewablejohnAm I just being mad as retained as a Dutch barn it would give me far more room and the trusses would then become a room feature

Posted By: renewablejohn
Posted By: Ed Davies
Posted By: renewablejohnScandinavian glasshouse
Do you mean a greenhouse built over the top of the existing?

In effect yes that is what I will end up with. The two long sides of the trusses will form the A frame and the shorter sides of the truss will be covered in glass to form the greenhouses one on each side.

Posted By: Ed DaviesI think we need a picture.

+1
a picture of both (what type of Dutch barn do you mean?

A Frame House

renewablejohn — Thu, 17 Feb 2022 18:44:57 +0000

Hope this drawing explains it a bit better. Dutch barn in the sense you have a double pitch roof both shallow pitch and sharp pitch on the base of a 1mtr high wall. The internal rafters just happen to make the shape of an A frame so thought I could exploit this as part of the barn conversion. I have a surplus of 4mtr x 1mtr x 100mm concrete bog mats so was going to reuse them for the side walls as well as the ring beams and floor of the barn with it being 8 mtr wide.

A Frame House

renewablejohn — Thu, 17 Feb 2022 19:12:20 +0000

Think they call this type of Dutch barn roof a Gambrel roof. Footprint is 8 mtrs wide by 6 mtrs long with 5 rafters along its length so 10 trusses all the same size in total.

A Frame House

owlman — Thu, 17 Feb 2022 19:57:08 +0000

I think it's more of a Mansard roof John but I get the idea.

A Frame House

Ed Davies — Thu, 17 Feb 2022 20:11:27 +0000

Thanks for the drawing, that's a lot clearer.

Posted By: renewablejohnAm I just being mad as retained as a Dutch barn it would give me far more roomâ€¦

Without being clear about what you're trying to achieve here, yes sorry, it does seem a bit mad.

â€¦and the trusses would then become a room feature

Presumably you want to add these trusses for structural reasons? Supporting the upper floor? As such you'd need to consider what would happen to them in a fire if they're exposed to the room.

Putting PV behind glass might not be a great idea as you'll lose a lot of insolation, especially if the glass is at a different angle from the glass on the front of the panels. When light arrives square on to a glass surface most goes through but as the angle increases away from the normal (perpendicular) reflections increase. With the top glass on your gambrel roof a lot of sunlight will bounce off, particularly in the winter when you need it most.

A Frame House

djh — Thu, 17 Feb 2022 20:32:31 +0000

Posted By: owlmanI think it's more of a Mansard roof John but I get the idea.

According to wikipedia, a two-sloped roof with gable ends is called a gambrel, whilst a two-sloped roof with hipped ends is called a mansard. Who knew? I've always called them all mansards.

A Frame House

renewablejohn — Thu, 17 Feb 2022 21:17:52 +0000

To put it into context the barn backs onto a steep hill and the upper floor has a bridge across to the upper part of the hill. If I locate the doorway in the A frame then that rear room is no use as a bedroom as it will become a walk way. Now if I install 2 bridges across from the greenhouses and access from the A frame into the greenhouses I will still have access to the hillside but then the bedroom is no longer a walk way. The trusses are already there supporting the roof its just a case of do we down size into an A frame or use the full space of the gambrel roof. Having not lived in an A frame I dont know how I will get on with the sloping roof. The other downside with the gambrel roof would be no views east or west whereas sat in the glasshouses the views would be retained.

A Frame House

renewablejohn — Tue, 22 Feb 2022 11:39:00 +0000

Have seen some A frames with doors built into the steep sides and thinking I could do the same using the existing gambrel roof maybe on the North aspect which is sheltered by a wood. Have seen others use that space created for large picture window and kitchen area. Sounds Ed your not convinced with A frame. I notice yours does not have these add on side areas with hindsight would you have put them in.

A Frame House

Ed Davies — Wed, 23 Feb 2022 10:51:35 +0000

I'm planning to have the â€œfront doorâ€ into the steep side of my porch/greenhouse. The temporary OSB door you see in my pictures linked above will become the main â€œsecurityâ€ door but the second one you go through to enter the house.

With hindsight I think I'd make the house about the shape of my porch/greenhouse as shown in the image below but with the steep side on the south and the sloping bit go a bit further out/down to make a sort of lean to within the insulated envelope but outside the finished floor area to use for my big thermal store.

A Frame House

renewablejohn — Fri, 18 Mar 2022 22:45:48 +0000

Ed

Is the light blue on picture above thermal solar with PV above. If so is the thermal for UFH and PV for high temperature hot water

A Frame House

Ed Davies — Sat, 19 Mar 2022 10:27:32 +0000

Yes, solar thermal along the bottom with PV above.

An unusual thing about this house is that it'll have a large thermal store along the north side under the edge of the A-frame (part of why an A-frame makes more sense than it is usually thought to). About 10 tonnes of water; not quite interseasonal storage but approaching it. Any excess solar thermal or PV energy, beyond what's needed to charge the battery and heat DHW, will get chucked in that store.

Exactly how the solar thermal and PV get used is a matter for experimentation. Obviously, if the battery is at all low then the first call on the PV will be to charge that. Also, if the solar thermal is only producing relatively cool water, too cool to be useful for DHW, then it'll have to go to the thermal store. Beyond that the choice of how to use the energy harvested is a small matter of programming; I'm thinking about optimisation looking not just at the current conditions but also at forecast conditions. It might be that just using some simple rules will be sufficient, particularly in summer, but I suspect experience will show that making the best use of available energy in winter will take a certain amount of thought.

I'm not going to install UFH, relying just on heat leakage from the big thermal store plus a few radiators as experience shows to be necessary.

A Frame House

Peter_in_Hungary — Sat, 19 Mar 2022 13:26:25 +0000

Posted By: Ed DaviesI'm not going to install UFH, relying just on heat leakage from the big thermal store plus a few radiators as experience shows to be necessary.

Surely if the thermal store leaks enough heat to provide useful space heating then it will be leaking heat all summer when you don't need the heat to the detriment of any or all of the heat stored for the winter. I would have thought that the thermal store to be effective over weeks or months a very good level of insulation will be needed.

Out of curiosity what are the dimensions and construction materials will be used for the thermal store?

A Frame House

Ed Davies — Sat, 19 Mar 2022 17:20:49 +0000

Posted By: Peter_in_HungarySurely if the thermal store leaks enough heat to provide useful space heating then it will be leaking heat all summer when you don't need the heat to the detriment of any or all of the heat stored for the winter.

IMHO, labelling periods â€œsummerâ€ and â€œwinterâ€, generally in most maritime climates, is a confusing way of thinking from the point of view of heat storage. The shoulder seasons (spring and autumn) dominate.

Around here (NE Scotland), May and June tend to be nice, mid November to mid February tends to be nasty, the rest of the time is just meh. So the general plan would be to keep the store reasonably cool for July and August then start accumulating heat as its available, ramping the temperature up throughout the autumn (starting maybe in middle of August) with the idea of maybe breaking even through October then beginning to deplete the store a bit, on average, from the beginning of November but, obviously, grabbing whatever energy is available from then on.

It's all a bit experimental so some tuning is likely inevitable.

My current plan is that the store will be multiple EPDM-lined timber boxes but when I get to that stage I'll see if there's anything available off-the shelf which would involve less construction hassle.

A Frame House

djh — Sat, 19 Mar 2022 18:19:59 +0000

Posted By: Ed DaviesAbout 10 tonnes of water; not quite interseasonal storage but approaching it.

When I first started thinking about building a house, my idea was to use seasonal storage to make it zero-heating. I reckoned I'd need 20 tonnes and that seemed vaguely consistent with some examples by the likes of Jenni. It all depends on the losses and target temperatures etc of course.

Posted By: Peter_in_HungarySurely if the thermal store leaks enough heat to provide useful space heating then it will be leaking heat all summer when you don't need the heat to the detriment of any or all of the heat stored for the winter. I would have thought that the thermal store to be effective over weeks or months a very good level of insulation will be needed.

The plan I had was to wrap the tank in straw bales to provide the insulation and to have the tank in an airtight enclosure in the centre of the house, with more insulation arround the enclosure. Then I'd have vents into the enclosure such that I could send warm air to the house or discharge it externally. Similarly intake would be either internal or external. I think I would have been able to control the internal temperature of the house sensibly, but I gave the idea up because (a) I didn't think I could provide DHW for the full two month gap I thought I would need to and (b) it took an awful lot of floor space for an experiment.

Posted By: Ed DaviesMy current plan is that the store will be multiple EPDM-lined timber boxes but when I get to that stage I'll see if there's anything available off-the shelf which would involve less construction hassle.

I'd certainly go for multiple tanks if possible so you could isolate and drain down one if it had a problem. How will you fill them? And what will you insulate them with? I think you also need to think about ventilation to discard excess heat - I agree you can power down most of the storage in summer (you'll still need some for DHW) but I expect there'll still be times when you have too much heat.

A Frame House

Peter_in_Hungary — Sat, 19 Mar 2022 19:19:08 +0000

Posted By: Ed DaviesMy current plan is that the store will be multiple EPDM-lined timber boxes but when I get to that stage I'll see if there's anything available off-the shelf which would involve less construction hassle.

IBC tanks ???

A Frame House

djh — Sat, 19 Mar 2022 20:12:47 +0000

Posted By: Peter_in_Hungary
Posted By: Ed DaviesMy current plan is that the store will be multiple EPDM-lined timber boxes but when I get to that stage I'll see if there's anything available off-the shelf which would involve less construction hassle.

IBC tanks ???

Will they stand the heat? I suppose they could be extremely well-supported, but then what's the benefit?

One thought I had was to get some sheet metal tanks made to fit, galvanised in steel most likely. Not quite off-the-shelf but pretty easy to get made.

A Frame House

WillInAberdeen — Sat, 19 Mar 2022 20:48:49 +0000

There was a nasty accident where a polythene tank (DHW expansion tank) was accidentally heated too hot, due to failure of a controller causing hot expansion elsewhere in the system - the plastic softened and eventually dumped its contents onto someone sleeping in the room below, the water was by then hot enough to cause fatal scalding.

Dunno if this is relevant to Ed but I'd certainly suggest that anything connected to a heated water system, should be certified suitable/safe for high temperatures, even if it is not normally intended to be hot.

A Frame House

Ed Davies — Sat, 19 Mar 2022 22:07:17 +0000

Posted By: WillInAberdeen: â€œDunno if this is relevant to Ed but I'd certainly suggest that anything connected to a heated water system, should be certified suitable/safe for high temperatures, even if it is not normally intended to be hot.â€

What I have in mind is NC pipe thermostats on the input pipes which cut off power to the relevant pumps if the temperature gets too high. That'd be a second line of defence beyond what the normal control system does.

Thoughts have evolved a bit but this gives some idea of what I once had in mind: https://edavies.me.uk/2008/11/house/thermal-store.html I should delete/replace it, really.

A Frame House

Peter_in_Hungary — Sun, 20 Mar 2022 07:40:13 +0000

Posted By: Peter_in_Hungary
Posted By: Ed DaviesMy current plan is that the store will be multiple EPDM-lined timber boxes but when I get to that stage I'll see if there's anything available off-the shelf which would involve less construction hassle.

IBC tanks ???

Posted By: djhWill they stand the heat?

Given that you can get IBC tank heaters that go up to 120 deg C I suppose that they can take the heat. Quite how either IBC tanks or EPDM would fare over many years of continued high temperature may be a bit unknown.

https://www.kuhlmann-electroheat.com/en/ibc-container-heater/pn-28/
Available with different temperature limits, e.g. 0-90Â°C or 0-120Â°C.

Is the inter-seasonal store worth the effort and complication over say spending the money and effort on additional insulation and extra panels so that v. minimal heating is needed and for most of the year the heat produced by living would be sufficient?

A Frame House

renewablejohn — Sun, 20 Mar 2022 09:16:28 +0000

Posted By: Ed DaviesYes, solar thermal along the bottom with PV above.

An unusual thing about this house is that it'll have a large thermal store along the north side under the edge of the A-frame (part of why an A-frame makes more sense than it is usually thought to). About 10 tonnes of water; not quite interseasonal storage but approaching it. Any excess solar thermal or PV energy, beyond what's needed to charge the battery and heat DHW, will get chucked in that store.

Exactly how the solar thermal and PV get used is a matter for experimentation. Obviously, if the battery is at all low then the first call on the PV will be to charge that. Also, if the solar thermal is only producing relatively cool water, too cool to be useful for DHW, then it'll have to go to the thermal store. Beyond that the choice of how to use the energy harvested is a small matter of programming; I'm thinking about optimisation looking not just at the current conditions but also at forecast conditions. It might be that just using some simple rules will be sufficient, particularly in summer, but I suspect experience will show that making the best use of available energy in winter will take a certain amount of thought.

I'm not going to install UFH, relying just on heat leakage from the big thermal store plus a few radiators as experience shows to be necessary.

I was looking to do something similar with the thermal tubes but at higher temperatures. Apparantly if you fill the tubes with thermal oil they will operate upto 150C which is a far more useful temperature for power generation and heat exchange.

A Frame House

Ed Davies — Sun, 20 Mar 2022 09:45:43 +0000

Posted By: Peter_in_HungaryIs the inter-seasonal store worth the effort and complication over say spending the money and effort on additional insulation and extra panels so that v. minimal heating is needed and for most of the year the heat produced by living would be sufficient?

Wow, I hadn't given that any thought! I've only been thinking about the design of the house for about a decade and a half so give me a chance. /s

The â€œmottoâ€ of this house is â€œno combustionâ€, or as the Fully Charged Show puts it: #StopBurningStuff. It's intended to run solely off fusion at 1 AU, via different indirect paths [Â¹]. That's why there's no grid connection.

Of course it'll have a high standard of insulation but still heat losses are likely to be around 1 kW in the middle of winter [Â²] where there may well be runs of a week or more with no sun or wind to speak of. Unusual but they happen - there was one last December. So where would the â€œminimalâ€ heating come from in a no-combustion house?

[Â¹] PV, solar thermal and, if it proves to be necessary, wind. Hydro would be great but there are only so many sites you can do that. Mine is more or less at the top of a hill so not one of them.

[Â²] https://edavies.me.uk/2014/04/heatloss/ https://edavies.me.uk/2014/07/energy-budget/

A Frame House

Peter_in_Hungary — Sun, 20 Mar 2022 12:07:41 +0000

Posted By: Ed DaviesThe â€œmottoâ€ of this house is â€œno combustionâ€,

Posted By: Ed DaviesSo where would the â€œminimalâ€ heating come from in a no-combustion house?

Same place as the energy to cook the Sunday lunch and the morning cuppa ??
Which is a question of interest to me - From where will the energy for cooking and tea making come.