South facing conservatory for solar gain

BarneyMc

I've house plans (see them here) and would like to leave the option open for a conservatory on the southern elevation (from the kitchen/dining area).

I've just read some useful articles on passive solar conservatories here and here (no connection with either) and what I want to know is there anything I should do at the time of the house build to make it easy to build such a conservatory in a few years time?

My thoughts are for an unheated, all glass structure that can be used to 'trap' heat and be brought into the envelope of the building. I've attached an image that shows what I mean... I hope

gman2k

You could put in the foundations, and possibly even the subfloor.
Also, make sure there is no drainage pipes coming into this zone to make it easier on yourself down the line.
Allow for electrics etc.
Possibly install your lead flashing into the blockwork at the height you will need it for the future conservatory roof section.
Be aware of where your room vents are placed.

BryanF

BarneyMc wrote: »

I've house plans (see them here) and would like to leave the option open for a conservatory on the southern elevation (from the kitchen/dining area).

I've just read some useful articles on passive solar conservatories here and here (no connection with either) and what I want to know is there anything I should do at the time of the house build to make it easy to build such a conservatory in a few years time?

My thoughts are for an unheated, all glass structure that can be used to 'trap' heat and be brought into the envelope of the building. I've attached an image that shows what I mean... I hope

It's a great idea and works - do allow for carefully glass selection or auto shading and purge ventilation. carefully consider your thermal mass as that's the real benefit - hemplime might be worth considering locally in that area or some form of rain screen system that can be removed once glass is installed. As regards Mvhr integration you'd want a summer season inlet elsewhere.
In no way relevant to your query, has anyone used the waste Mvhr air for a winter garden/ glass house, For winter heating?

Supertech

Barney my opinion would be that if you think this is a runner, and are likely to build it, do it now. Economically it is always cheaper to build new than to have additions or alterations done. Add to that fact the better value there is out there in terms of costs at the moment and it's a no brainer. You will also begin to claw back your construction costs sooner by having this element built now rather than later.
Furthermore, you won't have the disruption of having your home turned into a building site in a couple of years time.

If building it now is not a runner, it might make sense to make it a little deeper than the 2 metres you've shown to try to catch the last of the sun on the SW and W orientation -not a huge deal I know but the longer you can keep sun into it the better. As it stands at present a lot of the roof will be in the shadow of the main house and there's no glass on the western side at all. It also might not be a bad idea to allow some opening into the current Living Room, although this would obviously effect the amount of wall you have in the conservatory in terms of thermal mass.

It's definitely worth doing, as the shallow room depths on your plans will maximise the benefit. The comments regarding ventilation are spot on and well founded. I have a south facing sun room at present - tiled roof, 3 large rooflights and glass on 3 sides (just double glazing, and not the new stuff with all the bells and whistles). With any sun at all, I close the doors on it to allow the heat build up, and then later in the day I open these doors and the doors of the adjoining dining room and kitchen (very high tech I know). The difference is phenomenal - and our house is badly in need of an insulation upgrade at present so we don't even get the full effect.

Do-more

Might be worth your while to consider a trombe wall or incorporate some of it's ideas into your conservatory plans.

BryanF

+ 1 with ST

Do-more wrote: »

Might be worth your while to consider a trombe wall or incorporate some of it's ideas into your conservatory plans.

that's the point I was making re thermal mass and the use of hemplime in the wall areas of the 'sun-space' (as its an insulator, breathable and could be used inside to outside - or rammed earth/ bricks/ stone etc are another options but not suitable if your doing this in different stages. see here for an example and see here for a local domestic example

BarneyMc

Wow lots of info guys! Thanks very much for your ideas and help. Here's some of my thoughts...

gman2k wrote: »

You could put in the foundations, and possibly even the subfloor.
Also, make sure there is no drainage pipes coming into this zone to make it easier on yourself down the line.
Allow for electrics etc.
Possibly install your lead flashing into the blockwork at the height you will need it for the future conservatory roof section.
Be aware of where your room vents are placed.

Thanks gman, some top points. Think I'll build at the same time as rest of house as per other comments.

BryanF wrote: »

It's a great idea and works - do allow for carefully glass selection or auto shading and purge ventilation. carefully consider your thermal mass as that's the real benefit - hemplime might be worth considering locally in that area or some form of rain screen system that can be removed once glass is installed. As regards Mvhr integration you'd want a summer season inlet elsewhere.
In no way relevant to your query, has anyone used the waste Mvhr air for a winter garden/ glass house, For winter heating?

I'm a bit lost here Bryan. Regarding thermal mass there'll be the insulated slab floor. Regarding the walls if I use the exterior walls then I assume there'll be a massive cold bridge between the exterior wall inside the conservatory and the exterior wall outside it? Could a row of lite blocks be layered just below where the lean-to glass rests (south elevation)? The shorer 2M wall might be harder to deal with.

Yes I understand that the MVHR would not work well in summer as the air would be too warm.

Supertech wrote: »

Barney my opinion would be that if you think this is a runner, and are likely to build it, do it now. Economically it is always cheaper to build new than to have additions or alterations done. Add to that fact the better value there is out there in terms of costs at the moment and it's a no brainer. You will also begin to claw back your construction costs sooner by having this element built now rather than later.
Furthermore, you won't have the disruption of having your home turned into a building site in a couple of years time..

yes think you're right Supertech.

Supertech wrote: »

If building it now is not a runner, it might make sense to make it a little deeper than the 2 metres you've shown to try to catch the last of the sun on the SW and W orientation -not a huge deal I know but the longer you can keep sun into it the better. As it stands at present a lot of the roof will be in the shadow of the main house and there's no glass on the western side at all. It also might not be a bad idea to allow some opening into the current Living Room, although this would obviously effect the amount of wall you have in the conservatory in terms of thermal mass..

Yes I was thinking that also but I plan to have a balcony over the living room. Anyway good point. I think 2 meters might just about be enough for a seating area to look out onto the garden.

Supertech wrote: »

It's definitely worth doing, as the shallow room depths on your plans will maximise the benefit. The comments regarding ventilation are spot on and well founded. I have a south facing sun room at present - tiled roof, 3 large rooflights and glass on 3 sides (just double glazing, and not the new stuff with all the bells and whistles). With any sun at all, I close the doors on it to allow the heat build up, and then later in the day I open these doors and the doors of the adjoining dining room and kitchen (very high tech I know). The difference is phenomenal - and our house is badly in need of an insulation upgrade at present so we don't even get the full effect.

That's really good to know. I think I would be better going with a glass roof? It would let in much more light.

Do-more wrote: »

Might be worth your while to consider a trombe wall or incorporate some of it's ideas into your conservatory plans.

Thanks Do-more but to be honest I don't really get it. It's basically thermal mass?

BryanF wrote: »

+ 1 with ST
that's the point I was making re thermal mass and the use of hemplime in the wall areas of the 'sun-space' (as its an insulator, breathable and could be used inside to outside - or rammed earth/ bricks/ stone etc are another options but not suitable if your doing this in different stages. see here for an example and see here for a local domestic example

Again a bit out of my understanding but it's basically thermal mass to soak up the heat?

BarneyMc

This is more of less what I'm thinking of (see attachment).
I wish I was this far on! :rolleyes:

BryanF

In simple terms Yes.
what you are suggesting potentially allows for
> preheating Mvhr (3 season)
> and the proper use of thermal mass will reduce your heating requirement.

But With increased glazing comes the risk of overheating, how you deal with this important. Are you still going 'near passive' ? If so, carefully consider this with an IES type modelling software. Considering the expense of the sunspace and the risks of overheating/ heat loss, in my opinion its worth looking at the passive gains and heating integration solutions carefully.

Do-more

BarneyMc wrote: »

Thanks Do-more but to be honest I don't really get it. It's basically thermal mass?

Barney, there are a number of different ways you can capture and make use of the solar energy from your conservatory.

The simplest way is to place the conservatory outside the thermal envelope of the house and to just use the hot air from it to help warm the house during the day.

Another approach is to construct the conservatory so that it forms part of the thermal envelope, the wall between the conservatory and the Kitchen/dining room then becomes an internal wall and can be constructed without insulation. The sun warms the thermal mass of this wall and it is released into the house during the night. This approach of course requires a lot more consideration in terms of it's design and it is highly debatable whether the extra expense offers a worthwhile payback.

A good compromise on the second approach is to construct the conservatory outside the thermal envelope as in the first approach and then place, closely spaced underfloor heating pipes just below the (dark tiled) surface of the floor and walls of the conservatory and circulate the water into more UFH pipes placed in a thermally massive internal wall in the house. The dividing wall between the kitchen and living room would be good to use for this.

The circulation pump could be powered by a small PV panel so you will have no on-going running costs.

If constructed from the outset this solution shouldn't add great expense to the cost of the house & conservatory (maybe €500?) and should offer a worthwhile payback.

BarneyMc

BryanF wrote: »

In simple terms Yes.
what you are suggesting potentially allows for
> preheating Mvhr (3 season)
> and the proper use of thermal mass will reduce your heating requirement.

But With increased glazing comes the risk of overheating, how you deal with this important. Are you still going 'near passive' ? If so, carefully consider this with an IES type modelling software. Considering the expense of the sunspace and the risks of overheating/ heat loss, in my opinion its worth looking at the passive gains and heating integration solutions carefully.

Yes this will be very important (still going with near passive house). The last point in the Summary here refers to "solar control glazing or roof blinds". There are more details in the document itself. Apparantly these blinds can be adjusted to meet the season. Does anyone know anything about these? I want to keep it simple and these seem like the best option.

BarneyMc

Do-more wrote: »

Barney, there are a number of different ways you can capture and make use of the solar energy from your conservatory.

The simplest way is to place the conservatory outside the thermal envelope of the house and to just use the hot air from it to help warm the house during the day.

I think this is the preferred method for me Do-more. I believe in keeping things simple and this certainly is. I work from home so opening and closeing windows/doors into the conservatory would be easy to manage.

Again my biggest question is with the outside walls of the house (inside walls of the conservatory) and how to best use this as a thermal store without having a considerable cold bridge to the outside (external wall of the house above and outside the conservatory. Would a row of lite blocks or something like this (no connection) built into the external wall, just below the roof of the conservatory help?

Do-more wrote: »

Another approach is to construct the conservatory so that it forms part of the thermal envelope, the wall between the conservatory and the Kitchen/dining room then becomes an internal wall and can be constructed without insulation. The sun warms the thermal mass of this wall and it is released into the house during the night. This approach of course requires a lot more consideration in terms of it's design and it is highly debatable whether the extra expense offers a worthwhile payback.

Too risky for me;)

Do-more wrote: »

A good compromise on the second approach is to construct the conservatory outside the thermal envelope as in the first approach and then place, closely spaced underfloor heating pipes just below the (dark tiled) surface of the floor and walls of the conservatory and circulate the water into more UFH pipes placed in a thermally massive internal wall in the house. The dividing wall between the kitchen and living room would be good to use for this.

The circulation pump could be powered by a small PV panel so you will have no on-going running costs.

If constructed from the outset this solution shouldn't add great expense to the cost of the house & conservatory (maybe €500?) and should offer a worthwhile payback.

This sounds interesting but perhaps unnecessary. Opeing windows and doors might be just as good. I'd like to hear of something like this working before venturing into this.

BryanF

BarneyMc wrote: »

BryanF wrote: »

In simple terms Yes.
what you are suggesting potentially allows for
> preheating Mvhr (3 season)
> and the proper use of thermal mass will reduce your heating requirement.

But With increased glazing comes the risk of overheating, how you deal with this important. Are you still going 'near passive' ? If so, carefully consider this with an IES type modelling software. Considering the expense of the sunspace and the risks of overheating/ heat loss, in my opinion its worth looking at the passive gains and heating integration solutions carefully.

Yes this will be very important (still going with near passive house). The last point in the Summary here refers to "solar control glazing or roof blinds". There are more details in the document itself. Apparantly these blinds can be adjusted to meet the season. Does anyone know anything about these? I want to keep it simple and these seem like the best option.

Blinds inside the glass would be best if this is your preference
As regards thermal bridge yes they will do and so will the quinlite which will be cheaper
Separate to thermal bridging issues -
If it were me I'd be looking at how a wall structure could provide the thermal mass without out a conventional insulation barrier

BryanF

Another approach is to construct the conservatory so that it forms part of the thermal envelope, the wall between the conservatory and the Kitchen/dining room then becomes an internal wall and can be constructed without insulation. The sun warms the thermal mass of this wall and it is released into the house during the night. This approach of course requires a lot more consideration in terms of it's design and it is highly debatable whether the extra expense offers a worthwhile payback.

I think your dismissing the variations of this option to quickly. Hemp lime for instance will do both- provide insulation and thermal mass solutions.

BarneyMc

BryanF wrote: »

I think your dismissing the variations of this option to quickly. Hemp lime for instance will do both- provide insulation and thermal mass solutions.

Yes possibly. I really don't know much about it and how would it join with the normal (wide cavity) wall to the sides and above it? If it's a viable solution then I'm all ears.

I suppose it'll all come down to the most pragmatic solution that'll work and not cost the earth!