We are planning a new house build, in an Eco village BTW. Lots of energy designers want you to build with lots of northern windows, even having clearstory windows facing into southern rooms. I built like this decades ago, solar North orientation, large windows facing North, no Western or Eastern windows, tiled floors, wall insulation, solar hot water etc. Everyone thought I was mad because the house didn't face the road. However while that house still performs way better than most 30 yr old houses it was far from perfect. Yet I still see houses built the same way today albiet with double glazing and better insulation. IMHO large areas of glass cause overheating in summer or even spring and loss of heat in winter when it is not sunny. While double glazed thermally broken windows are commonly used if the area of glass is large they still add to the heat load when it is 43deg outside. Keeping house window sizes modest is my plan. The idea (not a new one I know) is to have an 'glasshouse/deck' attached to the northern side of the house which will provide heat to the house in winter and provide a cool shaded area in summer, as an alternative to having large areas of glass on the Northern wall of the house. Thinking of ducting (solar panel driven fan) heat from the roof peak of the glasshouse to the south side of an internal rammed earth wall with air returning through a connecting door or window. The glasshouse could have clearstory windows which open at the top (summer cooling)and are shaded by eaves. Sliding doors or stacker doors will provide large openings as well. Hope to have an insulated roof on it and low mass floor like timber. Size about 6mx 4m with floor to ceiling windows/doors on the East side(4m wall) and Northern 6m side of course. Hope to have a room which can be used all year round (except winter nights). Looking for people's thoughts, ideas on the concept.
North windows or Greenhouse
(22 posts) (8 voices)-
Johnnojack
MemberPosted Friday 6 Feb 2015 @ 1:14:35 am from IP # -
arttt
Membersounds like another room of the house that is closed of and that space sacrificed in extreme conditions (winter nights/summer heat waves). Not a bad idea. It sounds like your building it to the level of finish as other rooms of the house? i see a few risks.
1)it might cost as much per m2 as the rest of the house but with reduced utility at times. For it to heat the rest of your house in winter that room is going to be pretty hot.
2)If its used like a room most of the time then you or a future owner might not like not having the use of it during those extreme times resulting in aircon/heating being installed in it or it being refitted and no longer being a 'glasshouse'.
3) your missing out on the winter benefits of sun exposed thermal mass to allow the heat to carry over into the evenings.Unless the glasshouse can be build cheaply i think i would try and bring the room into the house to make the space usable year round and carefully get the balance of shading,thermal mass and quality glazing right. With high levels of insulation you can still keep the windows to a modest size.
hope that is helpful.
Posted Friday 6 Feb 2015 @ 3:10:06 am from IP # -
scipe
MemberYes sir
I like the idea of some sort of 'sunroom' on the North side. I know this will be
your enemy in fierce heat, so do we need a design that eliminates heat contacting
the glass when required, shutters or something similar ???I recall some older houses having a sunroom - just the greatest 'space' in winter.
Some sort of 'sundeck' may be far cheaper to build than bricks & sticks, and still
very useful most of the year. Especially for those of us who prefer the 'outdoors'.If you (or friends) ever visit the excellent CERES eco complex in East Brunswick,
Melbourne, have a look at the North glass wall building they put up a long time
ago. If I am not mistaken it worked well after deciduous creeping vines established
on the north of the glass, giving seasonal shading, louvres at the top I think,
for venting. (?)Please keep the sundeck 'vision' coming
Posted Friday 6 Feb 2015 @ 6:27:01 am from IP # -
Chip
MemberWe currently live in an old rammed earth house with small windows and 2.7m verandahs all around. We glassed in the northern verandah and it gets nice and warm in there between 10am and 3pm in winter so we open the doors from the house to let that heat in. The heat also warms the 450mm thick rammed earth walls from the outside so that it at least slows the loss from the inside at night. With a gal iron roof, the enclosed verandah gets hot in summer though no direct sunlight gets in so it's bearable.
We are currently building a new house nearby and it will have the double glazed, thermally broken big northern windows to allow heat onto the slab floor. We'll close the curtains at about 3pm I guess to try to contain that heat.
So we are voting for the direct sunlight onto the slab and onto a couple of dark coloured masonry walls running back at 90 degrees from the northern wall of windows.
With both houses, the key is that they need to be driven. So whatever you decide upon, you will need to either be there to operate a few doors/windows/curtains or else have an automated system. Some houses that remain empty til the workers get home at 6pm have spent 3 hours cooling down in winter.
An advantage of the greenhouse idea is that you can grow a lot of useful and attractive stuff in there in pots.
Posted Friday 6 Feb 2015 @ 9:55:28 am from IP # -
Johnnojack
MemberThanks for the comments, will try to respond to some. It may cost as much per metre sq as the main house however there wont be a slab or a ceiling, if it heats the house it will pay for itself and save the cost of an a/c which would otherwise be needed to cool a house with lots more glass of its own.
As far as loss of use during winter nights it is not an essential room of the house yet should be more useable than an outside freestanding verandah which would need cafe blinds etc to make it more useable when it is windy (it is a windy area).
I am guessing that it won't be too hot to use in winter as hot air is ducted into the house (fan) it should keep the temp down to 25 -27deg I expect.
Quote " your missing out on the winter benefits of sun exposed thermal mass to allow the heat to carry over into the evenings" Not sure what you mean here as the house will be built on a slab and have a internal rammed earth wall so plenty of thermal mass inside. Thermal mass in the sunroom I see as detracting from its performance as the heat retained in say a brick floor would be lost at the end of the day and delay the heat flow to the house at the start of the day when it is needed most.
Scipe I hope it won't our enemy in 'fierce heat' as the roof will be insulated, window walls will open, and the highlevel windows will vent the hot air straight up. Agree some extra shading would be useful, a shade sail on the east side doing double duty shading the house northern windows and some sort of shade on the north side. Hopefully it will never get hotter than ambient temperature in summer, which gives a lot of time it can be used.
Grow plants yes, tomatoes in July yum, also dry clothes year round.
Posted Friday 6 Feb 2015 @ 12:17:39 pm from IP # -
arttt
Memberre the thermal mass.
i agree you dont want it in the green house for this appliaction (thermal mass is sometimes used in real green houses to avoid plant stress on cold nights).
In the house the thermal mass is only useful if you can get heat into it. The best way to get heat into the mass is to have the sun shining onto the thermal mass heating it directly. This gets the surface of the mass hotter then the ambient air and drives more heat into the mass. Warm air passing over the thermal mass isnt as effective.Your first post sounded like you were building a green house but wanted a room. I was wary of that because if you build the wrong space you just end up with an expensive,bulky solar heating system. Think i probably misinterpreted your initial post. If you get it right and the space is useful then its a great idea.
My kids think a sunny 25deg room in winter is only bearable in underpants. I almost agree with them. Its quite hot.
Also do look at the spec of some good windows. double glazed,lowe,argon filled,good frames are getting cheaper. The heat gain in summer if shaded is v low and north facing in winter in canberra (not sure how your location stacks up) on average they gain about 2kwh for every 1kwh of heat they loose over a 24 hour period. without even considering blinds/curtains. Its worth thinking about how this would have changed the performance and or design of your 30 year old house.
Posted Friday 6 Feb 2015 @ 1:20:08 pm from IP # -
Bushwalker
Memberarttt said:
Also do look at the spec of some good windows. double glazed,lowe,argon filled,good frames are getting cheaper. The heat gain in summer if shaded is v low and north facing in winter in canberra (not sure how your location stacks up) on average they gain about 2kwh for every 1kwh of heat they loose over a 24 hour period. without even considering blinds/curtains. Its worth thinking about how this would have changed the performance and or design of your 30 year old house.
Do you have any examples of effective designs for a north facing greenhouse style addition?
Posted Friday 6 Feb 2015 @ 9:35:06 pm from IP # -
Chip
MemberGreenhouse will serve as a solar air heater but cost of heat per Kw equivalent will be much higher than using a customised solar air heater. If you have the right roof orientation on house or nearby garage then you could build one cheaply. If there is sufficient internal thermal mass to store introduced heat then they can be very cost effective. eg a double brick wall with warm air circulated through the cavity can store heat without causing annoying little breezes and without impacting on air tightness.
Posted Saturday 7 Feb 2015 @ 1:58:58 am from IP # -
axess
MemberHi Johnnojack,
It sounds like you are considering adding a conservatory to your house rather than a greenhouse. I reckon it is a fantastic idea.
We looked at building a conservatory on the northern side of our rammed earth house.
The north facing windows include clerestory windows that exclude the sun from early November (Cup Day) until mid March (Labour Day). The space is approximately 58 square metres and is used as a kitchen/living space.
We also have a problem with heat gain in the hottest months and control this with a single ceiling fan and ventilation when the cool changes arrive from the south west. The winter is doesn't see temperatures drop overnight below 15 degrees. The only heating is a 20 year old (it was in our old house too)Rinnai powered flue space heater.
There is a deck outside the northern wall. The cladding is starting to fail so we considered replacing it with a steel tray suspended slab (the steel can be recycled in the future and the concrete crushed and re-used)with a sandstone paving.
The conservatory heat gain and heat loss issues can be controlled by adequate attention to shading and ventilation for the heat, and insulation and draught control for the cold. Do you require 24 square metres of space? Ours will probably come in at 20 square metres with a gable roof shape and vents at either end of the gables.
Glass, particularly double glazing, can be very heavy as the specification can require it to be able to withstand "walk-on" loads for maintenance/cleaning purposes. The weight also requires a very stiff foundation so the framing members will hold the shape over time and during the normal -4 to 45 degrees temperature variations.
These design considerations can be sorted but also provides some clues about the signifigant costs quoted by specialist conservatory suppliers. Particularly in the light of our tiny conservatory market here compared to Europe or the USA.
The use of a low (600mm - 1200mmH)perimeter wall below the glazing is one way to reduce glazing loads and light ingress and stiffen the foundation. Good attention to sealing the boundary between the house and conservatory is another.
I can see you already picking a tomato off the convervatory plant to have with your toast in July!
Good luck.Posted Saturday 7 Feb 2015 @ 2:18:12 am from IP # -
Johnnojack
MemberConservatory rather than greenhouse? Yes I suppose it is, just didn't want to appear too posh. It will be of a better quality than something down the back of the garden.
I'm not considering double glazing for the 'conservatory' in fact hope to use 2 single glazed 2.1 x 2.4 Aluminium sliding doors I already have. The glazing spend will be high enough with the house itself.
Arttt I understand what you mean about sun on the thermal mass rather than warm air but unless the northern rooms are only 2 metres wide then sun can't reach the Rammed Earth Wall (REW). Thinking how to duct warm air into the REW somehow. pipes breeze blocks?
We have come to see the disadvantages of living with the sun coming in a long way, sun on leather furniture and glare for a start. The present house was extended by 1.5 metres to the North to leave clear space for the sun but furniture tends to creep into the extra space. The new plan has the lounge behind the conservatory so is more protected from northern sun. Will design to get some sun into that room via the clearstory windows in the conservatory in the depths of winter, but only a metre of sun rather than 3 metres.
Axess we could get away with a smaller space but as it will double as our outdoor entertaining area it needs room for a decent table. We have no room on the block for another sizable area. Had not intended to have any glass or clear sheet in the roof, too expensive and need to shade completely in summer, just Northern and Eastern walls. Good luck with your ideas would love to discuss further.Posted Saturday 7 Feb 2015 @ 8:03:48 am from IP # -
arttt
MemberBushwalker said:
Do you have any examples of effective designs for a north facing greenhouse style addition?not really. Ive definitely read about plenty that indicate that they provide useful heat as you would expect but most 'eco' house articles dont really provide enough info to gauge how effective a particular design aspect is. The sceptic in me wonders how many of them truly work well so it makes them hard learn from. I would love to see sanctuary or renew do a series where they data log and analyse the performance for a year of the eco houses they publish.
the brits love them. greenhouses and conservatories attached to houses are pretty easy to find on google. so are products to try and heat them,cool them,shade them,insulate them etc. I suspect a good one works well but many are poorly conceived and work poorly.
i remember one in sanctuary a few years back (sorry dont have the details - think it was in Melbourne and they also turned the pool into a water tank but that is a vague recollection so may be incorrect). they sort of clad the outside northern wall with windows with a gap from the old wall of about a metre. seemed like it would work well thermally but it seemed to be an expensive solar air heater as it didnt provide usable floor space.
i extended my own house with a room with a long northern aspect. the room is about 55m2 and it has 30m2 of well speced north facing summer shaded windows, an edge insulated slab and good insulation all round. In winter it works very much like the greenhouse idea and heats the rest of the house just by convection through the large doorways between old and new but importantly it is comfortable year round and therefore can be the main living area of my home. So its not a green house but the same idea of having a space that does double duty as living space and climate control. I didnt need a greenhouse i needed living space so designed accordingly and worked my free solar heating into the design.
Posted Saturday 7 Feb 2015 @ 12:11:31 pm from IP # -
dixie509
MemberI am looking at a similar situation, and am very keen on concrete thermal mass, clerestory windows, and eaves to keep the sun completely off the slab in summer.
someone has now confused the issue by suggesting that phase change material in the ceiling and possibly upper walls, and a lightweight insulated floor can achieve the same effect much more simply. I haven't yet done the costing.
Does anyone have any views/experience on the phase change material/slab comparisonPosted Saturday 7 Feb 2015 @ 8:51:25 pm from IP # -
Johnnojack
Memberartt you say your extension is comfortable all year round, but can you please tell me what that room is like in a heat wave. I'm thinking it would need artificial cooling with the ratio of glass, despite the best windows. 30m2 is a lot of glass. If it does get a bit hot do you shut it off from the rest of the house?
Sorry you can't convince me to include the area as a normal room because we just can't live without an 'outside' living/entertaining area. On a nice day no matter how great the house is, outside is just better.
Just hoping hoping that this outdoor area can be even better than the last four I have built.Posted Monday 9 Feb 2015 @ 3:13:28 am from IP # -
Russell Moore
MemberWe have had a glasshouse attached to the north side of our house for over 30 years, it has been the best investment we ever made to heat the house in winter.
It is 4m x 2.5m, and has two external doors to vent it in summer, and a large sliding door into the house which we open on sunny winter days. In summer the whole front of the house has a pergola which is covered in shademesh, including the glasshouse. We have a light plastic streamer in the sliding door opening and you can see the hot air streaming into the house on sunny winter days.
It was never meant to be the main heat source, as we also had an active internal rock mass heat store combined with the glasshouse and roof top glass heat collector. It failed in the long run, but the glasshouse just keeps on giving, the KISS principle at its best.
Posted Monday 9 Feb 2015 @ 11:09:32 pm from IP # -
arttt
MemberJohnnojack said:
Sorry you can't convince me to include the area as a normal room because we just can't live without an 'outside' living/entertaining area.Sorry if i come across as trying to convince you. I think what im trying to say is build the 'room' that you need with an eye to make it work thermally.
regarding my high glass ratio. It sounds high but the rest of the house has a lot less glass so the total of the house is about 160m2 of floor and 40m2 of glass.
This summer hasnt had any but last summer canberra had plenty of hot weather (probably not quite as much as Adelaide) including a run of 4 days above 39deg with warm nights. The room touched 26 on the last afternoon of that run of high temps but mostly was around 24deg. The downstairs old bit of the the house has a fair bit of mass which helps and upstairs in the old bit of the house gets hotter but it always has and it gets lots of east and west exposure so its hard to improve on.There is no artificial cooling and we dont close it off from the rest of the house. Haven't even bothered with blinds as yet.
Its not perfect but pretty good for working in with a 50+ year old house. Despite careful planning and thermal calculations i was pretty worried before i built it that the window area would be an issue in the heat but im very happy with the result and that my fears were unfounded.
Posted Tuesday 10 Feb 2015 @ 3:00:20 am from IP # -
Bushwalker
Memberarttt, sounds like bliss!
Do you have any photos or design sketches?
Posted Tuesday 10 Feb 2015 @ 7:00:29 am from IP # -
axess
MemberHi Russell Moore,
I was intrigued to here about your " active internal rock mass heat store ".
I remember this technology from a CSIRO test house from the 70s and think it had problems with moulds growing on the rocks which were then circulated via the fan ducts. How well did your system run before the failure? I would be interested to know even though I know it's heading off topic.
Posted Tuesday 10 Feb 2015 @ 8:53:55 am from IP # -
Johnnojack
MemberArttt thanks for that info, sounds like its working well. can't be getting too hot if you havent fitted blinds yet let alone an aircon. axess you aren't heading off topic for me. Related to the conservatory idea I keep reading that thermal mass needs sun to hit it directly for it to be effective. Heat from our conservatory will be transfered by hot air to the thermal mass rather than hitting it directly as radiated heat. I feel 90% sure this will work but would like some confirmation. arttts example proves that heat can be transferred to thermal mass by warm air even without fan assistance. If it didn't his glass walled room would be roasting and the rest of the house freezing, obviously it works very well.
Many years ago on Solar House day we looked at a house in Willunga which had roof mounted solar airpanels ducted to a rock store within the house. Don't know if it is still working but it had been working well for over a year at the time.Posted Tuesday 10 Feb 2015 @ 11:06:21 am from IP # -
arttt
MemberBushwalker said:
sounds like bliss!We think so.
edit.... got rid of images... follow this link instead.
https://drive.google.com/folderview?id=0Bxi1d6yOlpKHcHM2eUlna2d6aTQ&usp=drive_webThe extension is an odd shape to face true north and avoid the deciduous tree in the back yard. It has a edge insulated slab floor for thermal mass this soaks up much of the winter sun and the old bit of the house has all brick internal walls downstairs further moderating the temp. Upstairs (not shown) is brick veneer with stud walls inside.
Posted Wednesday 11 Feb 2015 @ 3:24:33 am from IP # -
Bushwalker
Member -
Bushwalker
MemberThanks arttt.
Looks good, adding to my ideas folder.
Posted Wednesday 11 Feb 2015 @ 11:27:56 am from IP # -
Johnnojack
MemberRussell Moore said:
We have had a glasshouse attached to the north side of our house for over 30 years, it has been the best investment we ever made to heat the house in winter.It is 4m x 2.5m, and has two external doors to vent it in summer, and a large sliding door into the house which we open on sunny winter days. In summer the whole front of the house has a pergola which is covered in shademesh, including the glasshouse. We have a light plastic streamer in the sliding door opening and you can see the hot air streaming into the house on sunny winter days.
It was never meant to be the main heat source, as we also had an active internal rock mass heat store combined with the glasshouse and roof top glass heat collector. It failed in the long run, but the glasshouse just keeps on giving, the KISS principle at its best.
Russell what went wrong with your active system? A system like that I've always considered the best you can get, as it can store heat and release it later in the night rather than just having thermal mass doing its own thing (getting steadily cooler as the night goes on). Room area taken up by storage is one downside. Such systems are fairly rare I think, maybe a bit advanced for the general public despite the mechanics being very simple.
Posted Thursday 12 Feb 2015 @ 3:27:20 am from IP #
