You mention the use of low-e glass for a Trombe wall. Do you have data? Even with the latest, high-transmittance versions of this glazing system, the SHGC drops so far that I am not at all clear that this is a good idea. Any references to projects would be helpful. If not, This may not be good advice to publish. Thanks, Andy
Question: Living in the southern hemisphere (Australia) the sun does not shine from the South. I rises in the East and sets in the west. Does this mean the the Trombe wall would be best located on the North side?
In principal yes; but a Trombe wall is meant to act as 'time delayed' heating - so you will only get the area under your window acting as a storage heater that will give heat into the room beyond - assuming that the wall is brick of course. This also assumes the night thermal loss through the window will be less than that gained through the Trombe Wall. if I was you I would look for a full height wall to the side of the window to use instead, that way you can use curtains to cut out the night time heat loss by the window.
Thank You for your mind opening suggestion. Infact the side of the window can be made a trombe wall. However, in my case, this is school building working only during day time, so neglecting the thermal storage required for night time use, I wish this can be done to heat the room air passing naturally through the vents on the Trombe wall. Further, since the purpose is just for heating the air during day, only a single glaze would work I presume?
Hi Samar, for what you want I'd suggest going under the window and painting the wall surface black. if you have a thermometer check the inside and outside temperatures first thing in the morning when the sun strikes where the Trombe wall would be - if the inside is warmer have the lower vent feed from the inside, if the outside is warmer on average, feed from the outside. This way you don't waste heat. Also try to cut down drafts in the room itself, especially at the higher levels, this encourages the heat to stay inside the room.
I take it you must be in a colder region of India then is perhaps the norm?
Thank you for the suggestion. For, what your suggestion may be right especially for the first few hours. Then is there any possibility of having a (or two dampers) opening in both the direction( outside and inside)?
Yeah.. I am from Darjeeling in India.
You could certainly put in dampers, but if you add them in you need to be very careful to make sure they are air tight. Think of them as doors, in that they will need a lip to seal against with a 'lock' (usually a piece of wood that turns to hold shut) and make them sturdy enough not to warp. You won't need to cover the whole width of the wall with vents, just vents that are roughly in cutout area the least cross sectional area of the air behind the glass, as that will limit the flow possible.
I'm thinking of using a trombe wall as the common wall between the house and an attached (north facing - I'm in Australia) greenhouse to transfer heat into the house. Will the wall work with relatively diffuse sun coming through the greenhouse roof or does the sunlight have to be direct?
I'm assuming you are looking to provide heating in winter.. If so first check how warm the greenhouse gets and how warm the wall you intend use gets as well. Also check throughout the day to see how much actual sunlight makes it onto the wall. You will get some energy transfer loss from the greenhouse glass, but that would be minor, the fact the greenhouse is also acting as another layer of insulation should make up for that. Although do make sure when doing the Trombe wall in this situation that it is only cycling air from the room - the greenhouse air will quite likely be rather humid; which is not good for you and makes you feel cooler.
Actually the humid airwill make it feel warmer and using a green house is a great idea. use a shadehouse on the south side of the house. in summer open a vent to the outside of the greenhouse and the air will be cooled by the shadehouse and then drawn through the house.
I'm looking for a US source for automatic opening vents for the top and bottom of the trombe wall. I'm designing a cabin that will only be used weekends in the winter, but I want it to stay warm all the time. Nobody will be there to close vents at night to prevent the heat from reversing out of the cabin. Thanks for any help.
A West facing wall will work, but not as well as a full Sun facing wall (i.e. North or South depending on which hemisphere you are in). Also with a West facing wall the geography and ground features (such as trees and other buildings) will play a large factor on whether it will work. A West facing wall should work if it has clear view to the Sun, you just won't get the full effect.
I have a plastic enclosed 100 ft long greenhouse with the 100 ft facing South. Would a 4 ft high trombe wall be cost effective? Would appreciate suggestions re: venting structure, circulating fans, ideas to stop venting when wall begins to bring in cold air during night.
Thx for this great explanation. I am planning a small, offgrid cabin for a 3 yr Buddhist retreat, NW Ark Ozarks. full time occupancy. needs to have a cistern for water catchment. would like to consider trombe wall design using mix of cinderblocks and pvc pipe, or maybe even PVC alone! PVC would hold non-potable water, could even gradually fill with graywater over season. am considering all passive solar technologies, may mix with a micro photovoltaic system for lighting and fans. because of meditative activity planned, all uses should be down-scaled: less water, less heat, less energy consumption. also looking for less complexity in activity and building design (you can see the challenge as I begin to think with complexity about this). summer is humid, winters can be cold but lots of winter sun, so a Trombe wall seems a great idea. any references for experience with Trombe walls in Arkansas or similar partly arid, partly cold, partly humid climate, and for use of water as Trombe wall, either active or passive? thx!
all depends on the metal used and its specific heat transfer properties. Also on the surface of the metal and if its painted. Its not the light as such that is important its the heat (infrared) that gets into the bricks..
Thanks for this very useful information. A house I am designing in Rishikesh, India- the living room and master bedroom face the south. I am planning to have the bedroom wall as a trombe wall. The size of the wall is 7'9 long and 10'3 high. There is a yoga hall above the residence. 1. Can I have only the bedroom with the trombe wall. 2. What should the size of the vents inside the room and outside be?
Hi Shraddha, the vents do not need to be that large - think of the horizontal cross section area between the wall and the glass - that determines the absolute maximum air flow possible as you have no pressure fans 'driving' the air just the heat gain (i.e. making the vent areas in total on inlet and outlet bigger than that won't do anything). You can have the bedroom just have the trombe wall - but be sure of solar access.
Great article, thanks!
Q. Any experiences re condensation inside the glass? i imagine it can be minimised in cold damp weather by closing all vents..? Am hoping to work a cob trombe wall into strawbale house, but have to control moisture.
Im from europe,my question is gonna be different from the others. Im a student at universty and ı m working on a project about trombe wall. I need a catalog and it should imply the trombe wall capacity datas.But I couldnt find a supplier name on internet. How can I learn it or could u give me a few name please?
In the above information it states the Thermal Wall should be "X" thickness for a particular thermal mass substance. Is this referring to the overall thickness of the wall or the thickness of that particular mass substance?
Looking for some feedback.....I'm building a 6 metre x 3.5 metre hothouse in Tasmania...southern hemisphere that is. I have a north, east and west walls in glass windows (roof in laser light) and I am considering building a cob or straw bale or earthen or stone....southern wall. Could I build a glass wall (trombe style) inside the hothouse next to the southern wall (with gap) and have the bottom vent accessing air from outside into the gap and having the top vent opening from the gap into the hothouse....would this work for maintaining heat in the hothouse into the evening. Appreciate any advice you can provide...Regards Gordon