Turning sunroom into Passive Solar source..

ziontuckerMarch 12, 2008

I am working on turning a sunroom that is about 180 square feet into a more effective source of energy. I live in Zionsville Indiana, so there is some sun.

Currently the room mostly faces West, South, and has a sliding door on the North side. There is roof overhang and large desiduous trees to the west, which help shade the room in the summer. The East side has a 9 foot wide opening into the main living area of our home. The exterior walls of the sunroom are all sliding glass doors, there must be 8 of them. There is a ceiling fan, and several electrical outlets, the floor is tiled. There is a return above the interior doorway and three vents on the floor that go to the furnace. We have just been using blinds to open up the room with the fan during the day and the furnace rarely kicks on. It is about 30-45 degrees lately, and we set our thermostat to 70.

I plan to close the room off with frenchdoors and to further insulate the house as the sunroom is almost all glass. I am looking for advice on what to do with the return and vents in the sunroom. We have always just had them closed, I am thinking I might be able to use them. The floor is just ceramic tile and there is a crawl space under the room. Would it make sencse to add a layer of tile/flooring? Could I insulate below the floor in the crawlspace? I am in the process of getting the french doors, should I go with low e-glass? How do I tell if all these glass sliding doors that make up the current walls are worth keeping? They are probably 18 years old and double paned.

So if your still reading, thank you!! Any words of wisdom would be welcome!!

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Thank you Gary,
I had not heard of low-thermal mass applications like you suggest, but it makes great sencse. There is a larger return vent above the doorway which I might be able to get a fan into. It might a better job than the ceiling fan at pushing the air into the house. My guess would to be open up vent on he other side of the wall and have the fan in the wallspace...Currently this returns to the furnace so would I just try to add this in or close off the sunroom return from the furnace. You also mentioned low vents, I have three outputs from the furnace to the house that are on the floor in the sunroom and are kept closed. I guess I could turn on the furnace fan to move air through these, but that does not seem efficient. I will check out your suggested sites.
I also read here about the aluminum insulation that radiates the heat in one direction, maybe this would be usefull stapled to the joists under the floor??
Thanks again, Matt

    Bookmark   March 13, 2008 at 10:50AM
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Yes -- I'd leave the furnace vents closed.

The simplest way is to install a fan in an opening in the wall between the living space and sunspace that is as close to the ceiling as possible --the fan blows hot air from the sunspace into the living area. Then you need to have a 2nd opening in the wall that should be as low as possible to let cool house air back into the sunspace to replace the air that the fan blew into the living space.

The Shapiro book at the link above has some good information on how large these vents should be and what kind of fan to use. Its a good book, and is available used for next to nothing at Amazon.com and the like.
As you say, I don't think the ceiling fan is going to help much.

I think that adding the reflective layer under the floor would help as long as you leave an airspace between the floor and the reflective layer, but I think that insulation would be more effective.


    Bookmark   March 14, 2008 at 10:32AM
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Last night I was looking at the vents. The current larger retun vent in the sunroom is on the ceiling. It would seem I could hook a fan in there to push the hot air directly into the large living space, it would only travel about 3 feet and
the easiest way to create an opening would be high, like 8 feet off the floor.
Would it make the most sence to wind this vent down to floor level? Also, how will removing one off my three returns affect the furnace system? I am also wondering if this is a DIYJ or should I try to find a professional heating hand?
I think I will go with insulation under the floor as you suggest. There must be rolls that would fit and stable between the joists?
Now to Amazon...Thanks!

    Bookmark   March 14, 2008 at 12:48PM
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That is a good question, the sunroom opens up to 70% of our living space in one great room it includes kitchen, dining room, living room/family room. It is where we usually are if we are not in bed!! The thermostat is in this room. Currently the opening is huge, nine feet, I am closing this off with french doors and casement winds.
I am just in the initial stages of weaning this house off natural gas. A furnace upgrade will come come in several years. Right now I am focused on sealing this sunspace and spent the weekend begining to seal up the ducs and adding insulation. The gas fireplace will be the next big issue to address, it lies in the middle of the living space and has a brick chimmney going up the middle of the building.
Your questions "A and B" will be determined by how clever (or if) I can get a fan blowing out the ceiling in the summer. The larger deciduous trees do shade southwest and west in summer already. To get the air in I hope to rig the return to my furnace on the sunroom roof into the living space. I have yet to figure out the best way to do this.
So with a fireplace insert, insulation and sealing, and a functional passive solar space I would be thrilled to cut my gas bills in half.

    Bookmark   March 17, 2008 at 11:08AM
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