Any Solar people out there? How can I warm a sunroom that has no heat during the winter?

March 19th, 2008 | by Michael |
solar
Brigette m asked:


I have a sunroom on the second floor with nothing in the room to help keep it warm. My concern? that my plants are not going to survive because in the room? gets very cold in winter though? completely enclosed by windows. I want to somehow keep warm without having to use a stove (something that uses a lot of electricity?). Perhaps uses solar power but I don 't know to install it.

RICARDO
  1. 4 Responses to “Any Solar people out there? How can I warm a sunroom that has no heat during the winter?”

  2. By Don on Mar 21, 2008 | Reply

    It’s pretty hard to heat something with solar energy at a time of year when the sun doesn’t shine much. I’m not sure you can do what you want to do here. You may be only able to grow some things year round here, or perhaps for only 9 months, say.

    Otherwise, to have an energy efficient sun space, requires an insulated floor, ceiling, and preferably east and west walls, too. Only the south side really needs to be glazed - the other sides of a greenhouse bleed off more heat than they gain.

  3. By ishara on Mar 24, 2008 | Reply

    Off the top of my head, you might want to think about some sort of heat sink - this means something with high thermal mass that will store solar heat during the day and gradually release it at night. Masonery is itself a good heat store, but so, I believe are large tanks of water. You dont say what orientation your sun room is, but if it’s south ish, it will hopefully get some sun or solar energy during the day and if you positioned a tank appropriately this would warm it up. It’s not very aesthetic, but painting a tank, or indeed the wall, black would absorb more heat. A complementary suggestion might be to rig up what would essentially be a solar hot water system and rather than using it to heat your hot water, use it to heat a tank of water in your conservatory.

    My top advice would be to phone the Centre for Alternative Technology in Machylleth, Wales. They have a superb free advice line and also a great bookshop on how to DIY things like solar hot water…hope this helps.

    Oh, and one last point - you don’t say how warm you need it to be - I would have thought that there’s a big difference between keeping it above freezing (which is what my answer is really tailored towards) and keeping it at a temperature at which you could grow tropical plants, for example. You might want to think about - or specify - what you’re trying to grow and therefore what minimum temperature you are trying to achieve. If you really want to avoid heating it electrically (which makes sense), you just need to choose your plants accordingly, I would thought - use a max/min thermometer to work out exactly how cold it gets and go from there….

  4. By David M on Mar 26, 2008 | Reply

    There may not be a good answer if you can’t insulate the floors, walls, and ceiling. We use Zoneline 3900 in small projects like a room above a garage or small stand alone studios. These are very efficient and easy to install. Any insulating at all you can do will help.
    David

  5. By robling_dwrdesign on Mar 28, 2008 | Reply

    Excellent answer above. You need to use thermal mass, so heat is absorbed during the day, and slowly released at night. Masonry floors work best. Ideally, a concrete slab with tile absorbs a good deal of heat. The point is those materials have a low insulation coefficient which may be counter intuitive. But the exterior walls and roof needs to be highly efficient in insulation. And there is the problem, it is easier to design from the get go than retrofit. Also, the roof overhand is important. It depends on your latitude, but the idea is with the proper overhang, the summer sun with a higher declination is blocked. But in the winter with the lower declination, the sun is allowed. But again this is better determined in design rather than as a retrofit.

    So some things you can inexpensively do are:
    Make sure there are no obstructions, of course. But one is have deciduous trees to the south. Being on the second floor will not make much difference soon, but the idea is deciduous trees block the sun during the summer, but when they lose their leaves during winter allow sun.

    Use a dark masonry floor. Use a dark masonry back wall. But also add insulation behind those dark surfaces, so there is minimal heat lose from the materials away from the space you want to heat.

    Make sure the ceiling is well insulated, with material that will reflect the heat back in the sunroom.

    Hopefully, that will minimize the up and down spike is the ambient temperature. That being said, you may need use some supplemental heat. Although not the purist method, an electric heater on a thermostat used in conjunction with heat sink materials, it will minimize the energy used but still produce a stable temperature.

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