Replies

1. 
   Mike_Smith | May 11, 2001 05:19am | #1

   *
   steve , when we were building solar i did a couple of radiant slabs with hot air collectors...

   the largest was a commercial condo...3 units of 1200 sf each..
   we used Airfloor forms which have been around the california scene for more than 50 years...

   here's a link .... and you don't have to go to japan..

   http://www.airfloor.com/

1. 
   Don_Berinati | May 11, 2001 06:14am | #2

   *Consider a passive system that doesn't use any energy to move the heat (a loss there) and integrating the solar gain into the design of the house.A wraparound porch with a sunroom as part of the wrap is a good example. In such a mild climate, you can borrow space from the outside, layering privacy as you approach the house, and allowing you to reduce the interior size.Of course, if you're in the burbs, you may not want any connection with the local scene.Best and good luck - Don

1. 
   Steve_Wright | May 11, 2001 08:22pm | #3

   *Here's another company, out of Ontario, that has been doing this for awhile. Their system is installed on a south wall (Northern Hemisphere) instead of the roof. They have gotten good reports. They did a big installation for McDonnell Douglas building in Canada.http://www.solarwall.com/

1. 
   Steve_Tjiang | May 13, 2001 03:03pm | #4

   *Mike,Thanks for the reply. Hearing from somebody with experience with similar systems reassures me to the soundness of the concept: the possibility of collecting solar energy on the roof and transferring it to a slab, and storing enough energy to keep the house warm through a winter night, albeit a mild California one.What kind of backup heating did you use?I am also thinking that since I want to renovate to a three-level structure (including a partial basement), it may be simpler to store the heat in a rammed earth wall that spans the middle of the house and at least two floors. Such a wall, instead of three different concrete floors, would simplify the heat distribution problem and give me more flexibility.

1. 
   Steve_Tjiang | May 13, 2001 03:08pm | #5

   *Don,Thanks for the reply. I am considering passive solar but my site may make it difficult to do. My lot is a small narrow suburban lot 50'x150' with the long side oriented SSW. Soon, my neighbour in that direction will build a second story addition, blocking some of my solar exposure. Collecting hot air from the roof will keep more architectural options open.

2. 
   Mike_Smith | May 13, 2001 05:31pm | #6

   *all of our supplemental heat has been either radiant cove heat (wall mounted ) or occasionally.. heat pumps

2. 
   Steve_Tjiang | May 13, 2001 05:31pm | #7

   *
   I came across a reference to this solar space heating system from Japan

   http://www.omsolar.com

   In fact, via a link from the "Fine Home building site". The basic idea is
   that the system collects heat energy in the form of hot air from the integrated solar heat collectors on the roof. Fans move this hot air down to a concrete slab --- insulated from the earth --- on the ground floor. Heat not captured by the slab flows into the living spaces as in a normal forced air heating system. During the night, the fans stop as the collectors no longer heat the air. The concrete slab takes over the heating, radiating into the living space, similar to a radiant floor heating system.

   It seems like a good concept but I wonder how well it will work in practice. I do live in a mild climate, San Francisco Bay Area, but I wonder if it could really collect enough energy to heat a 3000 ft^2 two story home using a reasonable size roof.

   Any HVAC experts or solar experts on this list has an opinion?