Modified Trombe Wall
alternative to the solar greenhouse is the Trombe Wall that gathers almost as
much heat and takes up less space. The illustration on the left is actually a
modified Trombe Wall that allows household air to circulate through the
As winter approaches in the northern hemisphere sunlight striking a vertical surface is more direct. This is why a Trombe Wall actually gets hotter in the winter than in the summer. Flaps not shown in this picture are used to prevent heat loss at night. The original Trombe Wall used a solid masonry to store heat. The solid wall was then covered with a glazing material to retard heat loss at night. Openings at the tops and bottoms of the wall allow natural convection currents to increase heat gain process, but there is still a lot of conduction heat losses at night that take place through the masonry wall.
In cold climates this wall may be insulated to increase the net heat harvest.
A modified Trombe Wall is fairly easy to build with common construction materials such as plywood and 1x4's. Just frame out the box as shown in the picture. This Trombe Wall is made with a 4x8 sheet of quarter inch plywood and two 1x4x8's. The absorber plate is corrugated metal. Notice the top and bottom vents allow cold room air to rise and heat up inside. The back of the Trombe Wall is of course painted black to change visible sunlight into heat. OR a screen could be used to augment the heat exchange rate. Don't forget the glazing. Common glazing materials for a project like this include Kalwall Sunlite, Suntuf or Twin Wall Polycarbonate, or of if you must ... glass.
Many people would say this is no
longer a Trombe Wall and they have a point. We might just call these
modifications a hot air collector.