An
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
collector cavity.
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.
An
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
collector cavity. 
