Trombe Wall

The next generation of Trombe wall design prototype installed October 08 and out performing expectations.

It really isn't a Trombe wall, but rather a thermal mass window system that stores the sun's energy in your window. The photos to the right are a previous attempt at such a system, but it was quickly determined that this system, although it worked well and let a lot of light into the space, did not allow you to see out this window

I guess that wouldn't really classify it as a window.

The next generation is light years ahead of this previous version. Specialized exterior glazing that has incredible U-values and high SHGC make up the first layer of the system. The second is a water filled glass block, designed to capture and store the suns energy within the window. Allowing you to modulate the suns energy into the house. The third element of the window system is exterior shading. This will reduce much of the summer solar gains not previously addressed with overhangs and help to reduce night time winter heat losses.

Most passive solar homes have large areas of south facing glazing that allows the suns energy to enter the space and then typically store this within some kind of thermal mass. Such as a concrete floor. The problem with this design is the space during the daylight hours heats up tremendously and can be uninhabitable for much of the day, although it will still retain heat well into the night. The other problem is that you will need to wear your sunglasses if you don't want crowsfeet.

This new system addresses both of these problems and is about to be tested in a real world application for the first time. At this time I am not at liberty to discuss the full details of the system, as I am under a non-disclosure agreement with the inventor. But stay tuned for once it is installed photos and more information will be made available.

The Trombe wall was designed by Felix Trombe, a french inventor in the late 1950's and 1960's. The basic concept of the Trombe wall was incorporate thermal mass into the wall. This creates a large storage capacity for heat. a masonry wall was built behind a wall of windows. The wall would slowly absorb the heat of the sun. At night when heating was needed, vents were opened to the top and bottom of the wall to circulate air around the wall. This was transferred into the house by convection air movement. It required no mechanical parts, and is capable of providing 20% of your homes heating needs. The wall takes many hours to heat up, the length of time depends on the size of the mass. A typical 10" concrete wall will take about 8-9 hrs. to heat to design temp. At night while the wall is cooling it transfers heat into the living space.

The original idea for a wall heating system was patented by Edward Morse in 1881.

Many variations of this idea have been built, using different methods of thermal mass. Water is one that has been tried and has very good thermal storage properties. Another idea is to incorporate phase change materials into the wall. Phase change materials are materials that change from a solid to a liquid, or from a solid to another solid, when exposed to heat. In the process of phase change a large amount of heat is absorbed in the material. When the material cools and changes back to it's original form the energy stored is released. This is a very good way to reduce the amount of thermal mass needed, while increasing the amount of energy stored. Phase change materials are already being used in the electronics industry. These materials are used to keep electrical components from overheating, by absorbing heat away from the components.

Thermal Mass Window System

The window system shown above contains 3,000 lbs. of water, with the optical clarity of any modern window. The thermal mass effect along with specialized glazing allows this window to capture and store 10's of thousands of Btu's of thermal energy. The highest temperature reached in this window system was 115F while is was 34F outside. The average winter temperature of these windows was between 60-90F, with no other heat in the house.