Trombe wall …a [real] simple Passive Heating Solution

trombe-wall-sustainable-energy-efficientYes, a wall sometimes does more than just enclose or divide a space. It can actually help heat a space. A Trombe wall is a sun-facing wall, built from a material that can act as a thermal mass (such as stone, concrete, or adobe). Combined with an air space, insulated glazing and vents, it forms a large solar thermal collector.

During the day, sunlight shines through the insulated glazing and warms the surface of the thermal mass. At night, the average temperature of the thermal mass will be significantly higher than room temperature, and given that the glazing insulates well enough and outdoor temperatures are not too low, heat will flow into the interior space and voilá, you get a passive heating system.

So what does this all mean? It means that you can now reduce your energy consumption. It means the building is doing much more than shielding you from the elements. It means you're finally putting to use some of those simple concepts and ideas learned in architecture school and glorified by earlier modernist architects.

I know what you're thinking, why doesn't every building have one of these? Not all buildings have this because you must have the right ingredients: the proper climate where a building needs cooling during the day and heating at night, an appropriate building program that allows for slight temperature fluctuations, and a client that is willing to embrace sustainability.

We were recently awarded a project that met all these requirements, the CSU East Bay Recreation & Wellness Center. This passive heating system and other sustainable measures have helped the building currently improve Title 24 energy savings by 34 percent. The project is currently under construction and soon, we will be able to quantify its actual performance.

Ozzie Tapia is a BIM Modeler at California-based design firm LPA Inc. He uses BIM application tools to activate, study, and inform project designs for Higher Education Facilities. Tapia is a LEED Accredited Professional and active member of the U.S. Green Building Council.