Bruce R. Brownell, owner of Adirondack Alternate Energy.
By Bruce R. Brownell
When we hear the term solar used today, most people think of photovoltaic (PV) panels on roofs producing electricity from sunlight. It’s popular, supported by incentives, efficient and non-polluting, but there is a simpler way to utilize solar energy – passive solar buildings. It’s not new – the best body of solar law, creating access, was in ancient Rome.
Sadly, as a society enabled by seemingly endless fossil fuels, we have forgotten about the basics while embracing the “latest” technologies. The success of passive solar relies on an obvious path based on simple physics.
Passive solar is a term which defines an ancient and intuitive method of heating, where thermal energy flows through the system by natural means using radiation, conduction and convection. The building design embraces this simple method. It does not require separate collectors but operates in cooperation with the immediate environment. The passive solar building requires proper integration of the climate, site, available materials and the sun. The successful result – heat – comes from a never-ending supply of natural energy. This knowledge has been utilized since ancient civilizations, and in pioneer times most rural northeastern farm houses were universally orientated south. To achieve maximum advantage of the sun’s energy, we must:
First, orient the building (home) with the long wall facing south. Next, create a tight, performance-rated R36 insulated envelope on the outside of all six sides of the building. All six sides means insulating under the lowest floor plus all 4 sides and the roof. Then we place most windows in the south wall (but not an all-glass wall by any means). Windows are placed in east and west walls as needed, with a minimum of north glass. During the day, this leads to the need to store the excess, free solar energy which provides 60%-70% of the building’s demand.
Beneath the lowest floor of the building, but inside the insulation envelope, we create a heavy concrete mass system. This mass system, an embedded network of air pipes, is connected to a central vertical air shaft. A fan in the central airshaft draws air from the highest point in the house – the warmest air – down into and through the concrete mass, exiting back into the living space under windows. Thus, room air, warmed by solar gain from the windows, rises, is captured and directed into the concrete “heat battery” below, to be stored and used when the sun goes down.
Because the mass of the concrete heat storage system is far greater than the mass within the living space, the house temperature will not vary by more than ±2 F in any 24-hour period. This house, properly designed does not dump 11 tons of CO2 downwind as does the average northeast home burning 1000 gallons of oil every year.
Further temperature control is easily accomplished by adding a minor amount of back-up heating from an air-tight wood stove or cooling energy from a coil in the air shaft. It is then filtered and tempered by the mass with the occupants experiencing a comfortable and healthy atmosphere.
Passive solar homes are one of the best investments an individual or family can make – first for themselves, then for the generations to follow, and also for America’s economy and the planet’s future. This choice offers a future of minimal energy cost increases. It is an insurance policy guaranteed by the sun. The point is: payback is assured by the sun and by the absolute certainty that fossil fuel costs will rise. What could be more convincing to a family considering a new home, than to build a passive solar home? WHY AREN’T WE DOING MORE OF THIS?
Bruce R. Brownell is the owner of Adirondack Alternate Energy. A complete version of this report is available by calling 863-4338 or emailing aaeinc@frontiernet.net.