sarah
Don’t get me wrong. I know we need to adopt photovoltaics (PV), wind, and, with great care, flowing water generators to meet the increasing demand for electricity. Passive solar, however, requires little technology and reduces the demand for electricity as well as the embedded energy that is the dark side of photovoltaics.
The best material for thermal solar — glass — lasts indefinitely, if nobody breaks it. Moreover, passive solar has already been perfected in the U.S.; it uses no electricity except, seldom, a light bulb, reduces home heating costs, and in some instances increases quality winter living space.
In the 1970s and early 1980s as a response to OPEC cutting the petroleum flow to a trickle, gas lines formed at every gas station. Then, folks who think seriously about the future were worried about ‘peak oil,’ a future when the Earth’s petrochemical reserves were predicted to dwindle, eventually to the vanishing point. Unfortunately, the timing of those predictions was wrong. But energy concerns inspired an explosion of knowledge in thermal solar design and development. And then, it appears, most of us forgot about it.
Passive solar is a large topic, so I’m going to focus here on home heating.
Vermont has gotten the most important part right: promoting winterizing by sealing all the leaks in homes, the most efficient first step, with a quick pay-back in reduced energy costs. Insulation is next, with a longer pay back time. After that, every home with a south-facing wall can be turned into a solar thermal collector.
Windows can be fitted with ‘heat grabbers.’ South-facing porches can become solar greenhouses. And some portion of the housing stock without porches can be outfitted with solar greenhouses. All these options give a good rate of return on the investment in energy savings alone.
Heat grabbers or “passive solar warmers” can be homemade or could provide self-employment for anyone who takes the time to build them. They are hung outside a south-facing window, delivering warm air to the room, also removing cooler air.
The south-facing porch is an integral home greenhouse waiting to happen. While the vertical glass may strike you as being the wrong angle to collect solar energy, enough low-angle winter light penetrates to grow greens while heating the house. The roof overhang can be designed to let in winter sun and exclude summer sun.
You don’t have a south-facing porch? No problem. I’ve winterized a north-facing porch to create a buffer zone. The temperature in such a porch is intermediate between the house temperature and the outdoors. Because it is still warmer than outdoors, less heat flows from the wall of the living space. Such a buffer zone also intercepts wind, which otherwise strips heat away when blowing across an exterior wall.
The attached solar greenhouse, the most thorough home retrofit for solar heating, provides growing space for plants, food, and flowers. I have fond memories of drinking morning coffee in a friend’s attached greenhouse, snug and smug as I watch the morning sun glint and tickle the outside drifts, all enhanced by the aroma of Meyer lemon blossoms, a year-round phenomenon there. Attached solar greenhouses also represent one of a bundle of food security options that will be important when the main food producing areas of the country (and beyond) struggle to feed themselves, let alone feed regions such as New England, which presently imports most of its food. Large scale agriculture requires a consistent climate.
Much of Vermont has east-west flowing rivers. The north side of the river valley is a prime location for earth-sheltered homes with integrated greenhouses. Nestle homes just back from where the grade changes, with the north side cradled into the hillside. Soil shelters the north, east, and west sides. Unobstructed sun tracks across the sky, potentially providing almost all the heat needed in winter. The north wind cannot get at the building to twist its way through walls and strip heat away. Even a very tight, well-insulated building loses more heat when the wind streaks across its outer walls. If we Vermonters are smart, we will offer tax incentives for earth-sheltered, solar-heated buildings. As described, their placement minimally reduces forest cover, does not encroach on farmland, and promises multi-generational utility.
Thermal solar provides faster return on investment than the alternatives, is as durable as the quality of implementation, and does not put a strain on the electric grid. Implementing passive solar places no burden on an electric grid, which is not designed for the loads we will be placing on it.
Those in the building trades without special technical training can implement passive solar. It is decentralized and democratic. And it has no nasty byproducts. So why aren’t we remembering that we know how to do it?
We are flubbing the electric conversion by thoughtlessly pressing ahead without thinking things through. We know how to do better.
Dan Hemenway, a Montpelier resident, was a permaculture teacher, publisher, and designer from 1981 until his retirement circa 2010. He has international awards in conservation and community service and five advanced degrees from the International Permaculture Institute. He is also the father of The Bridge’s editor-in-chief.
The material presented here represents the opinion of the author and does not reflect the opinions of The Bridge. Commentaries may be submitted to editor@montpelierbridge.com. Preference is given to submissions by those who live in central Vermont. Submissions are encouraged to be 500 to 750 words in length.
