This solar house: Building with awareness

Filed under: Living on the Earth |

by Paul Shippee

This article is about super energy-efficient, conscious home building. As an example of this, it features a new 100% solar heated wood-frame house in the Baca by local strawbale builder Paul Koppana. First, I’d like to offer a brief background primer on cold climate home heating and review the evolution of builder consciousness as it applies to home heating.

Home heating

An “all-electric” home usually implies that home heating is done with electric resistance heating, like those baseboard units you see installed along exterior walls, or perhaps the boxy ETS (electric thermal storage) heaters, or even portable plug-in heaters. For decades, electric home heating has been touted as both “clean and efficient” by the manufacturers. But they conveniently leave out the fact that two-thirds of the energy in the coal or gas (fossil fuels) burned to produce the electricity in far-away power plants goes up the stack as waste heat—rejected into the environment along with carbon dioxide and other toxic elements—as necessary by-products of the fossil fuel combustion process, similar to your car engine.

More than two decades ago at a solar conference, held at what is now the Crestone Mountain Zen Center, I heard California architect Sim van der Ryn say, “heating a house with electricity is the thermodynamic equivalent of cutting butter with a chain saw.” Fossil fuels—coal, gas and oil—extracted from the ground are a finite supply of ancient solar energy; and these cheap fuels are surely limited going forward. This explains the growing popularity of the present “Leave It in the Ground” movement. John Nelson, local clay artist and professional masonry contractor, who attended my Crestone Solar School workshop last fall says, “We have to move our consciousness and economy away from this petro-based stuff to something that’s cleaner.”

A solar civilization

All life, everything we are and do, comes either from today’s sunshine or from ancient sunlight stored in the ground as fossil fuels. I made up a simple slogan to help guide the big-picture shift in awareness. It says, “Use Today’s Sun Today!” This slogan applies to solar electricity, as well as to solar home heating, with technologies and knowledge that are already well developed. There is also solar technology for cooling homes in hot climes.

There are two temporary barriers. One is political, where old fossil fuel interests resist popular solar initiatives; the other is financing the front-end cost of solar. However you look at it, it comes down to widening our consciousness to realize what local homesteader, organic gardener, biofuels enthusiast and musician Nick Chambers said: “We are indeed a solar civilization.”

A conscious home-builder

“What is a conscious home-builder?” It might be someone who is both practical and educated in the big picture of ecology, someone who sees how everything is interrelated and interdependent in every detail of the home building process, while at the same time being smart about project costs. Ecology, by the way, means “earth household” and it applies to our home the Earth as well as to our own house.

For starters . . . a conscious home-builder these days would not use electricity to heat a home or to heat domestic hot water, even if low off-peak rates are offered. Yet local builder Paul Koppana, whom I interviewed for this article, as one local example of a conscious home-builder, markets his new home as “all-electric.” What’s going on here? I was interested to find out.

The first thing I learned in talking with Koppana is that, in fact, this is an “all-solar” home. This means the largest energy use in the home, which is for space heating and domestic hot water, is supplied virtually 100% by solar energy. Virtually because there is an option to use electrical back-up when needed on cloudy days for domestic hot water. Another option, the wood-burning stove for space heating back-up, uses wood that took only a few decades to grow (ie, renewable, not a fossil fuel). It’s also worth noting that there is no large propane tank sitting in the yard of this house soaking up dollars continuously year after year.

Another thing I learned is that Koppana, a well-known Crestone strawbale builder, switched to wood-frame construction for this house as an experiment that includes various economic factors.

Since this new house was unoccupied all last winter, Koppana told me he took the opportunity to monitor the electrical energy usage in the absence of any use of electrical appliances such as the electric cook stove, refrigerator, washing machine, lighting, TV and computer devices.

The result was an average of 140 kilowatt-hours per month or $18/month (it does not include the fixed normal wires & maintenance surcharge.) Note that this average electrical cost to keep the vacant house warm at 70° all winter was not for heating but only to power the active solar pumps that send-solar heated water to the radiant floor and the hot water tank, and for the small fan that runs the heat recovery ventilator (HRV). The house was 100% heated all winter by the sun.

Four conscious building systems

The result of heating this house and hot water for an average of $18/month over the winter is, according to Koppana, due to the conscious deployment of four building “systems” that mutually reinforce each other. These four conscious building systems are smart energy conservation measures, large passive solar windows on the south side, active solar thermal collectors on the roof, and a heat recovery ventilator (HRV) system.

Out of these four building systems the best bang for the buck, by far, is the energy conservation measures. Some of these incur extra building expenses, but the conscious builder and the environmentally conscious home-buyer will view these extra costs as an investment, not an expense. It is a one-time investment today that returns future dollars saved by avoiding ongoing expenses for burning fossil fuels, either electricity or gas. This makes good investment sense by comparing today’s energy conservation costs to future savings in conventional fuel costs. In other words, you get your money back.

Some details

The energy conservation features in this house are numerous: smaller, triple-glass, low emissivity windows on the east, west and north; large plain, clear double-glass south-facing windows; an ideal aspect ratio where the south wall is about twice the length of the east and west walls; advanced wood framing methods on 2×6 walls that save trees; extra wall insulation (cellulose plus 1.5” foam board on the outside R30); extra ceiling insulation (blown-in cellulose R55); 2”-3” of foam insulation under the 5” concrete slab. And lastly, the 1508 sq ft size of this house is modest, neither large nor small, with an accommodating floor plan that makes it seem larger, and thus is easy to heat in cold winters.

Energy conservation features save home heat. They cost a little more at the front end and then deliver cash dividends long into the future. The consciousness at play here is known as a life-cycle costing, a practical and smart economic viewpoint that considers the fuel savings of the home over its lifetime compared to front-end costs. While energy conservation saves home heat, and solar (both thermal and electric) can provide free energy, these improvements may be financed through eliminating your utility bill.

The second and third building systems on this 100% solar-heated house integrate well with the energy conservation features. These are the passive and active solar heating systems. The passive solar system is large south-facing windows that deliver warm direct sunshine to the interior of the home during the daytime. The planter box you see along the large south windows acts as a thermal mass storage battery absorbing solar heat, storing it for nighttime release thus balancing temperature swings. It also provides warmth to encourage plant growth.

The active solar system, consisting of the five 4’x8’ solar thermal collectors you see mounted on the roof, delivers heat via solar hot water piped deep into the radiant concrete floor all day long. This free solar heat rises up through the slab, reaching the top surface sometime after sundown when it begins to radiate and release warmth into the home during the nighttime. Note that the radiant floor heat distribution is free because you already need a floor. Because the floor area is large, the heat distribution temperatures can be much lower than conventional baseboard heaters. Low temperatures allow the solar thermal collectors to operate more efficiently because they lose less heat through their glass covers.

In this way the day and the night heating requirements are met rather naturally by combining passive and active solar heating systems. These solar heating systems are kept small and less costly by the small house footprint and the variety of optimized energy conservation features outlined above.

The fourth energy system is the HRV heat recovery ventilator. This system consists of ducts and a silent fan that runs about twenty minutes each hour. It exchanges stuffy, polluted indoor warm air for incoming fresh air while capturing the heat from the outgoing air. Indoor air pollution is an energy-conservation liability resulting from building very tight homes in an attempt to reduce heat-robbing air infiltration. This system greatly reduces cold air infiltration, a large heat loss factor in conventional homes, to nearly zero.

You can view this solar home on the Crestone Energy Tour in August.

Paul Koppana would like to thank the following folks for their help in building this home: Touson Saryon of Integral Design Studio, design; Michael Wasserman of Greenstone Energy, solar; Steve Dossenback of Craig Electric, electric; Vincent Lopez of Lopez Plumbing, plumbing. 

 
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