This Endless Pool is Powered by Nature
Not many labs have a pool, fewer still include a sauna, and it's safe to say none include Anna Edey's mix of pool, sauna, and chickens. Anna's innovative, green- designed building at Solviva, her farm in West Tisbury, looks like a nicely finished, twenty-four-by-eighteen-foot cottage nestled amid the greenery not far from her main house. It faces south, and was built from the bottom up to embody her environmental ways. Because this pleasant little building is actually a lab to monitor its own design elements, all of its systems are being measured and notated for their energy generation and usage, including the chickens. To Anna, "a pound of chicken" has a different meaning than it does at Cronig's Market, as we shall see.
Anna Edey has been working on sustainability issues at Solviva for more than thirty years, and wrote a book documenting her findings, called Solviva, published by Trailblazer Press in 1998. This new building is the latest manifestation of her "solar dynamic, bio-benign" quest – a sort of model home that is, in Anna's terms, solar-powered and good for life.
In a lilting voice showing traces of her Swedish heritage, Anna says the motivation for building the lab was to answer this question, "Could I have a structure, in this climate, that has a zero-carbon footprint – all solar powered with wood back-up?" (But doesn't burning wood contribute to carbon emissions, you ask? Anna says it is carbon neutral, because wood releases that same amount of carbon whether it decays naturally or is burned.)
On the lab's ground floor, filling much of the main interior space, is a large, insulated wooden chest containing a solar-heated, seven-by-fourteen-foot and four-feet-deep Endless Pool – designed for swimming in place against an artificial current. A small upstairs room is the sauna, and the chickens' room is on the ground floor.
Both pool and sauna tie into the solar-heating system, and it seems to be working just fine. The interior temperature of the building in winter is in the seventies during sunny weather. Anna's record book, which she's kept since February 15, 2008, notates the building's temperature history. It shows that even under the most extreme weather conditions – which were on the night of March 3 when it was 17 degrees outside – the interior temperature never went below 55 degrees. At that point Anna could decide to put on another layer or light the small wood stove.
The primary solar component of the heating system is the south-facing, sun-absorbing, black, tin roof, which warms the air moving under it. There is an enclosed air-channeling system below the solar roofing, and inside the channel at the roof's peak, the hot air begins its descent down ducts in the sides of the house to a heat sink under the floor comprised of a two-foot-deep layer of small stones covered by an eight-inch concrete slab. With much of the heat deposited in the heat sink, the now-cooler air begins its travel up the south side of the building, cooling some more as it moves up the exterior wall and back to the hot roof again. Solar-powered fans keep the air moving in a circular flow around the envelope of the building. The hot air, having been sucked down in a continuous doughnut-shaped path enveloping the lab, warms the center of the doughnut – the interior space – mostly by the radiant heat emanating from the floor and the under-floor heat sink.
What is known from the monitoring of the system is that the rise in temperature of the flowing air can be significant in the two to three seconds it travels under the fourteen feet of south, sun-facing roof. The most extreme example was on the day the solar roofing was installed. That sunny, winter day, the air temperature at the bottom of the duct was 45 degrees coming up from the stone heat-sink layer, and 120 degrees after passing under the solar roof.
The two fans that move the air around the envelope of the building are powered by one twenty-by-thirty-five-inch photovoltaic (PV) solar cell, and they begin to operate only when the sun shines. If the sun is only halfway out, the fans turn at half speed, which is fine, because the roof, as the heat collector, is only producing half the heat. When it's completely overcast, Anna uses the wood stove. During the warmer months, the fans can be unplugged and vents at the roof's peak can open for air-cooling of the lab.
Anna has formulated a way to incorporate chickens into the design of the lab to supplement the heating. "I wanted to find out if people and chickens could really live together," she says. This question, one that few are asking, is an insight into Anna's investigative methods. It harkens back to the early times when humans and domesticated animals routinely sheltered together and hygiene was an unknown word. Anna is proving that this symbiosis is useful and healthful for both parties.
The first greenhouse of Anna's at Solviva, built in 1983, gave the clue. She remembers the first winter as being particularly cold and on days that were around zero degrees Fahrenheit the plant areas of the greenhouse were about 45 degrees – well above freezing – but the separately enclosed area of the greenhouse where rabbits were housed was 55 degrees, and the chicken area was 72 degrees.
Body heat is a free byproduct of the egg- and meat-producing chicken that has been ignored in the modern era. But back in the three-dog-night days, animal heat could be crucial for winter survival. In fact, Anna says the chicken heat is 8 BTUs per pound of chicken per hour – a new way of thinking of a pound of chicken. Today, Anna's twenty-four chickens can be a substantial source of heat, creating the equivalent heat of about a barrel and a half of oil during the six continuous heating months. That heat is free if you consider that the chickens pay for their upkeep by the eggs, meat, and compost they produce.
The chicken area is behind an interior wall of the lab, which has a see-through panel, and is enclosed by the north-facing outer wall. In the cold of winter, the chicken heat will keep the interior wall at 60 degrees. There is also a wire-fenced enclosure outside where they can exercise their scratching and pecking needs.
In their domain, the absence of olfactory evidence of the bustling chickens going about their business is striking. The lack of chicken scent is one of the keys to living this closely with fowl. Anna's smell-free chicken coop is the result of her studies of the earth under our feet. A rye grass planter inside the lab produces grass to feed the chickens in winter and is also an "earthlung filter." The soil mix in the planter absorbs air that is blown in from the coop by a solar-powered fan and contains both beneficial carbon dioxide and any traces of harmful ammonia from chicken droppings. This process feeds the ryegrass, while removing the chicken odors. The amazing ability of microbial life in topsoil to transform organic matter is why Anna also employs it on the coop's floor to handle the chicken droppings; she sprinkles a combination of about one-third topsoil and two-thirds leaf mold where needed to further eliminate odors. The lab's composting toilet uses some of these same bio-benign principles to deodorize, digest, and transform the waste matter into useful compost.
The pool, as you might expect, is heated by solar, and again that hot, black, tin roof is the source. For this purpose, there are copper pipes that cycle water pumped from the pool to zig-zag through the air-channels under the roof, absorb the heat, and send it back to the pool. That same pump also sends the water through a mineral filter, using natural germicides to kill bacteria, for the most part eliminating the need for chlorine. (There is a trace amount, only about 5 percent of what the pool would otherwise require, which Anna says could only be detected in a lab test and not by smell.)
Anna likes the pool temperature to be in the range of 81 to 84 degrees, which is no problem for the solar-heating system. With a wall-mounted hand-winch, Anna is able to open the hinged, heavily insulated pool cover for swimming, and then close it to retain the pool's heat. (She says it also helps keep the humidity in the room at a healthy level, averaging about 50 percent.) When closed, the pool loses only one degree per twenty-four hours. A second pump creates a current to swim against. Twenty PV solar panels mounted along the ridge of the roof power the electrical needs of the pumps and lights, and send excess power into the NSTAR grid. Anna says, "I love to use the pool all year, but especially thrilling under the coldest winter conditions, alone or with family and friends, swimming or walking against the current, doing aqua aerobics, and floating."
As to the sauna, Anna says, "The wood stove stove-pipe, surrounded by a copper coil for back-up pool heating, goes right through that little, very insulated room, which gets very hot with just a couple of minutes of wood fire. It also gets plenty warm when you open the small door of the large duct that leads the 105- to 120-degree solar-heated air down to the stone heat sink." So, in daytime, the sauna can be solar heated, and at night it uses the wood stove. Along with the sauna and pool, Anna has five different pieces of gym equipment in the lab, so there is plenty to do besides notating twice-daily temperature readings from ten different thermometers.
Looking toward this coming winter, the experiment continues. Anna says, "Now that the heat sink has had a chance to warm up to about 85 degrees over the summer, I expect that the interior temp of the house may never fall below, say, 64 degrees, while the top temp of the air going through the solar roof may exceed 130."
Anna sees the lab's heating system as a marriage between sun and home. With the sun merely rising and setting, turning it on and off, it is a self-regulating system, with no batteries, no controls. In this era, when solar is being touted as one solution to our energy problems, Anna Edey and Solviva are innovating simple and efficient methods to make that solution a pleasant one – with no carbon footprint (and with chickens, if you like).