Solar System: As we burn toward full energy dependence, a case for something simpler: the sun
Winter in Louisville. Ugh. The season too often means living on the crust of a cloud cream pie, below a layer of cumulus piled on stratus, topped off with whipped cirrus. We grasp at the meager gruel of sunlight that makes it through, embracing it like a stale Twinkie because it’s better than nothing. And yet, even in Louisville, capturing and using solar energy is not just possible, it’s quite doable.
Consider that the sheer numbers quantifying the energy output of the sun are staggering — incomprehensible to most who are not solar or stellar physicists. This energy is radiated constantly and in all directions. The total radiation our little planet intercepts is a minute fraction of that total output. By utilizing a tiny fraction of that minute fraction, significant beneficial changes to the structure of energy production and distribution could be realized.
Solar energy will not meet all energy needs in Louisville, or anywhere else with modern living. It can heat spaces and water in its initial form, and produce electricity in a more complex form. But an all-electric world is a distant horizon. Flight, ocean transport and internal-combustion land conveyance will continue to use chemical fuels in a liquid state, including from biological sources, for at least another half century.
Still, solar radiation remains a virtually untapped source of energy that could significantly improve conditions on planet earth, as well as of planet earth. Solar power is unique among energy sources, in that it doesn’t need to be mined, drilled or chopped. We don’t need to reach into the deepest atomic realm to get it. It is being delivered to our doorstep, to half our planet at any given moment. The overall question isn’t just can this be done, but shouldn’t it?
Here’s the deal.
Heat, which can be most simply defined as the movement of atoms or molecules (the more movement, the more heat), travels in three ways. Conduction happens when the top of a cold metal spoon becomes hot after sitting in a cup of tea. It happens when your oven door is opened and all that 450-degree air rolls out. Radiation is electromagnetic waves. The solar energy that strikes our planet is radiated heat.
The sun is not like a gargantuan oven with its door open, sending heat by convection 93 million miles through the vacuum of space. No.
The sun does send radiation 93 million miles to earth, and hundreds of millions of miles beyond. When you feel the heat of the sun, the actual heat you feel is happening on your skin, and to a lesser extent in the air around you. Your skin is intercepting the radiation, which is stimulating your skin molecules, producing heat immediately. By stepping into shade, much of the heat you feel subsides. This wouldn’t happen with conduction or convection.
Solar energy, then, is radiated energy that becomes heat when an object intercepts it. On a summer afternoon, a black garden hose sitting in the sun intercepts and absorbs solar radiation, heating the water inside, often to temperatures hotter than should be touched. That is solar energy, pure and simple. On a cold and cloudless winter afternoon, you trudge through rutted snow and ice to your car, where it has sat for the last eight hours. Inside, the car is warm and toasty. That is also solar energy, pure and simple. At any given moment, 50 percent of the earth’s surface is receiving solar radiation. Even on the cloudiest day we are being irradiated by the sun.
Here’s the further deal.
There are two types of solar energy: passive and active, also known as unconverted and converted, or low-quality and high-quality. Passive, unconverted solar energy is the use of solar radiation directly. The practical application of unconverted solar is to heat air and water, such as the air in your home in winter and the water used for washing. Unconverted solar cannot power our modern life. It cannot run your plasma set, recharge your cell phone or even light a bulb. All these devices need active (or converted, or high-quality) solar energy, as electricity, to work. Any technology needing electricity or fossil fuels, or for that matter biofuels, cannot use unconverted solar energy.
Does unconverted solar energy have any use, then?
Yes. It can heat spaces and water directly (the interior of a car and the water in the hose), and in the U.S., 45 percent of all residential energy consumption is used for heating purposes.
Can a home in Louisville be heated exclusively with passive solar? In January?
Yes, technically, but let’s get away from words like exclusively, totally and completely, which often translate into expensive, and that means inaccessible. The more usable question is, can a home in Louisville be heated significantly, meaning about 50 percent, with passive solar in January? The answer to that question is a simple, straightforward yes.
Just ask Gary Watrous.
Watrous grew up outside Ithaca, N.Y., in a unique, self-built community that was a delight for children, a literal kindergarten. His father, a graphic designer for General Electric, was an amateur architect who designed and built the family’s home — the same was true of most of their neighbors. This area of upstate New York is near Lake Ontario, on an unbroken plain with nothing to stop the weather coming off the water. Wind, bitter cold and snow measured by the foot defined their winters. That weather, and the memory of nearly getting lost in a blizzard with whiteout conditions, defined Watrous at an early age.
He defines himself as an environmentalist first, having chosen architecture as the medium in which to propagate his environmentalism.
“The architecture is my way of being an environmentalist,” Watrous says, “and also of showing people the way out. People can get easily discouraged trying to be environmentally accountable. But if they can see they can make an individual difference, that’s encouraging.”
He holds a master’s degree in architecture from Yale, and taught at the University of Kentucky School of Architecture. He started his Louisville firm, Watrous Associates, in 1985. The firm won an award recently from the National Renewable Energy Laboratories for the design of the St. Benedict Center for Early Childhood Education in West Louisville.
The simplicity of his designs, especially residential, accentuates his perception and definition of passive, which, unlike others in the solar business touting passive design, is almost literal. Many of his homes look completely traditional, although the interested observer will notice a long house, with the length oriented on the east-west axis. The north wall will have minimal window square footage, whereas the south wall will be nearly all windows. The living areas will be along the south wall, with the bedrooms and utility areas along the north.
Because the entire house is a collector and retainer of solar energy, don’t look for separate rooftop collectors. Do look for intakes at the highest interior points, which pull in risen heated air and, in his larger homes, circulate it down to a system of connected air domes under the concrete subfloor called an Air Floor, a patented system (airfloor.com). This method heats the concrete floor, which also retains heat during the day, to be released at night, when the solar gain is zero. Smaller homes designed by Watrous forgo the Air Floor system, but still utilize a ceramic and concrete floor as a heat sink.
The passive part of Watrous’ designs is completely so, but the overall system is an integration of passive solar with a traditional forced-air heating system. Is it off the grid, solar purists (with plenty of money) might ask? No. But here’s the deal: His houses don’t look funky, which can be a real issue. “I’ve made it a point,” he says, “to design the homes so that any carpenter can do it, because we bid them out. Most contractors have no experience at all with solar.”
They cost no more per square foot than any other high-end home. They don’t use photovoltaics (the manufacture of which isn’t exactly green) or banks of batteries (ditto for manufacturing, and also requiring energy to be recycled). His designs don’t need hydrogen vents (to prevent explosions), or power inverters, or expensive DC appliances. They do use a forced-air heating system on the coldest nights and the cloudiest days, and they do use the blower alone to circulate air through the Air Floor when solar gain is high. They also collect solar gain even on the cloudiest days, whereas an active system of photovoltaics is producing little-to-no usable electricity on cloudy days, depending on the amount of cover.
Americans tend to have a shirts and skins mentality about many issues, including technology. We wait for the next big thing instead of doing what we can today. Watrous’ designs can be put in place now. The real beauty of passive solar is that just using it, in one way or another, is more important than what those ways are. Efficiency doesn’t matter all that much because the area the passive collector occupies will be irradiated whether the collector is there or not, and so you really can’t waste passive solar energy. Let’s say you rig a passive collector that heats just two rooms, or that reduces your high-quality energy consumption by 20 percent, or even just 10 percent. Are you off the grid? No. But you’ve reduced your impact.
Another architect in town is pursuing additional green facets. Mark Isaacs is developing Legacy Lofts condominiums at Campbell and Main streets, immediately east of downtown. By using a combination of building techniques and geothermal heat exchanging, Isaacs will soon have constructed a building giving an astonishingly low LG&E bill for each unit (projections are around $8 a month). As Isaacs stresses, the building’s true net energy use won’t be known until the units fill and the actual lifestyles and habits of the residents emerge. But even numbers that fall short of Isaacs’ projections will still be a bona fide energy bargain. (Consider the $1,500 or so I spend per year on electricity to light, heat and cool my small home. In the best scenario, a Legacy Lofts resident will be paying one-tenth what I do.)
As Isaacs’ description of his core construction technique suggests, solar has become a casual synonym for efficient and green. “There are three basic parts to the Kool-Aid,” he says. First is simply the built-in efficiency of multi-family housing with shared walls and floors. That alone reduces energy consumption by 50 percent, regardless of the energy source. Second is super insulation. Legacy Lofts uses double-studded exterior walls, allowing for a thickness of insulation. Third is geothermal heating and cooling, a process that utilizes the stable temperatures within the earth to gain heat in winter and shed it in summer. The equipment for the process is expensive, but the inherent efficiency of the multifamily building makes it doable for Isaacs.
But so far, nothing about Isaacs’ approach uses actual solar energy. That will come with solar hot water heaters and awnings to keep out the summer sun that also happen to be photovoltaic panels. In addition, more than half the units will have a south-facing orientation. Clearly, the green approach is an amalgam of the thoughtful application of many ideas.
Isaacs is like Watrous. Both men started on their paths as boys, to the extent that what they do today seems like a calling. Isaacs went to the Massachusetts Institute of Technology intent on developing an operating manual for spaceship earth. Yes. It was the early ’70s (i.e., still the ’60s) and that’s what kids could and did do back then. He received both his undergraduate and graduate degrees in architecture from M.I.T. His concern for human life, all other life and the planet itself was a constant undercurrent in our recent phone interview.
However, green developers aren’t always just born. Filmmaker Gill Holland and his wife Augusta are developing a building at 732 E. Main St., due to open in September. It’s called The Green Building of NuLu. Yep, and it’s a mixed-use rehab of a former dry-goods store. As a commercial building, it’s on track to be the first in Louisville to receive the LEED (Leadership in Energy and Environmental Design) platinum certification for sustainable buildings.
As I mentioned in the introduction, and as Legacy Lofts and the NuLu Building indicate, passive solar is just part of the overall solar equation, which itself is part of the green equation. The economies of the 21st century will be defined not by oil and fossil fuels in general, but by electricity (and, while we’re at it, water). Human numbers are headed up quickly, even in the best scenario, and more and more of those numbers will denote people living a modern, consuming lifestyle. Even assuming the emergence of more efficient technologies, and cultures evolving in which conservation is second nature, electricity use will increase at least geometrically.
A solar economy — and really, a solar and green culture — will require both passive and active systems. Active systems include the direct production of DC current using photovoltaic cells, and of concentrating sunlight using parabolic mirror troughs to heat water into steam to drive traditional steam turbine generating plants. Photovoltaics will be both site-based and centralized. Site-based units will allow higher-density housing and rehabbed housing, which often don’t have the design and orientation to use passive solar, to still use solar in general. Centralized photovoltaics will utilize solar farms of photovoltaic cells, collectors by the square mile in the American Southwest. This electricity will be purchased by homes and business owners the same way coal-, oil-, natural gas- or nuclear-generated electricity is today.
Much, perhaps most, of active solar will be centralized, especially considering weather, and active solar will be the focus of the industrialization and commodification of solar energy. Why? That’s where the money is. Because passive is inherently site-influenced, and because the house itself is the collector, there are few if any passive products that can end up on the shelves of Lowe’s or Home Depot.
Still, many like Gary Watrous consider passive to be the first consideration. His designs use no special products other than the Air Floor, which is about as high-tech as a stovepipe. And that’s why we’re hearing less about passive solar — there is little manufacturing and retailing profit in it, although there definitely is profit in passive building design. We’ll know when we’re on the right track when we hear more about passive solar. As Watrous said of fossil fuels: “One hundred years from now people will look back on us and wonder ‘They really burned that stuff?’”