To avoid catastrophic climate change, experts say developed nations must reduce their greenhouse gas emissions by at least 80 percent by mid-century. Getting there will take major improvements in energy efficiency, particularly in energy-intensive buildings.
While 80 percent might sound like a tall order, good design principles and conservation techniques can already get a building close enough to carbon neutral for technology to finish the job, says architect Lawrence Maxwell, president of Spacecoast Architects of Indialantic, Fla.
Step one in sustainability, he says, is to reduce energy load.
The Odyssey Charter School, Maxwell's prototype for a sustainable school design, comes close to meeting that 80 percent cut. It needs less than 30 percent of the energy required by a typical school.
The school demonstrates how to program high-energy performance into a building's DNA using principles of building orientation, natural lighting, natural ventilation, advanced thermal envelope design, active and passive thermal storage, and demand management.
"Energy performance was achieved with natural, simplistic means using everything we know about how things work [energy-wise]," Maxwell says.
This aesthetically attractive, 47,000-square-foot school also cost half as much to build as a conventional school, $70 per square foot compared to $150 per square foot, without sacrificing comfort or facilities.
The first Odyssey school, built in 2005 in Palm Bay, Fla., easily qualified for the EPA's new Designed to Earn the Energy Star rating, earning 95 out of 100 points. Commercial buildings must earn at least 70 points to qualify.
The program was designed to provide architects with the tools to design buildings that meet ENERGY STAR performance standards, says Karen Butler, the EPA's manager of Commercial Building Design for Energy Star. Using the online Target Finder tool, a free service of the EPA, designers can enter data and evaluate the level of energy performance the design will achieve when it is built.
The tool allows architects to compare design alternatives to enhance energy efficiency. It also lets them select target designs to meet American Institute of Architects' Sustainable Practice and its 2030 Commitment goals, which aim for 100 percent carbon-neutral design within 20 years. Right now, buildings are responsible for about 40 percent of U.S. energy consumption. The tool provides a pathway for mapping carbon reduction along with energy performance, Butler says.
Designing for Natural Light
At the Odyssey school, energy efficiency began outside with proper site orientation; a thermally efficient building envelope with exterior insulation and finishing system on tilt-up concrete; use of light-colored, reflective metal roofing; and maximum levels of roof insulation.
A north-facing clerestory of 12-inch windows along the classroom roofline and row of four-foot-high windows at eye level capture indirect light without the heat, minimizing the air-conditioning load.
Sloped ceilings in the 26 classrooms increase daylight from the north and south and help balance the light distribution. Beginning at nine feet, the ceiling slopes up to 11 feet, then at the room's midpoint shoots straight up 14 feet to the clerestory of windows, creating a skylight effect.
A light-colored roof also shades the windows while reflecting indirect, natural light into classrooms, minimizing heat gain.
"Bouncing light off the roof deck strips heat out of long-wave radiation, creating a reverse greenhouse effect," explains Maxwell. "This way you bring in the visible light spectrum, but the heat doesn't pass through the window."
Inside, mirrored "light shelves" bounce light onto the ceiling, scattering and intensifying illumination throughout the room and eliminating glare on tabletops and computer screens.
The sloped ceiling also improves sound acoustics because classroom floors and ceilings are not parallel surfaces. Maxwell explains that varied surfaces give spaces tone and resonance, yet allow absorption of sounds so rooms are neither dead nor overly lively and reverberant.
There was no initial budget for photovoltaic solar panels, but the building is designed so energy technology could be easily added.
Creative Heating & Cooling to Cut Electric Bills
The school's heating, ventilation and air conditioning design was the one thing Maxwell refused to modify, because it is essential to holding down energy costs.
The high-ticket item was a digital, fully computerized energy management system that controls all mechanical and electrical systems, offers individual temperature control in classrooms, and allows staff to monitor systems remotely from a computer terminal. Outside air units dehumidify and cool outside air down to 50 degrees before it enters the air-handling units, which have 90 percent filters to provide the school with hospital-quality air. Variable speed controllers match and maintain ventilation requirements based on actual building occupancy load.
Odyssey school also has a chilled-water cooling system with thermal storage that produces ice at night during low electrical peak times and then uses the ice to cool the building during the day, when power demand is at its highest and most expensive.
The cooling system saves an estimated $2,000 to $2,500 per month in electricity costs, because power is purchased at night when off-peak are in effect, Maxwell notes.
The design also called for minimal impact to the site itself, placing the school on area already disrupted by a pile of soil left from digging a drainage canal. A 100-foot strip of existing vegetation was preserved around the school, and indigenous plants were used to landscape, he says, noting this provides a natural view and outdoor classroom to teach students about native plants and their habitats.
Odyssey Schools of the Future
A second Odyssey charter school proposed for Melbourne, Fla., will be a little larger and add clean-energy technology and an energy-efficient light-control system. With the building design already reducing the energy load more than 70 percent, Maxwell notes that it will be easy to get to carbon neutral and beyond, potentially even adding energy back to the grid.
He plans to use thin-film solar, which comes in 15-foot rolls, attached to the metal roof. While this product does not produce as much electricity as photovoltaic panels when the sun is shining, it continues to produce energy with varying degrees of cloud cover. It also costs less to install, has a 20-year warranty, does not require roof penetration or changes in roof design, and holds up well in hurricanes.
"The truly exciting thing about good, sustainable design is that it strives to find the best the earth has to offer to elevate the human experience," Maxwell says.
"It's not just about saving energy but more about preserving what is beautiful in this world, not taking more than you need, and designing spaces and experiences that elevate the spirit."