The first time I remember hearing about green building was in the early-'70s, when a perfect blend of hippie culture and rising oil costs resulted in, among other things, houses called "earth ships" that incorporated wall systems made from old tires filled with dirt. But also, through some hits and mostly misses, that period also led to a greater understanding of energy efficiency, moisture control, and comfort, and many of today's lasting improvements can be directly tied to those early "experiments."
But due to some really bad "solar" homes, lots of failures, and dropping oil prices, the era passed–leaving behind the basis for what today we call green building that, until recently, existed only as a small niche for progressive builders.
Builders who remember the early years and who had to deal with those failures can be hard to convince of the value of green building. "Builders are a conservative bunch," says Santa Fe, N.M., builder Dave Crosby. "We can't afford failure. If something works, we use it over and over. If it fails, we never try it again."
The world has changed in 30 years, however. We understand so much more about how building systems work and are getting building science dialed-in. And that knowledge, coupled with proven new products, good design, and simple attention to detail, allows us now to build better homes that use fewer resources, are more comfortable, last longer, make our customers happy, and make us more money.
If you're just getting into sustainable building, whether by choice or by necessity, here's a look at green building basics and the latest thinking about this important trend to help you better understand how to improve the performance of your homes and systems and get yourself moving into a continually greening construction market.
Education
Elk's Cool Color asphalt shingles have highly reflective granules to reduce heat buildup.
"A reasonable understanding of building science is the most important attribute of a green builder," says Alex Wilson, editor of Environmental Building News.
Indeed, education is a point raised by several experts. "Educating your clients about green building and why, for example, the house you build will be more comfortable and cost less to heat and cool, shows that you care about building," says HUD engineer Dana Bres, who works within the agency's Partnership for Advancing Technology in Housing (PATH). "They're going to wonder what else you're doing right." Bres points out that taking the time to learn about green building and sustainable design can pay subtle but real dividends.
"A builder must educate himself about appropriate technology," says Tucson, Ariz., green builder John Wesley Miller, who helps sell his homes by guaranteeing that energy costs won't exceed a set amount. He also cautions builders about focusing on just one aspect of green building, saying, "... a builder needs to get his arms around the big picture. Energy efficiency is important, but so is recycling and minimizing waste."
To start the learning process, here, in rough order of importance, are seven key green building points as suggested by experts interviewed for this story.
1– Design
"The single most important green design decision is size," says Wilson. Smaller houses automatically consume fewer resources both during construction and after occupation. "Houses should be sized to work for you every day," says Sarah Susanka, architect and author of The Not So Big House. Susanka further suggests that we stick to basic shapes. "Simpler forms lose less energy because the ratio of exterior surface area to volume is smaller. Every projection from a house is like a cooling fin."
Another well-known architect, Peter Pfeiffer of Barley & Pfeiffer Architects in Austin, Texas, applies a Southern take on design. "In cooling climates, solar orientation is the most important design element," he says, citing a study by the City of Austin's Energy Star program that showed cooling loads could be cut in half by orienting the long walls of houses east-west, shading south-facing windows, and avoiding expanses of glass on west-facing walls that get the full brunt of the flat afternoon sun.
Even for subdivision lots where the street dictates layout, Pfeiffer says there are still steps you can take. "You can reverse plans to place the garage on the west side of a house. Porches and broad roof overhangs can shade south- and west-facing windows. In cooling-load–dominated climates, a shaded single-pane window will outperform a double-pane, low-E unshaded window. Plant, or don't cut down in the first place, trees that shade the west side of a house."
2– Durability
If a house has to be bulldozed in 10 years, it was never green. Durable houses don't clog landfills and don't require the energy and resources used in tear-down and replacement.
What's the key to durability? "Water is probably public enemy one, two, three, and four," says EBN's Wilson. "Uncontrolled water rots homes, peels paint, and causes mold."
Moisture control is a huge focus of building science–inspired components like generous overhangs, proper window and door flashings, and rain-screen walls that allow siding to dry, improve paint durability, and avoid water wicking. In a tightly built house, as houses should be, mistakes that funnel outside water in just aren't acceptable. The one disadvantage of a tight house is that its walls, roof, and ceilings don't dry out quickly if they get wet. Normal construction details assume greater importance.
Understanding the demands of your climate is crucial. For example, controlling air and moisture leakage from inside to out not only saves energy, but also can prevent damaging condensation from forming in framing cavities. While there is great debate over the worth and placement of vapor barriers in mixed climates, their use in cold climates is accepted as an important moisture-control element.
Attention to detail–and construction techniques–is another key, and pointed to as a source for many of the moisture-related defects causing so many problems for builders. For example, the common method of simply slashing housewrap in an X at window openings and folding it into the rough openings is outdated and does nothing to keep water from leaking in. These days you have to follow a careful step-by-step flashing, sealing, and installation sequence to ensure proper performance over the life of the building.
Other details frequently skipped can be as basic as omitting housewrap or builder's felt as a secondary weather barrier. I've seen housewrap installed backward (top to bottom). Water that got behind the siding was directed right to the sheathing.
3– Energy Efficiency
Insulation is a job that's often awarded to the lowest-bidding contractor. From a green perspective, this can be a real mistake. And air sealing–filling the holes where inside air can leak out or outside air can leak in–is at least as important as insulation, because no insulation can achieve its potential if air can leak through it. "Air infiltration must be kept as low as possible," says Connecticut architect Lindsay Suter. "Air sealing takes discipline and supervision."
Lots of builders think that air sealing means going around the house after the mechanical trades are finished and filling around where wires, pipes, and ducts pass through walls and top plates with spray foam. This step is important, and foam guns are available to greatly ease this task, but it's also vital to eliminate big areas that allow inside air access to the thermal envelope. Examples include areas behind bathtubs, showers, and kitchen soffits. These areas should be closed off from the wall behind them with some sort of air barrier–drywall, plywood, ThermoPly, or other type. Recessed ceiling lights are another source of leakage, but new models are available that are air sealed to help control infiltration.
While you're thinking about HVAC equipment, don't neglect the ducts. Bill Asdal, a New Jersey contractor who was NAHB's Remodeler of Year in 2000, advocates both duct sealing with mastic and proper layout. For example, "Don't run any ducts in unconditioned spaces," Asdal says.
Pfeiffer claims that "normal air conditioning duct leakage is 20 percent."
If those ducts are in unconditioned spaces, $20 of every $100 paid for air conditioning is wasted. The importance of properly sealing ducts is easy to see in that light.
If you do an outstanding job of air sealing and insulation, you might qualify for rebates through your state's Energy Star program. You'll probably need a blower door test done to measure the home's tightness and a duct blaster test to measure duct leakage. Those costs might be worthwhile even without state rebates. A blower door test tells you if the house requires mechanical ventilation and dedicated combustion air. And, knowing exactly how tight a house is allows an HVAC contractor to properly size the equipment, which will not only help it perform better but is also often less expensive than larger systems specified without true performance criteria.
As Asdal points out, "It's the builder's responsibility to educate trades, spell out expectations, and follow through. Even though the subcontractor might understand your requirements, it's often his lowest-paid employee doing the work."
Pfeiffer is a fan of fluorescent lighting. Not only do you get more light for your energy buck from fluorescent (compared to incandescent or halogen), they also produce less heat than incandescents and halogens and can save significantly on cooling loads. So much so, in fact, that Pfeiffer includes replacing incandescent and halogen lights with fluorescents as one of the top five approaches to reducing cooling loads. Fluorescent lights don't necessarily give off a sickly green light anymore, either. Commonly available lamps with a color temperature of 2,600 to 2,800 kelvin give off light that's nearly indistinguishable from a cool white incandescent bulb.
Supplying Energy Star–rated appliances is another simple way to cut down energy use. Similar Energy Star–rated appliances can vary in actual consumption, so go one step further and compare annual energy use printed on each appliance's label, Wilson suggests.
4– Waste Reduction
Insulating concrete forms like Nudura allow for air-tight, energy-efficient walls for reduced heating and cooling loads.
If ever there was a green building strategy that's a no-brainer, waste reduction is it. Crosby's start as a green builder involved both waste reduction and streamlining his procedures. "The only thing I had to change to become a green builder was my mind," he says. Something as simple as getting various trades to work together can be green. Crosby noticed his plumber sent a lot of the framer's work into the Dumpster, which the framer then had to rebuild. By getting the two men on the same page from the start, he saved material and landfill space, and they all saved time and aggravation.
Mike Trolle, a Ridgefield, Conn., green builder, suggests the simple expedient of designing in 2-foot modules to use both plywood and lumber most efficiently. Trolle also advocates Optimum Value Engineering, an approach to framing that questions the use of every stick of lumber to optimize materials use. For example, most openings don't require double 2x12 headers for structural purposes, it just saves the framer from having to remember what size header goes where. If a double 2x12 can be replaced with a single member, it will save lumber and create space to add insulation.
Recycling is another simple approach. "I haven't needed a Dumpster on a remodeling job in years," says Providence, R.I., contractor Mike Guertin. "Cardboard and metal are easy to recycle. I reuse a lot of the lumber I tear out, and clean scraps placed at the curb with a 'Free' sign on them disappear in days." Not only does he keep material out of the landfill, but recycling saves some of the cost of buying new, and saves the cost of a Dumpster.
Trane's CleanEffects technology removes up to 99.98 percent of particles from air entering the home.
5– Indoor Air Quality
If there's a downside to air sealing, it's the potential to trap pollutants inside. Typical indoor pollutants include formaldehyde (off-gassing from OSB, most forms of particle board, and some carpet), volatile organic compounds (VOCs) (solvents from paints, finishes, automotive products, etc.), combustion by-products such as carbon monoxide (from gas stoves and any improperly vented fuel-burning appliance), and excessive moisture.
There are two approaches to improving indoor air quality (IAQ). The first is reducing the use of products that off-gas. Maria Del Bianca of NAHB's Green Building Council suggests using plywood floor sheathing, which off-gasses less formaldehyde than OSB. Pfeiffer advocates detached garages to separate exhausts, fuel, and pesticide storage from living spaces. Providing dedicated combustion air for furnaces, boilers, and water heaters can prevent back-drafting stack gasses into the house.
Proper ventilation is as important as reducing sources. The American Society of Heating, Refrigeration and Air Conditioning Engineers recommends a whole-house ventilation rate of three air changes per hour. The only way to know if your house achieves this is to do a blower door test and have a knowledgeable HVAC contractor calculate the proper ventilation equipment.
Delta's water-efficient showerhead with H20kinetic technology uses only 1.6 gallons per minute, compared to the standard 2.5 gpm.
Trolle strongly prefers using an energy recovery ventilator (ERV). ERVs and heat recovery ventilators (HRVs) bring outside air in, while exhausting inside air. In either type, the two air streams pass each other in the ventilator's heat exchanger, with the conditioned indoor air tempering the incoming outdoor air. The added benefit of an ERV is that it exchanges moisture as well as heat. So, in the winter an ERV ventilates without desiccating the house by retaining some indoor humidity. ERVs cost a couple hundred bucks more. Trolle's ERVs are "ducted to pick up air from bathrooms and feed the incoming air into the supply duct ahead of the air handler."
Pfeiffer, who builds in a milder climate than Trolle, doesn't bother with either type of ventilator. He simply ties a 6-inch duct from the outside to the main supply trunk. A damper in the outside air duct only allows air to flow inward, responding to leaks in the house.
6– Water Conservation
Particularly in the Southwest, the availability of water may be the factor that ultimately limits further development. But shortages occur in other areas as well. Other water issues include managing stormwater runoff to maintain natural ground percolation that recharges aquifers, as well as preventing siltation of waterways.
Many of us remember the federally mandated change to 1.6-gallons-per-flush toilets in the 1980s. Those of us who were builders then also remember customer phone calls about inadequate flushing and frequent clogs. Low-flow toilets deservedly had a bad name. But that has changed, and low-consumption toilets perform much better today.
Groundwater control isn't as easily addressed as choosing a toilet that flushes as expected. Here, Wilson suggests finding a local engineer familiar with and experienced at innovative water management practices. Most subdivisions require engineered water management anyway, and it's often possible to reduce the storm sewer infrastructure by increasing the ability of individual home sites to absorb storm flows. Techniques include draining roof runoff to absorption fields and the use of pervious concrete pavers on driveways. Wilson says that this approach may even "ease a subdivision's path through local land-use boards by showing that you're doing the right thing."
7– Green Products
Simple product swaps can make a big difference: For flooring, quickly regenerating options, like Expanko's Vallerex cork (left) and EcoTimber bamboo (right), offer an alternative to wood species that are less sustainable. Outside, permeable pavers like UNI's Eco-Stone (top) reduce stormwater runoff.
In some ways, simply choosing one product over another is the easiest path to going green. It was, however, rated as the least important aspect of green building by nearly every expert I interviewed. Nonetheless, no one said not to bother, and many had suggestions.
HUD's Bres says to look for "one-for-one swaps that take something not as green and replace it with something greener that requires no changes in worker skills." Examples include specifying concrete that incorporates fly ash (a waste product from coal-burning power plants) as a partial substitute for Portland cement. Another example is using bamboo flooring, which regenerates quickly, instead of wood species that are not as sustainable.
Guertin looks for Forest Stewardship Council–certified lumber and low-VOC paints. Although low-VOC paints cost a little more, Guertin says that the major brands all include a mildewcide, which makes them an easy sell to clients.
Prefab foundation panels are one of Trolle's favorite swaps. Not only does a Superior Wall foundation go up in a day, it's waterproof, it requires no concrete footer, and it's insulated. Trolle also mentions Elk's reflective roof shingles, which use a 3M mineral coating that reflects about 25 percent of unwanted solar radiation versus other shingles.
–Andy Engel is a writer and home energy consultant in Roxbury, Conn.
Green Building Glossary
Building science: The study of the physical behavior of buildings, particularly regarding heating and cooling and the behavior of water.
OVE: Optimum Value Engineering, the practice of engineering houses to be as strong as necessary while minimizing the use of material.
VOCs: Volatile Organic Compounds, typically substances such as the solvents used in paints and carbon-based chemicals that migrate from synthetic materials to the air.
Embodied energy: The amount of energy required to obtain raw material and manufacture and transport a product to its ultimate destination.
Rainscreen wall: Technique of furring siding away from the sheathing and building paper to encourage drainage and minimize pressure differentials that admit wind-driven rain.
Blower door: Diagnostic tool used to depressurize a house to measure its air leakage.
Duct blaster: Diagnostic tool used to pressurize ducts to measure their leakage.
Resources
Environmental Building News
www.buildinggreen.com
Building Science Corp.
www.buildingscience.com
PATH
www.pathnet.org
NAHB
www.nahb.org
Affordable Comfort
www.affordablecomfort.org
U.S. Green Building Council
www.usgbc.org
Home Energy magazine
www.homeenergy.org
The Green Building Initiative
www.thegbi.org
Northeast Sustainable Energy Association
www.nesea.org
Florida Solar Energy Center
www.fsec.ucf.edu
Kansas Building Science Institute
www.kansasbuildingscience.com
Energy & Environmental Building Association
www.eeba.org
Residential Energy Services Network
www.natresnet.org
Energy Star
www.energystar.gov