Indoor air quality (IAQ) was not priority No. 1 for Virginia Ranch Development project manager Davis Johnson as he oversaw construction of an 800-home community in Gardnerville, Nev., near Carson City. It seldom is. Like just about everybody else in the business right now, Johnson's biggest concern was lowering costs and bringing the project in on time.
Bent on efficiency at every turn, Johnson and Derwin Bass, the project's chief architect, came up with an engineering, design, and construction plan that would cut back on site excavation and result in less trucking of materials to and from worksites, less labor, less concrete, all in less time. It was an inadvertent bonus when the two men realized that, in their ferocious effort to save money, their plan would also achieve higher indoor air quality in each new home.
What Johnson and others discovered is that IAQ is getting faster traction among home builders in an assortment of shapes, sizes, and problem/resolution packages. For years now, home buyers have paid little more than lip-service to the notion of green building, healthy homes, and energy efficiency. Builders have been operating in a double bind. They know they can build more environmentally sound, higher performance homes, but they're reluctant to do so if they can not pass on the engineering, design, and materials cost premiums to home buyers.
But as sourcing, design, materials technologies advance in sophistication, home builders like Johnson and Bass are finding that high indoor air quality performance and optimal cost efficiency on 50 to 75 percent of the cost of goods sold for each house aren't by nature mutually exclusive.
In the case of Dayton, Nev.-based Virginia Ranch Development's Gardnerville project, on the eastern slope of the Sierra Nevadas, the solution led to a widely used sub-foundation system called Cupolex. Fact is, concrete slabs are known culprits for indoor air quality problems. In contact with the ground, moisture wicks through concrete and can contribute to the growth of mold and mildew. Radon gas and vapors from contaminated soils can also seep through the slabs.
Cupolex, created by Pontarolo Engineering, was developed in Europe 10 years ago specifically to address ventilation problems. Recently introduced into the United States, it involves setting up grids of ventilated cavities beneath normal concrete slabs. Ductwork, cabling, and wiring can traverse right through the grids. To form the cavities, builders lay out interconnected, domed, recycled-plastic forms—the Cupolex modules—reinforce them with steel or carbon fiber, and pour concrete over them.
According to Johnson, the new system gave his company some extra sales leverage when it came time to market their project. Plus, the savings the team achieved overall more than offset the $1 to $3 per square foot cost for Cupolex, which he admits is more expensive than traditional concrete slabbing. “It's an additional cost, but it will save more than it costs in the long run.”
DEFINING IAQ Indoor air quality is fast becoming an industry cause celebre. Although its benefits are intangible, and seldom salable, everybody would like to offer higher indoor air quality, as long as they don't have to pay more to do so. What's more, it's one of those things that are really hard to define. Everybody knows what it isn't, but few agree on what it is.
Sure, ventilation and properly sized air conditioning units, heating, ducts, and fans are critical elements for good indoor air quality. For air-related subcultures, standards do exist. Acceptable whole-house ventilation rates are clearly spelled out by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (or ASHRAE 62.2), while the sizing of appropriate air conditioning, heating systems, and ductwork are established by Air Conditioning Contractors of America (or ACCA Manuals S, J, and D). Home Ventilating Institute guidelines even determine the correct sizing of kitchen and bathroom fans.
All of these standards and guidelines notwithstanding, IAQ is a slippery phenomenon. “You must look at the whole house—the entire system all working together,” says Brian Binash, president of Wilshire Homes in Houston, an NAHB director and the director of the Greater Houston Builders' Association. “It's pressure balances, how you bring in fresh air, the right size AC, the type of filter. You can't just look at one thing.”