4– Waste Reduction
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 2×12 headers for structural purposes, it just saves the framer from having to remember what size header goes where. If a double 2×12 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.
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.
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.