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Net Zero Homes: Time to Ramp up Production?

7/28/2015

KB Homes is building them in several states.

Meritage Homes may build up to 50 of them this year alone.

Toll Brothers is sitting tight for now, gauging customer demand.

And Lennar Corp.? They now offer solar panels and other advanced energy-saving features in select markets but so far say the idea is "… far from commercially available and financially affordable."

The idea, of course, is the net-zero home. The subject is getting a lot of media traction these days. A Google search now presents nearly 12 million hits. What's your position? Time to steal market share from slow-moving competitors? Or wait on the sidelines? Here are some things to consider.

What Is a Net-Zero Home?

The answer isn't as obvious as it seems. True, it usually means installing photovoltaic panels on the home's rooftop. But from there, definitions can vary widely.

For example, the U.S. National Renewable Energy Laboratory (NREL) cites no less than four categories of definitions, each depending on the owner's net-zero objectives:

  • To offset the electric bill, use the term net-zero site energy.
  • To offset the utility's production to power the home, use the term net-zero source energy (remember, approximately two-thirds of the raw fuel energy used to generate electricity is lost largely through production at the power plant with, with much smaller loss through transmission and delivery).
  • To offset actual on-site power use, use the term net-zero energy emissions (home-produced energy must equal the amount from emission-producing sources, such as coal or gas-fired plants).
  • To offset emissions associated with the home's power usage, use the term net-zero energy choice (the difference between the amount of natural gas vs. electricity used).

Other definitions embrace zero-heating home concepts, such as the conservation approaches used in passive home construction (ample insulation, tight sealing, optimum site orientation, excellent windows, etc.). Most home builders settle on this simple one, says Katherine Austin, AIA, and member of the National AIA Board Knowledge Committee Advisory Group: "… an all-electric home with a solar array large enough to meet demand."

Reduce Before You Produce

Few dispute the growing consumer interest, if not outright requirement. In recent months, the U.S. Department of Energy has certified 370 "net-zero energy ready" homes. An additional 14,500 homes are considered close to zero-energy specifications by the agency.

If you're considering working with a home buyer to build at or near net-zero specifications, keep in mind the energy mantra, "Reduce before you produce." The home must be built to squeeze-out every possible dime of energy savings, starting with the insulation and running through the energy-efficient appliances, windows, doors, lighting, water heating, and the HVAC system.

Don't forget the passive building strategies mentioned earlier like the building orientation to the sun, window and door placements, deep overhangs, and other tried-and-true green building techniques. They reduce heating and cooling loads by using solar energy when needed and avoiding it during the summer months.

Next Steps

What's your next move if you're thinking of offering a net-zero option?

A good place to start is Home Innovation Research Labs of Upper Marlboro, Md. They've taken some of the guesswork out of searching for budget-friendly ways to build green by categorizing the most cost-effective building methods. For instance, builders who construct houses to its National Green Building Standard have access to information and resources that list step-by-step ways to construct economical high-performance houses.

The trend line is clear. If you're looking into net-zero building options, congratulations. You're making a prudent business move. If you haven't, there's never been a better time to start.

Related Tags: Performance | Sustainability | Health | Comfort/Livability | Trends