So…What is a “Zero Energy” Home?

Wouldn’t it be great if you never had to pay a heating or cooling bill? Or even pay for electricity? (On my professor’s salary, that would make me very happy.)

Well, it may not yet be common, but for those who have built homes that produce their own energy, it’s already happening. So called “zero energy” homes sometimes may use some energy from the power grid, and other times they may give some back. But in the end, the give and take balance out, and the homeowners’ energy bills net out at zero (although there may be an energy transmission charge).

Thus the terms “zero energy homes” or “net zero energy homes.” The U.S. Department of Energy prefers the term “Zero Energy Ready.”

Some homes even produce more energy than they consume—they’re called positive energy homes. And I want one.

Zero Energy Home Design

How is this possible? (If you guessed that plastics are involved, you’re correct.) These homes typically have two things in common:

• “passive” energy sources, such as solar and geothermal plus
• modern plastic foam insulation and related building products.

Each zero energy home is unique, but many use modern plastic foam insulation under and around the foundation, in the walls and in the roofing, which can dramatically decrease the energy needed for heating and cooling.

Some of these foam products do not simply insulate well (check out my article on insulation and R-value), they also reduce leaks and air loss to help seal the building “envelope” (the term for all the barriers between the indoors and outdoors that make up a building).

To demonstrate and publicize zero energy home technologies and opportunities, in 2013 the federal government built a test facility (actually a nice single family home) near Washington, D.C., using passive energy, various plastic foam insulation products and other energy saving techniques. In its first year, the home actually earned a credit by exporting surplus energy to the local utility, instead of paying the estimated $4,400 electricity bill for a comparable suburban Maryland home … despite months of below-average temperatures and double the normal snowfall.

How Plastics Enable Zero Energy Homes

So what kinds of plastics are used in many of these zero energy home plans? Here are some examples…

• Sheets of polystyrene foam under and around the foundation
• “Insulated concrete forms,” typically expanded polystyrene blocks that stack and are filled with concrete and rebar to create walls
• “Structural insulated panels” that sandwich large sheets of expanded polystyrene foam between wall boards
• Polyiso or polyurethane foam installed under the roof (instead of insulating the attic floor)
• Larger studs that can include thicker amounts of foam insulation
• Plastic foam insulation on the outside of the home, not just in the wall cavities
• Plastic house wrap that significantly reduces the infiltration of outside air
• Plastic sealants (caulks, mastics, foams, tape)

Granted, some of these zero energy homes likely will cost more to build than your typical homes these days, so the return on investment may take some time. But in the end, it can be worth it.

And zero energy home are becoming more common. In fact, California will require that all newly constructed homes must be “net-zero energy ready” by 2020.

That’s likely going to require plenty of plastics.