"Net zero," of course, means a zero-energy home -- that's right, no monthly bill -- that does consume energy but also generates enough to cancel out its overall footprint.
It's an incredible concept for homeowners and facilities managers alike, and no doubt you've heard of it on the local news.
But how do you actually get there?
To answer that question, I called up Barry Contrael, the director of the Low Voltage business division of Siemens.
Why Contrael? Because his team recently assisted popular television show Extreme Makeover: Home Edition to build an all-new, near-net zero energy home in Cocoa Beach, Florida.
With micro-inverter solar photovoltaic technology and some smart decisions, the homeowners have seen their electric bills drop from $400 to less than $100, despite a 50 percent increase in the size of their home. (If you've ever seen the show, them build 'em big.)
Here's what he had to say about pursuing a home of the future:
- Audit your home for energy efficiency. You can't plug the leaks if you don't definitively know where they are. "When you're approaching a net zero home, you don't start with technology. You start with a concept that says, 'I'm not going to pay capital costs to generate electricity that's not going to be used in a value-added way.' In other words, look first to where you've got waste."
- Change your behavior. It's as simple as flicking off the lights when you leave the room. (Or purchasing timers to do it for you.) Modern electronics draw less power, but vampiric standby modes may be adding to your energy bill.
- Plug the gaps. "If you were to add up all the leaks, the average home has a hole in the wall the size of a basketball. It's enough to run a fridge for a year." Install windows with a high R-rating, and consider slatted shades that let winter sun in and keep summer sun out. "40 percent of the unwanted heat in the home comes through the windows," he said. Install better opaque insulation -- the stuff in your roof, walls and basement. "At that point, you've gotten rid of the waste, and then you can begin to engineer solutions."
- Install compact fluorescent lighting. Modern versions don't have the greenish tinge of CFLs of yore. "People hate CFLs, but they last seven to 10 times longer and use one-fourth the energy," he said. "That's a 20 to 30 dollar savings over the life of the bulb."
- Buy a solar water heater. And wash more clothes in cold water. "A lot of the facets of heating water are big energy users," he said. Make sure it's set at 120 degrees Fahrenheit -- the "warm," not "hot" setting.
- Low-flow shower heads. Both for water conservation and energy usage. Less warm water means less energy to warm more.
- Take your refrigerator out of the garage. It's a common habit for secondary appliances in the suburbs, but "they're nasty -- a 10 degree increase in ambient [temperature] uses 20 percent more energy," he said.
- Purchase Energy Star appliances. If you've purchased a new appliance in the last few years, you're OK, but if it's seven to 10 years old, it's time to return to the store. "The efficiency on these new air conditioners makes them worth replacing your old," he said.
- Install ceiling fans. Some consider them unsightly, but the key word here is "ventilation." "Run them in different directions depending on the season," he said. "You can keep your thermostat a little higher," saving energy and money.
- Once you've exhausted your low-tech options, go high-tech with solar micro-inversion. Siemens says this solution -- in which inverters convert power from DC to AC at each panel, rather than in a centralized place -- is better for homeowners. "With string systems, if there's a poorly performing panel, the entire string's production goes down. If one panel goes out, you lose the whole string. With microinversion, you get more hours of generation per day and a higher efficiency on the overall system. It's also less prone to misapplication [by electricians]. In the home, it's a clear winner." It's also where the generation side of "net zero" comes into play.
Contrael says an electricity-generating home can even be a small financial boon. "The best type of [energy] storage is financial storage. In the [Extreme Home Makeover] system, he overgenerates -- so Florida Power and Light pays him back each year."
You need a "net meter" -- one that runs in both directions -- to accomplish this, but Contrael says "the lion's share" of automated meter reading rollouts by utilities support this. You just need to figure out what kinds of programs your local utility offers -- the DSIRE website can help.
"Some states have a feed-in tariff that let you make more money on what you generate than what you're using," he said.
If it were this easy, more people would do it, of course. What are the hurdles for the homeowner?
"There's a certain upfront cost," Contrael said. "Cash flow has been a deterrent to larger rollouts of solar.
"The nice thing about the micro-inversion is that you can choose your investment -- you can buy one or two or five panels, not 15. You have to watch that the incentives cover what you choose, but you can still usually get a federal tax credit and perhaps a state tax credit as well. It's not uncommon to get well over half the system paid for by different incentives."
It also helps to take a long-term view, Contrael said.
"Large businesses like ours look for a two-year payback, but if you're living in a home for a long period of time, you might look at a seven year payback," he said. "I'm 47 -- I want to do the investments now, before I retire."
The good news: financial schemes are coming for consumers to lower that initial hurdle, much like the power-purchase agreement does for the commercial sector. "We're working on financial institutions on second-type mortgages to help spread those costs out," he said.
A net zero home? Not so far-fetched. And perhaps not just a lofty goal, but a necessity in the near future. Consider the emergence of the electric car, Contrael said.
"When I think about the ability to add another 10 panels to my roof and offset what would be my gas usage," he said, "that's huge."
Photo: LifeStyle Homes/Flickr