Just when you thought you were getting somewhere with your green goals, new levels that will push the industry even further emerge as tempting targets. I'm referring in this case to an increasing push for zero-net energy homes, a trend we're seeing in a raft of projects coming online coast-to-coast in the coming months.

The focus of a zero-energy home is squarely on energy performance, and places more emphasis on alternative energy systems like photovoltaics than typically presented with broader green building strategies. Of course, zero-energy homes must still incorporate green building materials and details, and address green building concepts, but their focus on energy combines more aggressive efficiencies to minimize load requirements, with PV systems that work with utility-supplied power to meet the reduced loads. The goal: "net-" or "zero-"out fossil fuel energy consumption on an annual basis.

The concept isn't new; innovative architects and builders have been chasing zero since the early 1970s, but mostly as stand-alone, off-the-grid fringe homes that didn't inspire many in the mainstream. But many of today's zero-energy homes are grid-connected subdivision production units that, aside from the PV panels on the roof, look just like the houses down the street. We're excited by this movement and will be following a number of zero-energy homes through their design and construction in the coming months on our Web site.

Great Britain calls these homes "zero-carbon" and actually will require new homes to reach this goal--they call it Code 6--by 2016. The reference to carbon is strictly related to energy supply and consumption and not to the carbon footprint of the construction or building materials. That's a much different "zero," so watch carefully for anyone claiming zero-carbon homes--it could bring a new twist to greenwashing. 

Carbon emissions, though, will likely be the next target on the horizon. It would be impossible to build a true zero-carbon home, even if you did zero-out the carbon emissions from its energy consumption, because of the tons of carbon emitted into the atmosphere through the production and transportation of a home's materials, transportation of its construction workers, and even excavation of the site. Still, as zero-energy homes decrease the carbon emissions generated from operating houses, attention naturally will turn to the building process itself. Emissions-reducing methods already awarded points in green building programs, such as sourcing local materials, will gain momentum, and other solutions also will be sought.

For those of you searching for new horizons beyond green, even beyond zero-energy, learning about and incorporating carbon-reducing measures into your green building strategies will help you get closer to zero.