Because current models aren’t rated as residential units, builders should know that they don’t have to meet FVIR or low-NOx requirements; however, as of press time, residential units were expected to launch by the end of 2010. Once available, the DOE estimates that homeowners can cut water heating energy use by 30% versus standard gas storage models and greatly reduce greenhouse emissions by taking about 75 therms off their natural gas bill. Installing gas-condensing models can earn two LEED points. And while the NGBS does not specifically mention condensing models yet, gas-fired units operating with an EF of 0.80 and higher are generally eligible to earn 10 points.

Conventional gas tank water heaters also are getting more efficient. In September, Energy Star upped its energy rating requirements for gas tank units from 0.62 EF to 0.67 EF. To meet those levels, manufacturers have to add power to their units, which is why most high-efficiency models are power vented or power direct vented. While these units are easily installed in new homes, they do require additional work in remodeling because the venting system needs to be replaced with PVC. There are a few innovative atmospheric models on the market that are Energy Star rated, but keep in mind that most standard atmospheric models are unable to reach anything above 0.63 EF. Even so, 40-gallon gas tank units with an EF of 0.61 or above will still provide one LEED point, and 60-gallon and 80-gallon models only need to reach 0.57 EF and 0.53 EF, respectively, to earn one LEED point.