Tools & Equipment ReviewHigh Efficiency HVAC Meets Green Ideals While Fulfilling Real-World Comfort Demands

Heating and cooling systems account for nearly 50 percent of a house's energy consumption, so choice of equipment and the way it is installed are keys to success for any green builder. And as the focus on energy efficiency has led to improved building shell performance (including high-performance insulation packages and passive solar heating), selecting HVAC components that match the projected energy requirements will ensure that you optimize the system and meet the occupants' comfort needs and expectations.

Performance values
To reduce a house's energy usage, opt for high-performance HVAC units that exceed the required minimum standards when budget allows.

Since 2006, the minimum allowable seasonal energy efficiency rating (SEER) set by the U.S. Department of Energy for residential air conditioners and heat pumps is 13. (The higher the SEER rating, the higher the unit's energy efficiency.) That's a 30 percent increase in efficiency over the previous 10-SEER minimum—but also about a 30 percent increase in cost, according to manufacturers.

Now that 13 SEER is the industry standard, you need to move up an efficiency level or more to maintain a competitive edge as well as to meet the new Energy Star program minimums of 14 SEER for air conditioners and 14 SEER/8.0-8.2 HSPF (heating seasonal performance factor) for heat pumps.

Air conditioners and heat pumps with SEERs ranging as high as 21 have been available for a few years. But keep in mind that higher-SEER units also can cost anywhere from 40 percent to 100 percent more than a base 13-SEER system.

Recently, the DOE issued new standards for gas- and oil-fueled furnaces, upping efficiency ratings from the previous 78 percent annual fuel utilization efficiency rating (AFUE). The new minimum is set at 80 percent AFUE for gas furnaces and 82 percent AFUE for oil furnaces. (The new standards will go into effect in 2015.) High-efficiency furnaces with AFUE ratings up to 95 percent and 96.7 percent have been available for several years, as well; to meet Energy Star requirements, gas and oil furnaces must have AFUE ratings of at least 90 percent and 83 percent, respectively.

Efficiency Versus Cost
Except for some high-end builders, most pros still offer base-level HVAC systems because they are the least expensive and deliver adequate efficiency. According to Brett Sailors, vice president of sales for renewable energy solutions provider New Point Energy, return on investment (ROI) becomes a bit negligible when installing units higher than 16 SEER because of their higher initial cost.

In regions where cooling days are few, such as the northern states, there may be little value in installing a higher-SEER air conditioner or heat pump. It's true that a 13-SEER unit will use more energy than a higher-rated unit, but if the system doesn't run constantly or frequently, it will take much longer to see an ROI. In low-cooling-demand areas, 13 SEER may provide adequate efficiencies and comfort, especially if combined with ventilation and dehumidification systems.

Reshetar Custom Homes in Pipersville, Pa., has value-engineered the base HVAC system offered in its new green-built community, Springtown Knoll in Bucks County, to provide the best ROI. The houses, which will meet both Energy Star and Keystone Green Building Initiative guidelines, are built standard with 92 percent AFUE furnaces and 14-SEER air conditioners, along with whole-house humidification systems and heat recovery ventilators.

Local energy codes that preempt federal energy codes may require builders in some states to install HVAC units with higher-than-minimum efficiency ratings or to take additional building-envelope and duct-sealing steps when using minimum-rated units.