Net-Zero Homes Need Labeling, Instruction Manuals

Net-zero homes need clear labeling to attract homebuyers and an instruction manual for when they are sold, according to NIST.

Keeping size in check, incorporating passive solar techniques, and building a tight, well-insulated envelope are listed as high-priority design strategies for net-zero-energy homes, according to a new report from the National Institute of Standards and Technology (NIST). Strategies to Achieve Net-Zero-Energy Homes: A Framework for Future Guidelines is based on the input of experts from a workshop NIST held in 2011.

Acknowledging that homeowners are not widely investing in net-zero homes, the report recommends factoring the cost of energy into home financing as well as offering homeowners consolidated information sources. It says a new, consistent labeling system for multiple consumer preferences—including energy efficiency, durability, indoor air quality, and accessibility—is needed.

The report lists some available resources relevant to creating a comprehensive home scoring system, although, as Allison Bailes of Green Building Advisor observes, it oddly excludes the Home Energy Rating System (HERS) Index. Even though HERS does not cover all the categories the NIST report asserts a rating system should include, it has become an established platform to compare energy performance, and its scale accommodates net-zero buildings.

The report also delves into issues with technology, builders, and occupants. More efficient systems are needed (examples in the report focus on HVAC), but builders are sometimes wary of introducing unproven technologies, and occupants sometimes behave in ways that do not maximize efficiency capabilities (see Want a Net-Zero Home? Be a Net-Zero Family.)

To fill in the knowledge gaps, NIST has sponsored a $2.5 million test facility to study the performance of a net-zero home by running real appliances, such as televisions and toasters, as if a family of four were living in the house. Small devices, programmed by NIST scientists, replicate the heat and humidity occupants would produce in the 4,000 square foot house. Every move of the virtual family has been scripted—down to the 14-year-old daughter taking longer showers. The information will be used to understand how human behavior affects energy performance and to create guidelines for owners of net-zero-energy homes. After a year, the facility will be used to test new technologies.