The interest in zero net energy (ZNE) is reflected in the growing number of ZNE-related targets, goals and certifications, such as the American Institute of Architects’ 2030 Challenge, California’s ZNE goals for residential and commercial new construction, and DOE’s Zero Energy Ready Homes Program. According to a new report from the American Council for an Energy Efficient Economy (ACEEE), building energy codes can play a role in facilitating the move to ZNE buildings.
To meet goals for ZNE construction by 2030, building codes must be put in place that establish effective requirements for ZNE performance for most building types by 2030.
Current building codes present a number of obstacles to zero net energy:
- The limited set of regulated end uses covered by code, primarily envelope materials, HVAC equipment, water heating and lighting.
- Diminishing opportunities for energy savings in a number of regulated equipment types.
- Federal preemption of code requirements for equipment efficiency in products covered under the federal appliance standards program.
- Reliance on prescriptive requirements and/or performance methods based largely on the modeling of building design.
- A lack of mechanisms to account for or address building operations and maintenance.
Building codes should be strengthened so that higher levels of building efficiency become standard practice, ACEEE said. To do this, however, the approach to building codes should be modernized to reflect the evolution in construction practices, changes in building energy use patterns and new building stock goals:
- Expand the scope of codes to capture all building energy uses, including growing plug and process loads.
- Address the energy savings available in building systems rather than only focusing on individual components or products.
- Shift the focus from building design to actual building energy use through adoption of outcome-based codes.
The 2015 International Green Construction Code incorporates a version of this compliance approach and could provide early lessons on implementation of an outcome-based code prior to wide adoption.
Federal, state and local energy efficiency policies can also help make the transition to ZNE codes. They can increase understanding of building energy performance, increase demand for more energy efficient homes and buildings, grow market capacity for high-efficiency construction and introduce more certainty to market actors about future code requirements.