Designers can use superior building design and energy management strategies to create buildings that produce at least as much energy as they consume. These are called zero energy buildings (ZEBs). ZEBs exist in the United States and Canada now; however building energy codes will have to be continuously improved to achieve widespread ZEBs by 2030, a common goal of many cities and some states. Two codes, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 90.1 and the International Energy Conservation Code (IECC), set the standard for US commercial and residential building codes. They are amended on a three-year cycle. During each cycle, proponents of energy efficiency can suggest and support code changes. Energy advocates can also look to stretch codes, standards, and certifications like zero energy certification and the Passive House standard as models for upgrading the ASHRAE and IECC codes. Other organizations and jurisdictions such as Architecture 2030 and the state of California have also started to craft their own versions of a zero energy code.
Two metrics make measuring zero energy buildings increasingly easy: Home Energy Rating System (HERS) ratings for residential and Zero Energy Performance Index (zEPI) scores for commercial. Despite the simplicity of these metrics, ZEBs still face obstacles. Some observers feel that energy efficiency can be disregarded for solar energy in ZEBs; however this fails to account for the current economics and nonenergy benefits provided by efficiency. Stakeholders also debate whether to require onsite renewable energy (in the scope of building energy codes) or to allow community-generated energy (outside the scope of building energy codes). While onsite renewables can be used for many buildings, accommodations for buildings where enough onsite renewable energy is not possible will likely be needed.
Advocates and policymakers should start considering incremental energy code changes now so that progress can continue. Potential improvements range from an outcome-based performance path, which helps building owners measure and verify energy savings, to solar-ready roofing and connections, which provide buildings with the option to install onsite solar energy as costs continue to fall. Energy advocates at the national level should continue to submit and defend proposals that move the codes closer to zero energy. Policymakers at the local level should start evaluating the best method to achieve zero energy through their building codes. Developing voluntary programs and zero energy stretch codes now can be important initial steps toward transitioning to a minimum ZEB code in the future.
This white paper examines the current state of zero energy codes and provides an update on avenues to achieving zero energy codes by 2030. It presents an overview of current efforts to achieve zero energy and similarly high-performing buildings, example code proposals that help move the needle toward ZEBs, and thoughts on additional issues and barriers.