Differentiating among low-energy, low-carbon and net-zero-energy building strategies for policy formulation

Public policies are emerging that call for minimizing the built environment's contribution to climate change by means of a comprehensive shift to low-energy buildings powered by renewable energy sources. These policies also address other pressing global problems such as depleting energy resources and high energy costs. Policies promoting the implementation of net-zero-energy buildings have the potential to successfully reduce the scale of carbon outputs associated with the built environment. However, a lack of clear definitions for the terms used to describe net-zero strategies hampers the implementation of what is emerging as the potential cutting edge of sustainable construction. At present, a wide variety of ambiguous definitions exist for key concepts such as net-zero energy, renewable energy, low energy, and low-carbon buildings. Previous efforts to define these terms are reviewed and the gaps in understanding identified. Conflicting definitions for renewable energy and low-energy buildings are highlighted. European Union and United States policies are reviewed and compared to illustrate the similarities and differences. Recommendations for the resolution of priorities and definitions are provided with the motivation of helping to increase international collaboration and synergy for both refining policy and focusing investments in contributory research.