A zero energy building (ZEB) produces enough renewable energy to meet its own annual energy consumption requirements, thereby reducing the use of non-renewable energy in the building sector. ZEBs use all cost-effective measures to reduce energy usage through energy efficiency and include renewable energy systems that produce enough energy to meet remaining energy needs. There are a number of long-term advantages of moving toward ZEBs, including lower environmental impacts, lower operating and maintenance costs, better resiliency to power outages and natural disasters, and improved energy security.
Reducing building energy consumption in new building construction or renovation can be accomplished through various means, including integrated design, energy efficiency retrofits, reduced plug loads and energy conservation programs. Reduced energy consumption makes it simpler and less expensive to meet the building’s energy needs
with renewable sources of energy.
ZEBs have a tremendous potential to transform the way buildings use energy and there are an increasing number of building owners who want to meet this target. Private commercial property owners are interested in developing ZEBs to meet their corporate goals, and some have already constructed buildings designed to be zero energy. In response to regulatory mandates, federal government agencies and many state and local governments are beginning to move toward targets for ZEBs. However, definitions differ from region to region and from organization to organization, leading to confusion and uncertainty around what constitutes a ZEB.
A broadly accepted definition of ZEB boundaries and metrics is foundational to efforts by governments, utilities and private entities to recognize or incentivize ZEBs. A commonly accepted definition and corresponding methods of measurement for ZEBs would also have a significant impact on the development of design strategies for
buildings and help spur greater market uptake of such projects.
The definition of ZEBs needs to include clear and concise language to be effective and accepted. Metrics and measurement guidelines are required to allow verification of the achievement of the key elements of the definition. The definition, nomenclature and measurement guidelines should address how energy consumption is measured and what energy uses and types to include in its determination.
In practice, actual projects seeking to verify zero energy should work to ensure no harm is done in the process of achieving zero energy performance across other, non-energy-related considerations, such as water protection, optimized comfort for low-load buildings, and comprehensive indoor air quality. While these considerations don’t affect the definition of zero energy, it is important that in practice a design team ensures that other important building considerations and values are not sacrificed in pursuit of zero energy.
Creating a broadly agreed upon and supported definition of ZEB should involve participation from the many organizations that have a stake in the outcome.