TA-23-C008 – The Limits of ‘Net Zero’ for Specifying Building Performance ✓ Most Recent

The widespread positioning of ‘net zero energy’ as a performance goal for buildings and homes has been powerful and captivating for market forces and players worldwide. Its growing identification in the form of ‘net zero carbon’ and ‘carbon neutral’ has been useful in facilitating building electrification in addition to increasing renewable deployment and energy efficiency. One of the downsides of ‘net zero’ becomes evident as it is applied as a technical metric for building performance – frequently, it requires netting out widely differing measurement units of energy or carbon, where the conversion factors may dominate over the building performance itself, or where dual objectives are not well-served by netting. Additionally, ‘net zero’ does not (yet) account for time of use variations in either energy or carbon impacts. This paper will detail the technical challenges, policy misalignment, and enforceability of ‘net zero’ metrics in both new construction codes and building performance standards. The authors will consider the energy and carbon impacts of onsite energy storage and exports to the grid (‘net positive’) for different spatial and temporal grid scenarios, including the impact of using long-run marginal emissions rates for electricity on an hourly basis. The paper will also explore how to ensure that building energy efficiency demanded by the climate crisis is not eroded by ‘netting’ to zero by simply increasing renewable energy installed on or delivered to the project. While renewable energy can be reduced where more efficiency is provided, it does not work the other way around. Finally, the authors will position potential new terminology in a more technically viable framework and will explore the potential impacts on markets and audiences that successfully have employed terms such as ‘net zero’.