zEPI: charting the path to net zero
Blog post by Helen Sanders, Ph.D
The New Buildings Institute (NBI) has recently asserted that 2019 is the year of the energy code, stating that “there will be a convergence of activities around energy codes that will make or break our ability to reduce the amount of carbon emitted by buildings in the next most crucial decade.” We’ll take a deeper dive into what’s behind this statement next month, but first we need to understand the concept of “zEPI,” an abbreviation for Zero Energy Performance Index.
zEPI is a concept that has been championed by the NBI (and created by Charles Eley) as a way of providing a clearer view of the pathway to net zero energy buildings and to achieving the Architecture 2030 goals. It is unique in that it references performance to a static baseline – the 2003 Commercial Buildings Energy Consumption Survey (CBECS), which provides an assessment of the energy use intensity (EUI) of buildings in the year 2000.
zEPI is a scale from 0 to 100, where 100 represents the energy performance of an average building in the year 2000 (from the CBECS 2003 survey), and where 0 represents a building with net zero energy use. The scale can extend above 100 and below 0. For example, if a building uses 50% more energy than an average building (of the same type) in the year 2000, then it has a zEPI score of 150. If a building uses half as much energy as the 2003 CBECS average, its zEPI score is 50. If a building is net positive, meaning that it produces more energy than it uses, the zEPI scale can also be extended below 0...to continue reading click here.
(the full blog post, as well as previous posts, are hosted on www.usglassmag.com)