Net zero energy housing: An empirical analysis from measured data

Abstract

This study reports an empirical analysis of an all-electric, Net zero energy housing (NZEH) development located in a mixed-humid climate zone (4A, Virginia, USA). Circuit-level energy monitors were used to measure energy consumption and energy production data (solar photovoltaic) at 1-hr intervals in six identical apartments over 24 months. The study employs a multi-step case study methodology to a) empirically evaluate energy consumption and production data, b) identify the temporal variability of energy consumption and production data at different time scales, c) explore energy consumption and production outcomes from weather and select human-building interactions (HBI), and d) synthesize the study’s lessons learned toward data-driven recommendations for future NZEH researchers and practitioners. The study found that the development’s net zero energy goal was achieved in three of six identical 2-bedroom case units within 3 NZEH duplexes and that NZEH housing performance was more influenced by human-building interaction than weather variability. The analysis also found the solar photovoltaic (PV) performance to be reliable across the sampled units over the periods of measurement, suggesting that solar PV could be oversized as an approach to overcome variability in HBI and achieve NZEH performance goals.