Energy savings with outdoor temperature-based smart ventilation control strategies in advanced California homes
We developed and simulated the energy performance of smart ventilation controls based on outdoor temperature in homes located in California climate regions, designed to comply with the 2016 Title 24, Part 6 California Energy Code prescriptive requirements. The smart controls shift ventilation rates in time, but ensure an annual occupant pollutant exposure equal to, or less than, what would be experienced in a home with a constant ventilation rate equal to the whole house target airflow in the ASHRAE Standard 62.2-2016. Annual simulations of previously developed prototype homes with validated ventilation models, were conducted via co-simulation of EnergyPlus with CONTAM. Controller performance varied substantially by climate zone, airtightness and house prototype. Smart controls were generally ineffective in Climate Zone 1 (Arcata) due to its lack of a cooling season and low diurnal temperature swings. The most successful smart controls used parameters pre-calculated using an optimization routine. In order to better inform state energy policy, we also determined savings weighted by the amount of new home construction in each climate. The best controls averaged about one-third of ventilation-related energy savings that increased to about 48-55% when weighted. Annual average savings were about 650-700 kWh/year for the best controllers. The vast majority of site energy savings were for heating end-uses (>90% of total savings). Whole house ventilation rates increased between 0 and 42%, with typical increases in the 15-20% range. The best-performing control strategies shifted ventilation rates seasonally and modulated flows within each season. Peak concentrations during low ventilation times were kept below an exposure level of 3, well below the maximum of 5 required to avoid acute exposure issues.