Going beyond code: Monitoring disaggregated energy and modeling detached houses in Hawai'i

Abstract

Hawai'i was the first state to establish a statewide 100% renewable energy goal to be met by 2045. To address the potential impact of new residential construction, a team conducted field studies and developed whole-building energy models of detached houses in Hawai'i. The goal was to inform the state, a major developer, and the Hawai'i design community on how current residential design could be modified to meet the newly adopted energy codes and renewable energy goals. Seven houses with air-conditioning were monitored for disaggregated energy use, temperature, and humidity for one year. The building simulation software BEoptTM v.2.8 was used to conduct parametric analyses and cost/energy optimizations to evaluate design options. The energy-optimized model for this hot-humid climate included the following: increasing the efficiency of the air-conditioning system; utilizing ceiling fans with occupancy sensors while increasing the thermostat set-point; a light-colored exterior finish and roof; a radiant barrier; longer eaves; and Energy Star appliances. The energy-optimized model reduced the annual site energy by approximately 47.1% compared to the model that minimally complied with the International Energy Conservation Code 2015. A 4.5-kW grid-tied photovoltaic array would achieve a net-zero annual site energy value.