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What do Hawaiʻi households use their energy for? Data from a 2019 residential energy use survey shows that refrigerators have the highest share of the total household energy (21.4%), followed by electric devices (18.6%) and water heating (17.9%). Experts from the University of Hawaiʻi Economic Research Organization (UHERO) who analyzed the data also found significant differences among counties, as well as between households with or without photovoltaic systems (PV).

Hawaiian Electric Co. conducted the survey of its customers, collecting 2,992 qualified responses from residential households on Oʻahu, Maui, Lānaʻi, Molokaʻi and Hawaiʻi Island. Data included monthly energy usage, PV, weather, and the different types of appliance ownership and household socioeconomic status. Kauaʻi was not part of the study since Kauaʻi Island Utility Cooperative services the island instead of Hawaiian Electric.

Variations among counties

Across sample households on Oʻahu, refrigerators have the highest share of the total household energy usage (22.5%) followed by electric devices (20.9%). In Maui County, refrigerators and laundry are both the highest usage of total household energy, 23.4% and 23.3% respectively, while on Hawaiʻi Island, water heating tops the list (26%) followed by electric devices (19.5%).

With PV vs. without PV

Researchers also discovered differences in households with or without PV. In single- and multi-family households without PV, refrigerators have the highest usage of total household energy at 20% and 22.9%, respectively. However, in single-family households with PV, water heating has the highest energy (26.3%) compared to refrigerators (20.5%).

In households on Oʻahu, water heating, laundry and refrigerators have a larger share in the total energy usage in single-family households with PV than in single-family households without PV. However, the share of usage of electric devices in single-family households without PV is higher than that of single-family households with PV. For multi-family households without PV, the share of energy usage by cooling equipment (air conditioning and fans) is the highest.

“Households without solar PV are more conservative in their energy usage as compared to households with PV. The additional energy from the PV sources have enabled households to use energy more liberally,” UHERO said.

Future research

UHERO will continue to work with Hawaiian Electric to study the household-level impacts of Hawaiʻi’s decarbonizing energy transition and what it means for the state’s economy. They will dive deeper on the differences in the energy usage between households with and without PV. The main question they will ask is: Is it because households with larger energy usage are more likely to install solar PV, or is it because residents change their behavior and consume more energy once PV is installed?

For more and to see the data dashboard, visit UHERO’s website. UHERO is housed in UH Mānoa’s College of Social Sciences.

This work is an example of UH Mānoa’s goals of Building a Sustainable and Resilient Campus Environment: Within the Global Sustainability and Climate Resilience Movement (PDF) and Excellence in Research: Advancing the Research and Creative Work Enterprise (PDF), two of four goals identified in the 2015–25 Strategic Plan (PDF), updated in December 2020.