Environmentalist and renewable energy advocates are hailing a court decision Tuesday ordering the state Department of Business, Economic Development and Tourism to follow state law mandating all new single-family homes include solar water heaters and to consider variances for gas water heaters only on a case-by-case basis.

In 2008, Hawaii became the first state to require Solar Water Heaters on new homes. The bill was signed into law by Governor Linda Lingle, a Republican. It required the energy-saving systems in homes starting in 2010. It prohibited issuing building permits for single-family homes that did not have solar water heaters.

However, a Solar Water Heater variance came about. Stating” All new single-family dwellings built in the State of Hawaii are required to have a solar water heater (Hawaii Revised Statutes §196-6.5). If a solar water heater will not be installed, a “variance” (exemption) from this state law must be requested and approved for building plans to be accepted. “Single-family dwelling” includes Accessory Dwelling Units and similar single-family dwellings.”

In the past 11 years, the state Department of Business, Economic Development and Tourism approved — according to Earthjustice “rubber-stamped” — almost all variance requests for gas water heaters, totaling more than 6,500 exemptions to date. Earthjustice said several large subdivision developments on Oahu, including 15,000 total units, were seeking such exemptions in the foreseeable future.

HSEA estimates DBEDT’s failure to properly review variance requests from the solar water heater mandate has cost Hawaii’s solar industry about $36 million in economic and job benefits to date, as well as millions in energy savings for Hawaii homeowners and electric consumers. The legislature also found that the solar water heater mandate would avoid 10,000 tons of greenhouse gas emissions per year.

“Closing this exemption represents a massive victory for common sense and clean energy in Hawaii,” said Will Giese, Executive Director for HSEA. “Solar water heating is a no brainer solution, which is why it was mandated in the first place, and it generates huge upside benefits for Hawaii residents well into the future.”

Hawaii last year became the first state to establish a goal of 100 percent renewable energy by 2045.