This post is by Sheryl Canter, an online writer and editorial manager at Environmental Defense Fund.
People tend to do things the way they've always done unless something forces them to change – even if the new way is better and cheaper. So Hawaii has taken action to spur people along. From an article in the L.A. Times:
California last year passed legislation offering homeowners and businesses $250 million in incentives to install 200,000 solar water systems over the next 10 years.
But Hawaii Thursday took far bolder action, becoming the first state in the nation to require all new homes built after January 1, 2010 to be equipped with solar or other energy-efficient hot water systems.
The article goes on to say that Hawaii's switch to solar hot water will save homeowners money, and prevent the emission of more than 10,000 tons of greenhouse gases per year.