One of the most cost-effective ways to include renewable technologies into a home or building is by incorporating solar hot water. 

A typical residential solar water-heating system reduces the need for conventional water heating by about two-thirds. It minimizes the expense of electricity or fossil fuel to heat the water and reduces the associated environmental impacts.  In Europe and Asia solar thermal heating systems are required by building codes to be included in any new home.  This trend is quickly being adopted to North America as can be seen in Hawaii's new building codes requiring solar thermal heating.