ABSTRACT
SWHs have been around for over a century, and the technology is robust, mature, and relatively straightforward. The degree of complexity and cost of SWH in part depend on a nation’s climate, since more sophisticated (costly) systems tend to be needed in colder climates. Fortunately, there are independent certification agencies in the United States and other countries that evaluate the many systems on the market, and allow homeowners to assess the virtues of various systems relative to their needs. A decision to replace an existing system with SWH depends on many factors, especially economics. Replacing a hot water heater that has many years of life left with a SWH that saves energy but results in only a modest dollar savings per month would make neither economic nor environmental sense-considering the “embodied energy” represented in the existing unit.
