I have designed houses with both point of use and zone hot water heaters. Point of use consists of a small box with cold water in, hot water out, and a 110 or 220 lead. These work great for remote locations where you only have a sink like in a garage. Zone hot water heaters are placed outside or inside the building and heat either several fixtures or the entire structure. Both use a heating coil which heats when a flow senser trips. If your buiding has high use(such as an industrial structure with alot of traffic, 15 or more persons per hour or more throughout the day), stick to a normal water heater, it is cheaper to operate. Under that you will see significant advantages.