Developing countries are grappling with energy and water insecurity, impelling governments to
encourage end-users to conserve and e ciently consume these vital resources. With water heating
being among the largest energy users in residential buildings, it is imperative that the e ciency
and conservation of both energy and water are achieved. Heat pump water heaters (HPWHs) are
a superior choice in e ciently providing domestic hot water. However, there are still challenges
in their optimal operation and high initial cost in developing nations. Further, since they are
normally centrally located in a house, there are water and associated energy losses during hot
water conveyance to the end-use, as the cold water has to be poured away. This paper introduces
an optimal control strategy of a hybrid HPWH and instantaneous shower powered using integrated
renewable energy systems. This strategy has the potential to save 23:4% and 19 l of energy and
water in a day respectively, while also promising lower energy and water bills to the end users.
Further economic benefit can be achieved through the sale of excess renewable energy back to the
grid through an appropriate feed-in tari .