Abstract: Disclosed herein is a heat exchange apparatus. The apparatus comprises one or more double walled conduit, each having an outer conduit and an inner conduit located coaxially inside the outer conduit. The conduits define a first fluid passageway for cold water at a first temperature. A drain defines a second fluid passageway for grey water at a second temperature and is located in the drain and downstream of the grey water flowing therethrough. The grey water when flowing in the second fluid passageway effects heat transfer to the cold water flowing in the first fluid passageway across the inner and outer conduits.

Abstract: Disclosed herein is a heat exchange apparatus, which comprises a hollow blade member having a first fluid inlet and a first fluid outlet and a first fluid passageway for a first fluid that extends between the inlet and the outlet. The blade member is sized and shaped to be located in a second fluid passageway for a second fluid. The blade member is configured to enhance thermal energy transfer between the fluids as they flow along their respective passageways.