RACA Journal I October 2026 www. refrigerationandaircon. co. za 15
HEAT EXCHANGERS
Heat pumps magnify this opportunity. Conventional electric or gas resistance heating typically gives you one kilowatt of heat out for every kilowatt of energy in: COP, for example, 1:2, or 1 kW / h electricity delivers 3 kW / h of cooling / heating / hot water energy kW / H. A well-designed heat pump, by contrast, can deliver up to four kilowatts of heat for that same kilowatt of electrical input – COP 1:4. This“ one in, four out” performance is the reason heat pumps have become the default choice for hot-water production in many markets, explains Fawcett. Heat pumps were originally designed for underfloor heating at 45 ° C and have been upgraded to deliver hot water at 60 ° C. When integrated with heat recovery from HVAC & R systems, they allow commercial operators to slash their hot-water energy bills, often to a quarter of their previous levels.
Effective thermal storage is equally important because recovered heat must be available when required. Pressureless, stratified storage tanks minimise temperature losses through high-performance insulation and carefully controlled flow patterns. Carter notes that well-designed tanks may lose as little as 1 ° C over 24 hours, whereas poorly insulated alternatives can lose ten times as much, resulting in substantial lifetime energy losses.
In that context, it no longer makes sense to treat boilers, chillers, VRF systems and domestic hot-water plants as isolated islands. They form a single energy ecosystem. The more tightly they are integrated, the less energy is wasted.
“ Solar PV fits naturally into this whole-system approach, but we don’ t start by covering the roof in panels – we start with efficiency. First you use heat pumps and heat recovery from the HVAC and refrigeration plant to drive your thermal loads down as far as possible. Once the demand for hot water and space heating has been slashed and stabilised, it becomes much easier to size and justify a grid‐tied PV array to feed what’ s left. At that point, every sunny hour is feeding an already efficient system, and hot water is often effectively free whenever there’ s sun and grid power. Where there is excess PV generated between 10:00 and 12:00, that free heat can be captured especially in commercial student accommodation blocks.
“ The big wins are in buildings that already have serious cooling and hot water needs: hospitals with round‐the‐clock chillers and heavy laundry loads; hotels and lodges with high shower and kitchen demand tied to central air conditioning; laundries and food plants with boilers and ovens throwing away heat; and data centres or server rooms that run cooling 24 / 7. In all of those, plant that was installed for one job can, with a bit of design thought, be turned into a combined heating and cooling asset that cuts net energy use dramatically,” says Carter.
Fawcett adds:“ By recovering and storing energy you ' ve already paid for, HVAC & R systems become energy assets rather than energy consumers. Every kilowatt of waste heat is a resource waiting to be used.” Recovery rates of up to 40 % are achievable, reducing purchased energy to around 60 % of previous levels. RACA
“ Effective thermal storage is equally important because recovered heat must be available when required. Pressureless, stratified storage tanks minimise temperature losses through highperformance insulation and carefully controlled flow patterns.” business
RACA Journal I October 2026 www. refrigerationandaircon. co. za 15