VWART (Volume Weighted Average Return Temperatures)
CIBSE Heat Networks: Code of Practice for the UK (CP1 2020) clearly states as a minimum requirement the VWART should be no higher than 33.C. This is due to the low temperature network at 60.C or even 55.C primary flow, reducing VWART will increase efficiency and lower energy usage.
It’s also important to note the YGHP HIU – during Hot water demand – recorded one of the lowest VWART figures 16c proving YGHP’s model to be one of the most efficient on the market.
Achieving a low VWART will allow designers to select smaller pipework size, smaller plant equipment such as pumps. Smaller plant and pipework will reduce the heat losses in the building and avoid the overheating many early district heating schemes suffered from.