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 Energy saving% of demand% CO2 reduction Capital costAnnual saving at 2007 pricesPayback at 2007 prices
Heat recovery on waste water125MWh (h)7.34.2£35,000£38009.3 years
Rooflight45MWh (h) 22MWh (e) 2.8£25,000£29008.6 years
Rainwater harvesting910m311 £100,000£136573 years
Ground-source heat pump 500MWh (h)297.7£255,000£620040 years
Solar thermal74MWh (h)4.32.5£120,000£220054 years