Developing figures for ‘gain’ in relation to refrigerated cabinets in a supermarket building

Heat transfers into refrigerated cabinets from their surroundings. Currently, this heat transfer is ignored in building design compliance protocols (National Calculation Methodology), and a heat gain to the zone is included in modelling the retail floor, to represent the energy use of the refrigeration system, although this is normally outside of this zone. Previous work has established that a store designed for energy reduction with the heat transfers to refrigerated cabinets from the surroundings included in the modelling could have at least 20–35% lower energy demand (and CO2 emissions) than a store modelled and ‘optimised’ on the National Calculation Methodology basis. This paper therefore offers an appropriate algorithm for ‘negative gains’ relating to refrigerated cabinet heat transfers for use in design and compliance modelling of supermarket buildings. Practical application: The algorithm offered, when incorporated into design modelling, will enable significantly improved identification of the sensitivity of the thermal balance of the supermarket building to variation of building envelope parameters, and thereby enable significantly improved energy savings to be realised.