Energy demand attributable to the operation of supermarkets on-site is thought to be responsible for 1% of UK greenhouse gas emissions. In use data show a performance gap approaching a factor of three for overall energy use, with a gap of a factor of six in energy demand for heating. This performance gap indicates significant faults in the conventional modelling route. Current building regulations in the UK require the "building related" energy use of new commercial buildings to comply with particular requirements. Supermarket buildings are therefore modelled according to these protocols to establish their predicted energy demand. The impact on this predicted energy demand of the exclusion of process energy (eg for refrigeration) from these protocols is explored by modelling a supermarket retail floor with heat transfers related to refrigerated cabinets, and comparing the sensitivities of such models with those of models compliant with regulatory protocols. Whereas models compliant with regulatory protocols indicate an advantage of limiting the level of insulation and airtightness, and allowing stratification, to facilitate heat loss through the store envelope; models that include heat transfers around the refrigerated cabinets are found to show that energy demand may be decreased by up to 40% by doubling both insulation and airtightness, and by destratification. This will, however, only apply if rates of air change in buildings in use match those modelled. This shows the importance of including heat transfers around refrigerated cabinets in design modelling, so that appropriate decisions may be taken with respect to building envelope parameters. Compliance modelling protocols should be changed to reflect this. In order to facilitate this change and enable modelling of refrigerated cabinets within a compliance model through a few simple inputs, a set of data and associated algorithms is derived and offered for inclusion in compliance modelling tools.

The aim of this study is to investigate the heat recovery potential in supermarket refrigeration systems using CO2 as refrigerants. The theoretical control strategy to recover heating demand from refrigeration system is explained thoroughly and the heat recovery process from two existing supermarket using CO2 booster units is analyzed and evaluated. The measured data of refrigeration systems is obtained through Iwmac interface, processed using Excel and Refprop. The aim is to see what control strategy is used in these systems and weather it matches the theoretical one and at what level heat is recovered from the system. Besides, a simulation model is made by EES to investigate the potential of higher rate of heat recovery in the supermarkets. The simulation results are compared with field measurement and validated by measured values. Then, the ability of refrigeration system to do heat recovery at quite high rates for covering the total heating demand without using parallel heating system is evaluated and efficiency of the system is calculated. At the next step the heat recovery potential at other refrigeration solutions such as R404A conventional and CO2-ammonia cascade systems are studied and the results are compared to booster units. Finally, the potential for selling heat from the refrigeration system in supermarket to district heating network is investigated. Two different scenarios are made for such purpose and the results are evaluated. The heat recovery control strategy of existing supermarkets does not match the theoretical strategy and regarding the capacity of the system, heat is recovered to low extent. Simulation shows that heat can be recovered to higher extent at quite high heating COP of 3-5. Additionally the other heat recovery solutions for R404A conventional and CO2-ammonia cascade systems are found to be competitive to CO2 booster system.  The analysis of selling heat to district heating network shows that CO2 booster system is capable of covering the demand at reasonable heating COP as the first priority and selling the rest to district heating network at heating COP of 2 as second priority.