Investigation of energy efficiency performance of frozen food retail stores

Lead University: Brunel University London

Professor Maria Kolokotroni, Professor Savvas Tassou, Zoi Mylona

Collaboration: Iceland Foods Ltd, Graham Ireland Head of Energy and Mechanical Services

Summary

Food retailing in the UK is responsible for the 3% of the total electricity. Future targets set by UK food retailers require reducing carbon emission from retail operation by 25% by 2020. Supermarkets are high energy consumption buildings compared to retail buildings due to the refrigeration needed for the preservation of chilled and frozen products. UK represents the Europe’s largest market for chilled and frozen food over the retail sector.

The project focuses on the investigation on the energy efficiency of frozen food stores and the development of a thermal and energy model to depict the current energy performance of food retail stores and to create energy efficient control strategies in order to reduce the total energy use and thus the carbon foot print.

Energy demand analysis and prediction by creating a thermal and energy model of supermarkets is a difficult task because of interlinked heat exchanges between the building and the systems (mainly HVAC and refrigeration) coupled with varying requirements of stored products, hours of operation and transient occupancy patterns.

The two case studies refer to two similar medium size supermarket stores of Iceland Food Ltd with almost 1/3 of the products to be frozen food. The newest and the smallest store is in the southern part of London, in a typical small out-of-town retail centre. The oldest and the biggest case study is in a typical town centre road of London west suburb area. They have different HVAC systems but same refrigeration system.

Very little work has been reported in the previous researches on the dynamic modelling of coupled refrigeration/HVAC/building.

This research has addressed to following aims:

  • Monitoring of the two case study buildings regarding to total energy use in combination with refrigeration equipment energy consumption.
  • Monitoring of environmental conditions inside the stores (temperature, RH, CO2 levels, light intensity).
  • Development of an EnergyPlus model for dynamic simulation which facilitates integrated, simultaneous solution of the thermal zones of the stores HVAC and refrigeration systems for accurate prediction of the energy and environmental performance of the stores.
  • Investigation of the interactions between the subsystems in terms of energy performance, the provision of desirable internal environmental conditions for staff/customers comfort and food products and impact on refrigeration system performance.
  • Optimisation of HVAC control strategies (like freen night cooling, heat recovery or demand driven ventilation) in order to achieve energy demand reduction while not affecting any subsystem energy consumption and the maintenance of the appropriate environmental conditions.

Highlights

  • 1. Energy and environmental performance analysis of operational supermarket stores according to monitoring data
  • 2. EnergyPlus modelling is used for dynamic simulations to investigate further the energy performance of the stores and the interdependence of the subsystems
  • 3. Optimised controls strategies of HVAC systems to maintain acceptable environmental conditions with reduced energy demand of the subsystems.

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