Summary

The Cooperative Flower Auction of Aalsmeer, in the Netherlands, is a world centre for the flower trade. It is housed in the world's largest trade building, covering 846,000 m². Every day, 19 million flowers and 2 million plants are auctioned off in 50,000 transactions. The auction house has several large cold stores at its disposal. The aim of this project was to identify opportunities for reducing energy consumption in the stores. One of the largest units, a 35,000m² storage facility, was taken as a test case. The store is used to cool flowers to a temperature of 6 °C. For 12 hours each day, the unit is used as an uncooled storage facility and test room. The store has 13 doors, with a total surface area of 136m². For most of the day, at least half of the doors are open to allow movement of flowers. The unit is cooled by six compressors. The energy saving potential was assessed by combined monitoring and model studies. Monitoring over several days revealed that, for part of the 12-hour cooling period, the store cooled down too fast and the compressors ran at a COP of 4 rather than their usual COP of 5. This was easily remedied by adjusting the control system. The model studies were used to determine the unit's potential energy consumption, taking present use into account. The studies showed that lighting could be reduced by 67% and losses through the open doors by 50%, while the heat produced by service vehicles could be minimised. These measures combined could reduce cooling energy demand by 30%, or 395,000 kWh/year. The main importance of the project is that it shows the effectiveness of combined monitoring and model studies. The brief monitoring period at Aalsmeer already revealed some (minor) malfunctions and irregularities that would otherwise have passed unnoticed. The relatively simple model used to calculate the effect of a number of energy saving measures nevertheless demonstrated the opportunities for optimising use of the store at virtually no cost.