Comparative analysis of traditional vs. sustainable chilled water plant design

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Session 18 Paper 3, Heriot-Watt University Edinburgh, 14-15 April 2016

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This case study investigates and compares the energy, economic and environmental advantages of sustainable chilled water plant design methodologies with traditional design methods in Saudi Arabia. The constant flow primary only system and constant-flow-primary / variable-flow secondary chilled water systems are generally considered to be traditional design methodologies while the variable primary flow chilled water system is considered as sustainable design methodology. Carrier HAP v.4.5 software was used for modelling and simulating three different chilled water systems at Green Ville Hotel located in Jubail city of Saudi Arabia. HAP is approved by United States Green Building Council’s LEED program certification and also achieved ASHRAE standard 90.1 compliance. The results obtained by simulating three different chilled water systems was used in quantifying and comparing the energy and economic advantages of variable primary flow system with other two traditional chilled water systems. The overall simulation results indicated that nearly 17% of annual energy cost savings were achieved by variable primary flow system with optimized chilled water Delta-T as compared to the other two traditional chilled water systems. The economic analysis of three different chilled water systems was also performed to investigate the cost-effectiveness of the variable primary flow system and the results indicated that capital cost of variable primary flow system was 4% to12 % lower than the other two traditional chilled water systems considered. In addition to this, nearly 4 % to 11% savings were also achieved in 20 years life cycle cost of a variable primary flow system as compared to other two traditional chilled water systems. It was also noted the variable primary flow system creates less impact on the environment as the resultant CO? emissions were found to be nearly 18 % to 23 % lower than other traditional chilled water systems.