HVAC&R management
Delivery of trigen project A recently opened hospital in Queensland employs trigeneration as a means of achieving greater efficiency and cutting energy needs including HVAC demands, writes Paula Wallace.
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he new Lady Cilento Children’s Hospital (LCCH) is the state’s largest specialist children’s care centre boasting around 80,000 sq.m of floor space over 12 clinical levels and with additional basement car parking. Managing contractor Lend Lease (formerly Abigroup) chose mechanical and energy service specialists AE Smith to construct and commission a world-class trigeneration central energy plant. Designed by Floth Sustainable Building Consultants, it offers LCCH greater independence from the grid, and improved resilience to energy shocks. AE Smith has applied Building Information Modelling (BIM) processes and integrated prefabrication solutions to remove cost and risk, and improve on critical path delivery. The intelligent building management software interface will ensure the plant can be easily managed and maintained into the future. With energy efficiency, insurance against climate and return on investment all in mind, this trigeneration project is just what the doctor, and engineers, ordered. At the heart of the system is a central energy plant contained within a purpose built five level structure. The plant occupies 4,500 sq.m and meets all the power, heating, cooling and steam requirements of the hospital, research facility and a planned future building.
The decision to use trigeneration has come from core initiatives to make the project more energy efficient, energy secure and with reduced emissions. “Hospitals historically are large energy users, and typically HVAC solutions form the majority of this usage,” says Josh Daley, LCCH project manager for AE Smith. The trigeneration energy plant at LCCH will be the largest of its kind in Australia, including two single-stage lithium bromide absorption chillers, each 1,100kWr and two 2,400kWe gas generators with hot water heat exchangers providing 5,400kW of heating hot water. The system will also reduce its nitrous oxide emissions using two selective catalytic reduction (SCR) systems. During peak consumption times, the new energy system is expected to lower the LCCH’s demand on grid energy by 60%. This will be achieved by capturing and using the waste heat produced through the combustion of natural gas. Floth principal mechanical engineer R. Glenn Ralph estimates that with the use of the central plant for most of the facility’s energy needs, emissions of carbon dioxide will be reduced by 17,831,779kg per annum.
Benefits of building off-site The use of BIM made it possible to navigate the tight spatial constraints
of the project and improve project coordination and communication. By using 3D CAD software as part of a holistic approach to BIM, AE Smith were able to systematically analyse and improve computer models of the energy system prior to any fabrication. This BIM model has also allowed precise detailing of every element in the system making prefabrication a core stage of overall construction. Through greater prefabrication, AE Smith has been able to cut time spent on site for installation. Daley remarks on the reduced install time, noting the role of AE Smith’s design and management teams: “Our teams put together a prefabrication strategy that has seen the majority of this energy plant prefabricated off-site,” he says. “Having everything from fans and associated duct built on skids to literally thousands of pipe spools pre-fabricated all but eliminated on-site welding. By commissioning the system before installation, we reduced time by 65% compared to traditional commissioning processes.” AE Smith will now spend 12 months reviewing the energy performance of the LCCH trigeneration system. Over this time the data collected will be used to accurately fine-tune the performance of the system.
Installation of a truck-sized prefabricated module manufactured by AE Smith. The prefabricated fan module for the isolation room extraction contained 40-50 fans that work in unison ensuring if one fan fails, another one starts up to ensure a high level of redundancy.
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DECEMBER 2014/JANUARY 2015 WME magazine