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Providing mechanical engineering services to improve occupant comfort while saving the client over a million dollars in energy costs
When Property Manager GWL Realty Advisors took over management of the 34-storey Scotia Tower at 650 West Georgia Street in 2002, they recognized an opportunity to reduce operating costs by upgrading infrastructure, with a focus on improving energy efficiency in the more than 40,000-square-metre (450,000-square-foot) facility.
"Robert [Greenwald, president of Prism] has been instrumental in firing up our guys about energy reduction. He is probably the most passionate guy I know about energy management and efficiency and it spills off of him. And the mechanical engineering's there, it's not smoke and mirrors. Prism is by far the leading edge and, as a result, they are my go-to guys for energy projects."
--Peter J. Laforest, Manager of Technical Services, BC Region, GWL Realty Advisors
The building had an inefficient cooling plant that was nearing the end of its life cycle and was using CFC (chlorofluorocarbon) refrigerant R11 which, due to its high chlorine content, has the highest ozone depletion potential of any refrigerant. In addition, building automation controls were outdated and had limited flexibility.
Based on Prism's audit and recommendations, in 2003 the following mechanical improvements were made:
- Two 1,000-ton R11 centrifugal chillers were replaced with two new high-efficiency R123 centrifugal chillers (nominal sizes 900 and 600 tons) through a crane hoist setup and a hole cut in the roof Two chilled water pumps were replaced with new smaller pumps controlled with variable speed drives, and the chilled water valves in the building were modified to provide a variable flow system (one of the first of its kind in Vancouver)
- Two condenser water pumps were replaced with two new smaller pumps, and four cooling towers were replaced with new cooling towers with variable speed fans
- A minimum of 800 tons of chilled water cooling capacity was provided at all times to cool the building during the installation period
- A dedicated control system accessed via a Web-based operator interface was added to control the new chiller plant
- All previous-generation direct digital and heating, ventilation and air conditioning (HVAC) controls were updated to current technology
Since 2004, GWL has used Prism's proprietary MT&R (monitoring, targeting and reporting) tool to monitor its electrical and steam savings on a monthly basis. Results and recognition include:
- more than 11 million kilowatt hours of electricity and almost 11 million kilograms (24 million pounds) of steam (36,000 gigajoules) saved over a three-and-a-half-year period, for a total cost savings of over $1 million
- annual reductions of 19% in electricity use and 29% in steam use, compared to the base period
- complete elimination of R11 refrigerant in the building's chilled water system and a 24% reduction in the steam-related greenhouse gas emissions
- the Business Owners and Managers Association's "Go Green" accreditation awarded in December 2004 for its leadership on environmental practices
- a project payback of less than four years, with an annual return of over 20%, after incentives are factored in. This calculation considers the incremental cost for the energy-related projects