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Part 3: Consider Whether Design is Still Sensible During Retrocommissioning
March 2014 -
Energy Efficiency Article Use Policy
In addition to optimizing equipment, how should facility managers consider whether design of equipment is still sensible and efficient?
When considering the efficiency and operation of existing systems it may become evident that the original basis of design is no longer appropriate for the current use and/or needs of the building. This sometimes becomes clear during an RCx investigation when it is apparent that the existing system is clearly grossly over/under sized for the current loads. Undersized equipment shows up as a shortfall in capacity (not able to meet space conditions) during peak periods (hottest days during the summer and coldest days in the winter), and grossly oversized equipment can be identified when the equipment is cycling frequently or having problems while running at very low capacity during peak demands.
If the RCx agent determines that the control of the system has been optimized and these symptoms still show up then a new set of load calculations should be completed. Once the proper sizing for current conditions is known, the most economical solution should be vetted. The age of the equipment, its current condition, and its efficiency, can be compared to several alternatives evaluating the return on investment of replacing it in kind with right sized equipment and with more cost effective alternatives. Usually it is apparent if the equipment is at the end of its useful life which can be evaluated through a combination of existing conditions, useful life expectations (available from BOMA, DOE, and ASHRAE), and maintenance repair records. If current conditions point to an end of life replacement the analysis becomes one of life cycle comparisons of the replacement alternatives. Local gas and electric utilities should be contacted as soon as possible to determine if they offer technical and financial assistance for these projects. Usually these types of projects fall into their “new construction/major renovations” programs. Answers provided by Paul Banks, Principal, B2Q Associates, Inc.
Ask An Expert: Paul Banks, Retrocommissioning
Part 1: First Steps to Retrocommissioning
Part 2: Types of Equipment That Should Be Included in Retrocommissioning
Part 4: How To Gauge Whether Retrocommissioning Was Successful