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Lighting Systems, Energy Use, and Strategies for Savings
OTHER PARTS OF THIS ARTICLEPt. 1: This PagePt. 2: Consumption Concerns: Use ASHRAE GuidelinesPt. 3: Taking the LEED Approach to Reducing Lighting UsePt. 4: Occupancy Sensors Help Reduce Energy UsePt. 5: Common Lighting Control Issues
Lighting systems use an average of 21-39 percent of an in institutional or commercial facility's overall energy. Unfortunately, many existing buildings are significantly overlit, compared to recommended foot-candle levels for various spaces as defined by the Illuminating Engineering Society (IES). Many buildings designed before the computer era were built with lighting levels intended for paper-only reading, compared to today's standards, which might only require one-third of the lighting for a similar space type, due to computers and enhanced printing operations.
Advances in lighting-control technology and associated strategies have made it simpler and more economical for maintenance and engineering managers to update their antiquated systems without breaking the bank.
One of the first steps in identifying electrical use from lighting and associated controls and in identifying potential energy-conservation measures (ECM) is to perform a base-level ASHRAE Level I energy audit of the space. Generally, it is better to have a third-party inspector complete this walkthrough, but a building maintenance team should have all of the required knowledge for this type of inspection.
For a building management team that might not have prior audit experience, a good starting point would be to buy ASHRAE's Procedures for Commercial Building Energy Audits. This document tends to serve as a general procedural guideline, while avoiding giving a step-by-step analysis in recognition that each building has its own characteristics.
Before performing the walkthrough, managers should focus on base-lining the buildings' energy utilization index (EUI) and comparing this to similar buildings. Managers can do this by compiling utility bills from 12 months to 36 months before completing the audit and determining annual energy use per square foot. From here, managers can determine if a building's EUI is high compared to similar building types in a region.