Rendering of Green Light New York's new Energy Efficiency Resource Center opening this fall.
Image Credit: Green Light New York
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Bright summer days can make office daylighting seem like a no-brainer.
Even though daylight harvesting can improve the quality of a workspace while cutting energy costs, it remains an under-utilized practice. Though some challenges remain, better understanding of proper retrofit techniques, more financial incentives and advancing energy codes leave building owners increased reason to implement a daylighting plan. Among those tackling these challenges is Green Light New York (GLNY), an advanced lighting education, research and advocacy nonprofit. This month ALG Online News brings you a special feature on their new report on advanced daylighting controls for offices in Latest Research. In our Featured Chapter, read excerpts from ALG's Daylighting chapter about electric lighting integration and first steps to properly bring daylighting into your space. What's New offers relevant lighting news and events.
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Special Feature: Green Light New York
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Analysis of lighting power impact of advanced daylighting controls. Image courtesy of GLNY.
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New York City has 542 million square feet of office space. According to Green Light New York (GLNY), about 114 million of that space could be retrofitted with advanced daylighting controls resulting in an annual savings of 340 gigawatt hours (GWh). That translates to $70 million for building owners and tenants. GLNY's report Let There Be Daylight, released earlier this year, indicates these savings could be achieved with available technology and at reasonable cost thanks to technologies like wireless sensors and the fact that buildings constructed before 1950 (roughly half of NYC office space) were designed to utilize daylight.
Adding to the potential savings from daylighting strategies is the fact that interior office lighting is the largest end use for electricity and a big contributor to peak demand, the exact time of day when daylight is most available. Effectively utilizing this resource will significantly reduce energy use at those times when electricity is most costly. Implementing an advanced daylighting retrofit requires commitment, capital, good design and installation and proper maintenance. In addition, a successful retrofit that results in optimal energy savings and occupant satisfaction also requires the cooperation of multiple parties including owners and occupants. As GLNY notes in its report, the majority of NYC office buildings is in the hands of a relatively small number of owners, managers and tenants--a clear advantage for scaling widespread retrofits. As part of a multi-phased roadmap to accelerate advanced daylighting systems, GLNY is organizing several daylighting retrofit demonstration projects that will result in case studies showcasing measured energy savings and successful solutions. Several major owners in NYC real estate, Bank of America among them, have signed on to participate. The results of these projects will inform incentive packages that GLNY hopes will support further energy savings measures.
Following a set of laws and code changes passed in 2009 and 2011, New York City's nonresidential buildings are required to bring all lighting up to current code standards by 2025. Coupled with incentives from NYSERDA and Con Edison, New York has a unique opportunity to broadly implement daylighting systems and further drive the market for dimmable ballasts and improved controls. The savings potential is further confirmed by an NBI white paper reporting the recommended metrics for measuring the savigs from integrated daylighting, lighting and control systems. Recent research found a significant gap between lighting use predicted in codes compared to actual metered results.
To learn more about GLNY's upcoming events on codes, retrofits and more, visit greenlightny.org and click on Connect.
Learn more about integrated daylighting design and controls.
ALG Online's Daylighting Chapter provides information about daylighting strategies, technologies integration and more to ensure spaces that optimize comfort, occupant satisfaction and energy savings. Log in for full access to this chapter. Not a subscriber? Subscriptions are available for a nominal annual fee or check out ALG Online for five days free. |
Daylighting: Energy savings through electric lighting integration
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Electric lighting used to balance daylight. Image courtesy of Barbara Erwine.
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Whether the use of daylight is designed into a new space or redesigned into an existing space, a successful daylighting scheme should be used to lay the foundation for the electric lighting design. During daytime, electric lighting integration assumes proper balancing of electric and natural light to ensure adequate light levels for various occupant tasks in each space, essentially meeting required illuminance levels at points of interest and comfortable luminance distributions without glare. Daytime l ighting integration should consider changes throughout the year with respect to different sky conditions, changing daylight distribution and, if necessary, changes in occupancy and use of space.
Adjusting electric lighting intensity based on available daylight contributes not only to luminous comfort but also to energy savings and peak electricity demand reduction. Successful daylighting designs optimize the daylight contribution to electric lighting, while minimizing negative effects on heating and cooling loads. The net impact on energy requirements is a function of location, window orientation, window-to-wall ratio and glazing visible and thermal properties.
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