When looking to install a new or upgrade an existing lighting system, where should you start to determine what you need?
First, survey the existing installation to determine the system age, era of equipment, and the basic type of system. For instance, you might find an office building full of 1980s-era fluorescent troffers that were retrofit with T-8 lamps and electronic ballasts in the mid-1990s. This will tell you whether the lighting system can be successfully upgraded in place, or whether a wholesale relighting is needed.
While you are at it, determine the type and age of lighting controls. Also take a look into how the branch circuits are wired. In most existing buildings you will find basic pipe-and-wire branch circuits with switching devices, such as wall box devices and ceiling sensors, but occasionally you will discover a prefabricated wiring system or a relay control system. This will inform you the extent to which lighting controls can be easily added.
Next, weigh relighting rather than retrofitting.
What Is A Lighting Retrofit?
In the context of an energy saving lighting project, the term retrofit typically means a straight replacement of components in an existing lighting system. In other words, a 1-for-1 replacement of luminaires.
What Is Relighting?
A relighting project treats the facility as a blank slate defining an entirely new lighting system. In these instances, the existing lighting is no longer meeting the needs of the illuminated environment. A solution is defined as one that meets new requirements in the most energy efficient and financially compelling way possible. The energy efficiency is of utmost importance, even over cost.
Retrofitting is usually the least expensive and the faster payback; relighting is usually much more expensive and has a longer payback. On the surface, most people would take the faster payback. But remember, the return is an annuity, not a loan payoff. With an annuity, increases in the rate of electricity will make the larger investment better over the long run, a wiser investment for an institutional property. Moreover, relighting increases the value of the property and usually makes a bigger difference in appearance than any other improvement. This can increase lease rates for commercial properties, and for institutions, they can modernize older buildings at a faction of the cost of major remodeling.
For tenant improvements the smaller investment might be better — but remember, when you cherry pick the smaller investment, then the longer investment is no longer available and you're stuck with less income over time. Also, be careful with whom you consult during this period. There are a lot of companies that "cherry pick" projects, putting in the fastest payback solution. They will offer 30 to 40 percent energy savings with payback in two to three years. They will not tell you about the 60 percent annual savings with a payback of six years.
Also, for goodness sakes, avoid any sales pitch that employs spectrally enhanced lighting or any of its other sales pitches. Many companies claim that the spectrum or color of their lighting systems are better and that is why they can reduce lighting energy. What they are doing is reducing light levels, too. The IES has now clearly stated that S/P ratio and related spectral enhancements cannot be used to reduce light levels or create "equivalent" light levels for general illumination purposes, and specifically NOT for energy efficiency arguments.
Lighting Controls Offer Energy Efficiency, Cost Savings
How can lighting control strategies offer increased savings? What is an overlooked control strategy that can help save money?
Outstanding savings are possible from controls — especially for lighting systems that are already moderately efficient. For instance, I assisted a major Southern California client in a controls-only retrofit with over 50 percent energy savings and less than 3 year payback — yet their lighting system had already benefitted from a T-8 lamp/electronic ballast delamping retrofit 10 years prior.
The most overlooked controls strategy is tuning. Tuning involves installing dimming ballasts and reducing general lighting levels 15 to 25 percent. This is fairly easy for most office buildings — provide users with 6- to 9-watt LED task lights and, if particular groups or departments complain, increase only their department to almost full output. Most workers are happy with lower light levels anyway. Just don't go too low — 20 to 25 footcandles is a good average light level for most offices these days.
Balancing Lighting Functionality with Aesthetics
How do you balance functionality with aesthetics?
Aesthetics are only part of the problem. Now that we know that the brightness of the ceiling and upper walls is critical in maintaining circadian systems, I like to start with ambient indirect lighting and wall washing for vertical surfaces, including walls and major partitions. Task lighting can be added as needed surprisingly, a large percentage of people are happy with a dimmer environment because they can see computer screens better. Of course, this really only applies to workspaces. For classrooms, I promote daylight first and then, direct/indirect lighting to help with the circadian benefits. For retail lighting, hospitality lighting, and other challenges, many times aesthetics are a more dominant part of the project, and some loss of efficiency and/or utility may be sacrificed to achieve an overall appearance or ambience. But I think that really good lighting designers give up nothing, although it may cost the owner a bit more. Take, for example, the Apple store in London — it grosses about $2,500 per square foot per year. Why save $2.50 per square foot in lighting construction with a resulting reduction in appearance and/or functionality of the store as a whole?
How Natural Lighting Affects Lighting Choices
How does the use of natural lighting change the way you determine what you need from both practical and aesthetic standpoints?
We can start by asking Walmart Stores, Inc. They studied skylights in 1998-2000, and discovered that sales could increase between 31 and 49 percent due to daylighting alone, regardless of other factors. And their approach is not fancy — one could say that Walmarts with daylight do not necessarily look better— they just FEEL better, and shoppers spent more money. The average Walmart’s sales are about $325 per square foot — skylights cost about $5 per square foot. Increasing sales at least $100 per square foot for a $5 investment sounds pretty good to me.
Or, in groundbreaking research by the Heschong Mahone Group, students in daylighted classrooms performed 20 to 25 percent better on standardized tests than students in classrooms without windows and using ordinary lighting. Ask yourself a question — if your child could learn 25 percent better every year, what is that worth to you? With daylighting costing about $5,000 per classroom, how many parents would line up to pay $100 a family to properly equip theirs schools? If it were a drug, this would be cheap. Well, daylight IS a drug, but natural and not a pharmaceutical. And don't forget, skylights save energy, which itself pays for the daylighting in 10 years or so. I can't imagine why schools aren't required to be daylighted.
What we don't really know for sure is office lighting and industrial lighting. Productivity improvements due to lighting are hard to measure, largely because human health and wellness factors enter into the consideration. People are less healthy with poor sleep quality, obesity, dietary issues, and other problems resulting in part from being indoors too much. I think employers don't believe that environmental improvements can make a difference in most cases, because these maladies are part of 21st century living. I also think that enlightened employers will learn to embrace wellness and encourage employees through a number of changes to their environment, as well as other benefits and rewards. For instance, add skylights to a warehouse or industrial space, and in office buildings, don't isolate workers from daylight by executive offices. The old dinosaur ideas about "cost effectiveness" and status need to give way to modern ideas of smart profitability.
Answers provided by Jim Benya, principal, Benya Lighting Design, and partner, Benya Burnett Consultancy. Benya is a professional engineer and lighting designer with 39 years’ experience in architectural lighting design. He is the author of two books, “Lighting Design Basics” and “Retrofitting and Relighting.”
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