Stan Walerczyk 2016-01-13 12:13:17
An expert with more than 27 years in lighting shares some practical knowledge. Introduction It really depends on your definition of cost effective. If you just look at saving energy with many of currently available, very efficient, and low-wattage LED products, you may find that the answer is often, “no.” This includes many applications where controls were cost effective, saving energy with previous LED products, and even high-performance legacy lighting products. Although controls will become much less expensive, LED products will also continue to get more efficient and less expensive. But, other substantial benefits that many controls can provide can make those controls quite cost effective. Those other benefits include: reducing HVAC load in addition to controlling lights, signaling exact wattage and peak load, providing cumulative hours of operation of lighting products, noting certain lighting products that are not working properly, turning on the next hibay for forklift drivers that motion sensors will not trigger fast enough, improving security, properly billing various tenants in master metered buildings, informing how and when various rooms are being used, interior GPS, measuring carbon dioxide and humidity, and, what is probably most important, Human Centric Lighting. Controls Can Still Save Energy Cost Effectively in Limited Applications Controls can be quite cost effective, saving energy with even very efficient lighting in some applications, which can include: • warehouse rack aisles when the hibays are on for long periods of time and nobody is there, • library book rack aisles when the lights are on for long periods of time unoccupied, • rooms and buildings where lights are left on during nights and weekends when nobody is there, • high school and college classrooms, and • rooms with skylights and daylights. But in Many Other Applications It Is a Brave New World Although numerous manufacturers and lighting professionals still promote controls to save energy, many LED products have gotten wattage so low that there is not enough kilowatt-hours for controls to save cost effectively in many applications. This is important for energy-efficient auditors and specifiers, who got in the habit including controls with lighting when lighting was not that efficient and controls were usually cost effective with them. This is also important for energy codes, which are still mandating controls for lighting. Following is a modified version of what I sent the California Energy Commission regarding Title 24, April 10, 2015. First of all, is the summary table for a typical private office (Table 1 above). Since Title 24 mandates controls, there are no rebates for them. If you think the paybacks are bad, they would be much worse with a lower kilowatt-hour rate, such as the national average of 12 cents—or even lower like 9 cents, which is common. Existing Typical Private Office • 10’ x 12’, which is 120 SF • Two 2x4 18-cell parabolic troffers (each with three basic-grade fluorescent 32-W F32T8s and generic standard ballast factor [BF] ballast, which consumes 90 W) • 3,500 maximum annual hours of operation, because the building facility manager or owner turns switch rated breakers on and off every day • 3,000 annual hours, because an office worker does an average job manually turning off the lights in an office when leaving • $0.18 kWh rate • $97.20 annual lighting consumption • There is already good LED task lighting, which will be kept. • Good-sized, south-facing window (with the sun’s intensity and glare, the window blinds are closed most of the time.) Lighting Only • $260 for parts and labor for two 20-W 5,000-K LED troffer kits • $21.60 annual electrical consumption • $75.60 annual electrical savings • 3.4-year payback without rebate • 0.33W per square foot (WSF) This could also be done by retrofitting each troffer with 1 high-lumen 32-W F32T8 850 lamp, 0.71-BF high-performance program start ballast, and upscale kit for about $110 parts and labor. Fixture wattage would be 25. Basic Grade Controls Only • $70.00 to install wall-mounted occupancy sensor • 16% estimated energy savings • $15.55 annual savings • 4.5-year payback without rebate Advanced Controls Only • $140 to install advanced controls; includes modules in fixtures and percentage of transceiver, computer, software, licensing fee, and optional service contract • 25% estimated energy savings • $24.30 annual savings • 5.8-year payback without rebate Lighting and Basic Controls • $330 for parts and labor (This does not include the extra cost for dimmable lighting.) • $79.06 annual electrical savings, of which controls savings are based on 40-W lighting • 4.1-year payback without rebate If controls are mandated, there are probably no rebates for them. Based on getting the lighting down to 40 W, the occupancy sensor would only save $3.46 per year—a 20-year payback—which may be infinite because the sensor may not last that long. Lighting and Advanced Controls • $400 for parts and labor • $81 annual electrical savings • 4.9-year payback without rebate Based on getting the lighting down to 40 W, the advanced controls would only save $5.40 per year—a 26-year payback—which may be infinite because controls may not last that long. Payback in Years Comparison • 3.4 lighting only • 4.5 basic controls only • 5.8 advanced controls only • 4.1 lighting and basic controls (20 years for occupancy sensor assistance) • 4.9 lighting and advanced controls (26 years for advanced controls assistance) Many real-world customers do not want anything over a three-year payback. This lighting option with decent rebates would usually be less than three years. Those customers would not approve any other option, so there would be no energy savings. Paybacks and other financial returns would vary depending on other parameters, which you could do. But even if the percentage savings from basic or advanced controls were doubled, their paybacks would still be terrible when done with lighting. In open offices, each 2x4 troffer could cover 80 SF, compared to 60 SF in this private office, so there would be 0.25 WSF with the same LED troffer kits in an open office. Some lighting professionals consider getting down to 0.5 WSF, the tipping point for controls, to not be cost effective in saving energy. We can usually get well below that. Currently, lighting is often twice more cost effectively saving lighting energy than controls, and LED products will continue to get better and less expensive. Occupancy Sensors May Actually Increase Hours of Operation Occupancy sensors can actually increase the annual hours of operation more than some control proponents may want to admit. This can especially be the case in “owned” spaces such as private offices and elementary school classrooms where a teacher pretty much stays in one classroom all day and/or there are “energy cop” students. Often, people are quite good at turning off lights when they leave, but occupancy sensors allow a 10–15 automatic delay for the sensor to turn off the lights. Based on the average 12-minute delay—4 times per day, 5 days a week, and 45 weeks per year—that is an extra 180 hours per year, which can be considered a wasted month of lights being on. I consulted for an energy service company (ESCO) on a Central Valley of California K–12 school district. The ESCO recommended occupancy sensors in classrooms and did pre and post data logger tests. Although the sensors were cost effective in middle schools and high schools, they increased burn time in most elementary schools. I’m glad I didn’t have to tell people at the school district that they paid for parts and labor for occupancy sensors, which increased burn time. I have seen data logger reports of numerous private offices, showing that office workers are doing a good job of manually turning lights off. Diminishing Returns Diminishing returns are common with lighting retrofits, mainly because there is so little low-hanging fruit left. Although we can still reduce the wattage by 50–65%, the electric bill reductions are about half of what they used to be, and LED products cost more than high-performance legacy products cost in the past. Here is a typical troffer example: A 2x4 troffer with four F34T12 lamps and two energy-saving magnetic ballasts were often retrofitted with two F32T8 lamps, high-performance standard ballast factor electronic ballast, and a reflector. • 90 W = 144- to 54-W reduction (63%) • 3,000 annual hours • $0.15 kWh rate • $40.50 annual energy savings • $65 parts and labor cost • 1.6 payback in years without a rebate Now we can re-retrofit that troffer with a 20-W LED troffer kit. • 34 W = 54- to 20-W reduction (63%) • 3,000 annual hours • $0.18 kWh rate • $18.36 annual energy savings • $130 parts and labor cost • 7.1 payback in years without a rebate So, with these diminishing returns for lighting retrofit projects to be approved, money cannot be wasted on controls, which are not cost effective in saving energy and make the financial returns even worse. Although some people and organizations push lighting for demand response, if you do your homework, you will probably agree with me that electric chargers and air conditioning are much better. For example, one addressable 5-ton HVAC unit at 1 kW per ton can shed the equivalent of 100,000 square feet of 0.5 WSF lighting, which may have 1,250 troffers. One-ton HVAC handles about 400 square feet. Before you recommend lighting controls, do your homework to check if they will be cost effective in saving wattage from lighting. This can include doing the audit while people are working, looking at exterior office windows at night, and installing data loggers. It may be much more cost effective to do more lighting and less controls. Even if people in private offices, school classrooms, conference rooms, break rooms, etc., are not currently doing a great job turning lights off, educating and reminding them may be more cost effective than buying and installing controls. The free stickers that go on light switches can often be useful. Although controls may be cost effective, saving energy from lighting in some applications, you can decide if they should mandated across the board, or if it would be better for lighting professionals and end-customers to decide where controls should be installed. Now Let’s Look at the Bigger Picture of Cost Effectiveness Although controls are often not cost effective, saving energy from lighting, various advanced controls can be very beneficial and cost effective in other ways, as shown below. Reduce HVAC Load in Addition to Controlling Lights Various occupancy sensors, usually wireless ones, can partially close motorized vents in unoccupied rooms, in addition to turning off the lights. Although this can be quite cost effective in new construction, it may be a challenge for retrofits. In general, lower wattage and turned off lighting produces less heat, which reduces alternating current (AC) load. Signal Exact Wattage and Peak Load Various facility managers and corporate “energy gurus” want to know exact energy consumption at any given moment and peak load, which they may try to reduce for lower demand charges Provide Cumulative Hours of Operation of Lighting Products This can be used to help plan relamping, reballasting, or replacing. Typically, group relamping and group reballasting saves considerable money, compared to doing it when individuals burn out. It is usually good to do group relamping and reballasting at about 70–80% of rated life. LEDs usually do not die, but get dimmer and dimmer over time. They are considered end of life at L70, when they have lost 30% of their initial lumens. Since LED products are expensive to replace or retrofit, often one or two years are necessary to obtain enough money. If an LED model has an L70 of 50,000 hours, and it is measured that this model averages 5,120 hours a year, that model should be replaced or retrofitted in 9.8 years, so money should start to be allocated for that about year 8. Note If Certain Lighting Products Are Not Working Properly Signals can be sent that specific lamps, ballasts, and LED products are not working properly. For example, if the LEDs and/or driver are operating too hot in fixtures, they can be automatically dimmed so their life is not shortened and a facilities engineer can be notified. Turn On the Next Hibay for Forklift Drivers That Motion Sensors Will Not Trigger Fast Enough As you may already be aware, many forklift drivers seem to be NASCAR driver wannabes, because they drive so fast. That can result in the motion sensor in each fluorescent or LED hibay not turning on that hibay fast enough. Advanced controls can turn on upcoming hibays fast enough. Improve Security If the lights are automatically turned on in room 911 on a Sunday morning at 2 a.m. and nobody is supposed to be there, a signal can be sent to security. This system could also automatically lock doors so intruders could not escape and maybe also call the police. Properly Bill Various Tenants in Master Metered Buildings Usually, tenants are billed for electricity based on their SF, which is not fair if one tenant is basically only there 8–5 Monday through Friday, and another tenant with the same SF works much longer on weekdays and also works on Saturdays. An advanced occupancy system could measure the monthly hours the lights are used in each tenant space for equitable electric billing and maybe also HVAC usage. Inform How and When Various Rooms Are Being Used Let’s say a company needs more office space and is not sure if either or both of two conference rooms are used very much. Advanced occupancy sensors could be used to determine usage to evaluate if one or both rooms should be converted to offices. Interior GPS This is exciting. Each LED fixture can have a digital address, which merchandise, stock or other materials underneath each lighting fixture can be programmed for that lighting fixture and a cell phone app can be used to locate that material. The image below is a Philips grocery store example. GE has a similar system. Target has started to install a similar system in its stores. Measure Carbon Dioxide and Humidity With this information, HVAC airflow can be increased or decreased. In college dorms, marijuana smoke could also be detected. Human Centric Lighting This is probably the most important in most applications, because this lighting affects both the visual and nonvisual or biologic parts of the visual system. It is optimal dosing of light intensity and spectrum at different times of the day for various tasks to improve circadian rhythms, alertness, visual acuity, mood, productivity-performance, sleep, and general well-being. This really makes lighting much than a commodity. Features and Benefits Features are all of the bells and whistles a control system can do, and benefits are what each customer will really use. For example, Microsoft excel can do a lot of things, but I know that I only use about one-third, so that one-third is my benefit. So, even if a control system looks like it is the best thing, become aware of what you think you will really use. It may not be worth it to spend a lot of money on a control system that has a lot of features, if you will realistically only use a fraction of those capabilities. Combining Diminishing Returns With Soft Benefits As discussed, hard savings—which are reduced electric bills, rebates, and lower maintenance costs—are usually no longer sufficient in projects that were built with fairly efficient lighting or have been retrofitted at least once. This is important, because there is not much low-hanging fruit left, except for “mom and pop” stores and offices that still have fluorescent T12 lamps with magnetic ballasts. Now soft savings usually have to be included. There are two types of soft savings. Basic soft savings include improved light levels, better contrast ratios, less glare, more personal control, and getting rid of parabolic louvers. Based on wasting five minutes less per day, which is 1% of an eight-hour shift, that is a $500 annual benefit for an office worker making $50,000 a year. Advanced soft savings include Human Centric Lighting benefits. Lighting affects both the visual and nonvisual or biologic parts of the visual system. Human Centric Lighting is optimal dosing of light intensity and spectrum at different times of the day for various tasks to improve circadian rhythms, alertness, visual acuity, mood, productivity-performance, sleep, and general wellbeing. This really makes lighting much more than a commodity. A benefit from Human Centric Lighting, then, may be the equivalent wasting 25 minutes less per day, which is 5% of an eight-hour shift, which is a $2,500 annual benefit for an office worker making $50,000 a year. Adding both basic and advanced soft savings may be $3,000 per office worker per year, year after year. End-customers have to approve soft savings amounts. Here is one example: Eight years ago, I specified a lighting retrofit project for several California County buildings and the installation followed. The most common lighting fixture was an 18 cell parabolic 2x4 troffer with three basic grade 32-W F32T8s and generic standard ballast factor (BF) electronic ballasting, which consumed 89 W. They were retrofitted with an upscale kit, two high-lumen 32-W F32T8s and high performance low BF electronic ballast, which consumes 48 W. With 14 cents per kilowatt-hour and 3,000 annual hours, each troffer only consumes $20.16 per year. Now that county wants to do a re-retrofit. But with the low electric consumption, significant costs of dealing with California Title 24, and the International Brotherhood of Electrical Workers (IBEW) cancelling the lighting fixture maintenance category, which otherwise requires $90 per hour inside wiremen, cost effective solutions are a challenge. Retrofitting with TLEDs (tubular LEDs) driven with existing ballasts, which does not trigger California Title 24, may provide the best basic payback based on just hard savings. But this is still not very good. Financial returns are terrible for a fixed Kelvin LED troffer kit. Retrofitting with tunable (dimming and Kelvin changing) 2,700–6,000 K LED troffer kits and adding tunable LED desk mount task lights may provide the best comprehensive long term financial returns when both basic and advanced soft savings are included. This may be the case even though DesignLights Consortium (DLC) does not approve products for rebates that can go over 5,000 K, even though they can also be used below 5,000 K. DLC has not provided any good rationale for that arbitrary Kelvin cap. Good neuroscience and case studies show that over 5,000 K can be very beneficial. Even with a lower hourly rate for installation and without Title 24 costs, basic paybacks would still not be very good. Last Words I have been in lighting and controls for 27 years, and things have really been changing rapidly the last few years. But the evolution should approach the speed of light the next few years. As the Apples, Ciscos, Googles and Qualcomms of the world get into lighting and controls and the IoT evolves, basic and advanced control prices could plummet to less than a dime (Yep, 10 cents for an entire sensor, such as an occupancy sensor, in a fixture. These are small enough to fit into a dimple of a golf ball)—but that is going to take at least a few years. Upcoming sensors with TOF (Time of flight)—sensors, which can detect movement, like how people use a conference room—or other technologies, will be able to self-adapt and learn. This will reduce the need for installers adept with controls, commissioning, and tweaking. It may also reduce the need for lighting designers. So, it will be a greater challenge for lighting and control auditors, specifiers, and others. Stan Walerczyk is principal of Lighting Wizards and vice chair of the Human Centric Lighting Society. He wrote this as an individual; it is not a Human Centric Lighting Society document.
Published by Forester Media. View All Articles.