Building Operating Management

Make Lighting Upgrades Match the Paybacks

Efficient lighting can save money, but not all upgrades deliver on their promises. Simple steps can avoid disappointment

By Lindsay Audin   Energy Efficiency

Amidst all the buzz about new energy-efficient lighting technologies and how much money they save, a fair amount of grumbling may still be heard. Many facility executives who have done lighting upgrades are looking eagerly at their energy and maintenance bills and are surprised (and frustrated) they haven’t realized the savings they were expecting. Some have been so dissatisfied that they are putting off more lighting upgrades until they feel certain such efforts will bear financial fruit.

To avoid disappointment, start by determining just how much is being spent on existing lighting — in energy, labor, and materials. Use that baseline to measure the savings — or extra costs — that actually occur, instead of just wondering if one is canceling the other. When ordering new lighting systems, specify in advance what results are to be attained for a project to be considered successful. And don’t be dazzled by the latest gimmicks. There’s plenty of well-proven technology to apply.

Put in place the necessary metering or data loggers to demonstrate savings, and stock spare parts for the inevitable early failures during the startup period. Track the life of installed products, and don’t be shy about enforcing warranties. Consider ways to contractually hedge potential costs, such as failed components, so they are both limited and known in advance.

A basic point about lighting upgrades bears repeating: Savings are measurable reductions in costs or use. Projections or back-of-the-envelope estimates are not savings. They are sales tools. Too often, they are supported by assumptions on lighting energy use that are erroneous, overly optimistic or based on misinformation. To measure a change requires establishing a baseline against which new numbers will be compared. Without such a starting point, there’s no way to tell whether savings really exist.

One of the most common errors made by contractors trying to sell lighting projects is in the assumed annual burn hours of a lighting system. In many cases, actual operating hours are much lower. Lights assumed to be on more than 3,600 hours a year — based on a facility’s 14-hour per day schedule — may, on average, really be on only about half that time. While hallway and bathroom lights, for example, may indeed be lit 24/7, cleaning or security people may shut off the other 90 percent of the lighting after only 9 hours per day. Some spaces, like storage or unused rooms, may be off for months at a time.

To secure a more accurate assessment of burn hours, place temporary lighting loggers in typical rooms for a week or two at a time. Such devices run on long-life lithium batteries and record when lights are on and when rooms are occupied. The data is easily downloaded through a standard computer connection and can show load and occupancy profiles on an hour-by-hour basis, or on shorter, user-defined intervals. Knowing when lights are on may also help determine the potential reduction in peak demand once new lights are installed. Knowing when rooms are lit but unoccupied qualifies possible savings from deploying occupancy sensors.

Determine Burn Hours

If lighting loggers are not feasible, a quick-and-dirty way to estimate evening operating hours is to observe the building from outside on several nights, both weekday and weekend. Log the proportion of windowed perimeter spaces where lights remain on for extended periods.

Accurately determining burn hours is, however, only part of the battle. Knowing the true wattage draw of existing fixtures is also essential. Many err by using the rated watts of existing lamps and ballasts, multiplied by their quantity, to determine total lighting wattage. In reality, magnetically ballasted fluorescent fixtures may draw less power in hot locations such as high ceilings, spaces lacking mechanical cooling or unventilated plenums. Lamp light output will also be lower than their ratings, occasionally resulting in overlit spaces once cooler or more efficient lighting is installed. To avoid such situations, contractors or in-house electricians should use a watt meter to sample actual wattage loads of fixtures running in place for at least an hour. Don’t be surprised to find that a fixture expected to pull 92 watts is pulling only about 84.

Some lighting audits or fixture counts fail to take into account existing burnouts. Where burned out lamps are not quickly replaced, realize that some “savings” have already occurred due to their missing wattage. Instead, an increase will occur when a new lamp is installed, regardless of its efficiency, assuming the total number of lamps remains unchanged. The space will be better lit, but such improved conditions tend to chip away at projected wattage reductions.

To get an accurate feel for overall lighting power use and patterns, take sample consumption and demand readings on lighting risers feeding known spaces. Clamp-on current transformers, connected to portable data loggers, work as de facto submeters to segregate power usage for lighting from the rest of the loads seen on the building’s main utility meter. Only a few weeks of such data collection is typically needed to establish usage numbers and patterns. Data loggers are available with several channels, allowing multiple risers at the same location to be easily monitored. Both consumption and hourly demand will be seen using the logger’s software.

Performing a similar analysis right after the lighting installation allows a realistic determination of lighting energy and cost savings. When tied to a performance contract that ensures payment from a contractor for savings the system fails to deliver, the customer is generally protected from bogus claims or savings projections.

Another common error in estimating dollar savings from lighting upgrades arises when average electric rates are used instead of taking into account how power prices vary over time. Most facilities use much more power during peak hours than at other times, and the hourly cost of electricity is typically higher during such periods. Using an average electric rate, derived by dividing annual costs by annual kilowatt-hours, blends together all uses of power, including those that occur during off-peak hours. As a result, the true cost of lighting may be obscured.

On the other hand, lighting used during off-peak periods may not cost as much. Shutting off or dimming lights at those times will therefore not save as much, especially in locales where peak demand charges are high. To properly assess the dollar impact of an upgrade, a professional lighting efficiency design takes into account the prevailing cost of electricity as it impacts each type of change, including fixtures, sensors and daylighting. The end result may be that some improvements save more dollars — and others fewer — than is seen when average rates are used.

Where Savings Come From

High-performance T8 lamps and ballasts offer significant savings over early T8 systems installed only a decade ago. T5 lamps may offer higher photometric efficiency in smaller fixtures. Dimming ballasts, combined with daylight sensors, may significantly reduce power consumption. Occupancy sensors are getting smarter, while LEDs are all the rage. But do they last, and why are replacement parts so expensive?

First, let’s be clear about how high-tech lighting saves money: It cuts electrical usage and demand. Yes, it may cost more to install and maintain than older technology. But look at the total picture: Energy represents about 86 percent of the overall cost of lighting. Labor is only 10 percent. Material costs trail far behind at only 4 percent, with recycling included.

Some facility executives, seeing only work orders and lamp invoices, but not energy bills, fail to understand that while maintenance costs may rise, such increases pale when compared to reductions in energy bills due to more efficient lighting. And don’t forget some of the hidden bonuses: more efficient lighting also cuts cooling loads, postponing chiller plant upgrades.

But there are ways to avoid, or least minimize, such sticker and overtime shocks. Start by specifying the upgrade more thoroughly and completely. When requesting bids, require that the cost of replacement lamps and ballasts be defined in the bid, as well as product failure rates. A ceramic metal halide lamp that replaces a high-wattage incandescent, for example, may cost 10 times as much, but may last 10 times as long, thus canceling out its initial cost over time while avoiding nine relampings in the process. Many electronic ballasts are now failure-rated (e.g., “less than 500 per million”) so specifying a maximum acceptable rate is no longer unusual.

Avoiding Problems

Insist on lamp and ballast warranties, and enforce them. Doing so may require better tracking of what-got-installed-when-and-where, but a computer spreadsheet of such data, provided as part of the upgrade and maintained by facility staff provides the necessary warranty backup. Doing so may also reduce maintenance time: Knowing in advance what type of lamp/ballast is in each space avoids any need to return to the bulb room to find the right unit.

To minimize the irritation of early failures, build into all bids a small stock of replacement parts (especially ballasts and sensors) or ensure that such parts are readily available within 24 hours.

And resist the temptation to go with the highest level of state-of-the-art technology. Early adopter’s remorse may result. Every new device has a break-in period during which kinks are worked out, typically in the field. Once again, demand and enforce warranties. If a vendor is unwilling to provide the same warranty for a new device as exists for a standard off-the-shelf version, don’t buy it. Be ready, however, to pay a bit extra to secure that warranty.

If all this seems like too much for in-house personnel having many other duties, consider using a lighting efficiency consultant or project manager to oversee the design, specification and installation of the project. Problems will be avoided, immediate installation costs secured and a more easily maintained system installed.

To cut overtime needed to replace failed lamps and ballasts during the rated lives, consider specifying that a maintenance contract be built into bidders’ proposals as an add option. Such a contract would act as an insurance policy in case of early failures by requiring, at a fixed annual price, labor to replace failed equipment. If the offered price is high, that may reveal that the contractor’s confidence in the parts being used is low. As with any insurance policy, payment occurs even if no failure occurs, but the annual cost is known and the risk of high overtime cost has been hedged.

Similar steps may be taken when installing devices, such as occupancy sensors and daylighting systems, that may involve callbacks for adjustments. Specify that the contractor’s bid include unlimited, or a defined number of, callbacks during the three months following job turnover. Consider an option for quarterly “tune ups” during the first year to address any need for adjustment due to seasonal variations in natural lighting. Some types of occupancy sensors are self-adjusting and, while more expensive, may greatly reduce the need for later adjustment. A contractor may suggest using them to minimize callbacks, so don’t immediately dismiss that option because of its higher price.

Understand System Interactions

One cause for early burnouts is excessive cycling of lighting by occupancy sensors set for too short a time-out period. While a bit more energy is saved by short time-outs, there’s a point where lamp/ballast life may be compromised. Most fluorescent lamps, for example, have rated lives based on three hours per start. A lamp designed to last 24,000 hours may therefore be expected to survive roughly 8,000 starts (24,000/3 = 8,000). If started 20 times a day for a year, however, nearly all of those 8,000 starts will be consumed in one year, regardless of actual burn hours. Under normal use (i.e., 3 hours per start), the same lamp could be expected to last between five and 10 years.

Overall lighting cost savings may instead be maximized by setting a longer time-out period, 15 minutes instead of five, for example. Doing so may burn a bit more energy, but lamp/ballast stress is greatly reduced. Because much of the energy saved by sensors is during long periods of absence, the extra 10 minutes of burn time may have a negligible effect on energy cost savings, but a huge impact on lamp life.

Proper ballast specification also plays a part. When using occupancy sensors, it may pay to use programmed start ballasts instead of instant start units. While the latter save a few watts per ballast while running, and may have a lower first cost, the former are much kinder when starting lamps, thus stretching their lives.

Because any new technology may create unknown challenges, some facility executives perceive “holding off until I’m sure” as a viable risk management policy. With energy prices both increasing and becoming more volatile, that’s a bit like hiding one’s head in the sand. A more professional approach is to find ways to play a small risk against a bigger one, in this case the potential for a bit more maintenance against ever-rising energy costs worth nine times as much.

Check Your Power Quality

In the case of electronic ballasts, early failures at a given site may be an indicator of hidden power quality problems. While magnetic ballasts were highly resistant to power fluctuations, many electronic ballasts are more vulnerable. In areas with extreme electric storms, or far from transmission lines, or where voltage sags and spikes are common, some attention may be needed to the electric service, installing capacitor banks or surge suppression, for instance.

The same may be true in buildings with very old electric service, or industrial facilities where process loads, like electric furnaces or very large motor startup loads, routinely stress site power distribution. In such situations, use a clamp-on data logger to assess the consistency of the power wave form and the magnitude/duration of power transients. If a problem is found, fixing it may also save electronic systems, like computers, worth far more than lighting.

— Lindsay Audin


Saved by the Submeter

In one case, a lighting upgrade at a medical facility appeared to save little or no money: The monthly electric bill barely budged. Unknown to the contractor was that, simultaneous with the upgrade, the facility had installed a new MRI and other heavy duty medical loads which ate most of the lighting savings. Had the lighting upgrade not been installed, however, the monthly bill would have instead shot up due to the cost of those new loads. But — not being engineers — the bean counters in the accounting department claimed there were no savings and held up paying for the new lighting.

Fortunately for the contractor, the electric service was split to serve several panels, each monitored by a separate utility meter. Those meters were then totaled by the main utility billing meter. By reviewing the untotaled meter readings, the contractor found that one meter — which monitored power for only the lighting panels — showed a distinct drop, relative to readings prior to the upgrade. Readings on meters covering the new medical loads, however, jumped considerably. The savings had been found, and the bean counters satisfied.

— Lindsay Audin

Lindsay Audin is president of EnergyWiz, an energy consulting firm based in Croton, N.Y. He is a contributing editor for Building Operating Management.

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  posted on 5/1/2008   Article Use Policy