Lighting uses about 18 percent of the electricity generated in the U.S., and another 4 to 5 percent goes to remove the waste heat generated by those lights. Lighting in commercial buildings accounts for close to 71 percent of overall lighting electricity use in the U.S.
Lighting consumes close to 35 percent of the electricity used in commercial buildings in the United States and affects other building systems through its electrical requirements and the waste heat that it produces. Upgrading lighting systems with efficient light sources, fixtures, and controls can reduce lighting energy use, improve the visual environment, and affect the sizing of HVACR and electrical systems.
Low, mid and high cost energy saving solutions for electrical systems were covered briefly in Chapter 4 – Your Potential Energy Cost Savings. However, when initial investment, life-cycle costing, and energy savings are taken into consideration for electrical equipment upgrades, the end of this chapter provides a detailed list of these with the greatest energy savings potential.
A Whole-System Approach
Many lighting-efficiency efforts are oriented toward the installation of specific pieces of equipment, such as electronic ballasts or compact fluorescent downlights. But as with many other types of complex systems, the interactions among system elements in lighting equipment create energy and power savings that can be greater than the sum of their parts.
Starting with a system of fixtures containing four energy saver T12 lamps, an upgrade to standard T8 lamps and electronic ballasts can produce energy savings of more than 25 percent; using high-performance T8 lamps boosts savings to more than 40 percent.
The next option begins to capture some system interactions. Each fixture is equipped with a specular reflector and a new acrylic flat prismatic lens. Because these are significantly better at getting light out of the fixture than the old, white-painted luminaire and aged diffuser, the fixture can be delamped by 50 percent—to two high-performance T8 lamps—and still provide virtually the same amount of light for the task. Adding reflectors and new lenses to the fixtures enables delamping—a reduction in the number of lamps required per fixture—with little loss in light levels, for a savings of 71 percent compared to the base case.
Adding occupancy sensors and daylighting controls can boost savings to more than 80 percent compared to the base case, and more than 50 percent compared to a system with standard-grade T8 lamps and electronic ballasts.
Use Efficient Light Sources
Efficient lighting begins with the use of as much daylight as possible. After that, choose the lamp / ballast / fixture combination that will maximize efficiency while balancing the considerations of lighting quality and quantity described above. There is a wide variety of light sources to choose from including fluorescent (linear and compact), high-intensity discharge (HID), and newer sources such as induction lamps and light-emitting diodes (LEDs).
These sources vary widely in their efficacy, color quality, service life, and the applications for which they are best suited. Historically, fluorescent lighting has been used for high-quality, general purpose indoor diffuse lighting. HID lighting has been used for industrial and outside lighting.
However, technical advances and a flood of new products have led to some crossover in the way these lamps are applied—fluorescent lighting is now the most effective choice for many industrial and exterior lighting applications, while HID lighting (specifically metal halide) is now a good choice for some interior uses.
Fluorescent lighting systems offer high efficacy, long life, and good light quality, and they generally have few operational limitations for most indoor lighting applications. They are the best choice for general lighting in commercial, institutional, and industrial spaces with low to medium ceiling height. In addition, the introduction of high-intensity fluorescent lamps and fixtures makes fluorescent systems a leading choice for areas with high ceilings (more than 15 feet)—the type of application that used to be the exclusive domain of HID light sources (see sidebar).
Picking the Right Fluorescent Lamp
Manufacturers have introduced a wide array of linear fluorescent lamp choices, including reduced-wattage, premium, and high-performance versions. There are also choices of CCT, CRI, lamp diameter, light output level (standard, high-output, or very high output), and starting method (rapid-start, programmed rapid-start, or instant start). For most general lighting upgrades, the best choices are:
T8 (eight-eighths of an inch in diameter)
Standard-output lamps are more efficient and less costly than high output (HO) and very high output (VHO) systems, and they are available with a wider range of color temperatures. T5HO lamps are often used for high-bay applications because their high-intensity light is useful in large spaces.
CRI in the 80s
CCT of 3,500 K to 4,100 K
Ballast choices can be equally bewildering. The best choices for ballasts are:
Finally, make sure that lamps and ballasts are compatible. Most lamps are only compatible with one starting method; the major exception is high-performance T8s, which can use either rapid or instant-start ballasts.
Compact Fluorescent Lamps (CFL)
Use compact fluorescent lamps (CFLs) to replace incandescent lamps in downlights, sconces, table lamps, task lights, and wall washers. They cost more initially than incandescent lamps do, but quickly pay for themselves through energy and maintenance savings. The longer the annual operating hours, the more attractive the economics of CFLs become, because more incandescent relamping costs are being avoided per year.
One of the most common uses of CFLs in commercial buildings is in recessed downlight cans. A wide range of fixtures is now available for this fixture class, some with very good reflector designs, good optical control, and dimming capabilities. Care must be taken in this application to ensure that excess heat buildup does not shorten the lamp life.
When using CFLs, remember these key points:
Go for a 3:1 ratio
Limit the number of CFL types
Use dedicated fixtures
Choose CFLs that have earned the ENERGY STAR rating
Other Light Types
Depending on the area of usage and purpose, some of these other lighting choices might be a better choice in your facility.
High-Intensity Discharge (HID) Lamps – Wherever an intense point source of light is required, HID light sources are the primary alternative to high-wattage incandescent lamps. Although HID lamps can provide high efficacy in a wide range of sizes, they have special requirements for start-up time, restrike time, safety, and mounting position.
Metal Halide Lamps – Metal halide lamps offer good color quality and efficacies of up to 100 lm/W. Were it not for several limitations of the older probe-start technology, metal halide lamps might be considered the ideal light source.
Sodium Lamps – There are two types of sodium lamps: high-pressure sodium (HPS) and low-pressure sodium (LPS). HPS lamps, which produce a yellowish light, vary widely in their efficacy and color quality.
LED's (Light Emitting Diodes) – LED’s are the latest and most exciting technological advancement in the lighting industry and are small, solid light bulbs which are extremely energy efficient and long lasting.
Induction Lamps – Also called electrodeless lamps, consist of a high-frequency power generator, a coupling device that generates a magnetic field (essentially an antenna), and a glass housing that contains the gases and phosphor coating—no electrodes required.
Submetering & Current Transformer (CT) Monitoring
You can’t manage what you can’t measure. Electric submeters can be installed at discrete points in a building to monitor energy usage by one or more electrical loads (e.g., individual HVACR units) and/or one or more segments of a building. Electrical submeters connect to individual circuits using Current Transformers (CTs).
Every entity that has an energy saving interest in a building (e.g., building owners and operators, energy service companies, consultants, engineering firms, etc.) will want real-time submetering data to track utility costs per floor, per tenant, per equipment, etc. Submetering and CT Monitoring provide a base foundation of understanding consumption profiles in a building.
Achievable Electrical Energy Targets for Commercial Buildings
Application of specific energy savings measures across all building types and climate zones resulted in cutting energy use by nearly half, according to results of approved research funded by ASHRAE. The national weighted change is 47.8 percent more energy efficient than ASHRAE Standard 90.1-2013 based on site energy and 47.8 percent more energy efficient than ASHRAE standard 90.1-2013 based source on energy.
The question of “how energy efficient can commercial and multifamily buildings become in the near future if first cost is not considered” was explored in ASHRAE 1651-Research Project, “Development of Maximum Technically Achievable Energy Targets for Commercial Buildings: Ultra-Low Energy Use Building Set.”
From the resulting list of almost 400 measures, 30 were chosen for additional analysis. Sixteen prototype buildings that were consistent with Standard 90.1-2013, Energy Efficiency Standard for Buildings Except Low-Rise Residential, across 17 climate zones were used as baseline models. The 30 measures then were individually modeled. Each of the 30 measures, often with many options, were applied to each building and climate combination. In general, the measures were applied in the following order:
Reduce internal loads
Reduce building envelope loads
Reduce HVACR distribution system losses
Decrease HVACR equipment energy consumption
Major HVACR reconfigurations
After each measure was applied to each of the 272 building and climate combinations, if the energy consumption was reduced, it remained in the model. After all, 30 measures (which included 9 electrical and 21 HVACR) were applied, the projected U.S. national weighted energy consumption for new buildings was nearly cut in half compared to Standard 90.1-2013.
The 2 general and 9 electrical energy efficiency measures modeled were:
Optimal Roof Insulation Level
Optimal Choice of Vertical Fenestration
LED Exterior Lighting
Highest Efficiency Office Equipment
High Performance Lighting (LED)
Shift from General to Task Illumination
Optimal Daylighting Control
External Light Shelves
Daylighting Control by Fixture
Today is the niinth of 15 installments of the 15 chapters of the second edition of ENERGY Cost Savings For Facilities, by Corey L. Wilson, that will will be presented each week in this newsletter. Each chapter is approximately 3 to 4 pages long covering essential info every FM should know about concerning energy cost savings for their facilities. If you can't wait until the last chapter, you can purchase the guidebook right now by following the instructions below.
ENERGY Cost Savings For Facilities Available in epub, pdf, and paperback versions for $7.99, $14.99 and $24.99. Excellent resource and textbook for facilities and operatons managers, energy industry professionals, sustainability workforce development, educators and students. CHAPTERS 1 – An ENERGY Savings Introduction For Facilities 2 – Your Facilities’ Electrical ENERGY Future is Now 3 – Electrical ENERGY Saving Systems For Facilities 4 – Potential ENERGY Cost Savings For Facilities 5 – Sustainable ENERGY Buildings Plans For Facilities 6 – ENERGY & Buildings Management Software For Facilities 7 – ENERGY Surveys, Inspections, Audits & Commissioning For Facilities 8 – Facilities ENERGY Benchmarking Using Portfolio Manager 9 – ENERGY Efficient Lighting For Facilities 10 – ENERGY Efficient HVACR Systems For Facilities 11 – California’s Time-of-Use ENERGY Rate Changes For Facilities 12 – ENERGY Code Compliance Measures For Facilities 13 – ENERGY Storage Batteries and Beyond For Facilities 14 – Utilizing an ENERGY Savings Plan Budget For Facilities 15 – Implementing an ENERGY Storage System For Facilities