Alleviate Your Energy Woes With Wireless Lighting Controls
By Brent Protzman
Commercial buildings in the United States have an installed base of 2.1 billion lamps—80% of which are linear fluorescent lamps. Despite the fact that lighting control strategies, including dimmers, occupancy sensors, timers, daylighting controls, and energy management systems (EMS), are acknowledged to yield very significant energy savings, fewer than 31% of these lamps are associated with any type of lighting controls in the field (Ashe et al. 2012).
That leaves 70% of lamps not associated with lighting controls, and a lot of missed energy-saving opportunity. Studies show that lighting accounts for up to 38% of electricity consumed in commercial buildings. Lighting controls can reduce that energy use by up to 60%, or 23% of total building electricity use (Energy Information Administration 2006). Lighting control strategies can also help buildings meet enhanced energy codes, contribute to Leadership in Energy & Environmental Design (LEED) certification, improve comfort, and enhance productivity.
Current Design Trends and Building Codes
Lighting control strategies deliver a variety of efficiency benefits, including reducing lighting energy, helping to minimize peak demand, and helping to reduce HVAC loads. Some of the most powerful motivators driving efficient lighting design in new construction and major renovations are code compliance and increasing concern about the capacity of the existing power grid, and energy costs.
The average retail cost of US electricity is 9.8 cents per kilowatt-hour, but in major metropolitan areas where commercial building space is at a premium, those costs are much higher—17 cents in Boston, MA; 14 cents in Los Angeles, CA; and 16 cents in Washington DC. In New York City, NY, electricity costs as much as 23 cents per kilowatt-hour (National Electric Rate Survey 2013).
In many states, prices for peak demand versus regular demand fluctuate wildly, driving businesses and utilities to look for ways to reduce energy use, especially during peak use times. Peak periods generally occur in conjunction with hot, bright, sunny days when daylight is abundant, and when the air conditioning is running nearly 100% of the time. This scenario is ideal for using daylight harvesting control to reduce both lighting power and additional demand on HVAC systems. Lighting controls can deliver significant savings that go directly to the bottom line.
Electricity cost is not the only factor. The US electrical grid has been plagued by increasingly disruptive blackouts over the past 15 years. In an average year, outages total 92 minutes per year in the Midwest and 214 minutes in the Northeast. Japan, by contrast, averages only 4 minutes of interrupted service each year. In August 2003, a power surge in western New York and Canada affected more than 100 generating plants, compromising the power supply in eight northeastern states and parts of Canada (Amin 2011).
As US utilities struggle to meet increasing demand for power, federal and state agencies are also stepping in to regulate energy use. Demand Response (DR) programs also help to alleviate stress on the power grid by managing customer electricity consumption in response to fluctuations in the electrical supply. The goal of these programs is to keep electricity supply at a steady, controllable state by automatically reducing energy use to avoid costly power outages. Lighting control strategies are extremely effective for quickly reducing lighting power in a facility, delivering immediate results in a demand event with virtually no adverse effect on employee comfort or productivity.
Energy efficiency standards and guidelines developed by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) are now mandated by the Department of Energy. As of October 18, 2013, all state commercial building codes must meet or exceed ASHRAE 90.1-2010 standards, and, in addition to occupancy controls, new standards generally include mandatory requirements for daylight control, multi-level control, and bi-level stairwell control. Other allowable building standards, such as IECC and Title 24, include similar daylighting requirements in their updated recommendations.
If this is all starting to make your head spin, stay with us, because installing energy-saving lighting controls in your facility can be much easier, and more cost-effective, than you might think.
Taking the Guesswork Out of Energy Savings
The first layer of opportunity is often a simple fixture retrofit, sometimes considered the low-hanging fruit. In buildings where T12 linear fluorescent lamps are still the primary light source, relamping with more efficient T8 or T5 lamps, or new LED sources, can immediately save 40% lighting electricity or more. Manufacturers now offer dimming technologies that can work with virtually any light source, and are offering enhanced sales and support services to ensure that the control technologies are compatible with whatever light source is specified.
Layered control strategies including occupancy sensing, dimming, daylight harvesting, and automated shade control can achieve lighting electricity savings of up to 70% (see the additional content section of this article), or more throughout a facility.
Occupancy/vacancy sensors work to ensure that lights are not left on when a space is vacant, generally saving an additional 20–60%. To further enhance energy savings and to meet codes such as Title 24, vacancy sensors will automatically turn lights off when a space is vacant, but lights will only turn on if the user manually activates the lights.
Digital dimming/Daylight harvesting
In perimeter spaces, daylight sensors can be used in combination with digital dimming controls to automatically adjust light levels based on the amount of daylight in the space. Daylight harvesting can also contribute 20–60% lighting energy savings.
Controllable window shades, controllable louvers, and dynamic glazing can significantly reduce or eliminate the heat contribution from solar radiation, which can be up to 93 W per square foot—1,000 W per square meter— (Ziegenfus 2012), while controllable window shades can also provide an air barrier for additional R-value (insulation’s ability to resist heat traveling through it).
Automatic shading systems create even greater efficiencies by working in conjunction with lighting control strategies to reduce demand on electric light, while improving comfort and even protecting furniture and carpet. Daylight sensors automatically adjust light levels based on the amount of daylight in the space. When sheer shades reduce heat and glare, but still allow ample daylight into the space, daylight sensors can reduce electric light levels accordingly.
Not only can lighting control systems make a tremendous contribution to energy-saving goals, but unlike other building systems, lighting power reductions can be implemented gradually so that they go unnoticed by the occupants in a building, resulting in a win-win, in terms of reduced lighting energy use without compromising comfort or productivity.
Wireless Controls—Retrofits Made Easy
Most lighting control technologies can be implemented using either wired or wireless protocols, but over the last few years, improvements in radio-frequency technologies and available controls often make wireless installations especially beneficial for retrofit projects. Wireless controls reduce labor costs and installation time, mitigate risks, and, depending on the manufacturer, are easier to reposition, repurpose, and reprogram.
Reduce material and labor costs; minimize downtime
In both retrofit and new construction, wireless solutions reduce the need for additional wiring, conduit, and other materials such as relay packs and cabling, and reduce installation time by as much as 70% over wired options. In addition, once the infrastructure is in place for wired controls, it is difficult to reposition sensors and controls if the existing physical space conditions change, or are modified. Wireless controls allow optimal placement onsite, further reducing callbacks and unnecessary changes to the project.
Most commercial building tenants cannot afford to be displaced during fixture retrofits. Unlike wired solutions, which require that walls be opened up and a space be temporarily unused, wireless installation can easily take place after hours, allowing employees to return to normal operation the next day.
In many older buildings—prime candidates for fixture and control upgrades—asbestos is a common concern. If materials containing asbestos are in good condition, left undisturbed by construction and renovation, they generally present minimal risk. Wireless solutions can be installed without disruption, minimizing risk and reducing cost. Wireless solutions also reduce design time and virtually eliminate installation errors. Contractors and engineers can spend less time identifying exact locations for the controls—they can effectively identify the optimal control location while they are in the space.
Easy to reposition, repurpose, and reprogram
Ideally, the locations of either wired or wireless solutions are determined long before installation, but realistically things often change during the construction/renovation process. Office partitions get moved, employees reconfigure workspaces—even tenants change. Repositioning an installed, wired control is time consuming and difficult, typically requiring new wiring, patching, and painting. Wireless sensors or controls can easily be adjusted to accommodate the current office layout or occupant in just minutes. And, depending on the product design, reprogramming a wireless control can also be accomplished quickly, and with the touch of a button.
Return on investment is top of mind for most facilities. Occupancy-sensing lighting control strategies typically pay back in less than two years. Total light management strategies, including dimming and daylight harvesting, typically pay back in less than five years while delivering significant flexibility and control for space occupants.
|Credit: ©Halkin Architectural Photography LLC
Sheer shades reduce heat and glare, allowing ample daylight into the conference room at
Ben Franklin TechVentures.
Wireless Controls More Broadly Recommended, Specified, and Installed
A recent survey by the Lighting Controls Association (DiLouie 2013) shows that wireless control solutions are gaining in popularity, due mainly to the reduced installation and material cost. Sixty-four percent of survey respondents said they were specifying wireless controls in a higher percentage of projects than they had in previous years, and in general, respondents indicated they were quite satisfied with the overall product installation, citing ease of installation and reduced overall installed cost as the major reasons for the growing acceptance of wireless solutions. More than 50% of respondents indicated that they were choosing solutions with manufacturer-based, or proprietary protocols.
Occupancy sensors are shown to be the most widely installed wireless technology (installed in more than 50% of projects), but respondents also reported photosensors in 40% of projects, a wireless switch or dimmer to provide additional control in a space that already had a single switch or dimmer in 30% of projects, and individual luminaire or addressable RF control in more than 40% of projects.
Survey respondents were also asked to rate certain factors as the greatest barriers to adoption. Their most significant concerns were related to integrity of the wireless signal and commissioning/programming requirements. With so many new players in the wireless control industry, it is easy to understand these concerns, but careful product selection can alleviate any uncertainty.
Choose a manufacturer with many years of experience with RF wireless technology, and be certain to demand proof that the controls will perform reliably, and without interruption from other wireless signals. When occupancy sensors are installed, investigate control sensitivity to ensure that lights will stay on when occupants are in the space and stay off when the space is vacant. Controls should be designed to detect fine motion so that an occupant who is reading, typing, or doing paperwork won’t be left in the dark.
Another factor to consider when selecting a lighting and control system is service-after-the-sale. Work with a manufacturer that offers a strong service organization with the bandwidth and experience to provide system startup, training, and ongoing support to keep the system, and the building, performing at optimal levels. Manufacturers may offer an optional service to ensure that the sensors are correctly placed, and operating as expected in the new or renovated workplace. These services can provide assurance that the lighting controls will perform as expected, maximize energy savings, ensure the comfort of workers in the space, and improve the facility’s bottom line.
Wireless controls have been installed successfully in office buildings, on college campuses, in historical structures, and many other space types, and are delivering proven energy savings that reduce the bottom line.
Glumac, a sustainable engineering firm, used wireless shade and light control solutions throughout their renovated office space to automatically adjust electric light levels in response to available daylight and space occupancy. The lighting and shade controls are fully integrated with the building management system, allowing Glumac to track, monitor, and adjust lighting energy use to achieve maximum efficiencies in the space, and ensure occupant comfort. The firm was able to reduce lighting energy use by 47%, compared to Oregon code.
Although energy efficiency was critical to space design, the firm’s principals were equally concerned about the architectural appeal of the space, and the installation budget. Wireless control did not require unsightly surface conduit, ensuring that the retrofit maintained the clean lines and uncluttered atmosphere that made the space so appealing.
|Credit: ©Halkin Architectural Photography LLC
Light management strategies can improve the experience of using a space, adding to the ROI.
Wireless occupancy sensors, switches, and relay modules allowed Pepperdine University to reduce lighting energy usage on their Drescher campus by 20–30%, and reduce overall HVAC use by an additional 14%. The school originally planned to install a wired system, but the installation and material costs exceeded budget requirements, and did not ensure the same, high-level results. By meeting budget and energy-savings requirements, Pepperdine was able to take advantage of a special program offered by its utility, Southern California Electric, to install the solution at no cost to the school.
Many utilities offer rebate, or direct install programs that can significantly reduce the cost of materials and improve return on investment. Be sure to check with the local electricity provider to take full advantage of available rebate opportunities.
Lighting control represents a tremendous energy-saving opportunity in virtually any commercial space, and wireless controls offer cost-effective, flexible, and results-oriented solutions for facilities working to reduce energy use, increase sustainability, and improve their bottom line.
Amin, M. (2011). US Electrical Grid Gets Less Reliable as Outages Increase and R&D Decreases. University of Minnesota College of Science and Engineering. Retrieved November 26, 2013, from http://tli.umn.edu/blog/security-technology/u-s-electrical-grid-gets-less-reliable-as-outages-increase-and-rd-decreases.
Ashe, M., D. Chwastyk, C. de Monasterio, M. Gupta, and M. Pegors (2012). 2010 US lighting market characterization. Prepared by Navigant Consulting for the US Department of Energy. Retrieved online November 15, 2013.
DiLouie, C. (2013). LCA RF wireless controls survey. Lighting Controls Association. Retrieved December 2, 2013, from http://lightingcontrolsassociation.org/lca-rf-wireless-controls-survey.
Energy Information Administration, 2003 Commercial Buildings Energy Consumption Survey. Building Characteristics Tables released December 2006. Online. Retrieved from www.eia.gov/emeu/cbecs/cbecs2003/detailed_tables_2003/2003set1/2003pdf/a1.pdf.
Lutron Electronics Case Study: Glumac Sustainable Engineers. Retrieved December 3, 2013, from www.lutron.com/en-US/Residential-Commercial-Solutions/Pages/SolApp/Corporate/OpenOffice/Glumac/Glumac.aspx.
Lutron Electronics Case Study: Pepperdine University. Retrieved December 3, 2013, from www.lutron.com/en-US/Residential-Commercial-Solutions/Pages/SolApp/Education/College/PU/PepperdineUniversity.aspx.
National Electric Rate Survey (2013). Lincoln Electric System. Retrieved online December 3, 2013, from www.les.com/pdf/rates/rate-survey.pdf.
Ziegenfus, S. (2012). Demand response and light control. ASHRAE Journal: November 2012. Retrieved December 3, 2013, from www.bacnet.org/Bibliography/BACnet-Today-12/Ziegenfus-2012.pdf.
Author’s Bio: Brent Protzman, PHD, LEED GA, CEM, LC, is Lead Architectural Engineer at Lutron Electronics, doing energy and application research and analysis, engineering system integration, and architectural applications.