Digitized lighting networks maximize LED value propositionJeff Perkins for Zondits, August 15, 2013
The lighting systems of 2013 would be instantly recognizable to Thomas Edison. Little has changed since his days in Menlo Park, NJ, with even his own screw-base socket and bulb all too dominant. And while the emergence of LED-based solid-state lighting (SSL) is spoken about frequently, it is not clear that people understand that LED lighting is more than just an efficient light source. SSL provides the means to completely transform and digitize lighting, creating networks that both extend energy savings and provide many other benefits to building owners, ranging from optimum light quality to maximizing usage of space.
If we rolled the clock back to 1990, Alexander Graham Bell would have instantly recognized the telecommunications network. Little had changed in 100 years. The network was still largely a copper, analog, mechanically switched network. By 2010, 20 years later, that entire network had been fully digitized — replaced and transformed into an optical, digital, packet-switched network. With that transformation, usage patterns changed and data volumes, revenues, and value all increased by orders of magnitude. A similar transformation awaits lighting.
People coming at this next generation of lighting from the silicon industry are highly optimistic. They are accustomed to rapid and complete domination by digital solutions. However, while they understand the need to accommodate an installed base, they are not familiar with the building trades and the convoluted array of stakeholders and difficult change dynamics associated with the industry. At the same time, those coming at this new technology from the energy-efficiency industry understand the difficult change dynamics of the building trades, but they are perhaps overly cautious about the technology based on decades of experience looking at gaps between promise and performance.
Of course, the reality of the LED promise lies somewhere between the exuberance spilling forth from the silicon industry and the caution exhibited by the energy-efficiency industry. At the LED chip level, the promise is incredible. Light output efficacy well over 250 lm/W has been proven and that is exciting. However, getting from these high chip-level efficacies at the R&D level into an office ceiling fixture at a competitive dollar per lumen level has been a different story.
The harsh reality is that the best system-level efficacies and lifetimes for LED luminaires available today only just match more widely understood and accepted fluorescent systems, and the SSL alternatives cost considerably more. At current levels, this technology cannot win on efficiency and lifetime alone.
Lost opportunities are growing
Energy efficiency in the US is a big business, with current spending on demand-side efficiency incentive programs at $7 billion annually, which in turn drives equipment spending of hundreds of millions. Moreover, efficiency incentive programs are expected to double by 2025.
Lighting systems have been at the forefront of these efficiency efforts from the start, and changes in overall system efficacies and reliability have been on a steady pace upward for more than 30 years. LED technology is just the latest entrant to this highly active market.
This level of ongoing activity means that older, less-efficient lighting systems are being replaced every day. While the costs of LED systems are dropping and will continue to do so, today on a like-for-like basis the price/performance gap persists. The real importance of the persistence of this gap is the fact that it creates lost opportunities. As traditional lighting technologies continue to win in the efficiency-driven lighting retrofit market, with system lifetimes on the order of a decade or more, every new T8, T5, or HID retrofit installation is a long-term lost opportunity for LEDs, and a delay in digitization.
Linear fluorescent costs will remain lower than LEDs on a dollar/lumen ($/lm) basis for the foreseeable future. In addition, the challenges of the retrofit market dynamics and a deeply entrenched analog mindset for lighting will further hamper the transition. While LED efficacies will soon exceed those of fluorescents, and costs will come down, persistence of fluorescent and HID technologies in the retrofit market risks creating ongoing lost opportunities for LEDs for at least a decade. This should be a concern to building owners and efficiency programs everywhere.
It’s the system, stupid!
The most unfortunate part of all this is that it should not be the case. Looking at the problem on a $/lm basis misses the greater potential offered by LED lighting: the means to create digital lighting networks. If LED technology is looked at as a one-for-one replacement for current analog lighting solutions, the greatest potential of the technology is lost. Like the transition in the telecom infrastructure and the benefits they have reaped, that is the transition awaiting the world of lighting.
The full promise of LED lighting systems lies in greatly expanded controllability, interoperability, and even future-proof upgradeability. Starting with the light source, we are replacing vacuum tubes with chips. Sound familiar? We have seen this movie before. Done correctly, in a digitized network traditional AC wiring is dropped for low-voltage alternatives, transforming protocols, simplifying installations, easing maintenance, and trivializing designed usage changes.
State-of-the-art control systems with natural two-way communication will complete the smart lighting network. Taken to the logical extreme, digitization will redefine the parameters of how we use lighting networks, but only if we allow it to do so. To drive these points home, let’s take a look at some concrete examples of the benefits offered by fully digitized lighting networks.
Case study: Data center
To remain consistent with the cloak-and-dagger nature of the data industry today, we can’t mention names or places; however, in an effort to reduce electricity consumption at a large data center, the owner engaged Redwood Systems to install 2,760 LED fixtures coupled with a low-voltage digital control infrastructure. The 2,760 40W LED fixtures replaced 3,000 83W fluorescent fixtures.
This project benefited from rebate programs offered by the host utility. Energy & Resource Solutions (ERS) oversaw pre- and post-installation measurements to verify savings. Using on-site readings, the pre-retrofit baseline consumption for the existing lighting system was calculated to be 2,180,386 kWh annually.
The digital lighting network installed included the lighting system composed of the 2,760 LED fixtures, 94 control engines, and a full array of sensors. Sensors monitor ambient light levels, point and area motion, and temperature. The digital control system or engine delivers DC power and control commands, and enables two-way real-time data exchange.
In the digital network, fixtures are individually addressable, and the network is highly dynamic. The main control engine records data on energy consumption of each fixture, and any fixture or group of fixtures can be totally reconfigured on the fly as needs warrant. The system is used to provide light, of course, but also to inform the building operator of zone access as well as additional building and system parameters.
The post-retrofit installation monitoring, overseen by ERS, was conducted for a period of 42 days. From this data, the annual lighting consumption has been estimated at 198,340 kWh — a reduction of 90.9% from the pre-retrofit baseline.
To be clear, the usage at this facility is extremely unique. In a data center there are long periods of no occupancy where light can be dropped to very low levels, followed by short periods of activity where systems need to ramp instantaneously as sensors detect a need. However, not just any system can match the need exactly, and it must be said that savings this high are the result of a system that is natively flexible and fully capable of matching needs and usage exactly. The overall average-per-fixture wattage use has been reduced from a pre-retrofit baseline of 83W per fixture to post-retrofit of 8.2W.
Case studies: Offices and streetlights
To highlight the networking aspects and non-lighting benefits we can look to a Menlo Park, CA office building with a digital LED lighting network installed that uses data from the system to enhance productivity. Conference room occupancy data generated by the system is monitored to gauge room usage, and is also fed in to building plans and a Microsoft Outlook scheduling system so employees can find and schedule available conference rooms from their desks. Gone are the days of spending time blindly seeking an empty room and then informing everyone where you landed.
Consider the potential of LEDs and networks in streetlighting applications. In a digital lighting network, every fixture can be controlled or addressed individually or collectively, on any scale from a single fixture to a whole neighborhood to an entire city, or any combination thereof. This is a huge benefit that comes with digitization, with communication carried out via the network as installed.
In addition to the energy savings and improved light quality offered, LED streetlighting networks offer a variety of new methods to assist fire and police efforts. In one example, the streetlight closest to a 911 incident can be made to flash on and off. In another case, light intensity can be increased to provide additional light when and where needed, from a specific street to an entire neighborhood.
Looking forward, lighting networks are key to dynamically managing power demand, interacting with the so-called smart grid. Imagine a summer-peaking utility with a large commercial-building lighting load someday in the not too distant future. Due to a crushing heat wave, an extreme demand peak is forecast, and the entire grid is preparing to meet the demand as cost-efficiently as possible.
Years ago, the utility had an aggressive campaign to digitize lighting networks, and as a result a huge percentage of the buildings have fully digitized smart lighting networks with two-way communication. Rather than cutting voltage to vast swaths of the city as was commonplace in years past, the utility now sends demand response signals to the digital lighting networks, and they go into an active demand-shedding mode to trim load.
Dimming LED lighting systems by 15% or 20% can be virtually imperceptible to occupants, and it has the added benefit of increasing efficacies, thus further aiding the grid. Special incentives offered to the largest users have allowed the utility to decrease lighting loads by up to 35% in areas where sensors indicate that daylight levels are sufficient. Faster shut-off times for unoccupied spaces will also be implemented for the peak period, and additional low-use-area shedding will be implemented on an as-needed basis.
These efforts together with other smart grid-enabled actions manage the load without excessive burdens or costs. Shortly after sunset, the demand peak subsides and the demand response signals from the utility cease, and then the systems return to normal function.
Yes, today LEDs can compete with the best fluorescents if we frame the problem in digital terms of greater controllability with a host of additional benefits and features. Utilities should be at the forefront, pulling the smartest lighting networks to market as rapidly as possible and focusing program efforts through design community outreach, pilot projects, and enhanced rebates targeting integration of super-smart controls. Doing so will allow them to build the all-digital grid they so badly need.