Lighting controls hold the key to ultimate energy efficiency

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As David Fisk, president of building services engineering body Cibse, recently commented: “Lots of people think they’re looking for LEDs, but what they ought to be looking for is the lighting performance that they’re trying to get, then go back to decide whether LEDs are the solution.” (Lux magazine Sept 2012)

 

This advice is echoed by Guy Simmonds, head of sustainable solutions – Europe at light control specialist, Lutron:  “Although LEDs are in vogue, the real trick is managing both artificial and natural light properly to achieve maximum efficiencies over the life of a building”. Although in the past lighting was the ultimate ‘fit and forget’ technology in commercial buildings, Simmonds explains the strategies that need to be built in from day one to ensure a successful long-term lighting control solution in terms of energy efficiency and occupancy satisfaction.

The test of a good lighting installation isn’t what it can control on day one, but what it can control on day two thousand and one. With this in mind, ensuring that lighting levels and energy consumption can be monitored, measured and then altered as required is essential for a building’s long-term energy efficiency. This is where individual fixture control is vital. Controlling each fixture digitally gives the user ultimate flexibility over the control of the building; allowing monitoring on a granular level. The digital fixtures can be interrogated by the control system and that data then be used to optimise the system. Regular reports on the usage patterns of the building, energy consumption of each space, the effect of seasonal daylight and many other factors provide information which can inform decisions on changes the user can implement to gradually drive down savings.

Alongside individual digital fixture control is the importance of choosing a lighting control solution that has an easy to use, flexible monitoring software solution. By having an intuitive control system that is straightforward to use and adjust, the building services manager has the tools at their disposal to monitor and make adjustments to the system on a regular basis, to continually reduce energy usage.

The key to the success of a lighting scheme in a commercial installation is two-fold; are the occupants productive and do the percentage energy and cost savings over time meet and/or exceed expectations? Although the former can be somewhat subjective in terms of measurement, the latter should be totally objective. This is only possible if a long-term monitoring programme has been built into the lighting control solution from day one. A case in point of the power of longer-term monitoring and regular adjusting for impacting energy consumption comes in the form of the iconic New York Times Building, which has indeed stood the test of time.

New York Times hits energy saving headlines

The New York Times Company’s headquarters in Manhattan was designed by world-renowned architect Renzo Piano, along with two major architectural firms, FXFOWLE of New York, and Gensler. The 52-story tower is a mix of office and retail space. “The whole building structure is designed for maximum light,” said David Thurm, vice president and chief information officer of the Times Company. “The number one priority was to allow natural light to make our employees feel more comfortable and to produce an energising work environment.”

After six months of testing in a specifically designed replica of a zone of the office space, the Times Company decided to select Lutron’s Quantum light management solution for its office space. Quantum employs a number of different strategies—including daylight control, occupant control, target set point control, time clock control, and emergency lighting control —to give building occupants maximum comfort and to give business owners the flexibility to adapt their work environments to meet changing business requirements. Quantum also features software to control, monitor, and report on the lighting usage in the building.

Following installation of the system, Glenn Hughes, the then director of construction for The New York Times Company during design, installation, and commissioning commented: “The energy usage savings are stunning. Lutron’s lighting control system has delivered an absolutely over-the top performance. When I talk with other construction and lighting consultants, they’re astonished at the results.” Thanks to the systems comprehensive monitoring and reporting software, the building’s lighting consumption was tracked and altered at regular intervals and the results have shown a significant progression in the building’s energy efficiency as engineers have been able to adapt lighting to suit occupancy needs.

After the building had been occupied for a year, Glenn Hughes, now president of Glenn D. Hughes Consulting Associates, utilised Quantum’s 30-day energy usage report to see for himself the energy saving statistics achieved by using the Quantum solution. “We designed our building to use 1.28 watts per square foot of lighting power,” Hughes said. “With Quantum, The New York Times Company is using only 0.38 — that’s 70% less.”  Hughes said the figure of 1.28 watts per square foot of lighting power was within the local code in effect when the building was constructed. It has since tightened to about 1.1 watts.

Following a full year in operation the data showed that Lutron’s Quantum total light management system was yielding a cost savings of $30,000 per floor, per year, with the lighting energy savings exceeding the previously reported benchmark. Hughes continued: “the Lutron lighting control system has established an excellent baseline and the building is poised to achieve even better energy savings as the system parameters are tweaked.” Thurm commented: “What we have achieved with our building is spectacular, but any office space eventually needs to move in different directions and this lighting system gives us the flexibility to change as we see fit.”

The lighting energy savings achieved by The New York Times Building is primarily from the following strategies (Source: Lutron Electronics).

• 58% - Light level tuning (setting the appropriate light level for each space)

• 30% - Daylight harvesting (dimming electric lights when daylight is available)

• 10% - Occupancy sensing (turning off lights when spaces are vacant)

• 2% - Scheduling (turning lights off during certain times of the day)

As can be seen from the New York Times installation, the energy savings were not from artificial light control alone, almost a third of lighting energy efficiency was achieved through daylight harvesting. The Quantum total light management solution used at the New York Times building included Lutron’s Hyperion Solar Adaptive Shading, which automatically adjusts and repositions the window shades based on the sun’s position throughout the day, effectively managing daylight penetration throughout the commercial space.

The power of daylight harvesting is obvious however its efficacy can be affected by installation and commissioning errors. Due to the unique nature of most daylight coverage, each daylighting zone needs to be tailored to suit that space’s requirements. This is where working closely with the manufacturer to ensure that commissioning support is provided is essential to the overall efficacy of the installation. Below is a detailed list from the US Lighting Controls Association of recommended calibration and commissioning activities to ensure a daylight harvesting control system operates to its maximum potential:

With many building spaces remaining unoccupied between 40% and 70% of the day (Source: Lutron Electronics), it is no surprise occupancy and vacancy sensors have played such a significant role in reducing energy consumption at commercial buildings such as the New York Times.

With the introduction of RF versions of formerly wired-in sensor solutions, there is even less excuse for retrofit as well as new build commercial properties to include these easy to install light control solutions. When integrated into a commercial light management solution, the savings they can deliver are significant.

Strategies for success

By managing both artificial and natural light properly, it is possible to achieve maximum efficiencies over the life of a building. The strategies that need to be built into a system from day one include the following: ensuring all of the fixtures are digitally controlled, using a light control solution that has easy to use, flexible monitoring software to facilitate regular monitoring and adjustments and making sure the installation and commissioning of the daylight harvesting system are supported by the manufacturer. Keeping these strategies in mind will maximise the potential of the lighting control solution in terms of long-term as well as shorter-term energy efficiency and occupancy satisfaction.

 

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