Energy Efficiency | May 20, 2021
Why LED Lighting Projects Should Include Controls
Upgrading from fluorescent lamps to LED lighting provides huge energy savings. Period. The efficiency gained from today’s LED lighting is far greater than when we would simply upgrade fluorescent fixtures with more efficient fluorescent lamps and ballasts in the past. Energy savings don’t just come from upgrades to lamps and fixtures anymore but can also be captured by implementing a lighting controls strategy.
Lighting controls should be a part of your retrofit projects when possible because of the additional savings and benefits they provide.
What are Lighting Controls?
Lighting controls are integrated, programmable systems which allow users to not only manage light output (and in some cases color temperature) but also monitor energy efficiency and even equipment location tracking. These controls are defined broadly as Tier One, Tier Two or Tier Three systems, with the abilities and benefits increasing with each Tier.
Types of LED Lighting Controls
There are several ways that LED lighting can be controlled. LED lighting retrofit projects most commonly utilize occupancy sensors, photocells (which can allow for control schemes such as daylight harvesting), high-end and low-end trim adjustments, grouping and/or scheduling.
We broke down the definitions of these common lighting controls types for you:
Occupancy sensors are a type of lighting controls that can sense a person in a space and turn on and off as required. Retail and grocery stores are applicable beneficiaries with occupancy sensors in freezers and reach-in coolers. Manufacturers, warehouses and libraries can also leverage this tool to control lighting above rows and aisles.
To leverage daylight harvesting, a fixture has a photocell which allows it to dim down to the input level set for matching foot candle requirements (definition below).
SIMPLE DEFINITION | Foot Candle
A foot candle is the measurement equaling a one-foot radius sphere or one candela (the base unit of luminous intensity).
The recommended light level for an office space from the IES (Illuminating Engineering Society) is 35 FC (foot candles). Though not a type of lighting controls, a foot candle is a measurement should be understood as an important part of lighting and controls design.
High-End Trim and Low-End Trim
High-end trim is defined as setting a fixture’s level of output during “occupied” mode. Many LED fixtures can produce much higher lumen levels than the fixtures they replace, and the high-end trim can match the needs of the space and comfort for those using it. As the LED fixture is used over many years it will slowly degrade, and this high-end trim can then be easily adjusted to match the same lumen output to bring back the original desired light level.
Low-end trim is set for when fixtures are in “un-occupied” mode. In some cases, this means shutting the fixture off. In other cases, such as a data center that has rows of equipment where a person could be obscured from a motion sensor, the low-end trim might be 5-10% for all lights so that a safety issue isn’t created if the system goes into unoccupied mode.
SIMPLE DEFINITION | Lumen
A lumen is the measure of the output of visible light from a fixture which can be measured in foot candles. A foot candle measures one lumen per square foot.
Grouping fixtures is self-explanatory: it means having the ability to group (or re-group) sets of lighting fixtures and program them according to different need sets because each grouping has its own aux sensor.
Examples of grouping: In the data center scenario described for low-end trim, that setting is used to keep light levels at a certain threshold depending on which part of the data center a technician is in. Grouping fixtures means two things: (1) that the data center can additionally group rows of fixtures or parts of a larger room together and control concurrently and (2) if it’s a colocation facility and server rows might change by tenant, the lighting groups can be re-grouped depending on the layout of the space.
Scheduling LED lighting fixtures means setting times for lights to turn on or off throughout the day.
Color Temperature and Color Tuning
Lighting controls with color tuning ability adjust a fixture’s lighting color temperature along the red to blue spectrum, measured in Kelvin. Color tuning is meant to mimic the changing color temperature of the sun throughout the day.
Circadian rhythm, though not technically a lighting control component, is the term for daily human cycles which we most commonly associate with sleeping at night and being awake during the day. In this context, the sun also has a daily cycle where it is brighter around noon and appears slightly red later in the day. Controls give LEDs the ability to match these color temperatures. This kind of solution would make a lot of sense for any company with 3rd shift workers. This helps nighttime staff experience the progressing rhythm of “natural light.”
Tiers of Controls for LED Lighting
The three tiers of LED lighting controls not only give you options for managing your lighting systems but can unlock greater energy savings and utility incentive dollars to cover project cost. Here’s a breakdown of lighting systems by tier:
Tier One lighting controls have limited benefits beyond manual adjustments.
- They can use individual wall occupancy sensors that can be programmed individually.
- They may also come as non-programmable ceiling sensors – there is no ability to control lighting levels beyond a wall dimmer switch.
Tier Two lighting controls allow for wireless integration directly from the fixture to a tablet or phone.
- These controls are also sensors which identify occupancy and vacancy of rooms/spaces.
- These allow for high-end trimming or output adjustment of lights. A LED fixture is brighter than the fluorescent fixture it usually replaces and typically does not need to be on at maximum capacity. Over time, the output for the fixture can be raised to account for the fixture’s output depreciation.
- These controls have the capacity to program gradual timeouts. As a space is no longer occupied or needs less light during certain times of day, the levels can/will change based on occupancy and your chosen settings. For example: if a restroom is unoccupied, the light levels may come down 25% at a time.
- You can also group the fixtures into zones, which can be done for part of a room or an entire floor of a building.
Tier Three lighting controls allow for monitoring and high-level sensor integration which reports back to a dashboard and can be integrated into a Building Management System.
- Not only do you get all the benefits from a Tier 2 system, but these controls are integrated directly into the Building Management System (BMS). This can be used to then have your HVAC to respond directly to the occupancy controls of the lighting, providing granular control of your mechanical systems.
- When spaces are not occupied the zoning can be programmed with the HVAC system for turning down the temperature as well as the lights. This saves even more energy while allowing for high-level monitoring and metering of all building systems.
- For large buildings, Tier Three Controls enable demand response capabilities for the lighting system. Utilities around the country have programs that pay large energy users to turn down energy use to relieve stress from the power grid.
- The cost increase from Tier Two to Tier Three controls is typically 10-40%. Depending on your facility and needs this cost will be absorbed into your savings when combined with other energy efficiency upgrades.
The Future of LED Lighting Controls
Adding controls to a lighting upgrade should be looked at whenever possible. Some technologies are more proven and economically feasible than others. Controls that can adjust color temperature or mimic circadian rhythm are available but not very cost effective – yet. As the adoption grows and costs lower, these controls could provide real advancement in lighting when integrated to a full BMS.
Our bodies are designed to respond to light levels as the day progresses. Employees working a night shift (nurses, manufacturers, security) are awake when there is no natural light. Programming buildings to mimic daytime light levels and colors may truly have health benefits for these and other individuals.
The effects of lighting at work and home cannot be overstated. Improved light levels combined with granular control deliver important aesthetic and practical impacts in an environment. At this stage of the energy efficiency evolution, LED lighting with some level of added controls is often an option for most efficiency retrofit projects.
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