By Susan Martig
From the October 2019 Issue
Whether it’s a commercial high-rise, campus laboratory, or office lobby looking for a refresh, odds are the legacy building you operate contains antiquated lighting. When it comes time to perform a lighting retrofit, those working with older facilities often find this more complicated than anticipated. Perhaps the lighting controls aren’t integrated into the building automation system (BAS); they lack the capacity to control the multiple zone lighting they desire; and facility infrastructure is years behind current code requirements. These can all be stumbling blocks to achieving the best new lighting design for your facility, but these don’t have to be.
Before engaging in a lighting retrofit, consider the following six best practices.
1. Design to the latest code IECC 2018, or beyond. Whether or not your state has adopted the latest version of the International Energy Conservation Code (currently, IECC 2018), compliance ensures energy and operational efficiency and will eventually be required of all facilities engaging in a retrofit. Here are three key IECC 2018 updates:
- Lighting power density requirements were lowered across the board by 4% to 24%, depending on type of space. Newer, more advanced LED lighting will help.
- Every 600 square feet of open office space needs to be controlled separately (previously every 5,000 square feet in IECC 2015). Having more zones allows for each area to be operated independently, resulting in increased flexibility. This updated rule also requires more coordination between the architect and engineer to allow for proper placement of corresponding switches.
- Time clocks are no longer allowed as the sole automatic control, as sensors must be used to control lighting in a space. While this change is significant, it will further increase energy savings.
Tip: Align furniture with the lights. If there is a row of furniture every 15′, place the lights every 15′, or 7.5′. Otherwise, occupants located in between controlled zones will not have a comfortable light level.
Tip: Place sensors at the middle of the controlled area where lights and furniture are aligned so no one is left in the dark—literally.
2. Lower power density. In line with IECC 2018, lowering lighting power density reduces wattage per square foot, while still maintaining the same light output. Traditionally, lighting designers would utilize dimmers to do this with dimming ballasted fluorescents, a fairly costly venture, but today that’s not necessary. Instead, the best way to do this is to employ LEDs with integral drivers and dimming as a standard feature. As many as 95% of new construction lighting is done with LEDs because these last longer and provide more light output compared to fluorescent and incandescent bulbs.
In addition to employing LEDs, consider increasing lumen efficiency or re-spacing the number of fixtures to lower power density while maintaining lighting levels. The most efficient way to do this is to utilize AGi32 or other digital lighting design software, which allows designers to pinpoint optimal placement and lumen output, based on code requirements and design objectives.
LEDs will run anywhere from 100 lumens/watt, to even more efficient 150 lumens/watt and up. This is in comparison to 50 to 100 lumens per watt for fluorescent and five to 20 lumens per watt for incandescent.
LEDs not only have a greater light throw, but also a longer lifespan. At a minimum, 50,000 hours of light output is probable with an LED, with ratings for 150,000 to 200,000 hours easily achievable.
3. Build in flexibility. When designing today, consider tomorrow. If the facility is located in an area where daylighting is not code yet, consider designing for daylighting. If you have a facility in a state that does not require vacancy sensors in lieu of occupancy sensors, consider installing them anyway. For example, when moving from IECC 2015 to IECC 2018, required zone size shrinks. Even if a facility manager doesn’t need to control multiple zones right now, he or she may want or need to in the future.
Case in point: A facility that was previously rented by a single tenant is now converting to a multi-tenant space and will need multi-tenant controllability. Choosing a modular lighting control system today will make this future conversion easier and less costly.
4. Connect base building lighting to the BAS, when applicable. For owner-occupied, enterprise facilities, this will give the building operators one point of control for the entire lighting system, providing the convenience of checking on a floor after-hours, or modifying control set points for areas from a single point for multiple areas at once.
In a tenant-occupied building with base building lighting, this provides the benefit of a single point of control for those base building lights in conjunction with the traditional BAS functions of the HVAC system.
5. Integrate advanced sensor systems. Sensors are the eyes and ears of a building’s lighting infrastructure. As facilities look to employ more IoT and smart devices and equipment, advanced sensor systems will become the data collectors of the lighting infrastructure. Similar to fixtures, more advanced systems will provide data on occupant usage, energy expenditure, and lumen output that can be used to inform building program and space use decisions.
6. Consider designing above code. Designing above code (i.e., to IECC 2018 or above), even if your state only requires IECC 2015 or less, is more energy efficient and also paves the way for future lighting upgrades. For example, IECC 2018 requires office buildings to be designed to a maximum of .79 watts/square feet, but if it’s possible to design to .50 watts/square feet or less in a space, that’s ideal. When designing a space for .50 watts/square feet vs. .79 watts/square feet, the savings would be 37% on lighting costs, even without other factors considered.
Most states have adopted either the International Energy Conservation Code (IECC) or American Society of Heating, Refrigeration, Air-Conditioning Engineers (ASHRAE-90.1) as their energy code, which follow a three year update cycle. For IECC, this means 2012, 2015, 2018, and so on. For ASHRAE, this means 2010, 2013, 2016, and so on. States will typically have a three or six year cycle of updating code. Check with the local authority having jurisdiction (AHJ) to determine which energy code applies in each area.
Ultimately, new codes raise the bar, challenging lighting designers and their clients to meet higher standards of energy efficiency with the latest in technological innovation, while still maintaining the program needs of each space. Following these tips will lead to a brighter tomorrow for today’s facilities.
Martig is a senior project engineer at Chicago-based Environmental Systems Design, Inc. She has designed lighting programs for buildings across Chicago and around the world and is passionate about finding a balance between code requirements and specific client needs.
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