Your questions answered: How codes and guidelines affect lighting design
A host of questions have been answered in writing for the Aug. 11, 2020, webcast Lighting: How codes and guidelines affect lighting design
Unanswered questions from the Aug. 11, 2020, webcast Lighting: How codes and guidelines affect lighting design are answered here by the presenters:
- Barrett Newell, LC, Associate IALD, Senior Associate, Lighting Design, CannonDesign, Boston
- Michael Chow, PE, CEM, CxA, LEED AP BD+C, Principal, Metro CD Engineering LLC, Columbus, Ohio
Question: What is the best way to document lighting control strategies on construction documents?
Barrett Newell: Lighting controls can be either captured in the electrical drawing with circuiting per fixture labeled, indicating zones. An additional method to document controls is to include a sequence of operations on the drawing itself.
Question: Can we opt for manual on or automatic on to 50% and comply with ASHRAE 90.1 or IECC 2015? If so, which method is easier for compliance?
Michael Chow: The ASHRAE 90.1 that would be compared against IECC 2015 is ASHRAE 90.1-2013. Both IECC 2015 and ASHRAE 90.1-2013 allows for manual on or automatic on to no more than 50% of the general lighting. It is recommended to review the requirements of each code if budget is a consideration. For example, manual controls for lighting are required to provide at least one control step between 30% and 70% plus full on and off. Applies to most spaces in ASHRAE 90.1-2013 and only spaces with timer control in IECC 2015.
Question: If an 11-watt LED lamp is installed in a conventional downlight and the downlight is rated at 100 watts, is the incandescent light able to be rated at 11 watts for energy calculation or does the 100-watt rating need to be used?
Michael Chow: Check with the authority having jurisdiction and/or electrical inspector to determine if this is allowed. Typically, this will be allowed if a permanent label is installed on the fixture (and the existing label removed) that states maximum wattage of 11 watts for replacement lamp. This should allow you to use the 11 watts for the energy calculation.
Question: Are the LED sources the best source for the low ultraviolet application used in the New York library case?
Barrett Newell: Yes, LEDs are by nature very low in UV light, making them a great source for this kind of delicate material. Traditional sources like halogen, fluorescent and incandescent lights have a higher UV content.
Question: Do you find indirect light fixtures to be easier to look at? For instance, in the autism building with a lower color temperature like 2,700 K and indirect lighting, would it be a better design?
Barrett Newell: Indirect fixtures can provide a lower glare lighting solution. Direct/Indirect volumetric troffers were used to reduce glare in offices, while an indirect component was used in the linear fixtures in the waiting area. By throwing light up on to the ceiling, as well as directly down, the contrast ratios in the space were decreased, making the whole space “easier” to look at.
Question: Based on your lighting controls budget during your design development phase of most of your everyday projects, are you looking more into stand-alone room controller specification options or more into the larger budget of network lighting control systems?
Michael Chow: It depends upon the client’s budget and if they require networked lighting control systems. For example, typically, it is more cost-efficient to install stand-alone occupancy sensors in private offices than it is to install networked occupancy sensors. However, network occupancy sensors could allow remote overrides, time of day shut-off, etc.
Question: How did you address controls in relation to emergency egress lighting code requirements? Did your design use UL 1008 branch circuit relays to transfer to emergency circuit?
Michael Chow: I work with the client to determine if they want battery backed emergency lighting or if they will utilize a life-safety emergency generator. Most often when a generator is used, I specify UL 1008 devices. These devices are transfer switches. Transfer switches are used to transfer the power source of the emergency circuit from normal power to backup power in the event of normal power loss.
Question: From time to time I am asked by an architect to layout 2×4 lighting to an office or corridor, and I’m an electrical engineer who doesn’t use any lighting design software. How do I know I’m picking the correct fixture and number of fixtures, spacing, etc.?
Barrett Newell: My recommendation would be to talk to a local rep agency. Most of them have staff in-house that are able to make fixture selections and run calculations to ensure that the appropriate fixtures, wattage and light levels are met. Or you can use the Lumen Method of calculating lumen output on the surface based on the information provided on a fixture cutsheet.
Question: Can you touch on how the LED is replaced in an integrally LED luminaire when it fails?
Barrett Newell: Most integral LED fixtures have a removable LED board that can be replaced down the line — this includes point source (i.e., downlight) or linear. Manufacturers track the lumen output and color temperature based on serial numbers so that if the source needs to be replaced, a consistent board can be provided.
Question: What is the solution for lighting maintenance in industrial dusty environment?
Barrett Newell: Gasketed or sealed fixtures should be considered in dusty environments. This will allow for simple cleaning of the outside of the fixture for removal of any dust, without allowing dust inside the fixture.
Question: Where can I find brief hospital light design details?
Barrett Newell: RP-29-16 Lighting for Hospital and Health Care Facilities
Question: What are the most critical considerations when selecting lighting and lighting controls based upon energy code?
Barrett Newell: Minimum code required lighting controls and wattage — all minimum code requirements for your specific jurisdiction should be adhered to including allowed lighting power density.
Question: Are there LED fixtures that do not have drivers?
Michael Chow: Some LED light sources come with their own internal drivers. Examples include screw-in LED lamps typically used to replace CFLs or incandescent lamps). Generally, screw-in LED lamps have a shorter life span than other LED lamps with separate drivers. This is because of the close proximity of the driver and LEDs. Heat given off by the driver may shorten the life of the LEDs. The screw-in LEDs have the driver and LEDs closer together than typical LED fixtures with separate drivers.
Question: Please describe the means for controlling glare on PC screens.
Barrett Newell: It is recommended to use lensed or indirect sources in locations where PC screens are being utilized a majority of the time. This may still be visible on a screen, but will be less harsh than say an open downlight where the source itself is visible.
Question: Are you concerned with all the brightness of bare lamps being shown?
Michael Chow: Yes, glare should be considered for all lamp sources especially LEDs. LEDs are directional. Indirect and/or prismatic lensed fixtures can help reduce the glare of LEDs.
Question: Can incandescent bulbs be legally manufactured?
Barrett Newell: According to Wikipedia, “In 2014, the Department of Energy issued regulations that would extend the efficiency standards of the 2007 EISA law to some specialty bulbs, effective January 2020. The new standards would apply to Edison, globe and candelabra bulbs among others. In February 2019, the Department of Energy announced a proposal to withdraw this change. In September 2019 the Trump administration rolled-back these energy efficiency standards for lightbulbs with the Energy Department’s Federal Register. The Energy Department announced the reversal of the 2014 regulation that would have taken effect Jan. 1, 2020. and implemented the last round of energy-saving light bulb regulations outlined by the Energy Independence and Security Act of 2007.”