How to Become a (Lighting) Control Freak
By Alex Rippere
While previous articles have covered 2016 New York City Energy Conservation Code (NYCECC) changes regarding building envelope and HVAC performance, one key area not addressed is lighting. The energy code has always set requirements for lighting controls and maximum allowed lighting wattage-per-square-foot (i.e., Lighting Power Density or LPD). In other words, designers have long had a budget of how much lighting wattage they can have, as well as a clear mandate on how to control that budget— from simple, manual switching requirements to ultra-complex daylighting schemes.
As a reminder, maximum LPD and lighting control requirements do not apply to dwelling units—including apartments, co-ops, condos, and 1-2 family homes—provided installed lights are “high-efficacy,” as defined by the NYCECC. Pretty much every light-emitting diode (LED) bulb and most compact fluorescent lamps (CFLs) meet high-efficacy requirements. These bulbs can be used extensively throughout dwellings with zero regard to control systems or LPD allowances [C405.1 Exception, R404.1, 90.1-2013 9.1.1 Exception 2].
All other occupancies, including the common areas of multi-family buildings, have a host of lighting rules to follow. Starting with ASHRAE 90.1-2013, known locally as Appendix CA, the lighting control sections in 90.1-2010 18.104.22.168, 22.214.171.124, 126.96.36.199, and 188.8.131.52 were apparently bundled into Section 184.108.40.206, Paragraphs (a) through (i). This complex section identifies specific control requirements for each individual space type, as outlined on Table 9.6.1.
A brief, paragraph-by-paragraph translation of lighting controls follows:
- Local Control. Also known as a manual light switch, which is very important as . . .
- Restricted to manual ON. None of our lighting can now come on automatically, unless . . .
- Restricted to partial automatic ON. However, half of our total lighting power can be auto-on (either half the lights come on, or all lights come on at 50% power), which brings us to . . .
- Bilevel Lighting Control. Just like air conditioning units, lights require their own setbacks. In addition to ON or OFF, an intermediate step should be set to 30%-70% of maximum allowed power. Also, dimmer circuits are always okay, which takes us into . . .
- Automatic daylighting responsive controls for sidelighting. Lights near glazing need to be on dimmer circuits linked to photosensors. Both NYCECC and ASHRAE now call for the same size sidelighting zone, which is way more complicated to calculate than the “15 feet off the glazing” rule from the old IECC.
- Automatic daylighting responsive controls for toplighting. Lights near skylights need to be on dimmers and photosensors. Plus, toplighting with skylights is now required for many occupancies with a suitable roof.
- Automatic partial OFF (full OFF complies). Like item (c) above, we can shut off half our lighting power within 20 minutes of all occupants leaving the space.
- Automatic full OFF. With a handful of exceptions, all lights must shut off within 20 minutes of all occupants leaving the space, unless Table 9.6.1 offers an “auto partial off” option per (g) above.
- Scheduled shut-off. A timer clock kills all lighting in the space during scheduled times, with the added caveat that a manual override can only turn the lights back on for 2 hours during scheduled “lights out.”
Armed with the above lighting definitions, we can consult Table 9.6.1 for the specific needs of our space.
- A simple “–” means “not required.”
- “REQ” means “required.”
- “ADD1” means “at least one of these ADD1s is required.”
- “ADD2” means “at least one of these ADD2s is required.”
An open office space requires local control switching, partial automatic on, bilevel (or dimmable) lighting, sidelight daylighting, toplight daylighting, and automatic full off.
An enclosed office greater than 250 s.f. requires local control switching, with a choice between manual full on or automatic partial on; dimmers; sidelighted daylighting; toplighted daylighting; and a choice between automatic full off or scheduled shut-off.
ASHRAE & NYCECC
Note that the above is all ASHRAE. NYCECC still breaks out interior lighting controls in Sections C405.2.1 through C405.2.4, but the general control flavor is broadly the same, with occupant sensors, timers, manual switches, lighting setbacks/dimmers, and daylighting controls all being generally required, depending on space type and size.
One key difference between NYCECC 14 and 16 is that “daylight zone” has been redefined to match ASHRAE, increasing the complexity of compliance. The old rule called for photosensors and dimmer circuits for any light 15 feet from a window. NYCECC 16 now incorporates similar rules to ASHRAE, with the function of daylight zone depth having more to do with window headers and “obstruction” heights. (The fine details of daylighting can be the subject of another newsletter.)
The Secret of Compliance
Many of these lighting control requirements are not new. Even the 2010 Energy Conservation Construction Code of New York State (ECCCNYS 2010) made extensive reference to daylighting zones and automatic controls. Each energy code update continues to clarify and refine these requirements, but the general compliance theme remains the same: shut the lights off when you don’t need them on.