Q: ARE THEY MANDATORY IN IECC 2012?
A: NO. WELL SORT OF, SOMETIMES.
With the recent adoption of IECC-2012 in several states, I’ve heard people say that automatic daylight responsive lighting controls are mandatory in IECC-2012. A close reading of the code reveals that automatic daylight responsive controls are not required, except in some special cases.
In simple terms, here is what IECC-2012 does say about daylight responsive controls: Lighting fixtures in daylight areas must be separately controlled, either manually or with automatic daylight responsive controls. And depending on some building envelope conditions, automatic daylight responsive controls might be required.
Let’s break it down.
Start in the lighting section of Chapter 4, C405, specifically, “C405.2.2 ADDITIONAL LIGHTING CONTROLS”. This says that each area that has to have manual controls (most areas), must also meet the time switch, occupancy sensor, and daylight zone control requirements.
The daylight zone control requirements are in “C405.2.2.3 DAYLIGHT ZONE CONTROL”. It says that lights within the daylight zone (defined in C202) must be controlled independently, according to either C405.2.2.3.1 (Manual daylighting controls) or C405.2.2.3.2 (Automatic daylighting controls). So you have a choice: manual or automatic. Automatic is not required. The lengthy description of the required functioning of daylight responsive controls that follows is just that. It does not say that you have to use automatic daylight responsive controls; it just says just how they have to work if you choose to use them.
Now here’s the part you’ll miss if you’re just looking at the Lighting section. Go to the Envelope section (C402), specifically C402.3.1.1 and C402.3.1.2. These sections say that the Architect can exceed the 30% maximum window-to-wall area ratio limit, or the 3% maximum skylight area limit, if you use automatic daylight responsive controls (and meet some other requirements).
Returning back to the lighting section we next see, “C405.2.2.3.3 MULTI-LEVEL LIGHTING CONTROLS”? It starts off by saying, “Where multi-level lighting controls are required by this code…” and goes on to describe mandatory automatic daylight responsive controls. This is pretty confusing! Didn’t we earlier conclude that such controls are generally not mandatory? And where in the code are these “multi-level” controls required? It’s not in the lighting section (C405). Yep, you guessed it, back in the Envelope section of the code (C402). Here it is: “C402.3.2.1 LIGHTING CONTROLS IN DAYLIGHT ZONES UNDER SKYLIGHTS”. What this section says is that in some “big box” type spaces that have required skylights, under certain conditions, you have to use “multi-level” controls as defined in C405.2.2.3.3. As best as I can understand it, “multi-level” in this case means “daylight switching”, two states – on, and somewhere between off and 35% power.
Short answer: In IECC-2012 automatic daylight responsive controls are generally not required, but might be needed in these cases:
- Buildings with large amounts of window area or skylight area.
- Certain types of large spaces with mandatory skylights.
Clear? No, it’s not you. Yes, this code is poorly written and confusing. I hope this brief explanation helps.