IECC Q&A: Switches and lighting occupancy sensors in storage rooms
In this column, we will address some of the typical questions asked of our technical support team. As always, code opinions issued by International Code Council staff are based on published Code Council codes and do not include local, state or federal codes; policies; or amendments. This opinion does not imply approval of an equivalency, specific product, specific design or specific installation and cannot be published in any form implying such approval by the International Code Council. As this opinion is only advisory, the final decision is the responsibility of the designated authority charged with the administration and enforcement of this code. All code citations reference the 2018 International Energy Conservation Code (IECC) unless otherwise specified.
Switches and lighting occupancy sensors in storage rooms
Q: The situation is a stock-storage room for a retail establishment. Section C405.2.1.1 of the 2018 International Energy Conservation Code (IECC) requires that occupant sensors need manual control. Our client wants a ceiling-mounted sensor only with no wall switch override. Section C405.2.1.1, Condition 3, says a manual control is required. Is it acceptable for this area to be controlled only by a ceiling occupancy sensor (on and off) without a manual control switch on the wall? The reality is the employees are likely not to use the switch and the ceiling sensor would control the lights 99 percent of the time.
A: No, Section C405.2.1.1 provides no exceptions for the manual control requirement. Occupant sensors are automatic control devices that detect occupancy and adjust lights in response to the presence or absence of people in the space. Most devices can be calibrated for length-of-time delay between the last detected occupancy and extinguishing of the lights. Section C405.2.1.1, Condition 1, specifically requires that this time delay cannot be longer than 20 minutes, the shorter the time delay setting, the greater the energy savings, as the lights will spend more time “off.”
Occupant sensors save energy by turning lights off automatically. In most spaces such as the stock/storage room referenced, occupant sensors must be configured to turn on automatically to not more than 50-percent power (Condition 2), and an accessible switch must be provided to bring lights to full output. Turning lights on automatically never saves energy because there are many instances where a user would not choose to turn lights on. For this reason, full automatic-on is only permitted in “public corridors, stairways, restrooms, primary building entrance areas and lobbies and areas where manual-on operation would endanger the safety or security of the room or building occupants” (see the exception to Section C405.2.1.1, Condition 2). Remember that even in these spaces, an accessible manual switch must still be provided to allow occupants to turn lights off where they choose (C405.2.1.1, Condition 3).