There’s nothing quite as unsettling as a dark stairwell. The thought of having to use a dark stairway instantly brings fear and uncertainty and makes many people feel unsafe. I think I might even want to walk down the middle of the ramp in a parking garage rather than venture into the unknown of its dark stairwell. This doesn’t have to be the case. We’re going to discuss stairwell lighting, how to properly light a stairwell, and some features of modern stairwell lights that will even help lower your electric bill.
Dangers of Dark StairwellsEvery multi-story building from commercial offices to residential complexes must have accessible stairwells. The biggest danger of the image we painted above of the dark stairwell has got to be occupant safety. Who knows what or who might be lurking in the dark landing below, just out of sight? The darkness can be used by criminals hoping to catch you by surprise on your way to your car at night. In a commercial or industrial setting, many common slip and trip injuries occur in the stairwells. While not every fall can be attributed to improper lighting, it can certainly be a contributing factor. Improper lighting might cause you to miss a step or trip as you go up the stairs. Ensuring properly lit stairways will eliminate at least some of these accidents at your workplace. There are other dangers present on public stairwells. These include the wear and tear of stair treads that result in an unstable surface, unsuitable handrails and uneven spacing between stairs. These issues can all be exacerbated by a lack of lighting.
Current Stairwell Lighting RegulationsAs with other types of spaces, there are recommendations and regulations in place that specify a lighting level that should be maintained in these areas. We'll summarize these below, but feel free to explore the codes for more detail. In general, the minimum light levels required in the means of egress is 1 foot-candle (fc). The NFPA, however, has specified that the minimum light level on new stairways should be no less than 10 fc measured on the floor when in use. There are some exceptions to this for performance areas during the course of a performance. For this type of space, for example, the light level is allowed to go down to 0.2 fc on the walking surface. In addition to the above, the stairwell is required to be lit even in the event of a power outage. The minimum light levels are still 10 fc and the lighting must be on for a minimum of 90 minutes.
Energy Efficiency OpportunitiesThe lighting system for stairwells traditionally has been designed to operate 24 hours per day. Not much thought was put into specifying a two-lamp F32T8 fixture and wiring it to be always on. This means that a building owner would expect to pay up to $78 in electricity per landing for each stairwell in the building. This can multiply quickly for buildings with many floors and multiple stairwells. For example, a building with ten floors, two stairwells, and one fixture per floor would consume $1,555 in electricity just to light the stairwells. Modern LED stairwell lights consume less energy and are easier to control. In addition to smaller emergency battery packs, we can now configure fixtures with occupancy sensors or step-dimming sensors. These will either turn the fixture off completely when the stairwell is empty or dim them down to a lower level to reduce the energy consumption of the fixture. As soon as someone opens a door, even if it’s on the landing above the fixture, the ultrasonic sensors would bring the fixtures back to full brightness. By implementing bi-level occupancy sensors, the ten story building from the example above can lower the energy use in the stairwells by 75% to 95%.
What to Look for in a Stairwell Lighting FixtureSince the stairwell is part of the emergency egress path for a building, it’s important to make sure that these are working properly. Here are factors to consider when choosing your stairwell lighting fixtures:
- Style: Do you plan for the stairwell to be used heavily and conform to the aesthetics of the rest of the building or should they be more utilitarian and economical?
- Ruggedness: Normally, these fixtures wouldn’t be exposed to harsh treatment in a commercial building, but if you’re working on a parking garage, you may want to consider vandal resistant fixtures. Some fixtures have optional wire guards that can protect the lenses without being fully vandal proof. These features will let the fixture stand up to abuse without breaking.
- Light Distribution: the amount of area that a single fixture will cover will heavily impact the total cost of the project. Placing a fixture on a wall vs. having it installed on the ceiling can mean the difference between one fixture per floor or more.
- Occupancy: For the vast majority of stairwell fixtures, occupancy sensors or bi-level dimming sensors should be considered. This would increase the savings in the space and still let the fixtures meet their intended life safety purpose.
- Emergency Battery: As mentioned before, these fixtures have to operate when the building loses power. An emergency battery pack or connection to building emergency circuits is required.