I’m sure we’ve all forgotten to turn of the lights when we leave a room, especially in a restaurant restroom where people are constantly in and out. No one wants to sit in a dark restroom stall and no one wants to be the reason that someone is sitting in a dark restroom stall. The restrooms are a part of the restaurant that are constantly used, but not continuously used. Using motion sensor lights reduces unnecessary electricity consumption from lighting and helps reduce greenhouse gas emissions resulting from energy production.
Why does it matter?
The U.S. Energy Information Administration (EIA) reported in the Annual Energy Outlook 2022 that the residential and commercial sectors combined in the U.S. used 211 billion kilowatthours of electricity for lighting in 2021. That accounts for 5% of the total electricity consumption by all sectors.
Better Buildings (a U.S. Department of Energy program) reports that lighting makes up 10% to 20% of a commercial building’s total energy consumption. For a restroom, it can save between 30% and 90% of the energy used.
The International Energy Agency (IEA) claims “increasing building space and population is driving additional demand for lighting.” A common and easy action to take is switching to LED bulbs decreases energy consumption due to increased efficiency of the bulb compared to its counterparts. As a result, a decrease in unnecessary lighting usage will further reduce the environmental impact of a building and its energy consumption.
In 2021, 875 MT of CO2 (carbon dioxide) was emitted globally due to lighting. That number may not mean anything to you, so how much CO2 is that really? The EPA Greenhouse Gas Equivalencies Calculator estimates that it’s equivalent to the emissions of 234 coal-fired power plants in one year. It’s also equivalent to the amount of carbon sequestered (carbon absorbed and stored naturally) by 1,035,505,991 acres of U.S forests in one year. Even if that didn’t help visualize how much CO2 was emitted, you can probably figure out that it’s a significant amount.
What’s the difference between sensors?
There are two different types of sensors: occupancy sensors and vacancy sensors. Occupancy sensors automatically turn on when it senses a person in the room, and automatically turns off when there is no movement detected after a specific period of time which is manually set. Vacancy sensors are similar, but they are manually turned on and if someone forgets to turn them off when leaving the room, they will automatically turn off like the occupancy sensors do.
There are several ways that sensors can detect movement and have different requirements depending on what fits for the space, new construction, or retrofits:
- Ultrasonic (not wireless) sensors emit high-frequency sound energy signals
- Bluetooth (wireless) sensors use a signal between a transmitter and a receiver
- Microphonic (wireless) sensors monitor for sound
- Video image (not wireless) sensors use a camera and video analytics
- Dual technology (not wireless) sensors use passive infrared (PIR) sensors with ultrasonic or microphonic sensor technology
Check out the U.S. Department of Energy’s (DOE) Wireless Occupancy Sensors for Lighting Controls fact sheet for more information on the types of spaces that benefit well from sensors and the type of sensor that works best for a specific space.
If there aren’t occupancy or vacancy sensors in your building, don’t forget to turn off the lights when you leave the room!