Much of the cleantech research I do focuses on innovative technologies, advances to existing appliances, and new software solutions that enable greater levels of control. But in nearly every conversation I have with ESCOs such as Johnson Controls or Schneider Electric, they emphasize the huge factor that human behavior plays.
This was driven home to me when our office building in downtown San Francisco announced an Energy Alert Day. In order to conserve energy, the facility manager was shutting down two of the 12 elevators that serve the 20-story building.
My first thought was that the actual impact of energy efficiency would be negligible, while the inconvenience factor would be great. I frequently ride the elevator alone to our office on the 10th floor, and so do many of my colleagues. We rarely have to wait more than a minute for an elevator, and taking 17% of the elevators offline would likely mean the wait time would increase by a similar amount.
My colleague, David Hague here at the Cleantech Group, did some searching and found an online calculation for the energy used per floor by elevators. A 20-floor roundtrip consumes 100 Wh, approximately the same energy used in 30 minutes by a desktop computer and monitor. To get to and from my office on the 10th floor, it’s about 50 Wh roundtrip, equivalent to a 60 watt bulb for a little less than an hour. Double that if I leave the office to go to lunch.
However, if I ride in the elevator alone each time, I could be responsible for four round trips per day, or 200 Wh of consumption. That’s the equivalent energy needed to for an hour’s worth of operation of the desktop/monitor or a 37-inch plasma TV.
By taking two of the 12 elevators offline, passengers wait longer and trips are consolidated. Let’s use a conservative estimate of one trip every five minutes, or 20 an hour. Of course, not everyone is going to the 20th floor, so let’s assume that the floors are evenly distributed in terms of visitors and use the 10th floor as a case study. In that instance, 25 Wh is saved per trip, and 500 Wh is conserved per hour.
That’s the equivalent of
- eight 60-watt bulbs
- a desk heater turned on its lowest setting for an hour
- the energy produced by three 180W solar panels in 60 minutes in bright sunlight.
When you look at the energy savings in terms of dollars, it’s obvious the building isn’t enacting these measures for cost savings alone. 500 Wh is the equivalent of 0.5 kWh. My colleague Debjit Mukerji pointed out to me that with Pacific Gas & Electric’s rates of around 12 cents per kWh, the building sees savings of only 6 cents per hour. Since the building is most active from 7 a.m. to 6 p.m., we’re looking at 5,500 Wh conserved per day, or 66 cents.
However, it’s an illustration that behavior modification can be the cheapest form of energy efficiency available. Those energy savings don’t require the installation of new technology or advanced sensors, and the building doesn’t need to secure financing for a retrofit project. So next time you’re in the elevator alone, hold the doors for the next person to join you. I’ll do the same.
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