Tuesday, May 15, 2007

Carbon Footprint: Take the Stairs

This social graffiti is a friendly reminder to folks in the teaching wing of the UW''s Health Sciences Building that taking the stairs is not only good for you, but good for the environment. The connection to the fish is that the power used for the electric elevator comes from hydroelectric plants, and that the demand for power is the main obstacle for salmon migration.

Taking the stairs also reduces electricity use in general. By how much, I am not sure. The best information I could find (from the National Park Service) is that using an elevator to travel 1 floor requires 350 watt-hours of energy. So if you take an elevator 4 times a day (twice up and twice down) 4 flights a day, that amounts to 5.6 kWh/day. Over a year, you would by yourself use 1.5 MWh or (using a standard conversion factor of 0.43 kilograms of carbon dioxide per kWh) 0.71 tons of carbon. And don't think you get out of this by sharing the elevator - the more folks in the 'vador, the more electricity is needed to run the lift.

I have to admit that I take the elevator every so often. (I guess it's funny that I bike to work and then am too lazy to walk up 4 flights...) Feel free to call me out the next time you see me push the button!


Toast said...

Usually the counter weight in the elevator is about 50% of the max load of the elevator + the car weight, so they use less power the closer you get to 50% max load (which is usually about a full elevator). Not intutitvely, an elevator uses max power when empty.

thomas said...

Thanks for pointing that out. I stand corrected! With this information, it seems like calling the elevator to your floor would have the highest power usage.

thomas said...

Can you recommend a comprehensive resource about how electricity consumption works with elevators?

(Although the behavior modification to always taking stairwells is my own personal goal.)