4 ms·

I assume it's the same for elevators? "Save the environment, take the elevator"?

by Jyaif 7y ago

_nhynes 7y ago
human: 1.2 (0.9) kcal/floor ascending (descending) [0, 1] elevator: 2.5 W•h/floor [2, 3] Let's assume 15 floors since otherwise you'd probably save time walking. The article suggests a grid efficiency of 50% and a motor efficiency of electric e-bike motors as 75%. It looks like elevator motors are actually more efficient (increasingly so as more people are loaded) [4]. It's only about 5 percentage points higher, so for simplicity let's keep 75%. Ignoring the transportation and manufacture cost of the elevator assembly (not totally unreasonable since it has a long lifetime), elevators have an energy ratio of 2.5:6.7 or 1:2.7, which looks far better than the 1:28 that the article quotes for humans. Gee, that kind of upends my worldview... I guess I'll just wait until bodies are deprecated in favor of high-efficiency cybernetics. [0] https://captaincalculator.com/health/calorie/calories-burned-stairs-calculator/ https://captaincalculator.com/health/calorie/calories-burned... [1] https://www.livestrong.com/article/301539-calories-burned-climbing-one-flight-of-stairs/ https://www.livestrong.com/article/301539-calories-burned-cl... [2] https://www.quora.com/How-much-electricity-does-an-elevator-use-per-floor-What-is-this-energy-usage-comparable-to https://www.quora.com/How-much-electricity-does-an-elevator-... [3] https://fatknowledge.blogspot.com/2007/02/how-much-energy-does-elevator-use.html https://fatknowledge.blogspot.com/2007/02/how-much-energy-do... [4] https://www.me.ua.edu/me416/LECTURE%20MATERIALS/MotorEffic&PF-CM5.pdf https://www.me.ua.edu/me416/LECTURE%20MATERIALS/MotorEffic&P...
- pmontra 7y ago
  > Let's assume 15 floors since otherwise you'd probably save time walking. Not many people would consider walking 15 floors either up or downstairs. Actually many people pant heavily when climbing (from their point of view) 3 floors to my place.
jonas21 7y ago
I wonder if elevators are even better because they're counterweighted, whereas when you take the stairs, you squander all of the potential energy you gained going up on your way down.

I assume it's the same for elevators? "Save the environment, take the elevator"?

by Jyaif 7y ago

I assume it's the same for elevators? "Save the environment, take the elevator"?

human: 1.2 (0.9) kcal/floor ascending (descending) [0, 1] elevator: 2.5 W•h/floor [2, 3] Let's assume 15 floors since otherwise you'd probably save time walking. The article suggests a grid efficiency of 50% and a motor efficiency of electric e-bike motors as 75%. It looks like elevator motors are actually more efficient (increasingly so as more people are loaded) [4]. It's only about 5 percentage points higher, so for simplicity let's keep 75%. Ignoring the transportation and manufacture cost of the elevator assembly (not totally unreasonable since it has a long lifetime), elevators have an energy ratio of 2.5:6.7 or 1:2.7, which looks far better than the 1:28 that the article quotes for humans. Gee, that kind of upends my worldview... I guess I'll just wait until bodies are deprecated in favor of high-efficiency cybernetics. [0] https://captaincalculator.com/health/calorie/calories-burned-stairs-calculator/ https://captaincalculator.com/health/calorie/calories-burned... [1] https://www.livestrong.com/article/301539-calories-burned-climbing-one-flight-of-stairs/ https://www.livestrong.com/article/301539-calories-burned-cl... [2] https://www.quora.com/How-much-electricity-does-an-elevator-use-per-floor-What-is-this-energy-usage-comparable-to https://www.quora.com/How-much-electricity-does-an-elevator-... [3] https://fatknowledge.blogspot.com/2007/02/how-much-energy-does-elevator-use.html https://fatknowledge.blogspot.com/2007/02/how-much-energy-do... [4] https://www.me.ua.edu/me416/LECTURE%20MATERIALS/MotorEffic&PF-CM5.pdf https://www.me.ua.edu/me416/LECTURE%20MATERIALS/MotorEffic&P...

pmontra 7y ago
> Let's assume 15 floors since otherwise you'd probably save time walking. Not many people would consider walking 15 floors either up or downstairs. Actually many people pant heavily when climbing (from their point of view) 3 floors to my place.

jonas21 7y ago

I wonder if elevators are even better because they're counterweighted, whereas when you take the stairs, you squander all of the potential energy you gained going up on your way down.