# I need to find the energy efficiency of an elevator. I have found 2 energy efficiency equations on the internet but don't know which one to use. Could someone tell me which one to use?

May 20, 2016

I am not sure this is going to help but...

#### Explanation:

I am also not sure the kind of data you have but I would use:
"efficiency"=P_("out")/P_("in")xx100%
Where:
$P$ is the power in Watts or $\text{joule"/"seconds}$ that measures the transformation (or use) of energy (in Joules) at each second.
You basically consider the rate at which energy is "lost" during your transformation as a pecentage.
Let say that you get

0.4xx100%=40%: this tells us that your machine is delivering only 40% of the energy per second it absorbs or if you give $100 J$ each second to the machine $60 J$ are "lost" each second.