# Questions tagged [efficient-energy-use]

Use the tag *Efficient Energy Use* in questions having to do with processes or engines or constructions where energy is spent or transferred and the efficiency thereof. Efficiency means both the measurement and the techniques and principles for its optimization.

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### Why does heat engine need to reject energy to environment?

The most efficient thermodynamics cycle is the Carnot cycle, it involves 1/ Receiving heat from hot source, expanding and doing work on the surround 2/ Receiving work from environment, being ...
421 views

### Why does intercooling improve the efficiency of a Brayton Cycle?

I've read in numerous sources that intercooling improves the efficiency of a Brayton cycle. The explanation given is that it decreases the compression work by minimizing the temperature during the ...
80 views

### What is the most efficient temperature to keep your house at? [closed]

I live in the north east of the USA. I am wondering if there is any information as to what the most efficient temperature to keep your house at. I have oil burning forced hot air with an efficient ...
1 vote
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### How to calculate the power required by a fountain pump?

How can I calculate the power required by a fountain pump, if just the efficiency of the pump, the height of the fountain and the diameter of the water jet is given?
2k views

### Should we take the elevator instead of the stairs to save energy?

In our university there's a posted sign that encourages students to take the stairs instead of the elevator to save the university electricity during the hot NYC summers. When you climb the stairs ...
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### Why is it so inefficient to generate electricity by absorbing heat?

When I turn on a heater, it's supposed to be roughly 100% efficient. So it converts electricity to heat with great efficiency, but why can't we do the reverse: generate electricity by absorbing heat? ...