Q: OS Sierra upgrade - fan continuously running

Hello

I've upgraded my MacBook Air (i7 2GHz, 8Gb RAM, 256Gb SSD) OS to Sierra, and after that I have the following symptoms that never had before the upgrade:

- internal fan is continuously running

- the battery drains pretty fast - in browsing mode it runs no more than ~1h

Is this normal? if that's normal, then how can I roll it back to El Capitan.

thanks,

Edu