Q: My 2011 MacBook Pro has started using the fan a lot. The machine is hot to the touch.  No change in atmosphere or workplace.

Hi. You are always using the fan. It's just that unless your MBP starts heating up you don't always hear it. With the MBP closed and off look at the heat vent at the back and make sure it's not getting clogged up. If you see a lot of dirt or dust bunnies use a vac to clean it. Do not use compressed air. If there are some pieces that you see that are stuck, carefully use a screw driver or something thin to help you but do not stick it way up inside, Download SMC fan control and open it and monitor you fan speed and heat.  http://www.macupdate.com/app/mac/23049/smcfancontrol   If your fan is running on high all the time try a pram reset Hold down Command/Option/P/R at startup for three chimes. Also SMC reset.http://support.apple.com/en-us/HT201295

Runaway applications can shorten battery runtime, affect performance, and increase heat and fan activity - Apple Support