newbie here have a question

Hi guys, 

first time posting on here so I'm a bit unsure how it works but here goes... i have had the alternator belt and pulley replaced recently and also the battery replaced less than a year ago .. when i start the car especially in cold weather there is what i can best describe as a whooshing noise seemingly from the alternator area which lasts a couple of minutes before either subsiding or becoming unnoticeable, today i was waiting in the car with the heater on to clear the windscreen and the battery suddenly to go low on charge as the everything dimmed and the power steering stopped working..having managed to nurse it home it seems to be ok but was wondering what you guys think maybe the problem.. on a side note i have been doing short journeys for a while to work and back could this be a cause 

thanks