I've heard that fluctuations as subtle as 5 degrees during fermentation can affect the final beer quality.
With this in mind, I'm concerned about my ability to maintain a constant temperature for my batches. My apartment isn't very well insulated, so during the summer it gets hot during the day and cools off at night. The problem is even worse in winter as my apartment is heated by somewhat inefficient radiators.
So I suppose my question is...what can I do/what do other brewers do to ensure decent temperature consistency throughout the process. Am I being too concerned about this, or is it a real issue?