The first thing you ought to do is get some stick on thermometers to get an idea of what the temp of the wort is. Fermentation kicks off a lot of heat so the wort is always going to be hotter than ambient temp during the active period. Maintaining proper fermentation temps is the key between good beer and great beer.
The critical time for off flavors is the initial 2 to 4 days as the yeast propagate and go through the fast part of the fermentation process while there is a lot of sugars present. Once the ferment slows down, you can let it warm to room temperature, depending on where you live, which may help get to the proper final gravity and take care of some of the esters that give off flavors.
There are many methods people use including putting the carboy in the basement, put the carboy in a water bath and use a fan, etc.
Personally, I live in Florida and I don't have a basement... I don't have a room that stays cold... It is hot here my wife would kill me if I kept the house at 65 degrees during the summer, but on the other hand, the power company would love me. Even if I kept my house that cold, there is still a temperature fluctuations to be considered.
Enter, The Ranco ETC. It is a microprocessor based temperature controller, suitable for switching 120Volts at up to 16Amps for heating or cooling applications, making it suitable for a wide range of applications. This is a popular choice for fermentation temperature control. Hook one of these bad boys to a fridge, turn the fridge to its coldest setting and let the controller cycle the fridge as needed to maintain temp.
Temperature Setpoint Range: -30° to 220°F
Differential range: 1° to 30°F
Input Voltage: 120VAC
Sensor: Thermistor, 2" long x 1/4"dia with 8' cable (included)
Control Ambient Temperatures
Operating: -20° to 140°
Storage: -40° to 176°
Ambient humidity: 0 to 95% RH, non-condensing
Enclosure: NEMA 1
Dimensions: 6.52" high x 2.7" wide x 2.48" deep
Relay Output Ratings (SPDT)
Normally Open (NO): 16 Amps @120Volts
Normally Closed (NC): 8 Amps @120Volts
In Florida, it really doesn't get that cold here, and if it does, it doesn't stay for long, so no need for a dual control. I've been using this for over 8 months and it has yet to fail me, the best $50 I'd have spent thus far.
No matter how you decide to control your fermentation temps, just remember, consistent temps are key and also just as important as your mash temps.
As always, Happy Brewing.