Keeping the temp

I have a heat pad on one side of my cages, but its in a basment and I'm concerned about the cold side being ot cold. How can I keep it heated?

I have to have a heat-pad on one side of my tank (the warm side) and a lamp above the other side, just to keep the cool side warm enough. Mine's in the basement, too. I've got my heat pad hooked to a thermostat and the lamp plugged into a dimmer-switch so I have good control over the temp variables.

Well what about putting another heat pad on the other side. Like putting one on medium and the other on low?