Besides the stated here is a list that helps in our rat house.

Fans both ceiling and oscillating to get good air movement

Keep the bedding clean and dry.

I put 2 tablespoons of apple cider vinegar to 1 gallon of water its helps with the smell.(we do the same with our rabbit)

I installed an attic fan that I wired to a light switch and bypassed the automatic temperature control, this allows me to turn it on as I need it.

Hope this helps.