I use a sealed room complete with weather stripping on the door. I run blinds and heavy curtains to keep a little more of the air off the window. This allows me to have a natural light cycle, albeit a very darkened one. Ceramic heater for regulation and most of the heating work. The ceramic is more efficient than most other types. I have the baseboard set just slightly lower in case of severe temp drop, door accidently left open, or ceramic heat failure. I keep it between 79-80. It works great and it makes husbandry a breeze with a rack system.
Regards,
B