Ann - make them as WARM as you can. Cool winters will effectively put your phals into a state of suspended animation. The first winter I had phals this happened to me - just like owning plastic plants - no growing - no dying - no nothing. Trying to save money on energy and making your phals happy doesn't compute unfortunately. As was suggested - try to increase the temperature - if you cannot make a room warm, think of potentially enclosing an area or partially enclosing an area for them - where they can be happy.
Good luck! Mike