Aside from the lights and an aquarium heater in the sump that contains the water I run down the back EcoWeb (which also water the plants), I have no other heating.
I see about 80° in the daytime and low 60's at night.
Well we keep our furnace turned off since we heat with our wood stove during the winter. Keeping the door closed all day and night allows the room to stay cooler. I have had the room down to 52 degrees at night when our temps were around 7 degrees outside. So I am sure the temp in the orchidarium was pretty similar, maybe in the upper 50's. I have since plugged in a space heater so the temps don't go below 58 since the majority of my orchids are intermediate or warm growers. During the day, the lights do all the heating and in the orchidarium it will get into the upper 70's to low 80's. While the room itself will stay around 72 to 74.
I wish my husband would let me turn the heater off in the winter. I would rather pile under blankets and long sleeve clothes. However he is a wuss and would rather pay $400 gas bill to heat the home. Maybe If I close the vent it will make a little of a difference? I am trying to get it to go a little lower than 65 in the kitchen that way the orchidarium temp will go a little lower, COME ON 50'S!!
I run a warm terrarium with annual range of 60-85, daily range around 15F. In winter I need to add heat with heat pads and a warm water waterfall with air blowing over it. In summer I use a aquarium chiller to chill the waterfall with air blowing over it. Indoor temp in winter is around 52 but the terrarium is right next to a big window to the outside (single pane) and we go down to 30s. In summer it gets well over 100, occasionally over 110, indoors easily up to 95. So both cooling and heating are necessary.