Hi Jim,
Really enjoying this greenhouse forum. My husband found our greenhouse on Craig's list. It had been removed from a house down cape by the original installer. We started this project in July of 2019. I live in Massachusetts Zone 6a. Do not know enough yet to do too much, and obviously a bit frozen in place physically and financially right now. We are completely insulated and set so the sun pretty much flows east to west over the greenhouse perpendicularly. Took a bunch of less than healthy trees down for safety. What is amazing to me is the drastic swings between day and night in temperature inside the greenhouse right now. I have been investigating how we could keep consistent warmth now and in order to grow inside for Nov. 2020-May 2021, with little funds and lots of willingness to be creative! Anyway, thank you all who ask and answer! I am learning a lot!!

Beautiful greenhouse! I would love to see more pics as you move forward.

Consistent temps are only achievable with a heat source on a thermostat when temperatures dip and exhaust fans/vents on thermostats when the temperatures get too high. It is best to automate all of this otherwise you will be "baby sitting" your greenhouse constantly opening vents, turning on fans or heaters, etc. as needed...which could be many times each day depending on outdoor temperatures and sun.

I would contact a L&B distributor to see what is available for your model as far as fans/vents/heaters. You can than purchase through them or shop around for similar. In any event, it is not going to be cheap, so since your funds don't allow right now, you may need to become very creative. i.e. portable electric heater with thermostat, box-store fans, etc., passive window openers, etc.