I can tell you about my greenhouse and see if any of the information is useful to you. My greenhouse is 36 x 48 feet=1728 square feet. It was built 15 years ago with a steel frame and single wall polycarb glazing. It has a gabled ceiling that is 20 feet at the gable. The greenhouse was built to be semi-automated. The electrical system is wired into what is called a 'step controller' which is basically a big thermostat. There is an air sensor that senses the air temperature, and depending on the settings that you plug in by hand for low and high temperature, it will perform operations like turn attic fans on and off, open the 36 foot back vent, turn on the 2 big box fans in front to pull air through the house, turn on a pump that pumps water over the cooling pad, or in winter, turn the heater (2000,000 BTU propane) on and off. It does NOT run the sprinkler system, or the floodlights. Those are manual. All it does is turn things on and off based on temperature parameters set by the operator. It works well, but being 15 years old, will eventually fail and I will have to make a decision on whether to replace it to have an electrical wire things so that I can do those things manually. The technology that is available now is probably quantum better than it was 15 years ago, but also probably quantum more expensive.
Although some of my plants are in containers, many are actual unground plantings. The greenhouse contains a pond and a 25 foot stream. I made to to resemble the greenhouse a botanical garden would have for tropical plants. There are no benches, no vegetables, nothing like that.
