I can't comment too much on the list as I have very limited experience with this all including farming. I will comment on:Originally Posted by JCO
#2; I am going to build a greenhouse myself next year and would love some feedback on DIY's.
#3; I would use solar heat tubes and water storage bins inside the greenhouse for heat or if using concrete and stone underneath the G/H run sufficient piping to transfer the heat from the solar tubes to the "heat sink" under the greenhouse. The storage bins would be the cheapest way to store heat in quantity. As far as cooling is concerned I would think natural ventilation would have to do it, I can't conceive of cooling a glass (or plastic) building with the sun beating down on it. Kinda like cooling the outdoors UNDER A MAGNIFYING GLASS Not that it is not done when in the A/C business I actually had a customer wanting to cool a very large outdoor space under an awning in Ft. Lauderdale. He though had more money than sense and yeah he went through with it. If specialized plantings were to be kept in an insulated building to keep cool now you have to deal with the cost of grow lighting.
#7; I have had to deal with the buyers of the "big box" stores and they are one PIA to deal with. Don't know unless you are really big if you could afford to do business with them. In many in the warehouses there are fees to "I'll call it store" your product there before it is distributed. I don't know how these perishables would be sold to them (terms) but if there are any guarantees connected you could get killed in returns. Places like Walmart actually like you to pay them to sell your product ... J/K... but almost that bad. Sometimes there are vendors that directly sell produce to the stores as in my case but now we are talking a delivery truck and driver. I would either buy at the market each morning or from the supplier that made his rounds each week. If I was selling I would stick with smaller stores where you can deal directly with the owner or Produce Manager but then it will reduce the amount you can sell. As I have a local small Organic Grocery by me they said they would buy all I had available but they are small and I doubt the volume would be enough to warrant any kind of an investment.
#12 Another line item to consider is cost per square foot of GB area. Would seem to me without doing any calculations that GB's of any size will require large pumps for both air (compressors) or air pumps, water pumping, fans, and heat for the greenhouse. At todays cost for electricity and fuel that can be a large amount at the end of the year to take into consideration. Solar is a way to go but it is the least efficient of all the modalities and the most costly to set up for the benefit you receive. Been there and done that although I would do again depending on circumstances. Most people do not realize that a 60A solar system is only 5.4A on 120V (if using batteries.) Even if using a grid tied system the benefit you will see in your power bill is not as much as you MAY BE thinking you will get. A 10K system will cost >$50,000 just for parts. Gotta sell plenty of lettuce.
#13 Approximate yield per planting
#14 Wholesale cost to the middle man.