As requested, here is a brief description of the walk-in cooler we built in our garage to hang our venison we harvest each fall.
Basically, we wanted a way to hang our moose meat, and process it ourselves, instead of having to rush off to the butcher imediately after the hunt, and get the typical, tough, gamey flavored moose that most are used to.
It needed to be big enough to hang 16 quarters of moose at the same time, and maintain a comfortable temp just above freezing. We sectioned off a 10' x 5' section in the back of our garage, 2x6 walls with pink insulation R20 all around and ceiling. Then inside, we put 2" of high quality foam insulation on walls and ceiling, and 4" on the floor, since cold air drops. We installed an exterior door and that was it.
To provide the cooling, we didnt want to spend a fortune on a comercial cooling unit that would be expensive to operate, and require 220 power. I found a website claiming you could maintain cooler temps using a home AC unit, controlled by a special PID type temp controller. It was the cheapest way to go, had good reviews, so we gave it a shot.
It worked out way better then we expected. Absolutely perfect for our needs. Will drop the temp to 1 degree celcius (roughly 33 Degrees Far.) in 10 minutes. With 8 quarters of warm meat, it will get down to that temp in about 2 hour. It gets down to 2 or 3 degrees quickly, then takes a couple hours to get to 1 degree. Any where in the 2 - 4 degree range is perfect for coolers. We didnt notice any significant increase in our electricity bill. Maybe 30 -50 dollars per month