I'm a former freezer owner and found I could live without the expense of it by purchasing a larger, energy efficient, refrigerator/freezer than our decade+ old model refrigerator/freezer and upright 3/4-size freezer. I could get the same amount of food in the NO-FRILLS (no water or ice dispenser) side-by-side refrigerator as I could our 3/4-size upright freezer. So I eliminated two energy "hogs" and got one energy efficient appliance instead. We recently checked the energy use with a Watt A Meter and it is 7-cents per day with more than enough capacity.
1. Freezers (and refrigerators) are designed to run at room temperature, which is 70°F, so they are more efficient if placed inside, not outside. Freezers are a wonderful convenience, but the food bargains you place in the freezer can quickly be off-set by the price of running it - especially if you run it in extremely hot outdoor temperatures, or if you are using an old inefficient model.
2. Chest freezers are more energy efficient than an upright. The drawback of a chest freezer:
-They usually aren't frost-free and have to be defrosted (once a year - or more if they are place in a location where a lot of hot air and humidity enters the freezer each time it's open).
-More difficult to get in and out if you are short.
-It's easy to forget items that get shifted to the bottom.
-The take up more floor space.
3. Don't over-buy. Bigger isn't always better. You want a size that you can keep filled. Consider the amount of money that will be sitting in the freezer - especially if you lose everything during a power outage. Freezers tend to contain large quantities of the highest priced food - meat.
It costs more to run if there's a lot of empty space in the freezer, so keep containers (milk jugs work well) of water frozen in the freezer if you don't have enough food to keep it relatively well-stocked. The jugs of frozen water also will aid in keeping the food frozen longer if the electricity goes off for a long period of time.
Uprights use more energy because they are often frost-free, and more air enters them when the door is open - which requires more cooling to bring them to 0°F (or colder) temperatures.
4. A general rule of thumb is to purchase a size that will keep 6-weeks of food in it.
5. If you don't have one, you may want to purchase a FoodSaver to go along with your new freezer. You'll find foods keep longer when vacuum sealed. NO freezer burn.
6. Keep track of what you have in your freezer. Wasted food is ALWAYS the most expensive food we purchase. Freezers tend to get filled with "good intentions", and wasted because of poor execution, improper storage methods, and poor meal planning. Be familiar with proper storage techniques to extend the freezer-life of foods and the storage times for freezer foods, to avoid waste.
http://www.cdc.gov/nasd/docs/d000001-d000100/d000066/d000066.html
http://www.ext.vt.edu/pubs/foods/348-960/348-960.html
I divide foods into small plastic baskets (even in my refrigerator/freezer) - one or two types of food per basket. When you use a FoodSaver to package foods in a single layer, you can "file" the packages upright in the baskets. When you flip through the vegetable basket, it's easy to check the inventory. It's also handy to be able to remove the whole basket of food and shut the freezer door, rather than rifling through the freezer for something with the freezer door wide open. Same with the fruit basket, breakfast meat basket, beef and poultry baskets, etc...
7. When possible, eliminate the boxes frozen food are stored in. They take up a lot of valuable freezer space. If possible, repackage items using a FoodSaver. Cut out the instructions on the box and file it in a file located in the kitchen, or place in the bag when you vacuum seal foods in a FoodSaver bag.