For the wine freak, like myself, I have wines that I need to store for 6 months to over a year. If you consume the wine you buy within one month, you can store it in room temperature or up to the mid 70's. For long term storage, you'll need something more robust. There are a handful of factors that will kill wine including light, prolonged exposure to heat, humidity (or lack thereof), and of course the wine and cork themselves.
For long term storage, you will want to keep your wine stored between 55 and 62 degrees Fahrenheit, with a relative humidity of 60-70 percent to protect the corks. Dehydrated cork can let oxygen enter into the wine accelerating its maturity and rendering it bad after a very short time. This is most evident in bottles with low neck levels or even on the cork when you find that its been saturated thru the entire cork.
If you are building a storage closet, use insulation and be sure that you are using a proper AC unit, not a window unit. Vinotemp and Breezaire make relatively affordable units that you can put into your cellar. Be sure to lay the bottles sideways as thats the most optimal way to store wine and use racks if you have them available. Don't stain the wood as varnish carries toxins that can seep into the wines over time. If you're building racks, use spanish cedar, oak or pine.
Its a lot of work, and can take a whole weekend, but will be worth your time and investment! Have a great weekend! - Alex Andrawes, CEO Personal Wine and Wines.com.