My husband and I were wandering around Lowe's for some reason or other, and came upon the area where they have the shelving units for in-home and garage. We saw a metal garage-type shelf unit, with about the size I'd need for the tubs. Jason was instantly inspired, telling me these would be perfect if we put plywood or something similar on the back and sides to hold some heat.

Now I've never seen anyone on here talk about using something like this, so I was wondering how good of an idea this was. It seems like a good idea to me, both cost-effectively (it's a lot easier to trade for something like this than a bunch of melamine (we are the barter masters)) and just for simplicity's sake. But I'd like input from people with more experience. I don't want to haphazardly go for this and then it not be effective or safe.

Here's a picture of the unit we saw. (Sorry about the ad, it's an Imageshack thing...) Input is much appreciated.