If you have a fold down attic stairway, you should view this 5ft x 3ft opening as a giant hole leading to your unconditioned attic.  Most attics vent directly to the outside through ridge vents, or ventilation fans.  Need more proof? Go up to the attic during the day and turn off all of the lights.  You will be amazed at the amount of daylight that makes its way through the ridge vent and soffit vents.  Most fold down attic stairways are constructed with just a thin layer of uninsulated plywood separating your heated/cooled space from that unconditioned attic.

Now that we brought this problem to your attention, there is a quick fix; the Owens Corning Attic Stairway Insulator Tent.  This encapsulated fiberglass tent simply sits over your attic stairs and provides an impressive R-10 insulation value.

I use most of the products listed on our site in commercial/industrial environments but very rarely do I take a consumer product like this one home to experiment with.  Here are some details from my personal experience with the attic door insulation cover:

First thing I noticed was that for some reason, Owens Corning leaves some of the fiberglass exposed which I didn't feel like touching every time I went up the stairs. I took a strip of foil tape and sealed up the bottom parts of the tent. 

Setting the tent up is simple, out of the box it takes some slight finagling to get the tent into the proper form so the stairs do not hit and lift the tent.  Resetting only takes a minute or so to get it to seal 100%, however if you go up and down the attic stairs everyday I would not recommend this item to you as resetting it would get annoying very quick.  

The results are hard to put a dollar amount on, I cannot say that this item cut my heating bills in half or anything like that. What I did notice is that the plywood used to be very cold to the touch and now its much warmer.  When I open the stairs up and stick my head up into the tent area before moving it, I noticed it is very warm.  When I move the tent over, I get that gush of freezing cold air.  So I can personally say this attic door insulation cover works and will help you stop that expensive heat from rushing out through the attic vents.