SHELTER

Convection >Seal

Most shelters try to focus mostly on controlling airflow around you. The closer you trap the air around you, the less air you have to heat.

Air exchange--Any drafts will provide exchange of air, which means you have to heat more air, so having control of any leakage is important.

Convection circulation Also--heat rises & cooler air cools, so where there is any temperature in a climate/microclimate, there will be convection circulation. Larger internal areas provide more room for circulation to build up. So in creating an emergency shelter to protect you from the cold, bigger is not better--bring it in closely around you. If you are too hot, you would use this principle in reverse to carry off heat, unless the air is hotter than you are.

Total Seal=plastic, but causes condensation problems, so breathable but wind-proof=next

--Laminates--ie., UltraTex

--Tyvek

Conduction >Insulation

Many overlook the fact that you lose heat faster by conduction heat transfer to the ground, than to the air, because solids transfer heat energy faster than air. Insulation operates by providing tiny pockets to trap air, & isolating them from other pockets, thereby reducing conduction. If you have a sheet of glass (or plastic, or anything solid) that totally seals you off from cold outside air, it will prevent any convection, but you will feel the surface of the glass is cold, and you will feel a cold convection circulation (draft) flowing down the glass. This shows that the cold/heat difference on one side of the barrier is trying to equalize itself. If you sit on something cold a few minutes, then move over, you will notice that where you sat is warmer than other parts of that surface. This shows how much heat the surface has drained from your bottom. Moisture conducts heat many times faster than dry air, so sometimes you have to keep a little circulation going, just to carry off the moisture your body gives off. Your breath is the biggest contributor of humidity, so having your breath outside of the innermost microclimate makes a huge difference. Closed-cell foam or similar under your body when sleeping, or rear when sitting, or feet when standing on snow/cold makes a huge difference.

BestTek=

#1=AeroGels=$100/gal or blanket

#2=DriDown 900fill

#3=PrimaLoftOne or Sport