I was thinking about some suitable shelter that is compact and can be easily carried for emergencies, particularly in cold windy conditions. Mountain climbers regularly experience extreme conditions and their gear includes good lightweight clothing, tent, good sleeping bag and sometimes a candle.
Si think something similar, but smaller and lighter, can be achieved by an emergency shelter, inflating mattress/chair/pillow (floor insulation) and suitable clothing (what you wear in case of emergency). I guess it is not going to be a comfortable or long-term resting equipment, but good enough to survive. What do you think?

Then there is another extreme - heat. In this case, you need a sun protection (double layer of a sheet separated by air) installed on poles and hide under it. Maybe even excavate the ground to avoid ground heat. I guess it is already something relatively lightweight. Are there lighter alternatives?

Thanks

Space blanket. The cheap ones, though, are effectively single use.

Can't fold them back up but are useful to break the wind in cold (but doesn't insulate) and also protects from sun in heat.

The classic mountaineering shelter for cold and windy is a bivouac sack - one that is basically just a bag, not a mini-tent. It will weigh under a pound and will keep off wind and rain. Often used when sitting out the night on an exposed ledge, it doesn't have bug netting or any weighty frills.

For sun protection, find some shade or rig a space blanket.Some distance hikers advocate a light weight umbrella if one is moving. Staying off the ground or finding natural shade is a good idea.

I prefer the Heatsheets 2-person blanket -- it's still small enough to fit in very small kits, but it's a lot more sturdy than the cheap mylar emergency blankets.

Recently I added a small, inexpensive tarp to my car kit (http://www.rescue-essentials.com/base-all-purpose-tarp/, no affiliation) but I haven't had time to do anything with it yet. It's small and light enough to go in a backpack fairly easily.

Just noticed this. Don't even think about it. You will expend far too much energy and get way too hot. I am archaeologist with a lot of desert experience. Actually, natural shade isn't that hard to find in most desert situations, especially if you are motivated.....

You don't have "people" to do that for you?

Extra large leaf bag. Use as a bivy in cold, wet weather.

Slit down sides to make a sun shade. Black is best for that. Beats the light space blankets for the darkest shade.

Kifaru woobie express.
http://soldiersystems.net/blog1/wp-content/uploads/2012/03/20120323-191543.jpg

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Snugpak patrol poncho.
http://www.proforceequipment.com/images/119/main.jpg

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Something to sit on that keeps the behind off the cold ground.

in my remain overnight bag....I don't sleep well on the ground, so have decided that I would most likely get a couple of hours of sleep propped against a tree, sitting on my pack or other insulating, elevating object...a vinyl coated nylon poncho, and boonie hat for upper body, and contractor's clean up bag for my legs... that would allow me to remove shoes and socks to allow feet to dry... a mosquito net and an additional head net with a light pair of cotton gloves to protect my hands from mosquitoes and no see ums ...a long sleeved nylon shirt and fleece jacket are also included... I typically don't encounter temps below freezing in my part of the state

Sometimes,yes, but not always. There are times when you just have to grab a shovel and start moving dirt.

Over the years, on various projects, I have used everything from road graders and backhoes to fine brushes. Even used dynamite, a quarter stick at a time, on one occasion.

Better to find a hole than dig one....