Your Body is Losing Heat Right Now. Let's Fix That.

Shelter isn't just a tent or a tarp. It's anything — the clothes on your back, the leaves under your sleeping bag, the angle of a tarp you rigged in the rain at 9pm — that creates a micro-climate you can control. That micro-climate is what keeps your core body temperature where it belongs: alive-and-functioning, not sliding toward hypothermia.

This article covers the five ways your body loses heat (and gains it), how to dress for different environments, and what shelter options actually work — from a garbage bag in your daypack to a fully thatched natural lean-to you built with your own hands. Yes, really.

The Rule of Threes — Your Priority Framework

The military uses this to cut through panic and prioritise fast. The order isn't fixed — it shifts depending on your situation, environment, and what you have with you. But as a starting framework, it works:

• 3 minutes without air — if you're not breathing or you're bleeding out, nothing else matters. Basic first aid comes first.
• 3 hours without shelter — exposure is the silent killer. Clothing, fire, shelter. This is where we're focused today.
• 3 days without water — the body can manage about 72 hours. After shelter, this is your next priority.
• 3 weeks without food — yes, really. Food is last. You have time. Don't waste energy chasing it when your core temp is dropping.

PLAN — Your Survival Acronym

Used by military and civilian agencies around the world, PLAN helps you work through survival priorities in order. It adapts to your conditions, your environment, and what you've got on you.

• P Protection — first aid, clothing, shelter, fire
• L Location — attracting, holding and directing attention — getting found
• A Acquisition — water first, then food
• N Navigation — travel and orientating yourself to your surroundings

How Your Body Loses Heat (and Gains It)

There are five mechanisms. Know them. Because once you understand how heat moves, you can stop it from moving away from you — or use them strategically to cool down. They work in reverse too.

Conduction — the ground is stealing from you

Direct heat transfer from your warm body to a colder surface. Lie on cold ground without insulation and you will lose heat fast. Water conducts heat away from the body 25 times faster than air — which is why wet clothing is so dangerous. Always have a layer between you and the ground.

Convection — wind is not your friend

When air or water moves continuously across your body, it prevents your immediate environment from warming up to match you — so you keep losing heat. This is wind chill. Even a light breeze in wet clothing can be lethal. Windproof layers matter.

Radiation — your head is a heat vent

Your body radiates heat directly to its surroundings, like a radiator. We lose 60–70% of our body heat through our head and neck. The naked human body starts losing heat to the environment at just 28 degrees Celsius. In hot climates, the sun radiates heat into you the same way. Cover your head. Always.

Evaporation — sweat is survival (sometimes)

When sweat evaporates from your skin it takes heat with it — about 600 calories per quart of sweat. In hot climates, this is your body's cooling system. Brilliant. In cold climates, sweating is dangerous because it soaks your clothing. In the heat: conserve your sweat, not your water. In the cold: avoid sweating at all costs.

Respiration — even breathing costs you

Every breath you take, your body warms the incoming air and saturates it with moisture. When you exhale, that heat leaves with it. You can see it on cold mornings. In extreme cold, covering your mouth and nose with a scarf or balaclava reduces heat loss through respiration significantly.

Clothing — Your First Line of Defence

Before any shelter, before any fire — clothing is what you're wearing right now, and it's doing the job already. Or it isn't. The choice of what you put on your body before you head out is one of the most important survival decisions you'll make.

Cold and wet climates

Fabric choice matters enormously here. Wool is your best friend: it retains around 70% of its insulation value even when wet, is moderately fire-resistant, and doesn't smell as fast as synthetics. Ideal for base layers. Sheep have been onto this for centuries.

Synthetics and polyester moisture-wicking fabrics are lightweight and dry fast — useful when wet conditions are unavoidable. But avoid anything that becomes wet through your own sweat and stays that way.

Cotton is the enemy in cold wet environments. It absorbs moisture, dries slowly, and sits against your skin conducting heat away. Leave the cotton t-shirt at home.

The COLD acronym keeps your layering strategy on track:

• C — Clean: dirty clothing stops breathing and insulating. Keep it clean.
• O — No Overheating: sweating in cold conditions can kill you if you can't get dry. Vent before you drench.
• L — Loose and Layered: trapped air between layers is what keeps you warm. Too tight = compressed air pockets = cold.
• D — Dry: non-negotiable. Wet = cold. Cold = dangerous.

Your cold climate layering system:

• Base layer — wool
• Warm intermediate layer — wool or synthetic
• Optional thicker mid-layer — wool or synthetic
• Outer layer — waterproof, windproof, breathable
• Don't forget: warm hat, wool socks. Non-negotiable.

Hot climates

Flip everything. In heat, you want loose-fitting cotton that retains moisture against your skin — sweat is your cooling system, so let it work. Synthetics that wick moisture away from your body in hot climates make you feel hotter, not cooler.

The exception: desert nights. When the temperature drops, you need to be dry and have a warm layer ready. Plan ahead for the swing.

Choose for your activity

Alpine trekking above the treeline calls for synthetic, lightweight, windproof, waterproof, breathable layers. The same kit in dense bush will shred itself in an afternoon. Dense scrub needs tough, durable fabric. Think about the specific terrain and task — then dress for it.

Shelters You Can Carry: The She'll Be Right Kit

No matter which portable shelter you choose, you'll need an insulation mat — either closed-cell foam or inflatable — to sleep on. Three-quarter length is fine. Without it, the cold ground will pull heat straight out of you through conduction all night. Do not skip this.

The Garbage Bag — ugliest, most underrated piece of kit ever

A large, un-pleated, heavy-duty garbage bag (260L if you can find one) is one of the most versatile things you can carry. One object, dozens of uses:

• Raincoat — cut a hole for your head, pull it on, done
• Ground sheet or moisture barrier
• Water carrier
• Stuffed with leaves: instant insulation layer between you and cold ground
• Flotation device
• Cut open and rigged as a lean-to shelter using basic knots
• Combined with a disposable space blanket: a heat-reflective lean-to that keeps you warm and dry

Reusable Space Blanket / All-Weather Blanket

Not the flimsy foil sheet from the marathon finish line. The proper, reusable version with built-in grommets and eyelets — this thing is a serious piece of kit. It can be:

• A heat-reflective blanket — Mylar side in = reflects body heat back to you
• Ground sheet
• Configured into multiple shelter types
• Mylar side out = reflects sun in hot weather, keeps you cooler
• A signalling device — the reflective surface is visible from distance

Lightweight Tarp / Hootchie — the most versatile shelter on the market

In the Australian Army it's called a hootchie. Everywhere else it's just a tarp. Whatever you call it — this is arguably the best lightweight shelter available. In anything but serious wind, it can be rigged as an A-frame, lean-to, pup tent, or connected with others to make a larger group shelter. In heavy rain, pitch it low. In fine weather, raise it.

Sleeping under a tarp keeps you connected to your environment in a way a tent never does. You hear everything. You smell the rain coming. You watch the sky. If you haven't tried it, you're genuinely missing out.

What you'll need alongside it: ground sheet, insulation mat (3/4 length), sleeping bag, bivvi bag (waterproof sleeping bag cover).

Hammock and Tarp — off the ground, above the chaos

Hammocks shine in hot, wet, tropical environments where the ground is crawling with things that bite. Built-in bug net is a must in those conditions. They're also great on uneven or sloped terrain where flat ground doesn't exist.

You still need insulation beneath you — a half-inflated sleeping mat prevents cold spots and heat loss through convection. In cold weather hammock camping there are some elaborate sleeping systems available, but frankly most are over-engineered and too bulky to carry practically. Keep it simple.

Natural Shelters — Build What the Land Gives You

No kit? No problem. If you understand the principles, the bush gives you everything you need. Lean-tos, A-frames, dome huts, wickiups, group shelters, raised jungle platforms — they're all buildable with the right knowledge and what's around you.

One caveat the reality TV shows never mention: building a proper natural shelter takes time. Depending on available materials and shelter type, you're looking at 3 hours minimum, up to 3 days for a well-insulated, weather-tight structure. Start early. Don't wait until dark.

Core principles for any natural shelter:

• Site it correctly — more on this below
• Build a sturdy framework first. Thatching falls apart without solid bones.
• 45-degree roof angle for proper water runoff

• Thatch from the bottom up, each row overlapping the one below by one-third — like roof tiles
• Use dead palm fronds, not green ones — green ones shrink and leave gaps
• Build an improvised bed inside to get off the ground. Conduction will drain you overnight.

Siting Your Shelter — Where You Put It Matters As Much As How You Build It

A perfect shelter in the wrong location is still a problem. Before you commit to a spot — whether you're rigging a tarp or building a debris hut — run through this checklist:

• Look up, look down, look all around. Dead branches overhead — known as widow makers — can fall without warning. Do not sleep under a compromised tree.
• Avoid low points and valley floors. Cold air sinks. The bottom of a gully will be noticeably colder than the slope above it.
• Avoid game trails and ant nests. You do not want company in the night that you didn't invite.
• Flat, even ground. You need sleep. Sleep on uneven ground is poor sleep, and poor sleep is a survival liability.
• Plan for rain runoff. Where will the water pool if it pours? Your shelter shouldn't be in that spot.
• Never dry creek or riverbeds. Rain kilometres away can send a flash flood down a bone-dry channel. This is not a risk worth taking.
• Hot climates: seek shade. The shade differential is significant and free.
• Stay back from water sources. Insects breed in still water. Running water masks sounds — predators approaching, or search parties looking for you.
• Orient for cross-ventilation. Any breeze should blow across the front of your shelter at 90 degrees — this carries smoke away and keeps air moving.

Practise this. For real, in the field.

Everything in this article — heat loss, clothing strategy, tarp rigging, natural shelter construction, siting — is practised hands-on at Camp She'll Be Right. In NZ terrain. In real conditions. With women who are done waiting to feel prepared.