What really keeps you warm is... air! Trapping warm, still air around your body should be the aim of your insulating clothing system. Here's how to achieve warmth nirvana without looking like a woolly mammoth.
Wear a protein fibre next to your skin (think silk, merino (wool) or cashmere). Protein fibres are synergistic with our skin, creating an insulating second-skin that warms to our body temperature. Silk is better than merino because it dries faster, allowing the skin moisture that causes heat loss to evaporate more easily. Silk layers are also very strong and won't go into holes like merino does. Pure cotton is not good, it holds too much moisture next to the skin and has no inherent warmth to offer. Synthetic fabrics are not an option - they are smelly, non-absorbent (sweaty) and uncomfortable. Not to mention non-compostable. We don't care what marketing words they dream up to try to convince you otherwise.
You can wear several thin protein layers together to trap maximum insulating air next to your skin and between the layers. Wearing them skin-tight is not actually recommended, for this reason.
Wear a lofty layer next. The more loft a garment has the more warm air it will trap. Try knitwear (a cardigan or jumper) made from protein fibres or, for the ultimate in warmth, a Silkbody Silkfleece. This award-winning 100% silk garment is luxuriously light and traps large amounts of delicious warm air because the garment itself is dual-layered.
We are not advocates of wearing synthetic fleece products. Not only are they the equivalent of wearing a fluffy plastic bag, they also release their tiny non-biodegradable fibres into the ocean via your washing machine whenever you wash them.
Here's a tip that will have you reaching for your Eighties ski-suit next time you hit the slopes: wear a belt. The "chimney effect" is the result of warm air rising up your body. If you wear loose clothing, any warm air will be moved away from the body like a bellows. By wearing a belt you stop the warm air escaping, especially when you're active. A tight-fitting high necked-top or scarf does the same thing, stopping the precious warm air from shooting straight out your neckline.
If you're heading outdoors, you'll need to wear a wind and rain-resistant layer on top to protect all those warm air layers you've built up. If that outer layer allows body moisture to evaporate, that's all the better for your overall comfort.
In summary, to stay warm this winter, remember these points:
1. Wear layers so that air spaces are built up in the clothing system. Building up several thin layers can be more effective than wearing a single thick layer for this reason.
2. Keep your core (torso and head) warm so that it can send excess heat to the extremities
3. Protect insulation from wind and water
4. Provide proper ventilation so body moisture can pass off into the environment and sweating can be avoided
If you have tips of your own or any questions, just comment below.
BCApSc (Clothing and Textile Science), University of Otago
Watkins, S. M. 1984. Clothing: the Portable Environment. Ames: The Iowa State University Press.