From filling choices to talk about tog – here’s what you should know before buying a duvet

A good duvet is a thing of warmth, making winter nights a pleasure and summer sleeps an airy dream. Others seem mismatched to their purpose, always either too hot or too cold. So, if you’re in the market for a new duvet (now that staying warm becomes numero uno), don’t get weighed down by all the jargon. We’re here to demystify some of the elements for you when it comes to choosing a wonderful, new duvet worth snuggling up in.


How a duvet actually keeps you warm

It may seem counter intuitive, but air is actually the thing that keeps you warm. Insulation is the act of trapping air between one surface and another, so while you may think that your big, fluffy duvet keeps you warm, the reality is that you keep it warm – it just prevents the heat from escaping.

Remember how granny used to pile extra blankets on the bed in winter? That was to create extra layers of insulation, to help prevent air from escaping. Because they are designed to keep a certain amount of heat in, duvets are a lot better suited to this task than blankets, especially in winter.

What on earth is the “tog”?

Without getting too deep into the science of it all, the “tog” is a term used to describe the thermal resistance of a material, as in the filling per square centimetre of duvet. Scientifically, a tog is 0.1 m2K/W. So, if it’s actually air that keeps you warm, a duvet’s ability to keep air from escaping determines it’s thermal resistance, or tog. Here’s a quick summary:

In summer you want a lighter tog: 3 – 4.5 tog so that more of your body generated heat can escape.
In winter you want a heavier tog:  7 – 13 tog so that that very same body heat can be retained by the duvet.


Choosing a filling: natural vs. synthetic

Some of you may remember (with varying degrees of fondness) the feather pillows and duvets of your childhood. These days, natural fillings are made up of either down or feathers or a combination of the two.

What should you know about down?

  • The smallest, finest feathers, often more finely curled, so they hold air better
  • More insulating and softer than other fillings
  • More pricey than other fillings

What then are feather duvets?

  • Feathers are the longer, harder, flatter feathers
  • These feathers hold onto less air than down so more of them are needed to produce the same amount of heat
  • Feathers are less insulating, tend to be slightly heavier and tend to stick through the duvet fabric more

Many duvets are a combination of the two, in an effort to reduce the cost and balance the whole experience.

Synthetic fillings, on the other hand, can be either one continuous piece of material (like batting in a quilt or comforter) or a loose fill designed to work the same way that a natural filling would. Cheaper, synthetic duvets are often the former, and can be blanket-like, in that they do not drape naturally over the body, whereas for a slight increase in price, a loose fill synthetic or microfibre duvet will drape just like a natural one would.

Why go with synthetic?

  • Synthetic duvets can be better for allergy sufferers
  • They can be washed quite easily
  • Less expensive than down duvets


So what are the distinguishing factors between duck or goose?

If you’ve settled on going with natural but can’t decide between duck or goose, here’s what you need to know before choosing. A lot of it comes down to quality and price:

  • Goose down is harvested in larger clumps, making it a lighter, more efficient insulator.
  • Duck down has smaller clumps, but it’s a lot cheaper (there are a lot more ducks in the world, apparently).
  • Origin also plays a role, and the origin of the animal (say Hungary or Siberia) will indicate to you how warm the down or feathers will be – Siberia is much colder, making Siberian goose down a lot better suited for colder winters.
  • Allergy sufferers will also be thrilled to know that modern down and feather duvets are treated to be dust and allergy free, allowing everyone the pleasure of a great natural filling duvet.


Still not sure what you need?

Here in South Africa, our temperatures vary wildly from summer to winter, so having two duvets isn’t really such a stretch. However, storing an enormous winter duvet can seem a bit extravagant, when really, our winters are not that long. Your best bet is to look at a combination or all-season duvet. Two duvets, a light one for summer and a slightly heavier one for spring/autumn, that can be joined together to form a lovely, warm one for winter. Everything you need in just one duvet, and nothing too enormous to store.

So, there you have it. The ins and outs of duvets – just in time for winter. Now all you have to do is choose a duvet cover set to keep your delightful bed looking as beautiful as it will be to sleep in.