The short answer: a down duvet gives the most warmth for the least weight, a synthetic duvet is the cheapest and can usually be washed at 60°C, and an alpaca duvet absorbs the moisture your body releases at night while being heavier and more expensive than both. The right one depends on what bothers you most at night: cold, sweat or allergies.
I sell alpaca duvets, so below I am also clear about where down and synthetic do better.
The comparison in one table
| Alpaca | Down | Synthetic | |
|---|---|---|---|
| Fibre type | Natural protein (keratin) | Natural protein (keratin) | Man-made polyester |
| Weight for similar warmth | Heavier than down | Lightest | Depends on the fibre |
| Moisture | Absorbs water vapour into the fibre | Warmest when dry and fully lofted | Polyester absorbs less than 1% moisture |
| Washing | No hot water; airing and spot cleaning | As the label says; large duvets best at a laundry, long drying | Usually machine washable, often at 60°C |
| Price | Highest | Medium to high | Lowest |
Down duvets: the lightest and loftiest
Down gives the most warmth for its weight. Its quality is described by fill power, which measures how much the down expands: the higher the fill power, the less down is needed for the same warmth. As an example, an all-season goose down duvet of 200×220 cm often contains about 700 g of filling, while our all-season alpaca duvet in the same size contains about 1.8 kg.
Down insulates best when it is dry and fully expanded. After washing it has to be dried very thoroughly, which is why manufacturers recommend taking large down duvets to a laundry. If the origin of the down matters to you, look for the Responsible Down Standard (RDS), which bans live-plucking and force-feeding.
Choose down if you feel the cold, like a light and lofty duvet and don't mind the care it needs.
Synthetic duvets: affordable and easy to wash
Synthetic duvets are usually filled with polyester fibre. They cost the least, and most can go in a home washing machine, often at 60°C. That matters for house dust mite allergy, because hospital guidance for allergy sufferers recommends washing bedding at exactly that temperature.
The weak point of polyester is moisture. The fibre absorbs less than 1% of its weight in water, so the sweat your body releases at night stays between the fibres, close to your skin. Some people feel this as stuffiness under the duvet. Polyester is made from oil and sheds microfibres when washed.
Choose synthetic if your doctor has told you to hot-wash your bedding, you are buying for a guest room or your budget is limited.
Alpaca duvets: a natural fibre that takes up moisture
Alpaca fleece is a protein fibre, like sheep's wool. It absorbs water vapour into the fibre (around 10–11% of its own weight) and gradually releases it into the air, so an alpaca duvet is less likely to feel damp. Some of the fibres have a hollow or partly hollow core that holds air. Alpaca also carries little grease (lanolin) compared with sheep's wool, which matters for people who react to lanolin.
The quilting stitches hold the fleece in place, so the filling does not shift.
An alpaca duvet is heavier than a down duvet of similar warmth and drapes closely over the body. Some people like that weight and others don't, so it is worth knowing before you buy. Alpaca must not be washed in hot water or tumble dried, because the fibre felts. Airing, a duvet cover and spot cleaning are enough.
We fill our duvets only with fleece from Polish alpacas, without any sheep's wool or polyester. The shell is organic cotton certified to GOTS and OEKO-TEX STANDARD 100, stitched with mercerised cotton thread.
The duvet is quilted, which keeps the filling from shifting. It also has no interlining, the thin, usually synthetic non-woven layer that can sit between the filling and the shell. An interlining makes a duvet easier to construct and stops fibres working their way through the fabric. Without one, choosing the right materials is critical, above all the shell fabric, but it means there is no synthetic material anywhere in the duvet.
Choose alpaca if you sweat at night or wake up alternately too warm and too cold, want a natural fibre with a known origin and accept a higher price and more weight.
UNWONTED alpaca duvet, all-season or winter
100% Polish alpaca fleece, quilted, no interlining or synthetics, 5-year craftsmanship guarantee.
What about sheep's wool?
Sheep's wool is the closest alternative to alpaca. It also absorbs moisture, costs less and is easier to find. It contains more lanolin, and its fibres have more pronounced scales, so it can feel coarser and felts more readily. If you want a natural filling and an alpaca duvet is beyond your budget, a good sheep's wool duvet is a sensible choice.
How to choose in practice
- You feel the cold and want a light duvet: down.
- You have a dust mite allergy and were told to wash at 60°C: synthetic, or a natural filling inside an anti-allergy cover.
- You sweat at night or sleep in a heated bedroom: alpaca or sheep's wool.
- You want a natural fibre on a moderate budget: sheep's wool.
- You want a natural fibre with a known origin and don't mind more weight: alpaca.
Once you know which filling suits you, the next step is warmth, covered in all-season or winter duvet. If you want to know where the price difference between these materials comes from, read why alpaca duvets cost more.