Which warmth class of comforters is the warmest?
Which duvet is the hottest? The answer to this question is seemingly very simple. After all, comforters from heat class 1 are seemingly always the warmest. However, before you get busy with this information, it is best to read on because there is more than just heat.
Thus, ambient temperature, the insulation of your bedroom, the properties of a quilt and your personal preferences also play a very powerful role. Dive into the wonderful world of duvet offerings and the theoretical explanation of how heat classes are created?
The technical explanation of heat classes
The classification below divides insulation capacity into 4 heat classes. We look for the thermal insulation of a unit area. In technical jargon, we call this the thermal resistance. In England, the so-called Tog was developed for this purpose. In the US, this insulation is expressed in Clo. For your information, 1 clo = 1.55 Tog. Specific to down, we also look at fill power.
| Heat Class | Ambient temperature outside | Seasons |
| Heat Class 1 | Average 4°C or lower | Very cold winters (11 – 13.5 Tog) |
| Heat Class 2 | Average 8°C | Cool winters and autumn nights (8 – 11 Tog) |
| Heat Class 3 | Average 12°C | Mild winters and spring and autumn nights (6 – 8 Tog) |
| Heat Class 4 | Average 16°C or higher | Warm summer nights (2.5 – 4 Tog) |
What is a Tog?
Tog is a unit of thermal resistance used to measure and classify the insulating properties of comforters. A higher Tog number represents better insulation and more warmth. Tog values usually range from 1 (very light) to 15 (very warm). Nice and easy right if you can just measure thermal resistance? Yes indeed! However, the story is not quite complete because this does not measure whether a duvet is insulating. Especially for down comforters, for example, this insulation value, filling power or CUIN value is very valuable.
The Tog value is very well known in Britain and the British Isles, and is actually rarely used in the Low Countries and by extension Western Europe. A lot of producers create their own interpretation. This makes it less easy for you, as an interested consumer, to compare properly. So often a warm duvet is called a 4-season duvet. These quilts can be used together or as individual quilts thanks to attached “cutters” or buttons. A warmer section for the in-between seasons and a lighter section for summer. Together, they then form the very warm winter comforter.
What is fill power?
Fill power is a scientific yardstick to measure the quality of down. The higher the fill power, called the CUIN value, the better the quality of a duvet. Simply put: at the same fill weight, down with a high CUIN value retains more heat. More air is retained and that insulates better. You also see more volume and often that down is much fluffier. The quilt is noticeably lighter with the same thermal performance. In this example, the best quilt is the one with the highest heat-insulating property at the lowest weight.
Here too we make a small remark, because this value is also approached theoretically. In ideal conditions, without humidity, the test is performed several times and then the average is calculated. However, the humidity of your bedroom is ideally 50% on average. The moisture in real conditions will cause the thermal insulation to be lower.
What is the impact of padding on the heat experience of a duvet?
As you can read, it seems easy to determine thermal resistance and filling power and the stocking is complete. However, we also immediately gave our comments on the results. And then there are also big differences between, for example, comforters made of natural hair (wool, etc.), down and feathers, silk, bamboo, Lyocell and synthetic fibers. Because all these materials also have other properties.
A duvet of Icelandic Eider down is one of the most exclusive down coming from the Eider duck. The video below also shows the unlikely fill power of this down. Immediately you also understand that it is not the species that determines the down quality. Goose down is no better than duck down, obviously if you compare both within their fill power and other down characteristics.
This leads them to react differently with perspiration or with excess heat. In other words, what are its moisture-regulating, ventilating and heat-regulating properties? And are they hygienic to sleep under, in other words are they washable or at least cleanable? And what about allergies? Are they hypoallergenic by nature or do you really need to wash at high temperatures?
How does bedroom temperature affect your choice of duvet?
The ideal bedroom temperature is about 18°C. This ideal temperature applies to every season. So that means also during the colder autumn and spring nights and especially during a cold winter. A lot of people choose to leave the windows open in the bedroom all year round. In terms of humidity and heat, that could be better.
During cold days, ventilate your bedroom vigorously and long enough in the morning. Then close your windows and open your bedroom door. This way you don’t let the heat get lost and a bedroom usually warms up to about 18°C. Just before you go to sleep, put your windows back ajar or open them. You crawl into a comfortable bed and your bedding is also well-dried during the day.
Sleeping with a window open?
If you sleep with a window open, then you know you can safely use an extra warm duvet. Are you cold easily? Then down comforters or class 1 wool or synthetic winter comforters are a good choice. If you’re always too hot, consider heat-regulating comforters such as camel hair, (Texeler) sheep’s wool or mixed natural hair comforters.
If you want to be able to work with 1 duvet in all seasons, there is only 1 choice: a 4-season duvet. You knot the two comforters together to make one thick duvet. If you remove the lightest duvet, it is perfect for warm summer nights. The one that remains is rather medium warm and fine to keep you warm during spring and fall.
Which duvet is hottest: conclusion
A heat class 1 is clearly the warmest variety. But look a little further than just the heat classes. Take into account the bedroom temperature. It is determined greatly by the insulation of your home, sleeping with windows open or closed, and whether you heat the bedroom lightly during the winter.
Also keep in mind the specific properties of the fillings used for comforters. Down is generally highly insulating and therefore warmer, while natural hair such as wool comforters are highly moisture regulating and often regulate heat better.
