The TOG rating system was launched by The Shirley Institute in the 1940s and is a way of measuring insulation properties but not comfort. A very similar method is used to get an R rating on insulation pink batts. TOG measures thermal resistance by using a large metal plate and a mechanism for measuring the air temperature above the quilt. The quilt is placed on the metal plate with a heat source underneath which heats to 33 degrees and time is measured as to how long it takes for the temperature above the quilt to reach the same temperature as below.
This is why a brick or pink batt has a high TOG rating but is not comfortable to sleep under. People don't sleep under a flat-board like quilt, so the real test is warmth to weight and breathability. You need to measure the TOG rating then divide by the weight of the quilt to get warmth to weight and then measure breathing properties of the fill and casing to get a true understanding of how the quilt will perform. The drape of the fabric is also important.
All three tests need to be incorporated to give the right grading for a quilt, but this is not usually done. Polyester casing and fill may insulate but does not breathe, so you get hot. While down is very light weight and has good warmth properties, it does not have the moisture management properties that wool does, so you get hot and clammy and then wake and shake the quilt to get cool air back in.
Wool scores a fairly good insulation rating, this combined with wool's moisture management, and amazing ability to breathe and adjust temperature according to the sleeper's needs, makes wool the only choice for a deeper, more restful and more comfortable night's sleep.
Put simply a high TOG rating usually means low moisture management or breathability properties, so it is just hot.
At MiniJumbuk we have come up with a simple way of choosing the right quilt for you based on the number of layers of wool inside our quilts. Ranging from our coolest and lightest quilt (Ultralight quilt) with one layer of wool/cotton blend, through to our warmest and most luxurious quilt (Thermal quilt) with five layers of Australian wool. Using Airlight Technology developed exclusively by MiniJumbuk, we are able to trap more air between the wool fibres. This innovative design offers superior insulating properties while allowing for the creation of lighter, more comfortable quilts that perfectly regulate sleeping temperature.