Material equal to . . .

Ian – Polartec 100 = ~ 5.7 oz/yd^2; loft = ~ .148; intrinsic clo = ~ 1.1; and clo/oz = ~ .2. A typical size M zip T in Polartec 100 will weigh ~ 10 oz. This material was originally market targeted as a base layer for aerobic pursuits. With the advent of Polartec Power Dry and Power Stretch, it has been retargeted as a light insulation layer.

For an insulation alternative with greater warmth with less bulk and weight, when dry, the market leader appears to be the Mont-bell UL Down Inner Series products. The size M jacket weighs 6.9 oz and the parka weighs 7.4 oz. The intrinsic clo for these garments = ~ 1.60. In simple terms, they are about 69% warmer and 30% less weight than equivalent Polartec 100 garments.

The Mont-bell U.L. Thermawrap Series is another insulation alternative to Polartec 100 with comparable moisture resistance but less bulk and better wind protection. At 8.7 oz and an intrinsic clo = ~ 1.163 it is close to the equivalent of a Polartec 100 plus a light wind shirt.

For an aerobic base layer alternative, there are two options that provide similar bulk for their warmth but greatly improved wicking performance. The wicking performance improvement is attributable to the addition of Lycra and the bi-component construction. Polartec Power Dry = ~ .085" loft and Polartec Power Stretch = ~ .135". The intrinsic clo values are in proportion to the respective lofts.

Thanks Richard, stats and a simple english explanation!
I'm not able to work out which new material is comparible to which and for old fashion me 100 fleece is a well known base to compare to. I like it still but the bulkiness is an issue in some situations. Thanks.