SubZero Factor 1 Base Layer

Review: SubZero Thermal Base Layer Factor 1+

It was with great anticipation that I looked forward to trying and reviewing the Thermal Base Layer Factor 1+ from Sub Zero.  I tend to generate a lot of heat when walking but this gets ‘wicked’ away too quickly when I wear a standard technical base layer, which can leave me feeling cold as soon as I stop.  I was hoping that this product would stop me over heating whilst walking yet keep me warm when resting.  Certainly their specification looked promising:

“High performance breathable base layer under garments act as lightweight thermals.  Part of the Sub Zero system of graded warmth that creates a micro-climate to control body temperature by effectively managing perspiration in any situation.

Made from our own super-soft hard-wearing duel texture fabric knitted from polyamide fibres.  Layer 1 is technically superior ands as such, much more effective than most performance clothing made from polyester fabrics.”

My first trip out with the garment was the first real cool day of autumn.  Air temp was about 8C with a chill factor of around 5C.  I had chosen a brisk walk along the Ridgeway with a reasonable amount of climbing to help generate a fair bit of body heat and had selected the very exposed Uffington Castle Hillfort to take a rest.  I was wearing the Factor 1+ next to the skin layered up with a standard short-sleeved technical top.

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My second trip out was on a cold blustery day with a chill factor approaching zero.  It was certainly cold enough for me to wear a hat and gloves.  On my upper body I had the Factor 1+ base layer and a fleece.  The walk was fairly arduous and allowed my to generate a lot of heat with a very exposed rest place chosen to try and rapidly reduce my body temperature.

On both outings I was very impressed with the performance.  Whilst walking I was kept comfortably warm and dry despite generating a fair amount of body heat.  The material wicked away any sweat generated and maintained a fairly even body temperature.  When I stopped for coffee, on both exposed hillsides, I felt myself cool down except my upper body which remained warm during the 30 minute break.


Over the years I have tried many base layers.  Some have been good at controlling the heat whilst working hard and some at keeping me warm during rest periods.  I have however, never had a base layer that could do both until I tried the Factor 1+.  I generate a lot of heat and have been known to sweat standing still!  Wearing the factor 1+ I never felt uncomfortable from excess sweat and when I returned to the car to change – all of my clothes were dry.

The SubZero thermal base layer Factor 1+ is very impressive and I highly recommend it.