A new fabric has become available which is claimed"opens and closes like a pine cone depending on ambient temperature". As the temperature rises from 10'C to 20'C breathability improves by 50% to about 20000g/m2/24hrs. As the temperature falls the reverse process is claimed to reuce heat loss.
There seems to me to be some confusion here about heat loss, venting and breathability:
Breathability (or moisture vapour permeability) allows moisture to escape through a fabric without allowing cool air back in - i.e. wind resistance.
Venting allows moist air to escape and allows cool outside air back in to the garment.
Heat loss is improved by increased venting and breathability, but insulation is also improved by increased breathability because trapped air insulates better when it contains less moisture. The reduction in thermal efficiency due to humidity can be seen here.
Therefore the "pine cone fabric" would be of great benefit if it allowed increased venting in warmer conditions (assuming it could also prevent warm rain from getting in)... but the above figures suggest that this isn't the case and that reduced breathability when the fabric is cold will ultimately reduce the effectiveness of any insulation worn beneath.
These arguments also indicate why polar explorers prefer to use the most breathable fabrics available!