Freaking out about Chicago record breaking cold

[The Lazy L]

Northern Indiana here. No heat in the coop or supplemental lighting and roosting area is draft free. Tuesday morning I had 8 healthy hens and Thursday evening I still have 8 healthy hens. Hens are less then a year old and this is their first winter. During the 3 day period they laid 22 eggs. 6 eggs were cracked (frozen).

Their run is enclosed on three sides with 1/4" hardware cloth and the fourth side (north) is covered with steel roofing material. This morning I could see them in the run pecking at anything that drew their interest.