Below is the temperature and humidity data from a recently completed passive house (EnerPHit renovation of a brownstone rowhouse in Brooklyn, certfication pending) during last week's "polar vortex" cold snap. The heat, a Mitsubishi 2-ton minisplit system, was only turned on at the point noted - other than that, the temperatures are maintained within normal (albeit variable) comfort levels without any heating system (other than the sun and internal sources, ie passive house principles). It should be noted that the temperature was measured in the living room where the family spends a lot of time. But still... I'm amazed.
Indoor temp & RH from a Hobo U14-001 logger, ambient temperature & dew point data from KNYBROOK22 via Weather Underground. Click image to embiggen.