Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Without seeing the input file, the most likely explanation is bad ground temperatures beneath a slab floor. Check the values input for Site:GroundTemperature:BuildingSurface. NIght sky temperatures can also result in heat loss enough to bring the zone temperature below outdoor air temperature, but only in special cases with a weak roof, and this is not likely to draw the zone ~5C below the air temperature.
