Densely occupied spaces calculation

Yes - this definitely applies to spaces of any size. We've had rooms as small as 70 GSF classified by densely occupied by reviewers and required them to include the relevant CO2 sensors. While there is something in the ASHRAE 62.1 standard that exempts rooms under a certain size from CO2 monitoring, GBCI has been very consistent/clear that they do not recognize that exemption and any rooms that meet the density threshold have to comply (I forget if it's an addenda/clarification or just generally in the standard - in either case, GBCI has rejected that as reasoning for exempting smaller spaces from requirements. Just including this factoid here so others don't go down that same rabbithole). To check the smaller spaces, simply check your room's designed density compared to the 25 people/1,000 GSF threshold (or in other words 0.025 people/1 GSF). So if you take your room's GSF (i.e. 100 GSF) and multiply it by that threshold (0.025 person/GSF), that gives you your densely-occupied threshold (i.e. 2.5 people). If the room is designed to hold 2 people, then it would be non-densely occupied. If it was designed to hold 3 people, then it would be considered densely occupied.