how to demonstrate compliance with natural ventilation in apts?

Hi, Courtney- I'm not sure why natural vs. mechanical ventilation would matter for the Thermal Comfort Design credit. The thermal comfort tool deals with temperature, humidity, etc. as well as the activity level and amount of clothing worn by the occupants. I believe you should be able to apply the thermal comfort tool in residential spaces without much difference from the way it is applied to your mechanically ventilated spaces. This credit has to do with mechanical conditioning, not mechanical ventilation. As long as you have heating and air conditioning in the residential units, it seems likely to me that you would be able to comply with the Thermal Comfort Design credit.

I agree with Julia. The thermal standard is not coupled to the ventilation standard.

That's a good question. I think the language in the v. 2009 reference guide is a bit muddled about the difference between natural ventilation and natural conditioning. There is a reference to Section 5.3 of ASHRAE 55-2004, but that section deals with natural conditioning, not natural ventilation. I think as long as you have mechanical *conditioning*, that for version 2009 the natural vs. mechanical ventilation should not matter. This is especially true in a residence where the required amounts of ventilation are tiny. I suppose a reviewer might question the impact on comfort if one is depending on natural ventilation for a high occupancy space, but that would be more applicable in a non-residential usage and also may come into play more in LEED v4 from what I have heard.