I am completing documentation for a dormitory that has a Summer/Winter operative temperature of 75/70, respectively. RH is 55, air velocity is 40 FPM.
Rooms with a 1.2 MET or lower are all noncompliant (or 1.2 MET and .5 CLO, which is also noncompliant). In order to comply, it appears my only options are to raise the CLO level or the operative temperature of the space (I think I can't change the activity level since, no matter what, the space use remains the same). Here are my questions:
1. Provided I supply a narrative stating clothing assumptions and these clothing assumptions are logical (not requiring occupants to wear a jacket in the summer, for instance) using the values provided for garments in ASHRAE 55, can I simply raise the CLO levels in the spaces (or come up with a 'standard' project CLO that passes in all spaces and I can then apply to each space for each season?)?
2. If I adjust the operative temperature of the space I'm assuming that if, for instance, I am cooling below the project setpoint we have designed to in order to pass, would I be required to provide calculations proving that the extra cooling required is achievable by the system and equipment provided in the space? The same question would go for spaces where the temperature required for comfort exceeds the design heating setpoint for the project.
3. Is it possible to adjust both values in order to change each as little as possible and remain as close to the ASHRAE standard number and the design setpoints in the project? Would each assumption for CLO in the summer and winter have to be a global change, or can each space use a different CLO level even though they all exist within the same building?
Neetu Singh
Building Performance AnalystThe Green Engineer
August 1, 2014 - 10:21 am
Clo and MET level will be different for different space types. Adjusting these numbers based on a broad division of space types (classrooms, living units, kitchen,lounge/cafeteria, etc.) with a logical explanation is acceptable. Having the same MET level for the entire building is not an IEQc7.1 requirement.
Also, confirm the airspeed for the project as per design. 40 fpm is an upper threshold to ensure user comfort per ASHRAE 55 with exceptions for elevated airspeeds. However, it is not mandatory to use the 40 fpm in your calculations.
If you have to show compliance through different operative temperatures than what the design setpoints are, I believe you will have to provide calculations confirming that the system is able to maintain those temperatures.