# Clothing level based on outdoor air temperature?

Usually, people will change clothes according to seasonal temperature change. So, shall we estimate the typical indoor clothing level based on outdoor air temperature and use it as input for the PMV thermal comfort evaluation component as shown below?

Please advise if the temperature ranges and the corresponding typical indoor clothing levels need to be adjusted based on your experiences in thermal comfort studies.

Thank you!

• Ji

Grasshope,

Yes, you should absolutely be changing the clothing with the seasons. There is now an overwhelming amount of research, which shows that using the PMV model with a fixed clothing value typically results not only in increased building energy use but also greater occupant discomfort when applied to real-world cases. In particular, there is usually greater discomfort in the summer because buildings are often over-cooled thanks to an assumption that many occupants are wearing more clothing than they actually are (such as a 3-piece suit or equivalent). This may be a fair assumption for winter cases but even conditioned buildings with the strictest dress codes will usually have some variation in clothing from summer to winter that will merit some warmer summer temperatures.

You can use an expression like you have there but there is also a component called the “Ladybug_Clothing Function”, which is made to help you generate an hourly list of clothing values based on the outdoor temperature. The function comes from research published by the thermal comfort scientist Stefano Schiavon at the Berkeley Center for the Built environment. I have also modified the function so that you can adjust the minimum and maximum clothing to suit different dress codes.

-Chris

Thank you very much, Chris!

Next time, maybe I shall ask if there is already a LB/HB component for certain function first.

• Ji

Dear Chris,

May I ask if the PMV comfort calculator component can take multiple list of clothing level values?

The following is the percentage of comfort hours calculated for 6 zones using a fixed clothing level of 0.5.

Using the clothing level component, a list of 8760 clothing level values are created, and it is duplicated for each zone, as shown below. However, when the 6 lists of clothing level is used for the PMV component, the percentage of comfort hours are obviously problematic as shown below. It seems the PMV component does assign each of the clothing level list to its respective zone.

May I ask what might be the source of the problem here?

Thank you!

• Ji