I’m glad to see that the new standard includes a reference to a specific known problem of thermal comfort (overcooling) and the ASHRAE-55 section on it but I am overall very disappointed that there are almost no changes to this credit that badly needs more attention. Large studies like the CBE "Occupant Satisfaction in Green and LEED-Certified Buildings" survey of thousands of occupants have shown that more than half of occupants are dissatisfied with their indoor thermal environment. Compare this to ~25% dissatisfaction with “visual comfort” and “amount of light,” which clearly also needs some attention but then we see there are 4 credits devoted to lighting while only 1 is devoted to thermal comfort. I don’t mean to diminish the lighting credits here but it just seems like the priorities are really skewed from what they should be.

At a minimum the standard could add another thermal comfort credit for providing personal thermal comfort devices such as heated chairs, foot warmers, and desk fans. The latest versions of ASHRAE-55 have a lot of guidance on how to implement these effectively.

Furthermore, there really needs to be a requirement to simulate indoor radiant temperatures in order to comply with ASHRAE-55. Or we at least need to tell people that they cannot assume the Mean Radiant Temperature (MRT) is the same as the thermostat setpoint unless the thermostat is specifically designed to sense radiant temperature. I can’t tell you how many engineers assume that the indoor radiant temperature is the same as the air temperature setpoint. So they believe they comply with ASHRAE-55 because their system meets the air temperature setpoint during the peak conditions. And I have seen this logic work for the exiting LEED Thermal Comfort credit.

In practically all EnergyPlus simulations that I run, the radiant temperatures are several degrees away from the thermostat setpoint. Typically, this is because of solar energy that enters through glass facades and warms up the surfaces to temperatures much hotter than the air at the setpoint. This is enough to push most cases out of the comfort zone, even without accounting for shortwave solar energy that can also fall onto occupants and can further increase radiant temperatures, (which ASHRAE-55 gives good guidance on how to account for). So we have many engineers designing the system to meet the indoor air temperature setpoint but occupants near the facade are uncomfortable and experiencing wildly different temperatures because of the radiant environment. So they do not technically comply with ASHARAE-55. Almost all major energy simulation software (EnergyPlus, IESVE, etc.) can give outputs of hourly mean radiant temperature (weighted by surface area) so many projects already have this info, which could be used to make this credit a lot more effective and bring to light the many cases where people are not actually complying with ASHARE-55.

Lastly, in an ideal world, there would be a requirement to run simulations of spatial thermal comfort looking at metrics like Heat Sensation Percent (HSP) and Cold Sensation Percent (CSP), which are similar to spatial daylight autonomy and would make this credit category a lot more like the lighting credits. I understand that this may not be a reasonable goal at this time since, to my knowledge, Ladybug Tools is the only software that computes these spatial thermal comfort metrics at the moment. But this Ladybug Tools software is free and open source and it uses the open source EnergyPlus and Radiance under the hood to perform the thermal and ray-tracing calculations. So I think it may not be long before other software starts offering similar functionality. LEED should start preparing for this now by at least requiring some basic simulation of MRT.

In summary, please, please give this credit category more attention.There is a wealth of missed opportunities at the moment.