HB PMV Comfort Map - Testing Radiant Mechanical Systems

Hi All / @chris,

From HB documentation, I confirmed long wave (surface temps) and short wave (direct sun) radiation are accounted for in PMV comfort map.

Link: PMV Comfort Map - HB-Energy Primer

In cases where I want to test impact of active radiant surface (e.g., radiant wall, ceiling panel or floor) and just want its impact on comfort, is there an ability to hard code child surface temperature (or temp profile) in Pollination interface or Grasshopper? For example, import surface geometry, set surface temp (fixed or profile) and get its view factor and impact on long wave radiation in comfort map.

Or would I need to set up full radiant system in Ironbug to control surface temperatures? ability to bypass full system definition seems very useful!


1 Like

Hi @chris,

Refreshing this request if you have a minute. Is there an option to add “dummy” active thermal surfaces to evaluate comfort impact of radiant system with the spatial thermal comfort map?

Hoping to bypass detailed HVAC system setup since I just want to model comfort impact and not energy.


Hi @victorbrac,

This could be an option - especially combined with a low thermal mass / insulated construction

Other Side Temperature - HB-Energy Primer


That’s the answer that I would recommend, @charlie.brooker . You can just make a surface with a fixed temperature on the other side and then use a NoMass material for the construction with a very low R-value so that the inside temperature is basically the same as the other side temperature.

Granted, if you ask me, you really should be modeling a real radiant system if you’re trying to inform a design decision here. The main reason why radiant systems tend to require more attention to thermal comfort is not because the intended interior surface temperature of the slab was not correct. Rather, it’s that the interior surface temperature is rarely a constant value or at this intended value when you account for things like the heat capacity of the radiant construction, the thermal lag of the space, the rate of heat gain in the space (especially solar heat gain for the case of radiant cooled slabs), and controls like how quickly you might switch between heating and cooling modes.

There are some template radiant systems available in the LBT plugin now and you can use the HB Radiant HVAC Proprties component to customize things like the type of radiant surface (eg. floors vs ceilings), the type of system (eg. slab or metal panel), and controls like how quickly you switch between heating and cooling modes. You can use this to investigate some of these questions without having to build a whole Ironbug system and I might recommend trying this in lieu of or in addition to your study with a fixed temperature boundary condition.


Thanks @charlie.brooker for taking the time to respond! Great suggestion.

Hi @chris -

Thanks for providing the alternate options and providing your feedback. Summarizing the three options, compared relatively:

  1. Simple - Other Side Temp
  2. Moderate - Radiant HVAC Properties
  3. Complex - Full Ironbug System

I don’t see (1) as final stop, but could help shed light on how thermally active surfaces impact predicted comfort and help establish target surface temperature. Probably more applicable in low mass radiant options (ceiling or wall panel) where surface temperature would be more constant.

Then we could progress through steps (2) and (3).

1 Like

@chris , @charlie.brooker ,

How have you evaluated comfort for infrared heaters (e.g., high intensity gas heaters), only rarely applied to office spaces but often found in warehouses/ industrial space or outdoor (e.g., restaurant seating) scenarios.

Wonder if setting the surface temp to the appropriate emitter temp through applying “other side temp” solution above would sufficiently show impact on comfort.

Otherwise, I’ve relied on manufacturer’s data and/or probably would have to consider CFD-type analysis where I could detail the heater emitter surface and placement in the zone.

Hi @victorbrac ,

You’ll find several template HVAC systems under the 4::HVAC section for “Gas Unit Heaters”, which do a good job of modeling the gas energy usage of these types of systems. But, while their convective vs. radiant fractions of these template Gas Unit Heater systems are meant to align with reality, they don’t have a real geometric presence in the energy simulation. So their radiant fraction is distributed using surface area of the Zone surfaces instead of view factors, making them less ideal for detailed thermal comfort studies.

For detailed thermal comfort mapping, using the other side temperature seems like an appropriate way to approximate this type of system.