Inside and outside surface convection algorithm

Hi is there any way to implement ASTM C1340 convection coefficients for inside surfaces? This is a new feature in energy plus 9.5. Now you can set this in the openstudio SketchUp plugin or at the openstudio app. For the new 1.3 LBT the HB adaptative comfort map recipe saves tons of work, but it doesn’t allow me to choose the inside surface convection algorithm when a radiant barrier is exposed to the inside, for the longwave radiation calculation that energy plus runs, the algorithm would have a huge impact on the operative temperature.
Having this as a simulation settings component would be great!

Hi @Sobrado ,

This is easy to do if you are on Windows with the latest development version of the plugin where you can import the OpenStudio SDK to Python like so: (58.8 KB)

The way that the comfort mapping recipes compute operative temperature is more sophisticated than the Zone MRT output from EnergyPlus. Maybe we can eventually make this type of convection algorithm and corresponding effect of radiant barriers on MRT a part of the comfort mapping recipes. The ultimate effect on the perceived operative temperature might not be a large as you think, though. It’s true that the surface temperature is physically different because of an exposed Low-E radiant barrier but, because it has a low emissivity, it does not participate as much in the longwave heat exchange with the occupants. In some of the tests that I did with interior Low-E coatings on windows, the ultimate impact on occupant-perceived operative temperature was not very different from a surface without the barrier. Still, I imagine there could be some special cases where it makes a larger difference.

Thanks for your answer Chis. I’ll try this for my parametric energy use studies. Regarding comfort recipes, I would like to share with you a couple of white papers which may help me to clarify my point. And perhaps give you a little motivation to consider using ASTM C1340 inside surfaces convection coefficient as an alternative for modeling comfort mapping results. Heat flow down reduction cut be significant in some models when a radiant barrier is installed under the roof of unconditioned attic space, this will contribute to decreasing ceiling surface temperature affecting the operative temperature inside the occupied zone or room. For a natural ventilated model, this technology will add comfort.

I see what you mean. I’m open to exposing the convection algorithms on the SimulationParameter class. If you want to open an issue for it on the honeybee-energy GitHub, I’ll try to implement it when I get the chance.