Hi to all,
This is Julio. I am running a comfort map analysis for a skylight at 1.8m in height from the floor. I was very confused about which approach would retrieve the most accurate results since there are several components to address similar studies.
My main confusion is whether should I use LB PMV or HB PMV comfort map, I have tried both with similar inputs and I obtain considerably different results. I was wondering if they are for different situations.
Does anybody have to use both of them? In which situations are either of them more appropriate? is there any component in the new LB version that calculates the longwave MRT?
Thanks in advance
Expample PMV LB VS PMV HB.gh
I noticed that the LB PMV component takes the temperature of total zone while HB component takes tenperature on each points from sensor grid. If you change the sensor grid dist_floor height the HB PMV result changes while LB doesn’t.
My guess is LB calculates the average PMV and HB creates a map of exact PMV on each point. Hope this is helpful.
Thank you for your response. However, the grid is the same in both cases. I belive there might be a difference in the way these components calculate the operative temperature, in HB with radiance and in LB with a simplify method. Still I was expecting similar values.
Could you please post a screenshot of how sensor grid is connect to LB PMV component?
Though the sensor grid is applied previous to PMV calculation, here in my script LB PMV component takes sql directly from energy simulation results, which are constructed in hourly format and there’s no detailed tamperture on each point.
While the HB PMVmap has a result in ThermalMatrix format which includes data points on sensor grid.
Really sorry for the late response here, @Julioamodia89 and thanks, @tiantmz , for answering some of the questions.
In general, I can say that the PMV comfort map recipe accounts for many more things that you’ll be able to account for with just the Ladybug components. Even when you’re computing view factors to the surfaces like your screenshot there, @Julioamodia89 , and multiplying them by the hourly surface temperatures from EnergyPlus. This is because the PMV comfort maps can model reflections of shortwave radiation using Radiance, which is something that would be very difficult to do using just the Ladybug Tools components. The shortwave solar calculation in the comfort maps also does a pretty robust job of accounting for the window solar transmittance by computing it from the energy construction. So, when in doubt, the PMV comfort map is likely to be a better representation of indoor conditions compared to anything that you’ll put together with just Ladybug.
Hope that helps.
Thank you both @tiantmz and @chris
I understand that these two components use different approaches.
I guess that the purpose is to use the LB PMV for a more preliminary studies so to identify the worst areas/scenarios and the HB PMV is to actually obtain more precise results regarding the indoor comfort.
Said this, my guess is that the LB PMV will yield worse results (more extreme PMV values) for most cases.