Hi everyone,

I would like to have precisions on the different methods to calculate mean radiant temperature.

If you have some time, could you please confirm/correct/comment the following asumptions?

- From the Thermal Comfort Indices component, Comfort Index 11 (TCI-11):

MRT = f(Ta, Tground, Rprim, e)

with:

- Ta = DryBulbTemperature coming from ImportEPW component

- Tground = f(Ta, N) where N comes from totalSkyCover input. Tground influences the long-wave radiation emitted by the ground in the MRT calculation.

- Rprim defined as solar radiation absorbed by nude man = f(Kglob, hS1, ac)

- ac is the clothingAlbedo in % (bodyCharacteristics input)

- I can’t find any definition in the code of Kglob and hS1. Could you tell me please what are those values referencered to? --> probably the globalHorizontalRadiation but how?

- e = vapour pressure calculated from Ta and Relative Humidity input

Do you agree that in this case the MRT does not depend on these inputs: location, meanRadiantTemperature, dewPointTemperature and wind speed?

It does not depend neither on the other bodyCharacteristics like bodyPosture, age, sex, met, activityDuration…?

MRT calculated by the TCI-11 method is the mean radiant temperature of a vector pointing vertically with a sky view factor of 100%?

For ParisOrly epw,

- From the SolarAdjustedTemperature component (that seems to be more used for the UTCI calculation examples on Hydra compared to TCI-11).

In contrast to the TCI-11, this component distinguishes diffuse and direct radiation and contextualizes the calculation thanks to _ContextShading input, right?

It can also be applied to a mannequin thanks to the CumSkyMatrix and thus evaluate the dishomogeneity of radiation exposure.

This component seems not to consider the influence of vapour pressure on the result --> is it then more precise to put the MRT output (from the TCI) as an input of meanRadTemperature for SolarAdjustedTemperature?

The default groundReflectivity is set to 0.25 --> is GroundReflectivity taken into account in the Tground or MRT calculation in the TCI component? If yes, what is the hypothesised groundReflectivity?

The default clothing albedo of 37% (TCI-11 bodyCharacteristics) corresponds to Clothing Absorptivity of 63%?

If the CumSkyMatrix input is not supplied,

I get 9 results for the mannequin --> where are those points/results coming from?

If the CumSkyMatrix input is supplied,

I suppose the calculation of the 482 results correspond to a calculation method similar to the radiation analysis component that is averaged over the analysis period. Right?

But I don’t understand why the mannequin is composed of 481 faces and meshFaceResult gives 482 results.

Finally, what is the link between the MESH results, the solarAdjustedMRT and the Effective Radiant field ? Is there a paper to have a detailed explanation of the method?

3. Here are some results for the ParisOrly energyplus weather data. You can find here attached the grasshopper definition.

There is no shading in this simulation and the result coming from the ThermalComfort indices for MRT is very different compared to the solar adjusted MRT.

Why such a big difference and which of the result should be plugged into the UTCI calculation component?

Results for ParisOrly.epw

M,D,H:1,1,12

Ta : 6.5°C

rh: 100%

globalHorizontalRadiation: 54 Wh/m2

totalSkyCover: 10

MRT (TCI-11): 1.2°C

_CumSkyMtxOrDirNormRad = directNormalRadiation : 0 Wh/m2

diffuseHorizontalRad: 54 Wh/m2

_meanRadTemp = Ta

solarAdjustedMRT: 10.64°C

MRTDelta: 4.14°C

_CumSkyMtxOrDirNormRad = CumulativeSkyMtx

diffuseHorizontalRad: 54 Wh/m2

_meanRadTemp = Ta

solarAdjustedMRT: 10.47°C

MRTDelta: 3.97°C

_CumSkyMtxOrDirNormRad = CumulativeSkyMtx

diffuseHorizontalRad: 54 Wh/m2

_meanRadTemp = MRT (TCI-11)

solarAdjustedMRT: 5.17°C

MRTDelta: 3.97°C

Thanks a lot for your help

Regards,

Aymeric

Comparaison_MRT.gh (469 KB)