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Heat transfer between floors placed at different heights

asked 2021-03-05 14:53:18 -0500

Elisa Matar's avatar

updated 2021-03-28 09:24:07 -0500

In order to check compliance with a thermal comfort standard, we need to model and analyze temperature and thermal loads of 3 different floors of a building: ground floor, top floor and a floor at mid-height.

The standard recommends not to consider any surfaces adiabatic, accounting for heat transfer between all adjacent surfaces, so that the effect of the adjacent floors are considered.

We have come up with the following procedure:

  1. The floors are modeled all adjacent and we solve the adjacencies between them to establish the correspondent floor and ceiling surfaces as boundary condition objects of each other.

  2. In the ‘BuildingSurface:Detailed’ object, we edit the Z-coordinates to place each floor at its real height (since we account for natural ventilation and neighboring surfaces shading in these simulations, we considered we should keep the floors at the proper heights).

  3. We remove Sun/Wind exposure and the View Factor to Ground from the formerly-adjacent floors and ceilings.

    **The fenestration surfaces of each floor also have their Z-coordinates edited

Is this procedure technically solid? Is there a more correct or efficient way to model this?

Thank you!

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What impact are you hoping to capture by modelling to floors at different heights?

willyJohan's avatar willyJohan  ( 2021-03-05 19:32:32 -0500 )edit

It's a requirement from the standard actually, to see how air temperature and thermal loads of the typical floor plan of the building change when facing effects such as ground heat transfer, height impact on natural ventilation (due to convection coefficients calculation) and roof exposure. In all 3 floors the zones should comply with some temperature and load requirements, compared to a baseline building.

Elisa Matar's avatar Elisa Matar  ( 2021-03-08 06:07:20 -0500 )edit

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answered 2021-03-06 04:51:12 -0500

What software are you using ?
If EnergyPlus it seems good but, but to verify your IDF geometry editing, I will check it through Euclid Sketchup plugin (the former Legacy Openstudio Sketchup plug-in). if I had to do it, I'll make geometry changes directly in a geometry visual editor, like Euclid mentioned before

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We are using EnergyPlus and editing the geometry in the idf directly with eppy, so that we can make it automatically. We used the Output:Drawing object to get the dxf file and check if everything had been moved correctly, and it worked. So it's good to hear that the rest seems ok!

Elisa Matar's avatar Elisa Matar  ( 2021-03-08 05:58:58 -0500 )edit

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Asked: 2021-03-05 14:53:18 -0500

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Last updated: Mar 06 '21