Best way to model a ceiling and raised floor

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Hello guys, I am developing a simulation of a four-story floors building with VRF air conditioning system and, when I’m designing the floors, I had a question regarding the modeling of the ceiling and the raised floor. Based on this, I thought in three scenarios:

1- Modeling without ceiling and without raised floor: In this case, the building loses about 6 meters high, which reduces the area of walls and windows, distorting the model.

2- Modeling considering a height in the ceiling and in the raised floor: The height of the building is closer to the real one, but climatized area's volume increases, changing the HVAC's load.

3- Modeling the ceiling and the raised floor as zones: In this case, it would give more work and I would need to disregard the area of these zones in the total area count.

In your opinion, what would be the best alternative to model this building?

Thank you!

117

Guinha

asked 2019-01-29 13:29:29 -0500

4.4k

__AmirRoth__

updated 2019-01-29 13:55:40 -0500

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3 is the best, but 1 and 2 are used a lot. Yes it is more work to model them as separate zones/spaces, however EnergyPlus thermal zones and OpenStudio spaces have a "Part of Total Floor Area" flag. When set to false the specified zone/space will not be included in what EnergyPlus reports for total floor area and will not impact floor area used for EUI calculations. If you are going to model daylight sensors, then having the relationship correct between the floor, ceiling, and window is particularly important. If you take approach 3 it is important to make sure unexpected internal loads such as lights, people, and ventilation are not included in these additional spaces, however you do still wan to included infiltration.

With approach 3 you also have the option to model the raised floor or dropped ceiling as a plenum to supply air to zones from the air loop and/or return air from zones back into the air loop. You can still use approach 3 when the raised floor and dropped ceiling are not part of the HVAC system, but I wanted to point out that functionality.