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Re: [EnergyPlus_Support] Adiabatic wall



Mark,

Depending on the year of construction of the existing building, could you not just assume minimal code compliance for the wall?

If you definitely want to go the adiabatic route, you could define the construction as composed of a Material:NoMass object.

this material gave me convection less than 4 BTUh without changing the boundary condition to adiabatic

  Material:NoMass,
    MAT-FLOOR-1,             !- Name
    Rough,                   !- Roughness
    1000000000000000,             !- Thermal Resistance {m2-K/W}
    0.00001,                    !- Thermal Absorptance
    0.00001,                    !- Solar Absorptance
    0.00001;                    !- Visible Absorptance

Hope this helps,

Jason






On Mon, Jan 10, 2011 at 6:41 PM, careym.cosmaj <mark.carey@xxxxxxxxxxxxx> wrote:
 

Hi,

Trying to comparitively simulate thermal envelope differences of an extension to an existing large zone building (warehouse).

We have two options;

1. Make educated guesses about the thermal performance of the existing elements or,

2. Model the interface between the existing and new building sections as adiabatic.

There are pros and cons of each and both can be considered by purists as fudges at some level.

"Wall:Adiabatic" only permits rectagular elements (the building has a pitched roof)

We are trying to use, "BuildingSurface:Detailed" with "Adiabatic" Outside Boundary Condition.

Eplus requires a Construction be specified whihc is non-ideal as we dont want the thermal mass effect of the adiabatic wall in the simulation as there is no wall in reality.

We are seeing non-zero "Surface Int Convection Heat Rate" for a wall which should be adiabatic.

We have defined a psuedo-material with very low specific heat capacity, very low density, and very low conductivity and still see much larger than expected Convection Heat Rates on the surface, any suggestions?

Thanks,

Mark Carey




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