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Analysing heat loss in a steel frame building

Question asked by Will Griffiths on Mar 31, 2020

I’m building a steel frame house and want to assess steel temperatures and optimise insulation placement for minimising heat loss. The trouble is that I don’t seem to be getting boundary conditions correct, since I don’t trust numbers provided.

 

I have drawn a standard section of the house incorporating a steel column. This included cutting the house down the middle. I have applied adiabatic conditions to sides of the computational domain that would be, in practice, another part of the house.

 

I have used an “internal” analysis and have created a box around the section of house to seal it. This includes sealing an outside air space section incorporating a Portico (which has been chopped down for the analysis). The house’s wall acts as the boundary between this air zone and the internal one…….

 

For the heat loss sides of the house, I have tried applying a fixed temperature to the outer surface (using Outer Wall). I have also trying using a volume heat source to the concrete slab, setting the temperature and emulating underfloor heating, but convective heat transfer within the internal air zone isn’t being reflected.

 

I think the main mistake I’m making is that air contained in the model is limited to internal cavities (if I use “show fluid volume” it highlights this), with no recognition of the air in the outside zone or the inside zone. This is despite there being no leaks.

 

Not sure if I should be adding a fluid subdomain, but the software doesn’t seem to recognise that there’s a volume to select…..

 

Please can someone help…….. thanks in advance

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