Dear all,
I have a question regarding boundary conditions used in thermal simulations.
According to the NFRC standard, the prescribed boundary conditions are:
i. Interior ambient temperature: 21ºC (69.8ºF)
ii. Exterior ambient temperature: –18ºC (–0.4ºF)These conditions are standardized and primarily intended for evaluating thermal transmittance (U-value) under severe winter scenarios typically found in colder climates like North America.
However, if this same boundary condition is applied to a country like Vietnam, where the minimum exterior temperature
rarely drops below 5ºC, I believe it may not accurately reflect real condensation risks on interior surfaces of glass or aluminum frames.
From my understanding, when the exterior temperature is low, it reduces the surface temperature of the interior face of the frame or glazing. If that surface temperature falls below the dew point of the indoor air, condensation will occur. Therefore, the risk of condensation depends directly on realistic exterior temperatures and interior humidity, not just a standardized condition.
My question is:
What would be a more appropriate set of boundary conditions to use when evaluating condensation risk in climates like Vietnam’s?
Should we define custom boundary conditions based on local climate data rather than applying NFRC's values, which might overestimate or misrepresent the actual condensation behavior?
Best regards.
Lam.