.BuildSysPro.IBPSA.ThermalZones.ISO13790.BaseClasses.OpaqueElements

Information

This model calculates the heat flow by solar gains through each opaque building element k. The heat flow is given by

Φ_sol,k =F_sh,k I_sol,k α_k R_se U_k A_k - F_f Φ_r,k

where F_sh,k is the shading reduction factor, I_sol,k is the solar irradiance per square meter of surface area, α_k is the dimensionless absportion coefficient for solar radiation of the opaque element, R_se is the external surface heat resistance of the opaque element in (m K/W), and A_k is the area of the opaque element.

The form factor between the building element and the sky F_f is set to 1 for roofs and 0.5 for external walls. The extra heat flow due to thermal radiation to the sky is given by

Φ_r,k =h_r ΔT_sky R_se U_k A_k

where h_r is the external radiative heat transfer coefficent which is approximated as 5 ε W/m²K (where ε is the emissivity for the thermal radiation of the external surface), and ΔT_sky is the average temperature difference between the external air temperature and the apparent sky temperature.

Revisions

• Mar 16, 2022, by Alessandro Maccarini:
  First implementation.