modelOpaqueElements
Information
This model calculates the heat flow by solar gains through each opaque building element k. The heat flow is given by
Φsol,k =Fsh,k Isol,k αk Rse Uk Ak - Ff Φr,k
where Fsh,k is the shading reduction factor, Isol,k is the solar irradiance per square meter of surface area, αk is the dimensionless absportion coefficient for solar radiation of the opaque element, Rse is the external surface heat resistance of the opaque element in (m K/W), and Ak is the area of the opaque element.
The form factor between the building element and the sky Ff 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
Φr,k =hr ΔTsky Rse Uk Ak
where hr 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 ΔTsky is the average temperature difference between the external air temperature and the apparent sky temperature.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | n | ||
| Real[:] | AWal | Area of external walls | |
| Real | ARoo | Area of roof | |
| Real | UWal | U-value of external walls | |
| Real | URoo | U-value of roof | |
| Real[:] | surTil | Tilt angle of surfaces | |
| Real[:] | surAzi | Azimuth angle of surfaces | |
| Real | eps | 0.9 | Emissivity of external surface |
| Real | alp | 0.6 | Absorption coefficient |
| Real | surRes | 0.04 | External surface heat resistance |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| IBPSA.BoundaryConditions.WeatherData.Bus | weaBus | ||
| Modelica.Blocks.Interfaces.RealOutput | y | Solar radiation through windows |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| BoundaryConditions.SolarIrradiation.DirectTiltedSurface[n] | HDirTil | ||
| Modelica.Blocks.Math.Gain[n] | solRadOpa | Solar radiation on vertical opaque surfaces | |
| BoundaryConditions.SolarIrradiation.DiffusePerez[n] | HDifTil | ||
| Modelica.Blocks.Math.Add[n] | irrOpa | Total of direct and diffuse radiation on surface | |
| Modelica.Blocks.Math.Add[n] | addOpa | Total of direct and diffuse radiation on vertical surfaces | |
| Modelica.Blocks.Math.Gain[n] | theRadOpa | Extra thermal radiation through walls | |
| Modelica.Blocks.Math.Add | irrRoo | Total of direct and diffuse radiation on the south facade | |
| Modelica.Blocks.Math.Gain | solRadRoo | Solar radiation on roof | |
| Modelica.Blocks.Math.Gain | theRadRoo | Extra thermal radiation through roof | |
| Modelica.Blocks.Math.Add | addRoo | Total of direct and diffuse radiation on the roof | |
| Modelica.Blocks.Math.MultiSum | multiSum | ||
| Modelica.Blocks.Math.Add | addTot | Total of direct and diffuse radiation on the south facade |
Revisions
-
Mar 16, 2022, by Alessandro Maccarini:
First implementation.