.Buildings.HeatTransfer.Windows.BaseClasses.WindowRadiation

Information

The model calculates solar radiation through the window. The calculations follow the description in Wetter (2004), Appendix A.4.3. with the difference that this implementation allows a window to have multiple states, thereby allowing to model electrochromic windows.

The absorbed radiation by exterior shades includes:

1. the directly absorbed exterior radiation: AWin*uSha*(HDir+HDif)*(1-tau-rho)
2. the indirectly absorbed exterior radiantion from reflection (angular part): AWin*uSha*HDir*tau*rho(IncAng)*(1-tau-rho)
3. the indirectly absorbed of exterior irradiantion from reflection (diffusive part): AWin*uSha*HDif*tau*rho(HEM)*(1-tau-rho)
4. the absorbed interior radiation is neglected.

The output is absRad[2, 1]

The absorbed radiation by interior shades includes:

1. the absorbed exterior radiation (angular part): AWin*uSha*HDir*alpha(IncAng)
2. the absorbed exterior radiation (diffusive part): AWin*uSha*HDif*alpha(HEM)
3. the absorbed interior radiation (diffusive part): AWin*uSha*HRoo*(1-tau-rho)

The output is absRad[2, N+2]

The absorbed radiation by glass includes:

1. the absorbed radiation by unshaded part (diffusive part): AWin*(1-uSha)*(HDif*alphaEx(HEM)+HRoo*alphaIn(HEM))
2. the absorbed radiation by unshaded part (angualr part from exterior source): AWin*(1-uSha)*HDir*alphaEx(IncAng)
3. the absorbed radiaiton by shaded part (diffusive part): AWin*uSha*(HDif*alphaExSha(HEM)+HRoo*alphaInSha(HEM))
4. the absorbed radiation by shaded part (angular part from exterior source): AWin*uSha*HDir*alphaExSha(IncAng)

The output is absRad[1, 2:N+1] = Part1 + Part2; absRad[2, 2:N+1] = Part3 + Part4

The transmitted exterior radiation for window system includes:

1. the transmitted diffusive radiation on unshaded part: AWin*(1-uSha)*HDif*tau(HEM)
2. the transmitted direct radiation on no shade part: AWin*(1-uSha)*HDir*tau(IncAng)
3. the transmitted diffusive radiation on shaded part: AWin*uSha*HDif*tauSha(HEM)
4. the transmitted direct radiation on shaded part: AWin*uSha*HDir*tauSha(IncAng);

The outputs are QTraDif_flow = Part1 + Part3 and QTraDir_flow = Part2 + Part4.

References

• Michael Wetter.
  Simulation-based Building Energy Optimization.
  Dissertation. University of California at Berkeley. 2004.

Revisions

• June 7, 2016, by Michael Wetter:
  Removed output QTra_flow and introduced instead QTraDif_flow and QTraDir_flow. This is for issue 451.
• August 7, 2015, by Michael Wetter:
  Revised model to allow modeling of electrochromic windows. This is for issue 445.
• March 13, 2015, by Michael Wetter:
  Removed duplicate text annotation.
• December 12, 2011, by Wangda Zuo:
  Add glass thickness as a parameter for tra and abs. It is needed by the claculation of property for uncoated glass.
• February 2, 2010, by Michael Wetter:
  Made connector uSha a conditional connector.
• January 4, 2011, by Michael Wetter:
  Added assert statement to check that uSha=0 if no shade is present. This is needed to avoid wrong results in the room model.
• December 15, 2010, by Wangda Zuo:
  Revise the model by separating transmittance and absorbance.
• December 12, 2010, by Michael Wetter:
  Replaced record Buildings.HeatTransfer.Data.GlazingSystems with the parameters used by this model. This was needed to integrate the radiation model into the room model.
• December 10, 2010, by Wangda Zuo:
  First implementation.