3. Results
We first provide an overview of the pre- and post-retrofit
periods by presenting time series over the entire measurement
period. Next, we evaluate the effect of the BIPV system retrofit by
accounting for differing weather conditions for the pre- and postretrofit
periods. We consider weather primarily by plotting building
temperatures, heat fluxes, HVAC energy use, and PV energy production
versus CDD18C. Finally, we report an analysis of energy
production and efficiency of the PV system.
3.1. Time series – entire measurement period
We first present time series over the entire measurement period.
Values are daily (24 h) means for temperatures and daily sums for
heat fluxes in the building, HVAC energy consumption, PV energy
production, and solar irradiation.
3.1.1. Daily solar irradiation and daily mean wind speed
Fig. 3 shows daily solar irradiation and mean wind speed for the
entire measurement period. Daily solar irradiation peaked during
the summer at about 9 kWh/m2. Some days had sharp decreases in
daily solar irradiation, likely due to the presence of clouds. Daily
mean wind speed ranged from about 2 to 8 m/s and was slightly
higher in summer than in winter. Convective cooling of the roof
surface tends to increase with wind speed.