Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 445

overheating, while daylight illuminance stayed above the illuminance
setpoint. As shown in Figure 7.68 , the average interior daylight illuminance
level is reduced to 350 lux, instead of the illuminance set point of 300 lux.
This is because other windows also provide daylight.
Fig. 7.68 Winter design period performance, daylighting window (VC) size
is 2.5 times the original
Eventhoughthetransmittance isreducedtoavoidspaceoverheating, useful
solar heat gains continue to enter the building and warm up the slabs and
rooms.TheVCreducestheintensityofsolarheatgaintoalevelthatmatches
the heat-absorbing capacity of the room. It is also seen that the room
temperature of the north zone is relatively low compared to the south zone.
Measures such as ceiling fans can be deployed to enhance the interzonal
heat transfer, and hence increase the absorptivity of the entire space. This
means more solar heat gain can be utilized. Furthermore, supply air
temperature can be set lower to take advantage of abundant passive solar
heat gain, and hence lower the energy consumption in warming up the fresh
air.