Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 370

Fig. 7.19 Distribution of heat losses
The benefit of removing the dividers in the windows was examined.
Currently, most of the large south-facing windows are operable and have
two dividers in them. This not only increases the conductance of the
envelope, it also reduces solar gains. The removal of two-thirds of these
(leaving enough operable windows to enable natural ventilation) reduces
predicted heating energy by about 12%. The upgrade to better-insulated
window frames and doors only yields a modest reduction in heating loads
and thus they were not changed.
The addition of intelligent shade control - either manual or automated -
was considered. For the cooling season, shades were assumed to be closed
during periods when the zone air temperature exceeds 22 °C. This is
predicted to reduce cooling loads by about one-third, resulting in 90 kWh of
electricity savings. Proper shade control also improves thermal comfort by
mitigating overheating and direct beam solar radiation on occupants.
The addition of 1 m 2 K/W of insulation on the basement and above-grade
wallsofthehousewasfoundtoyieldanannualreductioninelectricityuseof
about 150 kWh. This was not considered practical, and thus, the insulation
levels were left as-is.
The energy implications of each upgrade are quantified in Figure 7.20 .
With these upgrades, there are few good remaining opportunities to reduce
consumption without modifying occupant behavior. The total predicted