Following on from the data analysis on the pilot study, the vertical south façade of the pilot study unit was replaced by a tilted façade with a 115° inclination. The simulations were carried out using the London future weather files. As the modelled data showed, there was a significant drop in summer operative temperature when using a 115° tilted wall, whereas the operative temperature did not significantly drop in winter. The implementation of a steeper façade, on the other hand, will block the required solar gain in winter while an angle around 115° will guarantee solar heat in winter and obstruct the high solar irradiation on hot summer days.
Figure 8 and
Figure 9 indicate the annual monthly mean operative temperatures for heating (
Figure 8) and cooling (
Figure 9) demand when comparing the vertical (θ = 90°) and the suggested tilted façade (θ = 115°). The line graphs indicate operative temperature of the pilot unit with vertical and tilted south façades for current and future climate predictions. The bar charts indicate the amount of heating and cooling needed to provide comfortable temperature,
i.e., indoor temperatures between 20 and 25 °C. As mentioned earlier, Passivhaus, due to its super insulation, is capable of maintaining an internal temperature of 20 °C. The heat recovery system also operates by utilizing the heat given off by appliances, occupants and solar gain. However, a small amount of supplementary heating was required during the coldest period of the year (
Figure 8). With the vertical glazed façade in the south elevation the pilot study unit experienced a marginal summer overheating rate under current climate conditions. Therefore, to ensure a comfortable indoor environment, the unit required a small proportion of supplementary cooling. This need was eliminated by implementing the tilted façade of 115° (
Figure 9a). For the climate periods of the 2030s and 2050s the building experienced over 9% and 11% overheating respectively, exceeding significantly the 1% benchmark limit. This was reduced by the self-shading façade to just over 2% and 3% for the 2030s and 2050s climate periods respectively (
Figure 9b,c). By the end of the century overheating is expected to occur in shoulder seasons, when high indoor temperatures could be seen from May up to September in the 2080s. Supplementary cooling for the Passivhaus pilot study unit with a vertical, highly glazed façade leapt to the point where the electricity consumption for summer cooling just surpassed the energy demand for space heating. Introducing an angled façade, however, cut the amount of supplementary cooling by up to 50% (
Figure 9d), whereas the energy consumption for heating climbed only marginally, ensuring it did not exceed the maximum energy demand requirement of the Passivhaus standards. Overall, the current climate overheating risk of 3.2% was eliminated to below the benchmark number of 1%. For future weather projections the overheating rate was significantly reduced by the angled façade. However, the angled facade did not completely eliminate the potential overheating risk, especially for the climate of the 2080s.