*3.3. Urban Planning Strategies for The Hague Southwest*

For the urban district, The Hague Southwest, three urban planning strategies (abbreviated to strategies) were examined, and the impact on the number of tropical nights and UHImax was evaluated. The current climate does not indicate clear absolute differences in tropical nights between urban areas, due to the scarcity of these nights in low- and mid-rise urban areas. Therefore, the different strategies were shown for the future WH scenario only. The additional heat stress (measured in number of tropical nights per year) will be mostly scattered over the urban district in the strategy where new residences will be built on the currently green corridors around the neighborhoods (Figure 8A,B). The other strategies concentrate the heat stress particularly within the neighborhoods. The largest increase in the number of tropical nights takes place in neighborhood 2, which has the highest density of residences with the largest building assignment (Figure 3). For the hottest place in this district, the average number of tropical nights per year will increase from 3.1 to 3.5 in the current climate (not shown), and from 11 to 13 nights in the WH scenario shown in Figure 8C,D (the mildest GL scenario shows an increase from 4.7 to 5.4–5.5 tropical nights per year). Thus, the maximum expected numbers of tropical nights for this neighborhood in strategy C and strategy D are very similar. However, strategy C (construct low- and mid-rise buildings) shows larger patterns of these maxima than strategy D (construct high-rise buildings to preserve green spaces). Strategy C is moderately warmer than strategy D for the entire urban district, especially in neighborhood 2. This is best seen in the continuous scale of the 95th percentile of UHImax in Figure 9 for the current climate. The maximum increase in the 95th percentile of UHImax is 1.2 ◦C for strategy C and 0.8 ◦C for strategy D, and remains nearly constant for the future scenarios. Note that these relative differences in the scenarios are also reflected in the expected minimum temperatures. In summary, the realization of high-rise buildings to preserve existing green spaces appears to be a better strategy than constructing low- and mid-rise buildings on existing green spaces for The Hague Southwest.

**Figure 8.** Modeled number of tropical nights per year for the WH climate scenario in 2050 for The Hague Southwest for: (**A**) current housing, (**B**) building on green corridors around the neighborhoods with low- and mid-rise buildings, (**C**) constructing low- and mid-rise buildings on green spaces within the urban neighborhoods, and (**D**) constructing high-rise buildings within the urban neighborhoods to preserve existing green spaces.

**Figure 9.** Difference in the modeled 95th percentile of UHImax between (**A**) strategy C (constructing low- and mid-rise buildings) and (**B**) strategy D (constructing high-rise buildings). Both are compared with the current housing for the current climate.
