Greening can usually have a cooling effect on urban space; but is this law also applicable to coastal sloping urban space? The coastal urban space of Qingdao Haizhifeng Square, with a sloping topography, was the area we selected to study. The study area contained two parts: a coastal green space and a residential area. ENVI-met was used to create six scenarios. Different lawns, black pine and ash were planted in the two areas to study the cooling effect. The results showed that the closer the area was to the sea, the better the thermal comfort. In both the coastal green area and the residential area, trees increased the PET of the site, and the higher the LAI of the trees, the more obvious the thermal effect. At 15:00, the hottest time during the summer, the highest PET at pedestrian height was lowest in the scenario without trees, reaching 28.3 °C, and the highest was with full ash, reaching 34.3 °C. At the same time, the average difference in PET between the two scenarios was 1.4 °C. The highest PET at pedestrian height was generated in the area of the building away from the sea breeze, especially in the case of the sloping topography behind it or dense street trees on the urban road. Finally, it was concluded that, in urban spaces with a coastal slope topography, lawns should be planted in the coastal green part and low LAI trees in residential areas, and shade trees should not be planted on the coastal walkway. This afforestation strategy can provide a basis to formulate a strategy for promoting the design of regions with similar geographical and climatic conditions in the future.

Urban green space is considered an important part of urban ecological construction be-cause of the efficiency of green space in reducing ambient temperature. It was previously reported that the quantity and layout of arbors and paving are very important factors for cooling. To research the combination mode of the quantity and layout of arbors and paving able to effectively lower the temperature during the summer in a coastal open space environment where little architecture exists, we built a numerical model of heat transfer using ENVI–met numerical modeling simulation, for which the May Fourth Square in Qingdao was selected. The results showed that the ratio coverage of the arbor layer and pavement fragmentation were positively correlated with the cooling effect. We found that setting the passageway conformed to the sea breeze by arbors and close planting at the air outlet effectively reduced the site temperature. After optimizing the site’s greening layout, the cooling effect over the process of time decreased in the height direction. At the same time, the cooling effect increased before 15:00 and then reduced gradually in the time dimension. Compared to the original site, the total cooling efficiency reached 1.41 × 108 J, equaling electric energy of about 39.2 kW·h. This research solves the issue of the synergy between planting and pavement for cooling coastal open spaces in summer and provides a basis to formulate a promotion strategy for landscape design areas with similar geographical and climatic conditions.

The intensification of urban heat islands in high-density coastal slope areas poses significant challenges to sustainable development. From the perspective of sustainable urban design, this study investigates adaptive greening strategies to mitigate thermal stress, aiming to elucidate the key microclimate mechanisms under the combined influence of sea breezes and complex terrain to develop sustainable solutions that synergistically improve the thermal environment and energy efficiency. Combining field measurements with ENVI-met numerical simulations, this research systematically evaluates the thermal impacts of various greening strategies, including current conditions, lawns, shrubs, and tree configurations with different canopy coverages and leaf area indexes. During summer afternoon heat episodes, the highest temperatures within the building-dense sites were recorded in unshaded open areas, reaching 31.6 °C with a UTCI of 43.95 °C. While green shading provided some cooling, the contribution of natural ventilation was more significant (shrubs and lawns reduced temperatures by 0.23 °C and 0.15 °C on average, respectively, whereas various tree planting schemes yielded minimal reductions of only 0.012–0.015 °C). Consequently, this study proposes a climate-adaptive sustainable design paradigm: in areas aligned with the prevailing sea breeze, lower tree coverage should be maintained to create ventilation corridors that maximize passive cooling through natural wind resources; conversely, in densely built areas with continuous urban interfaces, higher tree coverage is essential to enhance shading and reduce solar radiant heat loads.

In coastal residential areas, the combined effects of high temperature, high humidity, and weak wind conditions during summer intensify outdoor heat exposure and reduce pedestrian thermal comfort. To investigate the influence mechanisms of tree height and spatial layout on pedestrian-level thermal comfort, this study selected a typical residential community in Chengyang District, Qingdao, as the research site. Based on field meteorological observations, an ENVI-met model was established and validated. Using the existing composite greening scenario as the baseline, three tree layout types (row, cluster, and free layouts) and four height scenarios (4 m, 6 m, 8 m, and 10 m) were configured to quantitatively compare variations in physiological equivalent temperature (PET) under different planting schemes. The results indicate that tree configuration significantly affects summer thermal comfort. Its regulatory mechanism is governed not only by air temperature reduction but also by shortwave radiation interception, longwave radiation accumulation, and shading continuity. Although low-to-medium height trees can reduce local air temperature through transpiration, their limited canopy height and shading continuity restrict their ability to effectively attenuate direct shortwave radiation at pedestrian level, and in some cases may even increase mean radiant temperature (Tmrt) and PET. In contrast, 10 m tall trees arranged in row and cluster layouts can form continuous shaded cores, with the 10 m cluster layout demonstrating the best overall performance by significantly reducing Tmrt and PET. The free layout, characterized by dispersed canopies and fragmented shading, provides relatively limited thermal comfort improvement. The findings suggest that residential greening optimization should strengthen the coordination between tree height, canopy structure, and activity spaces. Tall trees should be prioritized in children’s play areas, elderly resting areas, residential entrances, main pedestrian pathways, and west-facing sun-exposed zones, while integrating building shadows and road orientation to create a continuous yet not overly enclosed shading network, thereby enhancing summer thermal adaptability in residential areas.