The cooling effects of green infrastructure (GI) have been extensively investigated as part of the efforts to tackle the urban heat island (UHI) phenomenon. Experts agree that further research is necessary to compare how thermal benefits are being provided by different types, amounts, compositions and distributions of urban vegetation across varied urban configurations. Thus, it is crucial to synthesise the great variety of current GI types into a more comprehensive climate oriented classification system. To support this process, this paper proposes a typology to identify, characterise and organise GI assets from a climatological perspective. A systematic literature review was conducted to analyse existing classification approaches and criteria worldwide. This has informed the present proposal for a standardised classification scheme that requires the logical division of GI into vegetation layers, ground surfaces and building structures, each of which may be disaggregated into classes and sub-classes. These are combined in a double-entry matrix to generate different typologies commonly recognised in the literature as (a) tree canopy, (b) green open spaces, (c) green roofs and (d) vertical greenery systems. The new typology will facilitate the spatial analysis of the thermal conditions delivered by GI at different spatial scales and locations, providing researchers working on urban microclimate and UHI with a more robust protocol to evaluate, compare and report their results. Although this typology has been initially designed in terms of one of the regulating ecosystem services of GI – that is, urban microclimate – it may also be used for performance assessment across the other ecosystem service categories of supporting, provisioning and cultural

The local climate zones (LCZ) scheme has attracted the interest of climate researchers as it enables the standardized study of urban heat islands by combining thermal and physical parameters of built and natural structures. Most recent work on LCZ has concentrated on understanding air temperature differences, adapting the scheme to different contexts and improving satellite-based classification methods. However, studies using very high-resolution imagery, including 3-D descriptors and analyzing their land surface temperature (LST) variability are scarcer. Since a correct delineation of LCZ implies significant temperature differences among classes, the aims of this study are 1) to test a GIS-based method for the classification of LCZ based on cut-off values valid to the Australian context; and 2) to examine the quality of classifications by analyzing the LST variability among LCZ using high-resolution airborne remote sensing data. Results show that diurnal and nocturnal mean LSTs significantly differ among most LCZs. Welch's ANOVA and subsequent post hoc tests for pairwise comparisons also demonstrate that these differences prevail for 71.8% of zones during the daytime and 73.6% of zones at night. Overall, LCZs A, 8, and 3 are the most distinguishable zones during the daytime and LCZs D, G, 1, 4, and 5 are well differentiated at night. In contrast, LCZs 1 and 4 are the least distinguishable at daytime and LCZs 10, A, and E are not well differentiated at night. The present study has successfully validated the present airborne-based classification method which is contingent on further accuracy assessment and improvements.

Urban and building typologies have a serious impact on the urban climate and determine at large the magnitude of the urban overheating and urban heat island intensity. The present study aims to analyze the impact of various city typologies and urban planning characteristics on the mitigation of the urban heat island. The effect of the building height, street width, aspect ratio, built area ratio, orientation, and dimensions of open spaces on the distribution of the ambient and surface temperature in open spaces is analyzed using the Sydney Metropolitan Area as a case study for both unmitigated and mitigated scenarios. Fourteen precincts are developed and simulated using ENVI-met the simulation tool. The ambient temperature, surface temperature, and wind speed are extracted. The parameter ‘Gradient of the Temperature Decrease along the Precinct Axis’ (GTD) is introduced to study the cooling potential of the various precincts. In the mitigated precincts, the GTD ranges between 0.01 K/m to 0.004 K/m. In the non-mitigated precincts, the GTD ranges between 0.0093 K/m to 0.0024 K/m. A strong correlation is observed between the GTD of all the precincts, with and without mitigation, and their corresponding average aspect ratio, (Height of buildings to Width of streets). The higher the aspect ratio of the precinct, the lower the cooling potential. It is also observed that the higher the Built Area Ratio of the precincts, the lower the cooling contribution of the mitigation measures.