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Trees provide important ecosystem services to urban human society. Their absence can lead to more 10 pronounced environmental and social consequences, for example the urban heat island effect. 11 Evapotranspiration (E t) from trees reduces air temperature in the urban microclimate by converting 12 sensible heat to latent heat. Quantification and valuation of the ecosystem services provided by urban 13 trees is important for improving cost-benefit evaluations in support of protecting tree planting and 14 maintenance budgets and, thus, for building climate change resilience into cities. Inclusion of E t cooling 15 could improve ecosystem service valuation models by producing a more complete picture of the 16 benefits that urban trees provide to society. 17 18 This study explores two approaches for evaluating climate regulation as an ecosystem service of urban 19 trees. Firstly, an enthalpy-based approach was adopted to valuate latent heat of evaporation from tree 20 transpiration (in three case study urban forests) by equating it to an equivalent service from an active 21 direct evaporative cooling system. Secondly, energy savings to air-conditioned buildings was modelled 22 using TRNSYS and TRNFLOW simulation programs with and without air precooled and humidified by 23 urban trees. 24 25 Trees are shown to provide substantial urban cooling with an annual valuation of £84 m estimated using 26 the enthalpy-based approach, or ranging from £2.1 m to £22 m using TRNSYS and TRNFLOW dynamic 27 simulation programs; both for inner London case study. The latter savings arose from a modelled 1.28-28 13.4% reduction in airconditioning unit energy consumption. Challenges around assumptions of 29 homogeneity in both built form and urban forest canopy effects are discussed. 30 31 The case study examples highlighted differences in E t cooling between tree species, with Castanea 32 sativa, Prunus avium, Quercus petraea, Platanus hybrida and Fagus sylvatica typically providing more E t 33 cooling than any of the other tree species commonly found in urban forests. The research highlighted a 34 shortage of published E t data, particularly for urban environments.

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To quantify the environmental impacts of building construction, many environmental assessment methods for measuring building performance have been proposed worldwide, such as BREEAM (UK), LEED (US) and Green Star (AU). However, much debate exists about the efficacy of these international assessment tools in measuring building performance outside their country of origin, due to global variations in climate, geography, economics and culture. To address this debate, this study proposes a framework for developing domestic sustainable non-residential building assessment criteria for Saudi Arabia. To create this framework, five major building assessment methods were compared with respect to their application methods, major characteristics and categories. Surveys were conducted with a range of Saudi sustainable construction experts to gain their expertise in reflecting the local context of Saudi Arabian construction. The analytical Hierarchy Process (AHP) method was applied to evaluate survey data. Nine criteria and 36 sub-criteria were defined in this study for inclusion as the most appropriate assessment criteria for sustainable non-residential construction in Saudi Arabia. These criteria include water efficiency and energy efficiency, indoor air quality, materials selection, effective management, land and waste, whole-life cost, quality of service and cultural aspects.

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