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Achieving environmental sustainability by improving the urban microclimate is a key principle in mitigating the urban heat island (UHI) effect. This study aimed to (a) investigate the outdoor thermal comfort by establishing Heat Index (HI) values to identify thermal hot spots and (b) model green infrastructure possibilities to alleviate UHI in Colombo urban metropolitan in Sri Lanka using ENVImet climate model. Daytime temperature and humidity values of 14 urban locations were collected to determine HI to recognize thermal urban hotspots in Colombo area. A pretested comprehensive random-stratified questionnaire survey has been conducted to appraise the thermal discernment of the general public. ENVImet microclimate model was accompanied to test the temperature reduction levels in different bioclimatic green infrastructure scenarios [Two belts (R1), three belts (R2), four belts (R3), five belts (R4)] in the selected study site. Five sites (Borella, Colombo Fort, Maradana, Wellawaththa, Liberty junction) were identified as thermal hotspots in Colombo metropolitan. HI values were fluctuated within 33.82–40.35 °C range and the highest average day time HI value was observed at Maradana (40.35 °C) and the lowest HI was observed at Thummulla (33.82 °C). Survey results revealed that 89.3% people are affected with thermal uncomfortability and 5% were affected with heat-related skin diseases. Inserting trees into curbsides (R4) reduced temperature remarkably by 2.07 °C in the urban metropolitan. Therefore, the proposed green infrastructure scenario has proved to be the most suitable way to improve the thermal comfort conditions of urban environment, as it can reduce the UHI effects.

Application of advanced techniques to ensure the environment sustainability and freshwater ecosystem conservation is a paramount importance. Industrial sector is mostly accused for the increased water pressure with high water consumption rates and increased grey water footprints. Industries must take action toward implementing water conservation strategies to enhance natural water cycle, increase water-use efficiency and address future challenges. The significance of water footprint as a driving force to water conservation is spotlighted with severe water scarcity. “Sustainable Development Goals (SDGs)” proposed by the United Nations are focused on creating a sustainable way of life to reduce the impacts on ecology and achieve economic and social benefits. Water is a central part in sustainable development; thus, all SDGs are interlinked with sustainable water use. The paper reviews incorporating the concept of water footprint to achieve SDGs in relation to industrial water conservation and the future pathways that lead to sustainable water resource management.

Different growth parameters and thermal performances of selected plant species grown on vertical system modules in urban tropical climate have been investigated under the study. Further, outdoor thermal comfort simulation has been modeled by ENVI­met 4.4.5 to investigate the applicability of selected plant species in three different tropical conditions (Colombo Sethsiripaya administrative complex, Matara urban council building and Kandy Urban council building). Sample modular vertical green living wall panels were fabricated by using timber frames (60 × 40 × 5 cm) packed with cocopeat medium with a depth of 3.8 cm. Nine plant species; such as Desmodium triflorum, Roheo spathacea, Centella asiatica, Axonopus fissifoliu, Axonopus compressus, Elusine indica, Dieffenbachiae spp, Tectaria spp, and Bigonia spp were selected for the study. Plant survival percentages, plant height and leaf area index (LAI) were recorded for 8 weeks. Thermal performances were evaluated by considering temperatures at (a) 20 cm distance in front of the green wall, (b) substrate surface of the green wall modules and (c) inside the green wall compared to (d) adjacent bare wall (Control). The highest LAI was recorded from Roheo spp (3.99) followed by Axonopus f. (3.20) and Elusine spp (2.21). Axonopus f. exhibited the highest coverage on the living wall due to high LAI (>1). The highest temperature reduction (5.06 °C) was displayed by Axonopus f. compared to the other species as it covers large extent of the wall. The simulation study of the green walls developed with Axonopus f. signified a possible maximum temperature reduction of 2.07 °C, 3.29 °C and 2.03 °C in Colombo Sethsiripaya administrative complex, Matara urban council building and Kandy urban council building, respectively. Hence, modelling vertical greening with Axonopus f. can effectively enhance the thermal performance in urban context due to their LAI values and the thermal performances.