College of Architecture and Fine Arts
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Item Urban greenery : mitigating urban heat island effect in Lower Session Road, Baguio City(2021-01) Bernardo, Jerico Jordan A.The study of temperature has been one of the major endeavors of man in the search for mitigating the effects of climate change considering the environment and the overall health of the inhabitants found in major urban centers, especially in densely built-up environments. One of the environmental problems faced in the central business district is the apparent increase of temperature especially in densely built-up areas. This increase of temperature could be attributed to the Urban Heat Island (UH1). According to (Shmaefsky, 2006) The urban heat island effect is best described as a situation in which the air in an urban area can be 2° to 5°C warmer than surrounding forested or suburban areas. There are numerous factors that may contribute to the urban heat island effect as stated by (Shmaefsky, 2006) which could be observed in Session Road namely: 1. Few trees and vegetation to block solar radiation 2. Few trees and vegetation to carry out evapotranspiration 3. A large proportion of paving materials with low reflectivity 4. High amounts of carbon dioxide pollution 5. Large amount of vehicular traffic that generates heat These observable factors of Urban Heat Island Effect in the central business district of the city calls for immediate action to mitigate the effects of urban heat island effect where air quality and public health as a few of the problems brought about by this phenomenon needs to be arrested. Furthermore, human thermal comfort is reduced and this, in turn, influences labor productivity and causes sleeping disorders (Rovers, Bosch, & Albers, 2014). This study attempted to mitigate the problem of detrimental effects of urban heat island in Session Road, Baguio City by assessing the current land surface and air temperatures within the expanse of the area comparing vegetated areas and exposed areas of the road and recommending an alternative streetscape solution. This paper aims to evaluate the correlation of vegetation and land surface temperatures of different pavement surfaces affecting urban heat island effect in a major thoroughfare within a highly urbanized city where temperatures of different surfaces and materials have been analyzed together with thermal remote sensing techniques in order to formulate recommendations on how to mitigate adverse effects of urban heat island effect within the heart of the city. Much of what causes this phenomenon is the poor choice of surface materials that supposedly has low amount of albedo and the lack of vegetation in the form of urban greenery to aid in cooling Session Road by means of evapotranspiration. In terms of field measurements done from April to May of 2019, impervious areas were measured to have a mean LST of 29.80 °C and pervious surfaces had a mean LST of 22.43 °C. Mean air temperature was measured to have a mean temperature of 26.98 °C. Drone images of Session Road taken with the thermal camera measured a maximum surface temperature of 439 °C, a mean reading of 26.64 °C and a minimum of 18.05 °C. Time lapse thermal photos of lower Session Road showed how heat is stored in exposed surfaces with lower albedo in the afternoon which causes urban heat island. Furthermore, thermal images taken with vegetation were seen to have lower temperatures than surfaces without vegetation. Remote sensing data gathered from satellite images resulted in a mean LST of 36.47 °C but individual points selected along Session Road returned with an LST of 34.39 °C for an exposed asphalt and 32.81 °C for point shaded by vegetation. These remote sensing data were for the same months of field measurements for comparison. On the other hand, air temperature using Terraclimate data resulted in a mean temperature of 27.15 °C also for the month of April of 2019. Thermal comfort survey was conducted along with field measurements of air temperature in order to assess to which temperature would the respondents rate their level of comfort. This resulted with majority of the respondents being uncomfortable with the minimum temperature of 26.74 °C this would mean, anything above this temperature would be uncomfortable to most people along Session Road. Furthermore, majority of the respondents described their level of comfort to be slightly warm and would prefer the temperature of Session Road to be cooler. NDVI remote sensing data was also gathered in order to quantify the vegetated and built-up areas along Session road. The analysis of the NDVI scatter plot resulted in a composition of 89% built up areas and only 11% are vegetated along Session Road. With the conducted survey, majority of the respondents disagreed that the current streetscape along Session Road is sufficient. In addition to this, they strongly agreed in providing more trees, integrating more shading elements, vertical gardens, and flowering plants in the streetscape along Session road where all of which would aid in mitigating the urban heat island effect within the central business district of Baguio City. Vegetation is essential in creating a cooler environment as established by this study where latent heat is dissipated more in areas that are shaded with vegetation rather than surfaces that store heat and would cause night time temperature to rise. According to (Asaedaa, V.T., 20001 Asphalt and concrete have low albedo, with values as low as 0.1 on average for asphalt and 0.3 or 0.4 for concrete. This makes these surface materials warmer and retain more heat when exposed lo solar radiation. In response to this, as a strategy for mitigate the UHI, surface materials should be chosen with high albedo and emissivity since they remain cooler when exposed to solar energy. The incorporation of the microclimate of the central business district in the urban planning process is essential to provide its citizens with a better quality of life and would include the betterment of the environment in its developmental plans for the future. A major shift in the planning process of major cities must be done in order to avoid environmental problems that could cause harm to its citizens. The inclusion of a climate atlas in the comprehensive land use plan of the city would be beneficial in preserving the natural state of the environment, avoid certain problems that comes with urbanization. In the advent of climate change and global warming, more attention must be placed in cooling cities rather than trying to fill up every empty parcel within the city for the sake of development. Careful surface material selection should also be part of the design of the built environment where design professionals and decision makers should be leaning towards more green solutions rather than profit or economy. These recommendations might appear to be simple solutions but would add up to better planning solutions in creating a city geared towards development but has avoided to compromise the natural state of its environment. Cities like Baguio could be able to mitigate adverse effects of urban heat island by giving more importance in providing green infrastructure within the built environment. Careful planning and strict implementation of policies on open space requirements could also be a mitigating measure on the said phenomenon. A development of a streetscape incorporating urban greenery along Session Road is needed in order to help in mitigating the effects of urban island effect. This would include planting more trees within the urban landscape, encouraging business establishments to incorporate vertical gardens on the facade of their buildings and replacing exposed surface materials with a higher albedo rating or permeable surfaces that could store moisture and would help cool the environment during the day. The incorporation of more pervious surfaces along the road could potentially lower temperatures together with planting trees that could shade the impervious surfaces from direct solar exposure. Here, the shoulder of Lower Session road could be converted into planting strips instead of the current use of the shoulder as parking spaces. This would also reduce the heat produced by vehicles along the road. Greenspace can take many forms, including for example: urban forests, parks, street trees and verges, private gardens, fringes of transport corridors and vegetated roofs and facades. (Gunawardena et al., 2017) Since green spaces could induce evapotranspiration that could help in lowering temperatures in a certain area, buildings along lower Session Road could be encouraged to install green infrastructure by installing vertical gardens for their facade and green roof system if of all applicable in order to minimize surfaces with low albedo and would therefore absorb less radiant heat from the sun that causes higher temperatures in built up areas.