b'SYDNEY - BOSTON - FUKUOKA 2018 - 2019intensity of the anthropogenic heat producedozone. Important research has been carriedby building structure, cool roofs, cool and liberated in the city. Intensive experimentalout to identify the energy penalty induced bypavements and urban infrastructure.studies performed in numerous cities of theurban warming. It is commonly accepted thatMonitoring of numerous large-scale world report Urban Heat Island intensities ashigher urban temperatures increase peakapplications aiming to augment the global high as 10 Kalmost every city has a heatelectricity demand as well as the energy spentalbedo of specific urban zones, has island. for cooling purposes while the heating energyshown that cool material technologies demand is decreased. present a high mitigation potential and Furthermore, the actual urban warming cannotmay decrease peak urban temperatures be explained solely in terms of the UrbanUrban warming has a serious impact on indoorup to 2 K; Heat Island. Global climate change resultingand outdoor thermal comfort. Several studies from the increase of greenhouse gases in thehave correlated the levels of outdoor thermal(b) increase of latent heat losses to the atmosphere caused by human activity alsocomfort in cities against the correspondingatmosphere through evapotranspiration increases urban temperatures. In fact, theincrease of the urban temperature. In mostprocesses. This involves the use of suggested projections of the Intergovernmentalof the cases a significant degradation ofadditional green zones in the urban Panel on Climate Change (IPCC) of anthe outdoor comfort conditions is observed.environment as well as the application average ambient temperature increase ofIn parallel, studies investigating indoorof planted roofs on the top of urban 0.15 K to 0.3 K per decade for 1990 to 2005,environmental conditions during extremebuildings. Significant research has been have been verified by recent measurements.events report very warning results. Extensivecarried out on the mitigation potential Depending on the scenario chosen, the mostmonitoring of low-income houses shows thatof green roofs and urban green zones. recent estimates of IPCC suggest a worldwideindoor temperatures are significantly higherExisting knowledge on the topic permits increase of 1.8 K to 4 K to occur betweenthan the defined allowed levels, putting atus to take maximum possible benefit 1990 and 2100. Thus, urban warming shouldrisk the health and well-being of citizens. It isfrom these techniques and systems; be attributed to both phenomena. The relativewidely accepted that exposure to substantially contribution and synergy between the twohigh temperatures is a health threat. Medical(c)dissipation of the excess urban heat phenomena is for the time being a quite greyresearch has shown that high ambientto environmental sinks like the ground scientific zone. Evidence from numeroustemperatures cause serious respiratory,that present a much lower temperature experimental studies shows that in manycardiovascular and cerebrovascular problems.than the ambient air. Such systems locations, climate effects attributed to UHI areRecent research has proven that increase ofare already proposed and used in of similar or of a greater magnitude than thatthe ambient temperature up to a thresholddemonstration projects. Evidence from caused by global climate change. is associated with a significant increase inexisting studies show that their mitigation mortality rates and hospital admissions. potential may be very significant; Higher urban temperatures and frequent extreme events have a serious impact onCounterbalancing the impact of urban warming(d) decrease of the amount of heat various domains of human life. Numerousis a serious challenge for scientists and allreleased to the urban environment due studies have documented that UHI increasesthose involved in 21st century city-making.to various anthropogenic activities. the concentration of specific urban pollutantsMitigation technologies which aim to reduceDespite the mitigation potential of such and affects the urban air quality, increasesthe strength of the sources and enhancea procedure seems to be very high, very energy consumption for cooling purposes astemperature sinks in the urban environmentlittle information is available.well as peak electricity demand, raises thehave been developed and are already being CO2 emissions and the ecological footprintused in real scale applications. MitigationMitigation technologies can counterbalance811of cities while it has a serious impact ontechnologies focus mainly on:the impact of UHI and local climate change. human health, thermal comfort and economy.Existing mitigation technologies applied at Increased urban ambient temperatures(a) reduction of the solar heat storedcity or neighbourhood scale may reduce facilitate the formation of tropospheric ozone,in the urban fabric and correspondingthe peak ambient temperature up 23 K. A a harmful pollutant created as nitrogen oxidesdecrease in the sensible heat releasedfurther decrease may be achieved in smaller react with volatile organic compounds duringto the atmosphere. Cool materialsurban zones using advanced evaporation the day time. Evidence from numerouspresenting a high reflectivity to solartechnologies, provided that the local climate is observational and numerical studies, show aradiation, combined with a high emissivitydry. strong positive correlation between the UHIvalue have been developed and are used intensity and the concentration of troposphericto minimise the absorbed solar radiation Master of Urban Development & Design 2018-2019INTRO 8pt.indd 9 26/11/2019 4:11:23 PM'