ISE04/20-21

• Rising temperatures, exacerbated by climate change and urban heat island effect^{1Legend symbol denoting An urban heat island is a metropolitan area that is relatively hotter than the surrounding rural area. The difference in temperature is due to heat generated by human activities such as manufacturing, transportation and cooling/heating, and perpetuated by dense infrastructure and reduced vegetation in urban areas.}, can be more than an environmental but a public health hazard. According to World Health Organization, prolonged hot weather and extreme heat can cause life-threatening heatstroke and aggravate chronic conditions including cardiovascular and respiratory diseases, posing particular risks to vulnerable groups such as the elderly and children. During the hot season in Hong Kong, it is estimated that hospital admissions could rise by 4.5% for every increase of 1 degree Celsius ("°C") above 29°C.^{2Legend symbol denoting See Bulletin of the World Health Organization (2013).}
• The year of 2019 was Hong Kong's warmest year on record, with 33 days at 33°C or above. The number of "hot nights", defined as having a daily minimum temperature of 28°C, also soared to 46 in 2019, up from 28 in 2009.^{3Legend symbol denoting See Hong Kong Observatory (2020a and 2020b).} While the Government has released the Climate Action Plan 2030+ outlining key policies in response to hotter weather, Legislative Council Members have flagged concerns about the progress Hong Kong has made to combat climate change/extreme heat.^{4Legend symbol denoting Members have raised concerns about these issues on various occasions in the last three years. See GovHK (2018a), GovHK (2018b) and GovHK (2019).} Some have suggested that Hong Kong could make reference to overseas experiences to strengthen its urban heat resilience.
• Tackling urban heat is a complex issue. It often involves addressing a bigger cause - climate change - by cutting heat-trapping carbon emissions and promoting a greener lifestyle. While these long-term measures are fundamentally important, this issue of Essentials focuses on more direct and immediate measures that help adjust societies to withstand the effects of urban heat. The piece begins with an overview of relevant measures in Hong Kong and is followed by a discussion of various approaches in Singapore, Australia and Canada. Either located in the tropics or faced with more frequent heat waves^{5Legend symbol denoting Australia and Canada both reported instances of heat waves in recent summer months. It is projected that Toronto will have 66 days with maximum temperatures above 30°C by 2040-2050. See City of Toronto (2019b) and BBC (2019).}, these places have scaled up efforts to beat the heat by (a) providing targeted heat relief for specific community/vulnerable groups; (b) enhancing heat relief measures/shelters in public places; (c) incorporating greenery in building design; and/or (d) fostering research collaborations to develop urban cooling solutions.

Coping with urban heat in Hong Kong

• Various heat relief measures have been implemented in Hong Kong. As outlined in the Climate Action Plan 2030+ published in 2017, the Government alerts the public to extremely hot days and operates temporary night heat shelters under the Home Affairs Department for the needy to take refuge from 10:30 pm to 8:00 am during hot weather warnings. Besides, it has added more drinking fountains in public places.
• Hong Kong is home to 119 100 households living in various forms of inadequate housing, ranging from subdivided units to cage homes and rooftop structures.^{6Legend symbol denoting See Transport and Housing Bureau (2019).} Notwithstanding the above temporary shelter measures, some inadequate housing tenants reportedly struggle to pay high electricity bills and even lack access to air-conditioners during summer. Since hot weather becomes more frequent, there have been calls for additional heat relief measures, such as high-temperature subsidies and more free cooling facilities for those living in cramped, poorly ventilated inadequate housing, where indoor temperatures can reportedly reach above 40°C.^{7Legend symbol denoting See 香港社區組織協會(2018年)., 8Legend symbol denoting At present, there are no specific heat relief measures provided to those living in inadequate housing. Following the service renewal agreement with the Government, a power company has committed to allocating a sum from its energy saving fund to help the disadvantaged. For example, it has pledged to provide an annual financial assistance (HK$500) for 10 000 subdivided unit households. See CLP Power (2018).}
• As studies have shown that vegetation helps lower urban temperature^{9Legend symbol denoting Vegetation can reduce temperature by providing shaded surfaces, which can be 11°C to 25°C cooler than unshaded ones. See United States Environmental Protection Agency (2019).}, Hong Kong has also promoted greening of public spaces and buildings as part of its heat reduction plan. For greening of public spaces, the Government has taken the lead to include greenery provisions in public works projects, such as roads, key promenades and public housing estates.^{10Legend symbol denoting Some examples include roof greening on suitable structures, planting on the roadside, and requiring at least 20-30% greenery coverage for site areas exceeding 1 000 m2. See GovHK (2018a) and Development Bureau (2019).} For government buildings, it is required that all new larger-scale projects should incorporate greenery elements and aim to obtain the Building Environmental Assessment Method ("BEAM") Plus certification.^{11Legend symbol denoting BEAM Plus is Hong Kong's assessment tool for green buildings, based on criteria such as construction materials, energy and water usage, among others. It awards points for projects using heat mitigation design such as shade, light-coloured materials, green roofs, etc.} As for new private buildings, the Government has a policy of offering gross floor area ("GFA") concessions as an incentive for developers to include green/sustainability features (e.g. sunshades and green roofs in the form of sky/podium gardens) based on relevant guidelines of the Buildings Department, provided that their buildings are registered under BEAM Plus.^{12Legend symbol denoting The prerequisites for granting GFA concessions include registration of the project under BEAM Plus and compliance with other sustainable building features (e.g. building separation, greenery coverage, etc.). This mechanism is currently under review, which recommends that a project would need more than BEAM Plus registration but also getting certified with a specific rating (e.g. gold or platinum) under BEAM Plus to apply for GFA concession. See Buildings Department (2014) and GovHK (2020).}
• Since 2010, some 1 000 private and public projects have been registered under BEAM Plus, representing 40% of all new buildings but only about 2% of the 50 000 existing building stock in Hong Kong.^{13Legend symbol denoting See Hong Kong Green Building Council (2017).} While larger-scale government projects generally have incorporated greenery features, there are concerns that private developers may not have adequate impetus to go green due to the voluntary nature of BEAM Plus. This is especially the case for smaller developers, which might be less resourceful to satisfy the registration criteria/attain BEAM Plus certification.^{14Legend symbol denoting See 經濟日報(2015年) and 明報周刊(2017年).} Moreover, for the vast majority of existing private buildings, there is a lack of incentives/support for their owners to adopt the above green building standards under BEAM Plus. The collapse of a university green roof in 2016 has also put a brake on related projects, sparking calls for more incentives and technical support to revive interests in roof greening.^{15Legend symbol denoting The Buildings Department ("BD") concluded that the incident was due to overloading caused by heavy structure, additional greenery and water ponding. While the BD had issued a circular to remind industry practitioners of the technical issues (e.g. load bearing and drainage) of roof greening as well as a guideline to educate the public about relevant safety issues, the incident reportedly prompted some schools to remove their green roof projects. See Buildings Department (2017) and 端傳媒(2016年).}

Overseas experience in tackling urban heat

Providing targeted heat relief to specific community/vulnerable groups

• Hit by occasional heat waves, some Australian states/cities have provided immediate relief to groups at greater risk for heat-related illness, in particular the elderly and homeless people. For instance, Western Australia has a policy of handing out air-conditioning rebates to eligible residents, including seniors and pensioners, during summer months. The rebate, which is paid annually and amounts to about A$60 (HK$334) per month, aims to subsidise the electricity cost of those living in areas of high heat discomfort. In 2018-2019, over 3 000 recipients benefitted from the rebate, which cost the state government A$886,000 (HK$4.9 million).^{16Legend symbol denoting The rebate applies to some 140 towns located north of the 26th parallel of south latitude. See Government of Western Australia (2020) and Western Australia State Budget (2019).}
• Melbourne has in place a homelessness specific programme for responding to extreme heat since 2014, covering not only street sleepers but also those living in temporary or inadequate housing. Different from West Australia's policy of providing air-conditioning rebate to specific community groups, Melbourne's programme gives out free movie tickets and swim passes to people experiencing homelessness, on days of extreme heat. While the Melbourne government bears the cost of the programme, local non-profit organizations with regular contact with vulnerable groups will help distribute the tickets/passes to ensure that the needy will have adequate access to cool, welcoming environments.^{17Legend symbol denoting See City of Melbourne (2019).} Besides, the homeless population may take refuge at a 24-hour community cafe serving free meals, during extreme hot weather.
• The responsibility to provide heat relief might also lie with landlords. To tackle heat in cramped, poor ventilated apartments, Toronto has updated its bylaw requiring that a landlord should fix or replace a broken air-conditioner.^{18Legend symbol denoting See City of Toronto (2020a).} Probably owing to the more spacious environment in Toronto's buildings, it is under discussion that the city government may consider imposing additional requirements on property owners to add shade facilities and air-conditioned "cool rooms" in common areas for tenants to escape the heat. These proposals will especially benefit people with disabilities and those without air-conditioning at home.

Enhancing heat relief measures/shelters in public places

• Rather than just providing temporary shelters during heat warnings, Toronto has established a "heat relief network" with an all-summer approach to provide more accessible cooling spaces for the public throughout the summer season. In recent years, it has partnered with private and non-profit organizations to map out some 300 free places across the city, including community centres, 24-hour respite sites^{19Legend symbol denoting These sites provide essential services such as resting spaces, meals and service referrals to people experiencing homelessness.} and several YMCA locations, which are actively promoted to the public seeking heat relief.^{20Legend symbol denoting See City of Toronto (2019a).} Participating organizations are provided with signage in visible locations to help the public identify these cooling places. An online map is also developed to show the location of these places, offering a live feed for service updates (e.g. closure of facilities).
• Heat relief measures may also involve using new cooling technologies in public spaces from streets to transport stations. Singapore's smart bus stop, which has been put on trial on the bustling Orchard Road, helps commuters beat the heat and pollution. The bus stop, designed by ST Engineering, a portfolio company of Singaporean state investor Temasek, features overhead nozzles that release cool air as low as 24°C, and filters harmful PM2.5 particles.^{21Legend symbol denoting See Temasek (2018).} The system is seen as more efficient than traditional air-conditioning. It uses cold water to cool air without the need for refrigerants, and adjusts its cooling cycle based on passenger flow and surrounding temperature.
• Besides, the city of Sydney in Australia is exploring innovative ways to cool public spaces. Following the 2019 launch of the Cooling Sydney Strategy by the Low Carbon Living CRC, Australia's national research centre, Sydney is in the midst of implementing some of the report's recommendations. Among others, these include building more water features such as water sprinklers and misting fans powered by solar energy.^{22Legend symbol denoting See City of Sydney (2020) and Low Carbon Living CRC (2019).} Sydney is also evaluating the effectiveness of a pilot project building cool pavements with pale surfaces in a suburb. Cool pavement is one way to reduce urban temperatures^{23Legend symbol denoting It is estimated that if pavement reflectance in a city could increase from 10% to 35%, the air temperature would be reduced by 0.6°C. See United States Environmental Protection Agency (2012).}, as lighter-coloured materials absorb less solar radiation than dark-coloured asphalt. In Hong Kong, there have also been suggestions of applying cool materials in footpaths and building walls to reduce surrounding temperatures.^{24Legend symbol denoting See 世界綠色組織(2017年).}

Incorporating greenery in urban building design

• To battle urban heat, some places have introduced clear legal frameworks and incentives to encourage developers to adopt greener design. Toronto is seen as a pioneer in green roof policy in North America with the passage of the Green Roof Bylaw in 2009. The bylaw stipulates that a green (vegetated) roof should be built on new developments with a minimum GFA of 2 000 m². If a developer chooses to build a smaller green roof than is required under the Bylaw^{25Legend symbol denoting The greening requirement ranges from 20% to 60% of the available roof space for a residential, institutional or commercial development, depending on the size of a building. See City of Toronto (2020b).}, it may seek approval from the authority and pay C$200 (HK$1,149) per m² as compensation.
• A notable feature of the scheme is that all funds collected above will be used to support the self-sustaining "Eco-Roof Incentive Program". This programme provides rebates for installing green roofs and/or cool roofs^{26Legend symbol denoting A cool roof reflects more sunlight and absorbs less heat through a special coating applied over the roof.} on existing buildings and some new smaller-scale projects.^{27Legend symbol denoting These include new buildings with a GFA of less than 2 000 m2 and some projects by schools and not-for-profit organizations. Eligible green roof projects receive C$100 (HK$575) per m2 while cool roof projects receive C$2-C$5 (HK$11-HK$29) per m2. See City of Toronto (2020c).} Technical support for building owners is also available in the form of structural assessment grants to determine if a building can support the extra weight of a green roof. These roof greening measures in Toronto are well-received, resulting not only in a rising number of completed projects, but also reduced urban heat. The city's widespread adoption of green roofs is estimated to have cooled ambient temperature by 1.5°C to 2°C and roof temperature by up to 5°C.^{28Legend symbol denoting See C40 Cities (2018).}
• Meanwhile, Singapore also requires all larger-scale projects with a GFA of 2 000 m² or more to comply with green building standards under its Green Mark Scheme.^{29Legend symbol denoting All buildings with a minimum GFA of 2&nbp;000 m2 must score at least 50 points to get certified under Green Mark, Singapore's assessment tool for green buildings. Green Mark awards points for the use of greenery (e.g. green roofs and sky gardens) and restoration of trees to reduce urban heat, among other evaluation aspects such as energy and water efficiency. Development projects achieving a higher Green Mark rating (i.e. gold or platinum) will be awarded GFA bonus. See Building and Construction Authority (2008).} The mandatory requirement applies not only to new buildings but also existing buildings undergoing major retrofits. Besides meeting the green building standards, the Landscaping for Urban Spaces and High-rises ("LUSH") programme introduced in 2009 further requires developers to replace the greenery lost at a development site, with an array of greening options on the ground, rooftops or mid-level sky terraces.^{30Legend symbol denoting Developments in core strategic areas will need to replace the greenery lost with new greenery at least equivalent to the site area. Examples of these areas are Marina Bay, Kallang Riverside and Jurong Gateway, just to name a few. See URA (2017b).} The list of eligible greening options was later expanded to reflect new greenery trends and include features such as rooftop urban farms, green roofs and vertical greenery (e.g. green walls), allowing greater planning flexibility for developers.
• In addition to mandatory greenery requirements, developers may be eligible for GFA concessions under the LUSH programme. The list of greenery features qualified for GFA exemptions is rather comprehensive. For example, GFA exemptions may apply to planter boxes, rooftop pavilions and ground floor gardens, in addition to urban farms, green roofs and solar panels^{31Legend symbol denoting For urban farms, green roofs and solar panel projects, the LUSH programme grants GFA exemptions on condition that the mechanical and electrical equipment (e.g. staircase and lift system) is relocated from the rooftop to one of the top three floors directly below the roof.} on rooftops. Since its launch, the LUSH programme has created more than 130 hectares of greenery in Singapore, the equivalent of 210 soccer fields.^{32Legend symbol denoting See URA (2017a).} Its government expects that by 2030, 200 hectares of skyrise greenery would be added across the country.^{33Legend symbol denoting See Ministry of National Development (2017).}

Fostering research collaboration on cooling strategy

• Singapore, on the other hand, has placed great emphasis on urban cooling research. The government announced in the 2020 Budget that it would pledge close to S$1 billion (HK$5.6 billion) to support research in urban sustainability, with a focus on cooling Singapore and renewable energy, among others.^{34Legend symbol denoting See Singapore Budget (2020).} A prominent state-funded research is the Cooling Singapore project, established in 2017. Funded by Singapore's National Research Foundation, the project has partnered with research institutes from home and abroad to develop solutions to Singapore's urban heat problem.
• While the Cooling Singapore project is still ongoing, it has resulted in a catalogue of 86 potential solutions specific to the context of Singapore. These include building green (vegetated) parking lots that trap less heat; promoting rooftop farming to achieve the dual goal of greening and food security; using smart shading devices that change shape and colour based on temperature and light; and allowing variations in building heights to create wind corridors.^{35Legend symbol denoting See Cooling Singapore (2017).} To bridge the gap between research and policy on reducing urban heat, a task force was created as part of the project. It consists of 14 other government agencies and research institutes, including the Urban Redevelopment Authority, with the hope of translating research outcomes into policy.^{36Legend symbol denoting See URA (2019).}

Concluding remarks

• Globally, more frequent and intense hot weather has prompted more places to beat the heat with new measures. Some regions/cities in Australia and Canada have provided immediate heat relief for the public, particularly communities at risk for heat-related illness. Heat relief also takes the form of using cutting-edge technology to cool public spaces from streets to bus stops. Elsewhere, attempts have been made by Toronto and Singapore to drive changes in building design to lower urban temperatures. Singapore has further promoted urban cooling research with considerable funding support. These strategies and innovation can be of reference value to Hong Kong, a city aspiring to greener, healthier and more heat-resilient.

Prepared by Jennifer LO
Research Office
Information Services Division
Legislative Council Secretariat
2 November 2020