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Urban Development

Cooler buildings and lower bills in summer thanks to green walls and roofs

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A 15% cut in the energy bill with a 40% reduction of the direct solar radiation in dwellings and a lower indoor temperature by up to 3 degrees thanks to plants grown on roofs, balconies and external walls. These are part of the outcomes of the Italian pilot project ENEA is conducting at its research center near Rome.

“We developed a green wall based on an extensive roof-garden system and a self-supporting structure positioned at 50cm from the wall of the School of Energies building, where we conduct training courses”, Carlo Alberto Campiotti at the Department Unit for Energy Efficiency, said. “Successively – Campiotti went on – we’ve begun to study the interactions among green coverings, energy flows, the microclimate and indoor comfort, diversifying the species”.

The “plant system” installed on walls, roofs and balconies, has proved capable of creating an actual insulating pad enveloping houses and condos; in this way vegetation can mitigate temperature peaks during summer, capturing most of solar energy, which doesn’t directly hit the building surface, dissipating through evapotranspiration of plants a large amount of thermal energy (up to 1 liter of water daily per square meter) which would otherwise be absorbed by the building and released as heat inside the house.

“In summer this vegetation system allows to reduce up to 15% of energy for cooling- Campiotti pointed out- while in winter savings for heating reach 10% thanks to the chimney effect between the wall and the vegetable blanket; in practice, a natural ventilation system removing moisture from walls and reducing the thermal dispersion of the building”. Each plant has its own type of leaf given by color, thickness, shape, arrangement on the stems and biological cycle, which determines the amount of solar radiation it captures instead of hitting the walls of the building.

The parameter defining the energy and bio-agronomic traits of plants is called green factor (kv) and it varies from a minum of 0 to a maximum of 1. In practice, if kv is 1, it means the green mantle doesn’t exert any shielding towards solar radiation and, in summer conditions, the temperature of the external wall is superior to both that of the air and that inside the building; but if the value is zero, it means that vegetation exerts a total shield and the temperature of the wall is equal to that of the air.

“The Pandorea Jasminoides variegata – Germina Giagnacovo at the Energy Efficiency and Productive Activities Department explained – is a climbing evergreen with an excellent ability of neutralizing solar radiation, as Lonicera hall prolific and Partenocissus quinquefolia do, although slightly less effectively”.

“In addition to an improved thermal and acoustic insulation and living comfort for individual dwellings, these solutions also have advantages for the entire urban context: green roofs and walls, in fact, contribute considerably to the reduction of the “heat island”, which can cause a peak of the electrical load during summer, between 3 and 8% for each additional degree of temperature.

Furthermore, less use of air conditioning means less greenhouse gas emissions such as CO2, methane, fluorinated gas and water vapor. Installing green roofs, balconies and walls also means mitigating the effects of the so called “rain bombs” – roofs and balconies account in fact for 20% of the total surface of cities and covering them with plants would allow to absorb up to 50% of rainwater, regulating its flow into the city’s water system- in addition to improving air quality, since 25 m2 of plant surface generate oxygen for one person, while 1m2 eliminates 0.2 kg of particulate matter in the air.

“For many sectors in distress in our economy, including the building sector, new prospects for recovering are opening up- Campiotti continued- also thanks to the introduction of the green bonus with the last Budget Law, a new fiscal incentive which allows to recover 36% of the costs, up to 5thousand euro incurred for re-greening single dwellings and parts of condos, an intervention which could increase the value of the building itself”.

Green coverings

“Extensive, mildly intensive and intensive are the three types of green coverings we’re experimenting with at ENEA- Susanna Mariani at the Department Unit for Energy Efficiency, explained. We are particularly interested in the experimental use of autochthonous varieties, such as climbers and evergreens, but also rare wild species such as Echium vulgare, also known as viperina grass, much loved by bees, which can guarantee maximum protection of biodiversity, adaptability to climatic variability and resistance to summer droughts “.

In detail, the extensive coverings are characterized by varieties of plants that are easy to grow (of the genus ‘sedum’, a set of various species of succulents, and perennials) that need little maintenance and rescue irrigation (mosquito-proof), since they can store a large amount of water. This type of roofing is particularly suitable for walls and slopes, since the installation reaches a weight of about 100 kg / m2. Intensive coverings, on the other hand, foresees the inclusion of trees, require high maintenance and increased irrigation, involving the installation of a weight on the building ranging from 400 to 1000 kg / m2, while the mild intensive is positioned halfway between the other two varieties of coverings, by type of plants and maintenance, weighing between 200 and 400 kg / m2

The courses

In september, at the School of Energies of the ENEA Casaccia Research center, the Energy Efficiency Department will organize a course on the cultivation of plants best suited for green coverings. The course is free of charge and is addressed to agronomists, land surveyors, architects, biologists and natural sciences graduates.

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Urban Development

Guterres promotes ‘enormous’ benefits of greener cities

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For the UN Secretary-General, the benefits of making cities more environmentally friendly are “enormous”, and include reduced climate risk, more jobs, and better health and well-being. 

“City leadership in using green materials and constructing energy-efficient, resilient buildings powered by renewable energy, is essential to achieve net-zero emissions by 2050,” said António Guterres in his message for World Habitat Day, marked on Monday. 

The theme for this year’s celebration of cities and towns worldwide is Accelerating urban action for a carbon-free world. 

Cities are responsible for about 75 per cent of the world’s energy consumption and over 70 per cent of global greenhouse gas emissions.  

Two crises 

Urban areas across the globe are facing the dual crises of COVID-19 and climate change, said the UN chief. 

Around 4.5 billion people live in cities today, but that population is projected to grow by almost 50 per cent, by 2050. By mid-century, over 1.6 billion urban residents may have to survive through average summertime highs of 35 degrees Celsius. 

For Mr. Guterres, cities and towns are at the core of climate action to keep the 1.5 degrees goal within reach. 

“Three-quarters of the infrastructure that will exist in 2050 has yet to be built,” he said. “Economic recovery plans offer a generational opportunity to put climate action, renewable energy, and sustainable development at the heart of cities’ strategies and policies.” 

As populations grow in emerging economies, demand for transport, which accounts for nearly 20 per cent of global carbon emissions, is also multiplying.  

The UN Chief said cities are already working on this, trying to ensure that this demand is met by zero-emission vehicles and public transit. 

Mr. Guterres concluded asking for a global moratorium on internal combustion engines to underpin these efforts, saying it should happen by 2040 at the latest.  

Opportunity 

In a message for the day, Executive Director of UN-Habitat, Maimunah Mohd Sharif, said that, unless the world takes urgent action, “the greenhouse gases produced by ever expanding urban centres, will continue to push global air temperatures higher.” 

Ms. Sharif remembered that, this year, the day is celebrated only weeks before the UN climate change summit, COP26, happening in early November in Glasgow.  

For the UN-Habitat Chief, the recovery from the COVID-19 pandemic is an opportunity for the world’s cities to put climate action on top of their agenda. 

“This is a chance to change how we generate our power, construct our buildings, heat, cool and light up our offices and homes, and travel around from home to work,” she said. 

Ms. Sharif asked for “well planned and well managed compact cities”, that allow for non-motorized transport and that reduce energy consumption from cooling and heating. 

“Cities are the incubators of innovation and new technology,” she said. “We must harness this strength for better climate change solutions.” 

For Ms. Sharif, “action will differ from city to city”, but “the green transition must benefit everyone, especially the most vulnerable, and create new jobs.”  

Activities  

Events this year will explore how governments and organizations can work together with communities, academic institutions and the private sector to create sustainable, carbon-neutral, inclusive cities and towns. 

World Habitat Day will also amplify the Race to Zero Campaign and encourage local governments to develop actionable zero-carbon plans in the run up to the COP26. 

This Monday, in a ceremony in Yaounde, Cameroon, UN-Habitat will also present the winners of the Scroll of Honour awards, one of the world’s most prestigious prizes for those working on sustainable urbanization. 

This year, there are five winners: New Urban Communities Authority, from Egypt; Shining Hope for Communities, from Kenya; Baoji City, from China; Let’s do it World, from Estonia; and Ciudad Emergente, from Chile. 

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Urban Development

City Climate Finance Gap Fund completes first year of operation

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The City Climate Finance Gap Fund (the Gap Fund) has approved technical assistance for 33 cities across the developing world since its operational launch in September 2020, filling a critical gap in technical assistance funding to help cities turn their climate ambitions into finance-ready projects.

Marking its one-year operational launch anniversary today, the Gap Fund has received over 140 expressions of interests and approved technical assistance for 33 cities in India, Mexico, Ethiopia, Morocco, Democratic Republic of Congo, Panama, Senegal, Vietnam, Kosovo, Montenegro, Ecuador, South Africa, Vanuatu, Colombia, Indonesia, Brazil, Guatemala, Uganda and Ukraine. An additional 30 cities are currently undergoing a detailed assessment for potential Gap Fund support, with a total target of at least 180 cities.

The Gap Fund is currently capitalized at €55 million, with a target of at least €100 million and the potential to unlock an estimated €4 billion in investments. The aim is to help cities understand their exposure to climate challenges, develop plans and strategies to reduce emissions and vulnerability to climate risks, and identify and prioritize climate-smart urban infrastructure investments.

The Gap Fund demonstrates a unique collaborative model: With funding from Germany and Luxembourg, the Fund is co-implemented by the World Bank and the European Investment Bank in partnership with the Deutsche Gesellschaft für Internationale Zusammenarbeit and works directly with city groups and networks including GCOM, ICLEI, C40 and CCFLA. This concerted effort has helped raise awareness about the importance of cities and urban systems in the climate agenda and could not come at a more critical time, as the latest Intergovernmental Panel on Climate Change (IPCC) report confirms that cities are the hotspots of global warming, with the global urban climate finance gap estimated in the trillions of dollars, especially in South Asia and Sub-Saharan Africa.

The Gap Fund also contributes cutting-edge knowledge, tools and recommendations. For example, by featuring in theState of Cities Climate Finance Report Part 2: Enabling Conditions for Mobilizing Urban Climate Finance, whichprovides critical systems-level conceptual frameworks and recommendations for city, country and climate decision-makers. The Gap Fund has also developed or packaged user-friendly practical tools and notes for operational practitioners and project developers on the ground.

The way cities develop in the coming years, especially in these regions, will influence the trajectory of future greenhouse gas emissions, and the susceptibility of cities to increased flood risks and urban heat island effects. The focus on cities is also reflected in the World Bank’s Climate Action Plan, which has identified cities and urban systems as a focus area on a par with energy, transport, food and industry.

Some of the Gap Fund’s most recent grant activities include:

  • San Miguelito, Panama: Identify climate-smart and energy-efficient urban interventions for new cable car infrastructure, with the potential to cut emissions and reduce vulnerability to floods.
  • Dakar, Senegal: Integrate low-carbon and climate-resilient considerations into the planning, development and construction of affordable and green housing in the greater Dakar region, including piloting  a green building certification incentive for building developers.
  • Mangalore and Kolar, India: Prepare a climate diagnostic report for solid waste management as well as an action plan for improving and financing low-carbon solid waste management services, including a pre-feasibility study.
  • Bogota, Colombia: Provide technical assistance for greenhouse gas and air quality analytics, city-wide coordination and recommendations to incorporate low-carbon and climate-resilient considerations in the Low-Carbon Vital Neighbourhoods in Bogota– the first pilot in Latin America to implement a “Proximity City Urban Development Model” (also known as the 15-minute city model).
  • Chefchaouen, Morocco: Prepare a study on low-carbon solid waste management activities including waste sorting, biogas recovery, leachate treatment and the use of solar energy.
  • Vinnytsia, Ukraine: Support climate change adaptation measures along the Southern Bug River, such as new green spaces along the embankments, development of beaches to improve river transport and the construction of a new bridge to improve walking routes north and south of the city.
  • Campinas, Sao Paolo State, Brazil: Promote climate change adaptation and reduce flood risks through nature-based solutions along the Capivari river.
  • Danané, Côte d’Ivoire: Support the deployment of a fleet of 600 low-carbon, low-cost solar tricycle taxis to meet the city’s most pressing mobility needs for people, including expectant mothers, and cargo.
  • Escuintla, San José and Iztapa, Guatemala: Assess the quality of existing waste generation and characterisation data of municipal solid waste and make any necessary additions, compare organic solid waste treatment alternatives and suggest improvements to the existing organisational structure and governance.
  • Santa Marta, Colombia: Improve and enhance the city’s urban forest and forest management, and identify funding opportunities at regional, national or international level as well as links to other potential natural infrastructure projects along Santa Marta’s ecological corridors.
  • Rio de Janeiro, Brazil: Improve hydrological modelling to assess urban flood risks and economic modelling to assess the viability of restoring wetlands as a natural barrier in flood-prone areas and carry out stakeholder consultations.
  • Makindye Ssabagabo, Uganda: Study existing waste generation, carry out a characterisation study of municipal solid waste using random and seasonal data, and compare organic solid waste treatment alternatives.
  • Palembang, Musi Rawas and Lubuklinggau cities, Indonesia: Prepare a cost-benefit analysis, strategy and action plan for green, resilient construction and energy-efficient affordable housing in these three cities. Project would help inform the national Government One Million Housing program which aims to provide incentives for developers to build 220,000 homes per annum and to upgrade 160,000 affordable homes. 

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Urban Development

WEF Launches Toolbox of Solutions to Accelerate Decarbonization in Cities

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With the percentage of people living in cities projected to rise to 68% by 2050, resulting in high energy consumption, greater infrastructure needs and, carbon emissions, cities have a critical role to play in the race to reach net zero. To help address this challenge, the World Economic Forum, is releasing today the first iteration of its Toolbox of Solutions, designed and built in collaboration with Accenture.

The toolbox is an interactive digital platform containing more than 200 practical solutions to help city leaders, national governments and businesses evaluate and identify optimal solutions for near-term implementation, kick-starting their decarbonization journey. The first-of-its-kind toolbox draws on input and case studies from more than 110 cities, businesses, academics, civil society leaders and other urban stakeholders around the world and across sectors to capture best practices and case studies for urban transformation and decarbonization.

The solutions include policy, business and finance models that result in reduced emissions and other valuable outcomes such as job creation and improved air quality. These solutions are also tailored to specific city attributes including the electricity grid’s health, local population density and income level.

“Decarbonization solutions already exist – we don’t need to wait for the next big innovation. This platform provides examples of policies and business models that have been used successfully around the world. We are starting with 200 solutions and expect to have many more over the course of the next year,” said Kristen Panerali, Head of Energy, Materials and Infrastructure Programme, Net-Zero Carbon Cities, World Economic Forum.

“Urban ecosystems are pivotal in our global journey to net zero, driven by clean and smart electrification. These sustainability initiatives can help accelerate efforts to address climate change with practical and integrated energy solutions for urban transformation for cities of any size around the world,” said Jean-Marc Ollagnier, Chief Executive Officer, Europe, Accenture.

Achieving net-zero emissions at city scale will require a transformation in how energy is produced, distributed, and consumed. A related report shows how the built environment and mobility can serve as a catalyst for urban transformation and decarbonization anywhere in the world.

The Toolbox of Solutions is part of the Forum’s Net-Zero Carbon Cities programme, which brings together businesses with city, regional and national government leaders to accelerate urban transitions to a net-zero future. The programme’s objective is to align and scale efforts across businesses, cities and national-level governments to deliver urban ecosystems that are sustainable, resilient and equitable. The programme aims to enable transformation towards clean electrification and circularity, using integrated energy solutions to address energy, buildings and mobility. The Net-Zero Carbon Cities programme is co-chaired by Jean-Pascal Tricoire, Chairman and Chief Executive Officer, Schneider Electric, and Francesco Starace, Chief Executive Officer, Enel.

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