Urban Environmental Risks

Transcription

1 Urban Environmental Risks Increasing Energy Use Urban Energy Consumption varies by Economic Sector In the global economy, economic activities are separated into four distinct categories: Primary Sector: Involves the extraction and production of raw materials Mining industry / Fishing industry / Timbering industry / Farming industry Secondary Sector: Involves the transformation of raw materials into goods adding value to that raw material Manufacturing industry / Construction industry / Food Processing industry Tertiary Sector: Involves the provision of services to consumers and businesses Retail Consumer Goods Industry / Tourism Industry / Entertainment Industry Quaternary Sector: Involves the research and development needed to produce products from natural resources and the assembly, transmission and processing of information and data Financial industry / Education industry / Media industry 1

2 In the economic core / industrialized economies of the world, city usage of energy is primarily for the operation and maintenance of the built environment Such as lighting and heating of commercial buildings Followed by (2) transportation, and (3) heavy industry use In the emerging, middle income and former semi peripheral industrialized economies of the world, city usage of energy is primarily for the transportation needs of the built environment Such as gasoline for individual autos, and for movement of consumer goods Heavy industrial usage and maintenance of the build environment are in competition for number 2 and 3 usage this is an indicator of development stages 2

3 In the newest developing urban places of South and South East Asia, urban energy consumption is greatest in the urban industrial centers of global exchange, like Beijing and Shanghai, China similar to the advanced economic countries In cities whose economies are not linked to global economic exchange (Bangkok, Kathmandu), transport continues to be a high usage of energy Ecological Footprint An Ecological Footprint is a measure of how much productive land and water an individual, a city, a country (or even a planet) requires to produce all the resources they consume AND to absorb all the waste they generate using the technology of the day 3

4 Ecological Footprint (continued) An Ecological Footprint is calculated be the sum of cropland, forest, grazing land, fishing ground, built up land, and carbon and nuclear energy footprints required to sustain them and to absorb their outputs Today s global ecological footprint is 2.2 hectares per person This is considered by the WWF at 21% OVER the earth s biocapacity Earth s capacity at current population is about 1.8 hectares per person Source: World Wildlife Fund Ecological Footprint of Selected Cities and Host Countries 4

5 Ecological Footprint of Countries by Income (2003) 1 hectare = 2.47 acres What economic sectors are making the global eco footprint grow? Source: World Wildlife Fund 5

6 Where is our ecological foot at on the globe? Source: World Wildlife Fund Urban Environmental Risks Urban Heat Islands 6

7 Urban Heat Islands (UHI) An Urban Heat Island (UHI) is created around a metropolitan area, where the central urban area s land cover (concrete, pavement, metal, etc.) absorb and retain more heat from the sun than those land covers of the surrounding countryside (grass, trees, dirt, etc.) Urban Heat Islands (UHI) Measuring Urban heat islands may be identified by measuring surface or air temperatures Surface temperatures have an indirect but significant influence on air temperatures For example, parks and vegetated areas, which typically have cooler surface temperatures, contribute to cooler air temperatures Dense built up areas, on the other hand, typically lead to warmer air temperatures Because air mixes within the atmosphere, though, the relationship between surface and air temperatures is not constant 7

8 Urban Heat Islands (UHI) Measuring Surface and atmospheric temperatures vary over different land use areas Surface temperatures vary more than air temperatures during the day, but they both are fairly similar at night The dip and spike in surface temperatures over the pond show how water maintains a fairly constant temperature day and night, due to its high heat capacity Urban Heat Islands (UHI) Measuring Remote Sensing techniques can be used to measure the amount of heat that is being generated by a conglomeration of land covers Remote Sensing is the acquisition of information about an object or phenomenon using equipment that does not make contact with the object. It takes measurements of various types of emitting energy / radiation from the object Atlanta, GA UHI effect All surfaces give off thermal energy that is emitted in wavelengths. Instruments on satellites and other forms of remote sensing can identify and measure these wavelengths, providing an indication of temperature 8

9 Atlanta surface heat signatures Urban Heat Islands (UHI) Impacts On a hot, sunny summer day, roof and pavement surface temperatures can be F (27 50 C) hotter than the air While shaded or moist surfaces often in more rural surroundings remain close to air temperatures These surface urban heat islands, particularly during the summer, have multiple impacts and contribute to atmospheric urban heat islands Air temperatures in cities, particularly after sunset, can be as much as 22 F (12 C) warmer than the air in neighboring, less built up rural regions 9

10 Energy Energy is defined as the ability to do work All ecosystems, including the atmospheric environment, require energy to function The atmosphere largely depends on heat energy Heat energy comes from the movement of atoms & molecules in matter The sun is the ultimate source of heat energy Atlanta surface heat signatures 10

11 Mechanisms of heat energy transfer Heat energy moves from objects that are hotter to objects that are colder when the two objects are in contact (land and air; or sea and air; or hot air mass and cold air mass) There are three mechanisms of heat energy transfer Conduction Convection Radiation Mechanisms of heat transfer 11

12 Conduction The transfer of heat energy through a substance when molecules in the substance collide with each other Convection The transfer of heat energy when a substance itself moves from one place to another 12

13 Radiation The transfer of heat energy from a substance into its environment by means of electromagnetic waves These waves vary by wavelength, which depends on the temperature of the substance Hotter substances generate more radiation energy and radiation of shorter wavelength Urban Heat Islands (UHI) An Urban Heat Island (UHI) is created around a metropolitan area, where the central urban area s land cover (concrete, pavement, metal, etc.) absorb and retain more heat from the sun than those land covers of the surrounding countryside (grass, trees, dirt, etc.) 13

14 Normal distribution of solar radiation 14

15 Solar radiation Ranges from long to short wave, but is largely shorter wave Includes visible light Solar radiation is (1) reflected By aerosols and gas molecules in the atmosphere back into space Aerosol Noun. Physical Chemistry. a system of colloidal particles dispersed in a gas; smoke or fog. By water and solid earth on the ground back into either the atmosphere or into space Albedo measures an object s reflectivity, expressed as a percentage of the radiation received by the object that is reflected Surface albedos vary considerably 15

16 Albedo (reflectivity) Solar radiation is (2) scattered By atmospheric aerosols and gas molecules to elsewhere in the atmosphere A greater concentration of larger aerosols results in more scattering Short wave radiation tends to scatter more Blue sky and an orange red sky both result from scattering of visible light radiation 16

17 Solar radiation is (3) absorbed By aerosols and gases in the atmosphere By water and solid objects on the ground Absorption results in the transfer of heat energy to the object with which the radiation comes into contact Urban Heat Islands (UHI) An Urban Heat Island (UHI) is created around a metropolitan area, where the central urban area s land cover (concrete, pavement, metal, etc.) absorb and retain more heat from the sun than those land covers of the surrounding countryside (grass, trees, dirt, etc.) 17

18 Normal distribution of solar radiation 18

19 Albedo (reflectivity) 19

20 Urban Heat Islands (UHI) An Urban Heat Island (UHI) is created around a metropolitan area, where the central urban area s land cover (concrete, pavement, metal, etc.) absorb and retain more heat from the sun than those land covers of the surrounding countryside (grass, trees, dirt, etc.) UHI Mitigation Remember: Mitigation means, to lessen the severity of something By increasing vegetative cover and by using construction materials that have similar energy absorption properties as the natural world, we can reduce UHI There are four main strategies to UHI Mitigation: Increasing tree and vegetative cover Installing green roofs Installing cool mainly reflective roofs, and Using cool pavement material 20

21 (UHI) Mitigation Strategies Vegetative cover Trees and other plants help cool the environment, making vegetation a simple and effective way to reduce urban heat islands Trees and vegetation lower surface and air temperatures by providing shade Shaded surfaces, for example, may be F cooler than the peak temperatures of unshaded materials Trees and vegetation are most useful as a mitigation strategy when planted in strategic locations around buildings or to shade pavement in parking lots and on streets Additional Benefits of increasing vegetative cover in urban environments: Reduced energy use: Trees and vegetation that directly shade buildings decrease demand for air conditioning Improved air quality and lower greenhouse gas emissions: By reducing energy demand, trees and vegetation decrease the production of associated air pollution and greenhouse gas emissions Enhanced stormwater management and water quality: Vegetation reduces runoff and improves water quality by absorbing and filtering rainwater Reduced pavement maintenance: Tree shade can slow deterioration of street pavement, decreasing the amount of maintenance needed Improved quality of life: Trees and vegetation provide aesthetic value, habitat for many species, and can reduce noise (UHI) Mitigation Strategies Green Roofs A green roof, or rooftop garden, is a vegetative layer grown on a rooftop Green roofs provide shade and remove heat from the air reducing temperatures of the roof surface and the surrounding air On hot summer days, the surface temperature of a green roof can be cooler than the air temperature, whereas the surface of a conventional rooftop can be up to 90 F (50 C) warmer Additional Benefits of using Green Roofs Reduced energy use: Green roofs absorb heat and insulate buildings, reducing energy needed for cooling and heating Reduced air pollution and greenhouse gas emissions: By lowering air conditioning demand, green roofs can decrease the production of associated air pollution and greenhouse gas emissions. Vegetation can also remove air pollutants. Improved human health and comfort: Green roofs, by reducing heat transfer through the building roof, can improve indoor comfort and lower heat stress associated with heat waves Enhanced stormwater management and water quality: Green roofs can reduce and slow stormwater runoff in the urban environment; they also filter pollutants from rainfall Improved quality of life: Green roofs can provide aesthetic value and habitat for many species. 21

22 22

23 (UHI) Mitigation Strategies Cool Roofs A high solar reflectance or albedo is the most important characteristic of a cool roof as it helps to reflect sunlight and heat away from a building, reducing roof temperatures A high thermal emittance also plays a role, particularly in climates that are warm and sunny Together, these properties help roofs to absorb less heat and stay up to F (28 33 C) cooler than conventional materials during peak summer weather Additional Benefits of using Cool Roofs Reduced energy use: A cool roof transfers less heat to the building below, so the building stays cooler and uses less energy for air conditioning Reduced air pollution and greenhouse gas emissions: By lowering energy use, cool roofs decrease the production of associated air pollution and greenhouse gas emissions Improved human health and comfort: Cool roofs can reduce air temperatures inside buildings with and without air conditioning, helping to prevent heat related illnesses and deaths 23

24 24

25 (UHI) Mitigation Strategies Cool Pavements Cool pavements currently refers to paving materials that reflect more solar energy, enhance water evaporation, or have been otherwise modified to remain cooler than conventional pavements Cool pavements can be created with existing paving technologies (such as asphalt and concrete) as well as newer approaches such as the use of coatings or grass paving Additional Benefits of using Cool Pavements: Reduced stormwater runoff and improved water quality: Permeable pavements can allow stormwater to soak into the pavement and soil, reducing runoff and filtering pollutants Lower tire noise: The open pores of permeable pavements can reduce tire noise by two to eight decibels and keep noise levels below 75 decibels Enhanced safety: Permeable roadway pavements can improve safety by reducing water spray from moving vehicles and increasing traction through better water drainage Improved local comfort: Cool pavements in parking lots or other areas where people congregate or children play can provide a more comfortable environment 25

26 Green Ranking and Rating Systems 1. Energy Star 2. LEED (Leadership in Energy & Environmental Design) 3. HERS (Home Energy Rating System) ENERGY Star sponsored by the US Govt. ENERGY STAR certified new homes are designed and built to standards well above most other homes on the market today They deliver energy efficiency savings of up to 30 percent when compared to typical new homes Requirements set by the U.S. Environmental Protection Agency (EPA) A new home that has earned the ENERGY STAR label has undergone a process of inspections, testing, and verification to meet strict delivering better quality, better comfort, and better durability 26

27 About ENERGY Star The ENERGY STAR program was established by EPA in 1992, under the authority of the Clean Air Act Section 103(g). Section103(g) of the Clean Air Act directs the Administrator to "conduct a basic engineering research and technology program to develop, evaluate, and demonstrate non regulatory strategies and technologies for reducing air pollution." In 2005, Congress enacted the Energy Policy Act. Section 131 of the Act amends Section 324 (42 USC 6294) of the Energy Policy and Conservation Act, and "established at the Department of Energy and the Environmental Protection Agency a voluntary program to identify and promote energy efficient products and buildings in order to reduce energy consumption, improve energy security, and reduce pollution through voluntary labeling of or other forms of communication about products and buildings that meet the highest energy efficiency standards." 27

28 LEED (Leadership in Energy & Environmental Design) sponsored by the U.S. Green Building Council (private sector) is a rating system that encourages innovative and established approaches to constructing the built environment LEED is a program that provides third party verification of green buildings Energy efficiency and environmental sensitivity are the defining attributes to a LEED certified homes LEED is a certification system for buildings and a professional credential that affirms your advanced knowledge in green building as well as expertise in a particular LEED rating system LEED Credentials (Professional) LEED Green Associate demonstrates a solid, current understanding of green building principles and practices LEED AP Building Design + Construction for professional with expertise in design and construction LEED AP Operations for professionals implementing sustainable practices through enhanced operations and maintenance LEED AP Interior Design for professionals in the design, construction and improvement of commercial interiors and tenant spaces that offer a healthy, sustainable and productive work environment LEED AP Homes for professionals involved in the design and construction of healthy, durable homes that use fewer resources and produce less waste LEED AP Neighborhood Development for professionals participating in the planning, design and development of sustainable, pedestrian friendly neighborhoods 28

29 LEED Rating Systems (Buildings) Rating systems are groups of requirements for projects that want to achieve LEED certification. Projects earn points to satisfy green building requirements Within each of the LEED credit categories, projects must satisfy prerequisites and earn points The number of points the project earns determines its level of LEED certification LEED Rating Systems (Buildings) Rating systems are groups of requirements for projects that want to achieve LEED certification. Additional LEED for Homes credit categories Projects earn points to satisfy green building requirements Within each of the LEED credit categories, projects must satisfy prerequisites and earn points Additional LEED for Homes credit categories The number of points the project earns determines its level of LEED certification Two Bonus Credit Categories 29

30 30

31 Top 10 U.S. Cities Ranked By Total Number of LEED Projects as of 5/4/

32 Home Energy Rating System (HERS) Developed by the Residential Energy Services Network (RESNET) The HERS Index is the industry standard by which a home s energy efficiency is measured Government agencies that recognize the HERS Index Department of Energy (DOE), Department of Housing and Urban Development (HUD) and the Environmental Protection Agency (EPA) Home Energy Rating System (HERS) The HERS Calculations require us to think about energy in different conceptual ways, and requires us to identify what specific purposes we use energy for Legend: E=energy consumption, wh=water heating, la=lights and some appliances, PE=purchased energy (fraction) Legend: PE=purchased energy, E= energy 32

33 Home Energy Rating System (HERS) 33