Please enable JavaScript.
Coggle requires JavaScript to display documents.
Urban Heat Island (Causes (Anthropogenic heat: Heat discharged by human…
Urban Heat Island
Causes
Fossil Fuel Burning from factories and cars: emits heat and also greenhouse gases that get trapped in the atmosphere and also trap heat
Building Materials: Concrete, glass, brick, and tarmac are common materials used to build urban structures. However, they absorb heat very easily and dissipate heat very slowly.
Anthropogenic heat: Heat discharged by human activities. Heat released from vehicles, central heating, and industrial activities is exceedingly high.
Weather conditions: High-pressure systems with clear nights and still, sunny days will result in higher heat intensity. It also varies seasonally.
Lower wind speed: Urban areas have lower wind speeds compared to suburbs, a result of the roughness of the land surface as there are many buildings of different heights; higher surface friction.
Building Height + Shape: many vertical surfaces causes light to bounce around, and the heat gets absorbed in many different places
-
Organization of buildings: "Insolation" causes heated surfaces; the level of warming is dependent on the level of insolation absorbed by the surface.
Urban areas cool at a much slower pace compared to rural areas at night, which allows for higher air temperatures
Water Availability: Very little bodies of water within an urban city --> heat energy is being used as sensible heat (the kind of heat we can feel) instead of latent heat (used for evaporation)
Urban Canyon: Buildings get taller + streets get narrower towards the center of the city --> "venturi effect" where wind is "squeezed" to create turbulence
Consquences
-
Lower wind speed
Urban areas have lower wind speeds compared to suburbs, a result of the roughness of the land surface as there are many buildings of different heights; higher surface friction.
-
-
SOLUTIONS
PLANNING A CITY
Tree canopies : As plants and trees
are excellent insulators during summer and decrease the overall urban heat island effect.
-
Green parking lots
Green parking spaces utilize green infrastructure strategies to limit the impacts of urban heat island effect. In precise, it cushions against the elevation of pavement temperatures which can considerably prevent thermal pollution
-
Smart urban design : keeping more space while planning and balancing it with materials that make an urban heat island.
Smart Growth - These practices cover a range of development and conservation strategies that help protect the natural environment and at the same time make our communities more attractive, economically stronger, and more livable
ON EXISTING CITIES
roof sprinkling
It is another evaporative cooling solution. Sprinklers on the roof wet the surface so that the air around it cools through evaporation
Implementation and sensitization of heat reduction policies and rules
policies such as Clean Air Act, Low carbon fuel standards, uses of renewable energy, and clean car rule standards can impressively regulated the anthropogenic inducers of urban heat island effect.
Cool Roofs - Installing a cool roof – one made of materials or coatings that significantly reflect sunlight and heat away from a building – reduces roof temperatures, increases the comfort of occupants, and lowers energy demand.
Planting trees in cities he practice of tree planting within and around cities is an incredible way of reflecting solar radiation while at the same time decreasing the urban heat island effect.
Use of light coloured walls ad concrete: White and lighter colours reflect 50% of the sunlight as it is a good reflector
-
-