What is a Urban Heat Island?
An urban heat island (UHI) is a area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference usually is larger at night than during the day, and is most noticeable when winds are weak. UHI is most noticeable during the summer and winter. The main cause of the urban heat island effect is from the modification of land surfaces, which use materials that effectively heat up the surroundings. As a population centre grows, it tends to expand its area and increase its average temperature. The less-used term heat island refers to any area, populated or not, which is consistently hotter than the surrounding area.
How I will aim to reduce the Urban Heat Island effect
Many communities are taking action to reduce urban heat islands using four main strategies:
Increasing tree and vegetative cover
Installing green roofs (also called "rooftop gardens" or "eco-roofs")
Installing cool—mainly reflective—roofs
Using cool pavements I aim to use all of these strategies in my neighbourhood, starting with trees and vegetation. Trees and vegetation will help reduce the urban heat island by blocking some of the sunlight which will cool the air and surface making the temperatures drop. 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. Trees are also cheap and will always grow bigger and bigger. Trees also help to reduce energy usage by blocking sunlight form buildings which means air conditioning will not be needed as often.
Next, I will build my houses with green roofs, these help to provide shade and remove heat through evapotranspiration, 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, unlike the surface of a conventional rooftop (slate). A benefit of green roofs is that they absorb heat and act as insulators for buildings, reducing energy needed to provide cooling and heating, they are also cheap because you can just by a couple of plants.
Furthermore, I will have cool, reflective roofs on the top of the house. A cool roof is a roof which has a high solar reflectance and that 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 benefit of a coll roof is that a cool roof transfers less heat to the building below, so the building stays cooler and uses less energy for air conditioning.
After that, I will have cool pavements. Cool pavements include a range of established and emerging technologies that communities are exploring as part of their heat island reduction efforts. The term currently refers to paving materials that reflect more solar energy, enhance water evaporation, or have been otherwise modified to remain cooler