Do Now Please have out any information pertaining to heat islands as we will be discussing them today to prepare for your engineering design challenge

A Science Sisters Presentation

What is a Heat Island? “The term ‘heat island’ describes built up areas that are hotter than nearby rural areas. The annual mean air temperature of a city with 1 million people or more can be 1.8–5.4°F (1–3°C) warmer than its surroundings.” ~https://www.epa.gov/heat-islands What is the Significance of that: Evening temperatures remain elevated (as much as 22F/12ºC)

What causes a Heat Island? As urban areas develop, changes occur in their landscape. Buildings, roads, and other infrastructure replace open land and vegetation. Surfaces that were once permeable and moist become impermeable and dry. These changes cause urban regions to become warmer than their rural surroundings, forming an "island" of higher temperatures in the landscape.

Impacts of Heat Islands: Increased energy consumption (in summertime) air conditioning costs “On a hot, sunny summer day, roof and pavement surface temperatures can be 50–90°F (27–50°C) hotter than the air, while shaded or moist surfaces—often in more rural surroundings—remain close to air temperatures.” ~https://www.epa.gov/heat-islands/heat-island-impacts “Electricity demand for cooling increases 1.5–2.0% for every 1°F (0.6°C) increase in air temperatures, starting from 68 to 77°F (20 to 25°C), suggesting that 5–10% of community-wide demand for electricity is used to compensate for the heat island effect.” ~https://www.epa.gov/heat-islands/heat-island-impacts

Impacts of Heat Islands: 2. Air pollution and greenhouse gas emissions Companies that supply electricity typically rely on fossil fuel power plants to meet increased energy demand. The primary pollutants from power plants include: sulfur dioxide (SO2) nitrogen oxides (NOx) particulate matter (PM) carbon monoxide (CO) mercury (Hg)

Impacts of Heat Islands: 3. Heat-related illness and mortality Lack of cooling and night-time recovery of temperatures Health can be affected for those who have trouble with temperature regulation and self-cooling such as elderly, very young, and health –impaired individuals. Air pollution impact respiratory illness and those with respiratory diseases such as asthma

Impacts of Heat Islands: 4. Water quality Heated storm water runoff impacts any water source the storm runoff enters into such as ponds, lakes, streams, and rivers Increased temperatures affect aquatic life in those areas Upsets ecosystem

What is the Reducing Urban Heat Islands: Compendium of Strategies? Describes the causes and impacts of summertime urban heat islands and promotes strategies for lowering temperatures in U.S. communities. It provides an overview of heat islands, how they form, and their impacts, and describes key urban heat island reduction strategies in depth. It also describes voluntary and policy efforts undertaken by state and local governments to mitigate urban heat islands.

What are the strategies that can be utilized to reduce heat islands? 1. Planting trees and vegetation Increasing tree and vegetation cover lowers surface and air temperatures by providing shade and cooling through evapotranspiration. Trees and vegetation can also reduce stormwater runoff and protect against erosion. 

What are the strategies that can be utilized to reduce heat islands? 2. Green roofs Growing a vegetative layer (plants, shrubs, grasses, and/or trees) on a rooftop reduces temperatures of the roof surface and the surrounding air and improves stormwater management. Also called “rooftop gardens” or “eco-roofs,” green roofs achieve these benefits by providing shade and removing heat from the air through evapotranspiration.

What are the strategies that can be utilized to reduce heat islands? 3. 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.

What are the strategies that can be utilized to reduce heat islands? 4. Cool pavements Using paving materials on sidewalks, parking lots, and streets that remain cooler than conventional pavements (by reflecting more solar energy and enhancing water evaporation) not only cools the pavement surface and surrounding air, but can also reduce stormwater runoff and improve nighttime visibility.

What are the strategies that can be utilized to reduce heat islands? 5. 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.

A Science Sisters Presentation