Energy for buildings makes up almost 40% of the carbon footprint for LA County (UCLA Institute of the Environment and Sustainability), so any measures to reduce the energy required to heat and cool our environment can have an impact.
The EPA describes heat island as built-up areas that are hotter than nearby rural areas. The combination of reducing vegetation and replacing it with built materials like streets, buildings, and parking lots has the cumulative effect of increasing the temperature of the local climate. Negative impacts from this temperature increase include increased energy consumption, increased air pollution, compromised public health, and impaired water quality.
Primary strategies to mitigate heat island include replacing built materials with vegetation, and using/replacing built materials with a high reflectance.
We have analyzed some initial numbers as to the impact of urban forestry, or the process of replacing built areas with vegetation. To gain a sense of impact, we measured the impact of providing 500 additional acres of vegetated open space along or near the Los Angeles River. Using data from the EPA, we estimated this could reduce carbon emissions by 10,000 metric tons over 20 years, or 500 metric tons per year.
Temporary or permanent bodies of water can be considered as part of proposed improvements along the LA River. These bodies of water would have an effect on heat island through evaporative cooling. Because of the dry climate in Los Angeles, water can easily evaporate, and this action lowers the local temperature near the body of water.
For a map of where evaporative cooling is most effective, please click here.