Can Mapping Urban Albedo Help Control Urban Heat Island Effect?
Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation
Urban temperatures are rising and it has a great deal to do with the types of materials we choose to construct our habitat. Historically, our construction materials have been great absorbers of infrared and near infrared solar radiation. As our urban centers have grown they have accumulated an excess potential for heat absorption which has put them out of balance compared to more rural areas. This is what is called the heat island effect. The good news is that every urban surface exposed to the sun becomes a potential location to reverse this process and restore the balance.
While researching maps of Philadelphia (my home) for a previous blog on billing property owners for impervious surfaces that contribute to the rainwater run-off pouring into co-mingled storm/sewer systems, I came across the map used to identify these properties by the City (http://www.phila.gov/water/swmap).
The interactive map shows the relative water permeability of surfaces delineating between general materials such as roofing, parking areas, roads, and open spaces. I started to think about how we could use similar technology to identify the albedo of the surfaces – a material’s natural ability to reflect or absorb radiant heat gain from solar radiation.
Some creative person (with a lot of time on their hands) should be able to use tools like Google Earth, identify the nature of the surfaces they see, and draw from a database of Solar Reflective Index (SRI) values to identify the potential targets for improvement. How can we influence global cooling? By using technology that is available to identify the albedo of existing buildings. Once identified, municipalities can incentivize people to change to cool roofs or to living roofs where appropriate. The city could encourage the re-planting of native trees in unusable areas. There are all kinds of things each property could do to make a difference.
I would love to hear what other ideas may be out there to address this issue. Any takers?