As annual temperatures warm and precipitation patterns change as a result of climate change, disease-carrying insects have begun to migrate into areas that may not be prepared for them. Dengue is the most common mosquito-borne virus in the world, resulting in 50 to 100 million infections and 25,000 deaths annually. However, the U.S. had largely escaped dengue outbreaks from the end of World War II to 1980. Since that time, sporadic outbreaks have occurred in the Southern U.S., particularly Texas and Florida. The average cost of treatment in the U.S. is $17,803 per patient. (Source: 3rd National Climate Assessment.)
The primary carrier of the virus, the Aedes aegypti mosquito, is extremely sensitive to changes in temperature, precipitation, and the built environment. While models predict the spread of this mosquito north from Mexico and the Carribean into the contiguous United States, studies show that, historically, a combination of building design and social norms have largely protected Americans from infection when outbreaks occur South of the international border. A study of a Dengue outbreak in 1999 found that the level of dengue present in the population of Laredo, Texas, was 1/2 - 1/10 of the population in Nuevo Laredo, Tamaulipas (just across the border in Mexico). The findings were most closely correlated with the presence of closed windows and air conditioning in Texas buildings, effectively blocking exposure to mosquitoes. Furthermore, buildings on the Mexican side of the border not only lacked central air conditioning but their interiors were also often left open to the elements without protective screens over windows and doors.
As operable windows, passive cooling, and natural ventilation become more common features of green buildings, care must be taken to protect occupants from health threats that could enter from the outside. Otherwise, as has been noted in a number of multi-family developments already, building occupants are not likely to make use of these energy efficiency features – both to avoid the annoyance of stinging insects and to protect themselves from diseases like dengue.
Relevant LEED v4 Credit(s)
Benefits to Climate Change Mitigation and Adaptation
In this example, the homes and businesses in Mexico were more energy efficient than buildings in the U.S., because they did not use air conditioning. This is an example where energy efficiency (i.e., climate change mitigation) should be balanced with safeguards such as screens that protect building occupants from the health hazards associated with climate change (i.e., climate change adaptation).
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