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Below is a graphic showing the measured metro heat island effect on July 2, 2012. The graphic on the left shows the day-long average temperature variation and on the right shows night-time difference. The City of Arden Hills is outlined in black and shows a daytime heat island temperature increase of 2-4 degrees and a nighttime increase of 5-7 degrees. Arden Hills Impervious Surface and Heat Island (continued) Impervious Surface Area (University of Minnesota, 2002, and Minnesota State University, 2014) Total impervious area State Wide: Metro area: Ramsey County: Arden Hills: 13.7% 1.88% 25% 24% Arden Hills Impervious Surface and Heat Island The Minneapolis/St Paul metro area is the 9th top urban heat island zone in the country in terms of observed temperature differences between the urban area and surrounding rural areas. Temperatures within the MSP metro area can be up to 22 degrees hotter than the surrounding rural area, with an average year round temperature difference of 4.3 degrees. The level of the urban heat island effect of a region is largely driven by the amount of impervious surface. The City of Arden Hill’s current impervious surface area is twice that of the Metro area average. The existing City Hall site itself is 1.63 times the City’s average impervious surface coverage, and nearly 3 times the Metro area average coverage. (Source: University of Minesota Remote Sensing and Geospatial Lab) Sustainability in Context Based on a 2006 study done by Minnesota State University and the University of Minnesota, titled “ ”, the relationship between impervious surface percentage of a portion of a community and the corresponding degree of heat island temperature increase can be understood as a ratio. In Section 4 of this report, we will look at the existing site’s land cover characteristics and the corresponding estimated impacts and benefits.