Arboriculture & Urban Forestry 48(5): September 2022 Table 1. Land-cover distribution within the study area. The landscape is mostly dominated by other vegetation, such as shrubs and grasses, followed by tree canopy (TC) and other paved surfaces. Land cover Other vegetation TC Other paved Roads/railroads Buildings Water Bare soil Percentage of landscape 52% 13% 13% 8% 7% 6% 1% 265 tree canopy, impervious surfaces (roads/railroads and other impervious surfaces), and other (buildings, bare soil, water, and other vegetation). Buildings were not included in the impervious surfaces category as their height can provide shade throughout the day, in addi- tion to having sensible heat emissions, which results in a more complex relationship with urban heating. In addition, a recent study has suggested that the impact of building shade on sensible heat flux from the ground is relatively small, even from buildings as tall as 6 stories (Alhazmi et al. 2022). Our analysis was conducted in residential areas that only have 2-story homes or smaller; therefore, impervious surfaces were isolated to those surfaces that lie flat on the ground. In order to determine whether or not we were missing potentially large impacts associated with buildings, we completed a preliminary analysis includ- ing buildings in our models. These results suggested that adding buildings to the analyses did not change the effects associated with trees and impervious sur- faces in residential landscapes. To determine the maximum cooling benefit UTC had on summer electricity consumption, as well as the impact that impervious surfaces had on summer electricity consumption, we generated 4 buffers at 6-m, 12-m, 18-m, and 24-m distances around single- family homes by using the Buffer tool with a building polygon layer provided by the city as our input. This resulted in 4 polygonal buffers for each building in our sample. The 6-m distance buffers consisted of the area over the home up to 6 m away; the 12-m distance buffers were the area 6 m to 12 m from the home; the 18-m distance buffers were the area 12 m to 18 m from the home; and the 24-m distance buffers were the area 18 m to 24 m from the home. Each buffer was Figure 2. Buffers broken into quadrants: 6-m, 12-m, 18-m, and 24-m distance buffers were broken down by azimuth (North, South, East, and West) resulting in 16 separate zones. then broken into quadrants to account for azimuth (North, South, East, and West) using the Subdivide Polygon tool, resulting in 16 separate zones. We created our zones in size increments of 6 m in the 4 cardinal directions due to their usage in previously published studies that examined the impact of tree canopy on electricity consumption (McPherson and Simpson 1999; McHale et al. 2007; Donovan and Butry 2009; Nelson et al. 2012). Creating these zones was an important step to isolate locations of tree canopy and impervious surfaces according to their distance and direction from single-family homes in our study (Figure 2, Table 2). We summarized the area of tree canopy and imper- vious surfaces within each zone using the Intersect tool and converted area to percent cover for every household in our sample. This process was completed for the 16 separate zones, resulting in 32 explanatory variables (Table 3). The distribution of all land-cover variables was positively skewed but included a spread across all percentage values, negating the need for any type of transformation. Electricity Data Unlike many other localities, the city owns their elec- tricity utility, allowing us to obtain parcel-level elec- tricity consumption data for the year 2016. We restricted analysis to single-family detached houses ©2022 International Society of Arboriculture
September 2022
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
