78 Pandit and Laband: Impact of Tree Shade on Summertime Residential Energy Consumption the sample mean (2.5) is associated with a 3.39 kWh/day (5.8%) increase in electricity usage. But not all family members contribute equally to electricity usage. Females use significantly more electric- ity than males, and children under the age of 12 use more electricity than family members over 12. The latter finding will not surprise anyone who has had young children, who are apt to leave doors open, lights on, watch television, play video games, all of which imply a level of electricity consumption that is higher than that of adults. For every additional 9.3 m2 of living space above the sam- ple mean of 250.84 m2, an Auburn homeowner’s electric- ity usage increases an estimated 1.3 kWh/day (2.2%). These findings indicate newer homes use significantly less energy than older homes. On average, a one-year-old home uses ap- proximately 1.1 kWh/day (1.8%) less electricity, ceteris pari- bus, than an otherwise identical home that is 10 years older. Using electricity to run one’s water heater(s) increased elec- tricity use by an estimated 4.5 kWh/day (7.8%). Having an extra freezer added roughly 2.5 kWh/day (4.2%) to electricity consump- tion. Each additional load of laundry run per week, over the sam- ple mean of (5.53) increased electricity use by approximately 1.1 kWh/day (1.8%). A swimming pool is an energy pig, where daily electricity consumption was 21 kWh (35.9%) higher at homes with pools than at homes without pools. Every additional degree of difference between the mean daytime average temperature and the homeowner’s desired thermostat setting raised electricity use in the ‘typical’ home by an estimated 2.2 kWh/day (3.8%). Every 10% increase in the extent of shade coverage through- out the day reduced electricity use by approximately 1.6 kWh/ day (2.7%). Controlling for other factors in the model, the study authors estimate that electricity use at a ‘typical’ house in the sample, characterized by mean shade coverage of 17.5% (50%), was 4.7% (13.6%) lower than at a house with no shade. Table 3 reports OLS regression results for models simi- lar to those reported in Table 2, but with additional/alternative specifications of the shade parameters reflecting shade densi- ty and shade conditions at different times of the day. In terms of reducing electricity used for cooling, dense shade is bet- ter than light shade. At a ‘typical’ residence (17.5% average shade coverage during the day) with dense shade, the electric- ity usage was an estimated 14.4% lower than a residence with no shade. Moreover, shade is especially important in the late afternoon when summertime temperatures peak. At a ‘typi- cal’ residence with late afternoon shade, the electricity usage was an estimated 6% lower than a residence with no shade. CONCLUSION The electricity savings calculated from these models can be converted to monetary savings by multiplying the electric- ity savings in kWh per time period with the local power com- pany’s price per kWh. Auburn, Alabama is serviced by two electricity providers: Alabama Power Company and the Tal- lapoosa Electric Co-operative. Respective rates charged at the time of analysis were: USD $0.1152/kWh and $0.1229/kWh. For a ‘typical’ residence/family in this sample, the following monetary savings from shade during the summer months were estimated: * Shade on the average house (17.5%) reduced electricity usage by 4.8%, as compared to a house with no shade, to a savings of approximately $10/month. ©2010 International Society of Arboriculture Table 3. Regression results (shade conditions). Dependent variable = kWh/day. Explanatory Variables Intercept Family size Living area House age # floors Elec. Cooking Elec. H2 Window AC Laundry loads/wk Second Freezer Swimming pool Average humidity Percent shade Light shade Moderate shade Heavy shade Late a.m. shade percent Early p.m. shade percent Late p.m. shade percent Adj. r2 : F-statistic: N: z significant at 0.01 level y significant at 0.05 level x significant at 0.10 level * A house with 50% shade coverage during the day used 13.6% less electricity than an otherwise comparable house with no shade, to a savings of approximately $29/month. * At a ‘typical’ residence (17.5% average shade coverage during the day) with dense shade, the electricity usage was an estimated 14.4% lower than a residence with no shade, to a savings of approximately $31/month. * At a residence with 33% dense shade coverage during the day, the electricity usage was an estimated 16.7% lower than a residence with no shade, to a savings of approxi- mately $33/month. * At a residence with 50% dense shade coverage during the day, the electricity usage was an estimated 19.3% lower than a residence with no shade, to a savings of approxi- mately $42/month. 0.6030 153.8 1510 0.6043 145.0 1510 O heat Model 1 -1.543 (9.556) 3.594z (0.463) 0.013z (0.001) 0.057 (0.042) 1.416 (1.042) -0.912 (1.271) 4.443z (0.969) 4.530x (2.642) 1.009z (0.168) 2.519z (0.947) 22.223z (1.719) 0.013 (0.125) Daytime temp. diff. (mean) 2.155z (0.083) -0.254 (1.431) -0.507 (1.289 -9.174z (1.356) Model 2 -3.504 (9.575) 3.427z (0.467) 0.013z (0.001) 0.101y (0.045) 1.793x (1.051) -0.761 (1.270) 4.456z (0.967) 4.428x (2.638) 1.009z (0.167) 2.602z (0.946) 21.539z (1.739) 0.037 (0.126) 2.192z (0.084) -0.088y (0.036) 0.43 (1.457) 1.197 (1.469) -6.884z (1.655) 0.020 (0.028) -0.005 (0.047) -0.117z (0.022) 0.5957 149.2 1510 Model 3 -10.750 (9.592) 3.620z (0.477) 0.013z (0.001) 0.092y (0.047) 1.828x (1.072) -0.609 (1.291) 4.177z (0.981) 4.648x (2.670) 1.103z (0.168) 2.573z (0.957) 20.470z (1.765) 0.127 (0.126) 2.218z (0.085)
March 2010
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
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.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
