This map helps San Diego-area governments, home performance contractors and home energy raters identify areas where homeowners are most likely to engage in Energy Upgrade CaliforniaTM Home Upgrade projects. These projects typically include insulation, air sealing and duct replacements; some also include heating/cooling/water heating upgrades, window upgrades or other energy efficiency improvements.
The map was generated using a logistical predictive model to determine which variables were most closely associated with completed Home Upgrade projects between the program’s launch in 2010 and April 2015. (Some projects in Chula Vista and San Diego received matching incentives; to remove any systematic bias from the influence of matching rebates, these projects were removed from the analysis.) A measure for the likelihood of participation was calculated for each single-family parcel in San Diego County and these were aggregated to the census tract level.
The census tracts with the highest potential for completing Home Upgrade projects are shaded in red. Parcels shaded in grey have too little information to provide a likelihood estimate or contain no single-family parcels.
The six variables most closely associated with completed Home Upgrade projects were whether the home had adopted solar PV, owner occupancy, correlation of cooling degree days with electric consumption, median household income of the census tract, number of bedrooms of the home and build year of the home.
This data came from the California Solar Initiative and was analyzed at the household level. Homeowners who have invested in solar PV may be more energy-conscious and/or more interested in investing in major home improvements, including Home Upgrade projects, than the rest of the population. Furthermore, several Home Upgrade participating contractors also offer solar to their customers.View map showing only this variable.
This data came from the county assessor database and was analyzed at the household level. Occupants of the home are typically the ones to reap the utility bill savings and comfort benefits of a Home Upgrade project, so it is not surprising that Home Upgrade projects are correlated with owner-occupied homes.View map showing only this variable.
Correlation of Cooling Degree Days with Electric Consumption
This data point was determined by comparing weather station data with electric consumption data at the zip code level. It indicates residents’ propensity to increase electric usage (presumably by using air conditioners) on hot days. Households that are more sensitive to heat and experience higher seasonal energy bills are likely more motivated to complete Home Upgrade projects.View map showing only this variable.
Median Household Income
The relationship between income and Home Upgrade participation is positive (meaning Home Upgrade projects were associated with higher-income households) but increasing at a declining rate. The average Home Upgrade project cost in 2013-14 was approximately $12,500; the average rebate amount was approximately $1,500.View map showing only this variable.
Number of Bedrooms
This data came from the county assessor database and was analyzed on the household level. Home Upgrade projects were associated with homes that had a higher number of bedrooms but, similar to household income, this trend increases at a declining rate. This variable was not mapped because there is little variance among average number of bedrooms at the census tract level and maps were not generated at the household level for privacy. Contractors are encouraged to consider this variable on an individual house-by-house basis.
This data came from the county assessor database and was analyzed at the household level. California’s Building Energy Efficiency Standards (Title 24, Part 6) took effect in 1978 and have become progressively more stringent over time. Thus, older homes typically have more opportunity for energy efficiency improvements like the ones performed through Home Upgrade.View map showing only this variable.
For more information, please contact Laura Parsons or call (858) 244-7288. The Home Energy Upgrade Potential Map was funded by the San Diego Regional Energy Partnership, which includes City of San Diego, County of San Diego, City of Chula Vista, San Diego Association of Governments, Port of San Diego and San Diego Gas & Electric.