Healthy Development Measurement Toolkit

Indicator ES.1.a Residential per capita natural gas use

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Data Source

Natural gas usage by census tract provided by Pacific Gas & Electric Company (PG&E) through the San Francisco Department of Environment.

Map and table prepared by City and County of San Francisco, Department of Public Health, Environmental Health Section using ArcGIS software.

Map data is presented at the level of the census tract. The map also includes planning neighborhood names, in the vicinity of their corresponding census tracts.  Table data is presented by planning neighborhood. Planning neighborhoods are larger geographic areas then census tracts. SF DPH used ArcGIS software and a 'centroids within' methodology to convert census tracts to geographic mean center points. We then assigned census tracts to planning neighborhoods based on the spatial location of those geographic mean center points and calculated the planning neighborhood totals for the table.  Detailed information regarding census data, geographic units of analysis, their definitions, and their boundaries can be found in the HDMT at the following links:

http://www.thehdmt.org/etc/Geographic_Units_of_Analysis.pdf

http://www.thehdmt.org/data_map_methods.php

Explanation and Limitations

The above map illustrates disaggregated residential (single family and multi-family) natural gas use by census tract for 2003. To protect confidentiality, data is not reported where one single family or multi-family dwelling accounts for more than 85% of the demand in that census tract. Therefore, if one single or multi-family account represents 85% of the load in a census tract, census location is not given and natural gas use is not accounted for in this map. The neighborhood table represents total per capita natural gas use for neighborhood. Natural gas use by neighborhood is calculated using the neighborhood census tracts' natural gas use divided by the neighborhood census tract population. The neighborhood table was calculated with the census tract data and same data limitations exist.

The Table 1 illustrates natural gas use in San Francisco from 2003-2008. Average natural gas usage is calculated by dividing the number of normalized customer months in the year. Customer months are the number of months in a year that a customer has an active account. Normalized means full month and partial month billing periods were taking into consideration. By using this methodology the average value represents a more accurate monthly usage average for the group as a whole. Please note, this methodology is different from calculating residential per capita natural gas use and the figures are not comparable. Table 2 shows average natural gas use by sector. In 2008, 53% of the natural gas is used for residential purposes, while commercial use accounts for 47%.

There is substantial variation amongst the San Francisco neighborhoods with regard to energy usage. Many factors influence energy usage, such as climate, age of housing, housing density, perceived safety, building design, appliances, and equipment, and conservation practices. The South East sector of San Francisco, due to its distance from the ocean fog and breeze, receives more natural sunlight, potentially decreasing its use of heaters and in-turn decreasing its energy usage. In recent years, there has been more development in the South East sector of San Francisco, which has resulted in new dense residential housing. Dense multifamily units, require less energy than single family detached housing. The age of housing has been directly associated with energy efficiency--the older the home the more inefficient the use of energy.

Perceived safety may also influence how often residents open windows and doors to regulate the indoor temperature. If an area is perceived as unsafe, one may not leave windows and doors open, relying more on indoor appliances to regulate temperature, increasing their energy usage.

Effective November 2008, Chapter 13C of the San Francisco Building Code requires new buildings constructed in the San Francisco  to meet green building standards. Green building standards achieve energy efficiency through efficient appliances and equipment and design standards which include using daylighting techniques, insulation, double-panel windows, etc.  According to The Mayor’s Task Force on Green Building, energy savings of 220,000 megawatt hours of power can be achieved by 2012 through new building practices.

Why is this a Community Health Indicator?

Lower building natural gas use results in the reduced combustion of fossil fuels. Natural gas combustion produces both carbon monoxide and carbon dioxide. Energy efficient buildings reduce emissions from the products of combustion, which include less particulates and pollutants that can improve health and outdoor air quality. The combustion of natural gas also contributes to greenhouse gas emissions and to changes in the earth's carbon cycle and climate. On a carbon-equivalent basis, energy-related carbon dioxide emissions accounted for 83.8% of U.S. anthropogenic greenhouse gas emissions in 1997.

Climate change can also threaten health through more extreme weather events, increased air pollution, limitations on food production, increased water-borne and food-borne illnesses, and increased infectious disease vectors. For the major fossil fuels, the amounts of carbon dioxide produced for each billion Btu (British thermal units) of heat energy extracted are: 208,000 pounds for coal, 164,000 pounds for petroleum products, and 117,000 pounds for natural gas. Because natural gas is non-renewable and has relatively better environmental performance as a fuel, it will be important to conserve natural gas for the future.^a

The benefits of energy efficiency go beyond environmental sustainability. Energy efficiency can have economic benefits for both residents and property managers by lowering utility bills. Furthermore, energy efficient design and construction techniques can contribute to the long term affordability of housing through lowered energy costs.