185
we take a relaxed approach to what we mean by ‘carbon’ and include reviews of
studies that range from assessing carbon dioxide emissions only to those that take a
more comprehensive greenhouse gas approach. The main difference in results is
that emissions due to food make up a larger portion of the carbon footprint of a
household when the analysis is extended to a basket of greenhouse gases. What we
are more stringent about in this chapter is that we take a whole supply chain, life
cycle approach to assess the carbon emissions caused by households.
There are two basic categories of a household carbon footprint. First are direct
emissions that arise due to direct energy use in the home (such as gas for space and
water heating, and electricity for lighting and powering appliances and gadgets) and
due to burning personal transportation fuels (petrol and diesel). Second is ‘embedded’ emissions, such as those that arise during our example of the manufacture of a
TV made in China . Embedded emissions along supply chains (arising domestically
and abroad) account for the majority (around 60–70 %) of the carbon footprints of
Western households (Druckman and Jackson 2010 ; Dey et al. 2003 ; Bin and
Dowlatabadi 2005 ; Baiocchi et al. 2010 ).
6
Estimates of household carbon footprints are generally derived from expenditure
data. Carbon emissions arising from expenditure on transportation fuels and energy
use in the home are relatively easily estimated from information on prices, the carbon content of fuels and information from each country’s Environmental Accounts.
Estimation of carbon emissions embedded in other expenditures is harder and
requires information on the technologies used to manufacture all products and services purchased, wherever in the world this may occur. This is generally done using
Environmentally Extended Input-Output Analysis (EE-IOA) (Hertwich 2011 ;
Munksgaard et al. 2005 ; Baiocchi et al. 2010 ; Weber and Matthews 2008 ; Weber
and Perrels 2000 ; Lenzen et al. 2004 ; Wiedmann 2009 ). EE-IOA is a top-down
methodology that combines information on the structure of the economy with environmental data (see Miller and Blair ( 2009 )). There are some notable exceptions to
this methodology. The fi rst is hybrid analysis which combines process-based, bottom- up Life Cycle Assessment (LCA) with top down EE-IOA (Benders et al. 2012 ).
Another exception is the work by Girod and de Haan ( 2009 , 2010 ) who use a bottom- up LCA methodology only, based on physical functional units such as kg of
food, person kilometres and living square meters.
3 What Makes a Household Carbon Footprint?
In this section we fi rst examine the major socio-economic drivers of household
footprints , we then explore the composition of average carbon footprints, and the
fi nal sub-section examines carbon footprints from the perspective of time-use.
6 Estimates include 60 % for USA (Bin and Dowlatabadi 2005 ), 66 % and 70 % for the UK
(Druckman and Jackson 2010 and Baiocchi et al. 2010 , respectively), and 70 % for Australia (Dey
et al. 2003 ).
9 Understanding Households as Drivers of Carbon Emissions
we take a relaxed approach to what we mean by ‘carbon’ and include reviews of
studies that range from assessing carbon dioxide emissions only to those that take a
more comprehensive greenhouse gas approach. The main difference in results is
that emissions due to food make up a larger portion of the carbon footprint of a
household when the analysis is extended to a basket of greenhouse gases. What we
are more stringent about in this chapter is that we take a whole supply chain, life
cycle approach to assess the carbon emissions caused by households.
There are two basic categories of a household carbon footprint. First are direct
emissions that arise due to direct energy use in the home (such as gas for space and
water heating, and electricity for lighting and powering appliances and gadgets) and
due to burning personal transportation fuels (petrol and diesel). Second is ‘embedded’ emissions, such as those that arise during our example of the manufacture of a
TV made in China . Embedded emissions along supply chains (arising domestically
and abroad) account for the majority (around 60–70 %) of the carbon footprints of
Western households (Druckman and Jackson 2010 ; Dey et al. 2003 ; Bin and
Dowlatabadi 2005 ; Baiocchi et al. 2010 ).
6
Estimates of household carbon footprints are generally derived from expenditure
data. Carbon emissions arising from expenditure on transportation fuels and energy
use in the home are relatively easily estimated from information on prices, the carbon content of fuels and information from each country’s Environmental Accounts.
Estimation of carbon emissions embedded in other expenditures is harder and
requires information on the technologies used to manufacture all products and services purchased, wherever in the world this may occur. This is generally done using
Environmentally Extended Input-Output Analysis (EE-IOA) (Hertwich 2011 ;
Munksgaard et al. 2005 ; Baiocchi et al. 2010 ; Weber and Matthews 2008 ; Weber
and Perrels 2000 ; Lenzen et al. 2004 ; Wiedmann 2009 ). EE-IOA is a top-down
methodology that combines information on the structure of the economy with environmental data (see Miller and Blair ( 2009 )). There are some notable exceptions to
this methodology. The fi rst is hybrid analysis which combines process-based, bottom- up Life Cycle Assessment (LCA) with top down EE-IOA (Benders et al. 2012 ).
Another exception is the work by Girod and de Haan ( 2009 , 2010 ) who use a bottom- up LCA methodology only, based on physical functional units such as kg of
food, person kilometres and living square meters.
3 What Makes a Household Carbon Footprint?
In this section we fi rst examine the major socio-economic drivers of household
footprints , we then explore the composition of average carbon footprints, and the
fi nal sub-section examines carbon footprints from the perspective of time-use.
6 Estimates include 60 % for USA (Bin and Dowlatabadi 2005 ), 66 % and 70 % for the UK
(Druckman and Jackson 2010 and Baiocchi et al. 2010 , respectively), and 70 % for Australia (Dey
et al. 2003 ).
9 Understanding Households as Drivers of Carbon Emissions