Environmental Engineering Reference
In-Depth Information
5 Discussion
The purpose of this chapter is to analyse energy ef
ciency in heating and domestic
hot water systems, using CO 2 emissions, a set of demographic variables on each
household, energy consumption and the variable unit costs paid by each family for
the use of electricity and natural gas in 2012. CO 2 emissions are calculated
according to the
cation of new and existing
buildings approved by the Spanish government, a transposition of the European
Directive 2010/31/UE [ 2 ].
The direct rebound effect obtained for electricity demand in homes that use more
than one fuel is estimated at 0.71. This indicates that approximately 29 % of any
increase in energy ef
basic procedure for the energy certi
ciency in residential electrical systems translates into energy
savings. Similarly, in homes that use only electricity the rebound effect is higher,
i.e. 0.87. This reveals that much of the increase in ef
ciency in electrical heating
and hot water systems is lost due to increases in electricity consumption, i.e. only
13 % would go into energy saving. In respect to the natural gas model the estimated
direct rebound effect is 1.094. Thus, increased energy ef
ciency actually increases
natural gas consumption in 0.094 %. This is the opposite of the result that would be
expected in the wake of technological improvements.
Obtained direct rebound effects are relatively high in comparison with those
published in other papers. This may be due to the economic situation affecting
Spanish households in 2012, a year characterised by high unemployment rates and
energy price increases 7.3 percentage points higher than the increase in the general
consumer price index. Moreover, according to the Living Conditions Survey
conducted by the INE (Spain
s National Institute of Statistics), almost 17 % of
Spanish households admit to not having been warm enough during the previous
winter.
Thus, households may have become more sensitive to prices and reduced their
energy consumption for heating and domestic hot water [ 15 ]. In this scenario an
increase in energy efciency, which decreases the cost of service, results in a greater
direct rebound effect, as households seek to revert to their previous comfort levels
in consumption for heating and hot water.
However, it must be said that the direct rebound effects estimated here may be
overestimated due to the lack of signi
'
cant information on, for instance, capital,
maintenance and time-related costs. According to Sorrell and Dimitropoulos [ 14 ]
higher service costs result in a drop in demand for services and therefore in smaller
rebound effects. Indeed, Mizobuchi [ 11 ] demonstrates that when capital costs are
considered the direct rebound effect drops from 115 % to just 27 %. Accordingly,
the
ndings reported here may be interpreted as maximum levels of sensitivity of
energy consumption to changes in energy ef
ciency.
Another important point is the possible link between energy prices and energy
ef
ciency. If energy prices increase and remain high for a long period of time,
industry may develop more ef
cient equipment. Such a link would invalidate the
assumption of exogeneity, which would mean that the rebound effect measured via
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