The climate, primary PM2.5 exposure and acidification impacts per
GJ of fuel consumed from the measured emissions of the six
considered appliances are presented in Fig. 2. The climate impact of
wood-based appliances is predominantly caused by the climate
impact of bioenergy, calculated through the GWPbio factor, and for
batch-wise appliances also by BC. PM exposure is remarkably lower
with more modern appliances, and negligible for light oil. Acidification
is from NOx for the wood-based, and roughly equally from NOx and
SO2 for light fuel oil heating. Acidification is almost equal across all
appliance types. The PM2.5 exposure is measured as the population
weighted PM concentration, calculated with the FRES model with
current distribution of oil boilers as the emission source distribution
and average population density distribution of Finland.
The results indicate that the appliances’ impacts distribute differently
across the three impact categories. None of the appliance types
dominate the others, i.e. none of them is such that it would have the
lowest impact in all three categories, and there are notable trade-offs
between the appliance types.
As an example, a switch from oil heating to any other assessed
form of heating would reduce the climate impact, but increase
exposure to PM with a magnitude that depends greatly on the
substituting technology, and also increase the acidification
impact slightly. Even with the modern gasification appliances,
technology category V, the PM exposure is over 20 higher than
those of oil heating; and with batch-wise technologies many
hundreds of times higher. Due to these trade-offs, optimal
technology choice requires a comparison of the different emissions
or impacts on a common scale.
Marginal policy costs – the sum of marginal cost for the CO2, SO2,
NOx, and PM2.5 emission limits, multiplied with the respective emission
factors of each appliance – per GJ of fuel used in each appliance
are presented in Fig. 3. The difference in marginal policy costs between
oil heating and other considered appliances is vast, indicating a large
incentive – from the policy viewpoint – to switch away from oil
heating. It is also worth noting that should a policymaker pass this
marginal policy cost to the households, this cost incentive for oil
heating would be of considerable magnitude relative to the fuel price,
and thus could affect the appliance choice in reality.
The social costs arising from the climate and health impacts of
GHG and air pollutant emissions from the six heating appliances
are presented in Fig. 4. For the health impact, the average
population exposure is calculated separately for urban and nonurban
environments, by using the spatial distribution of oil
heating in these environments. Negative social costs (i.e. benefits)