Jarek Kurnitski's presentation at 10th anniversary REHVA seminar Clima2010 in Antalya, Turkey on 9-12 May 2010 Accounting CO2 emissions for electricity and district heat

1. Accounting CO2 emissions for
electricity and district heat used
in buildings – a scientific method
to define energy carrier factors
Jarek Kurnitski
Senior Lead, Built Environment
Sitra, the Finnish Innovation Fund
Adjunct Professor, Aalto University 11.5.2010
CLIMA 2010

2. Assessment of emissions caused by energy used in
buildings
• Buildings use energy measured or calculated in kWh-s
• The use of 1 kWh energy can cause very different emissions or
primary energy use, depending on production sources
• This is usually taken into account with energy carrier factors in energy
performance regulation
Two main purposes of this assessment:
• Estimate actual CO2-emissions or primary energy use caused by
energy production – can be calculated from energy statistics
• Regulative purpose, derivation of energy carrier factors used in energy
performance requirements of building codes
• Regulation has to take into account demand and capacity changes in
the market and direct construction according to energy policy
Jarek Kurnitski 11.5.2010
© Sitra 2010

3. EN 15603 – General framework for the assessment of
energy performance (EP) of buildings
• EP-rating sums up all delivered energy (electricity, district heat/cooling,
fuels) into a single rating with relevant weighting factors (EN 15603)
• Relevant weighting factors for energy sources (energy carriers) are the
key issue for accountable energy performance requirements
Delivered energy Building A Building B
Electricity, kWh/(m2 a) 100 50
District heat, kWh/(m2 a) 50 100
Total, kWh/(m2 a) 150 150
• With weighting factors based on CO2 emissions (example):
Delivered energy Building A Building B
Electricity, kWh/(m2 a) 100*2 50*2
District heat, kWh/(m2 a) 50*0.8 100*0.8
Total, kWh/(m2 a) 240 180 EP ≤ 200
Jarek Kurnitski 11.5.2010
© Sitra 2010

4. Energy ratings
• EN 15603: calculation of energy ratings in terms of primary energy,
CO2 emissions or parameters defined by national energy policy
Other services
cause often
confusion as they
are not included
in the rating in all
countries
• Based on net delivered energy (by all energy carriers), weighted
energy rating (primary energy or CO2 emission) is calculated (used in
majority of member states)
Jarek Kurnitski 11.5.2010
© Sitra 2010

5. Calculation of CO2 emissions and primary energy
Emissions [kgCO2] =
energy flow [MWh] x specific emission factor [kgCO2/MWh]
Primary energy = energy flow [MWh] x primary energy factor [-]
Weighted energy rating = energy flow [MWh] x energy carrier factor [-]
• Example house with 18 MWh natural gas and 7 MWh electricity use:
18 MWh * 200 kgCO2/MWh = 3600 kgCO2 = 3,6 tCO2 (natural gas)
7 MWh * 300 kgCO2/MWh = 2100 kgCO2 = 2,1 tCO2 (electricity)
in total 5,7 tCO2 per year
• Alternatively this calculation can be done with relative energy carrier
factors defined in relation to some reference (gas), i.e. 1.0 for gas and
1.5 for electricity, to use kWh-units
Jarek Kurnitski 11.5.2010
© Sitra 2010

6. Primary energy
• Primary energy use refers to the use of natural resources1
• Primary energy factor for fossil fuels is 1.0 if extraction, refinery, transport etc.
are not taken into account
• 1/0.4=2.5 for electricity generated from fossil fuel with efficiency of 40%
• Usually, only non-renewable primary energy is considered (i.e. the factor is
close to zero for hydropower, wind, solar)
• Nuclear energy is difficult to treat within primary energy concept:
- Primary energy factor depends on the selection, which energy (thermal or electrical) is
used as the primary energy form
- Thermal efficiency of 33% leads to primary energy factor of 3.0 (IEA, Eurostat) and if
electricity is used as the first energy form, primary energy factor will be 1.0 (UNSD)
1Definition (for a building): Non-renewable primary energy is the non-renewable energy used to
produced the energy delivered to the building. It is calculated from delivered energy amounts of energy
carriers, using conversion factors (EN 15603:2008).
Jarek Kurnitski 11.5.2010
© Sitra 2010

7. Primary Energy Factors of Electricity Generation in Europe in 2006
source: Eurostat 2009 (Eurostat primary energy conventions), non-renewable only
Norway 0,0
Austria 0,7
Finland, Sweden, Norway 1,0
Switzerland 1,3
Luxemburg 1,4
Sweden 1,5
Portugal 1,5
Latvia 1,5
Italy 1,7
Denmark 1,9
Spain 1,9
Ireland 1,9
Finland 2,0
Netherlands 2,1
United Kingdom 2,2
EU-27 2,2
Germany 2,3
Slovenia 2,4
Romania 2,5
Slovakia 2,5
Belgium 2,5
France 2,6
Greece 2,7
Hungary 2,7
Cyprus 2,8
Estonia 2,8
Poland 2,8
Lithuania 2,9
Bulgaria 3,0
Czech Republic 3,0
Malta 3,4
0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5
Jarek Kurnitski 11.5.2010 4,0
primary energy factor MWh primary/MWhgross_electricity
© Sitra 2010

8. Specific CO2-emissions of Electricity Generation in Europe in 2006
sources: Eurostat 2009 (IPCC default emission factors)
Norway 3
Switzerland 6
Sweden 27
France 81
Finland, Sweden, Norway 88
Lithuania 182
Austria 206
Belgium 228
Slovakia 283
Luxemburg 292
Latvia 324
Finland 352
Spain 388
Portugal 417
EU-27 436
Italy 448
Hungary 456
Slovenia 463
United Kingdom 498
Ireland 502
Netherlands 519
Germany 571
Denmark 601
Romania 714
Bulgaria 747
Cyprus 771
Czech Republic 816
Malta 941
Greece 943
Poland 1 051
Estonia 1 163
0 200 400 600 800 1000 1200
Jarek Kurnitski 11.5.2010 1400
specific CO2-emissions kg(CO2)/MWhnet
© Sitra 2010

9. CO2-emissions vs. primary energy concept
• Assessment of emissions vs. use of energy sources (primary energy)
• Nuclear energy causes the major difference, as the primary energy
factor depends on the definition by factor 3
• For other energy carriers, weighting factors are very similar
independently of the use of primary energy or CO2 approach (if
calculated as relative to some reference, e.g. oil)
• ⇒ somewhat higher weighting factor for electricity if primary energy
approach is used
• Use of CO2 emissions makes it more complicated to determine
weighting factors for mix of many production sources, as shown in the
following
Jarek Kurnitski 11.5.2010
© Sitra 2010

10. Variation of primary energy factors
Four possible definitions:
A. total primary energy and nuclear energy with 33% efficiency (IEA &
Eurostat definition)
B. non-renewable primary energy and nuclear energy with 33%
efficiency (IEA & Eurostat definition)
C. total primary energy and nuclear energy with 100% efficiency (UNSD
definition)
D. non-renewable primary energy and nuclear energy with 100%
efficiency (UNSD definition)
Jarek Kurnitski 11.5.2010
© Sitra 2010

11. Primary energy factors for electricity generation in
Finland, definitions A to D
Jarek Kurnitski 11.5.2010
© Sitra 2010

12. Primary energy factors for district heat in Finland,
definitions A to D
Jarek Kurnitski 11.5.2010
© Sitra 2010

13. Non-renewable primary energy factors (definition B) in
Finland (blue electricity and red district heat)
Jarek Kurnitski 11.5.2010
© Sitra 2010

14. Why primary energy factors are almost constant in
the long run?
• Major changes in Finnish energy production until 2030:
- Significantly increased share of nuclear energy
- CHP is used as much as today, almost constant district heat production
- Increased use of renewables (wind, bio, solar), as much as technically
feasible, but still less dominating than nuclear or CHP
• With IEA and Eurostat definition, primary energy equivalent of nuclear
and conventional condensing power very similar, so, the compensating
of condensing power will even slightly increase primary energy factor
(40% vs. 33% efficiency)
• ⇒ cutting emissions with nuclear energy has no effect on primary
energy factor…
Jarek Kurnitski 11.5.2010
© Sitra 2010

15. Regulatory aspects
Energy performance regulation:
• Controlling and directing the demand change
• How much and which energy is used in buildings
• Straightforward for new buildings, more complicated for existing
• Regulation is often not directly linked to policies for energy
production, however the both are important:
- Regulation generates demand change in the existing market with
consequences for developments in the production side
- Obviously to be fitted together so that emissions can be reduced most
efficiently
• Buildings account for 41% of primary energy use in EU (Eurostat) being the largest
single potential for energy savings
Jarek Kurnitski 11.5.2010
© Sitra 2010

16. Finnish case study to determine emission based
energy carrier factors including demand-capacity
coupling effects
• CO2-emissions from electricity generation and district heat production:
- Hourly data of specific emissions from 2000-2007
- Demand change analyses for electricity use
- Demand change analyses for district heating use
- Coupling with new capacity – scenarios
- Derivation of energy carrier weighting factors based on energy system
scenario calculations to show how much one energy carrier is causing more
emissions than another
Jarek Kurnitski 11.5.2010
© Sitra 2010

17. Electricity generation in Finland
Electricity generation in Finland 2007 (GWh), in total 78 TWh
(Statistics Finland)
Industrial CHP
CHP electricity electricity
15330 11430
Electricity generation,
20 % 15 % average specific
439 220 emission 2000-2007:
kg(CO2)/MWh kg(CO2)/MWh 273 kg(CO2)/MWh
Hydro power
Separate 0 kg(CO2)/MWh 13991 District heat production,
conventional 894 18 % average specific
kg(CO2)/MWh
thermal power emission 2000-2007:
14377 217 kg(CO2)/MWh
18 %
Wind power
0 kg(CO2)/MWh
188
0%
Nuclear energy
22501
29 % Jarek Kurnitski 11.5.2010
© Sitra 2010

18. Emissions of heat and power production
(calculated with benefit allocation method)
• Electricity generation in Finland 2007: 78 TWh
• District heat and industrial steam production 2007: 95 TWh
Total emissions of electricity generation 2007 (milj.t CO2), Total emissions of electricity and district heat production 2007 (milj.t CO2),
in total 21.7 milj.t CO2 in total 34.9 milj.t CO2
(Statistics Finland) (Statistics Finland)
CHP electricity
6.7 Total production of
31 % industrial steam
5.9
17 %
Industrial CHP
electricity
2.2 Total production of Total generation of
10 % district heat conventional thermal
7.3 power
Separate conventional 21 % 21.7
thermal power 62 %
12.8
59 %
Jarek Kurnitski 11.5.2010
© Sitra 2010

19. Specific CO2 emissions of total electricity generation as
a function of conventional thermal power 2006–2008
450
400
Specific CO2 emissions, kg(CO2)/MWh
350
300
250
200
150
100
50
0
0 500 1000 1500 2000 2500 3000 3500 4000
Separate conventional thermal power, MWe Kurnitski
Jarek 11.5.2010
© Sitra 2010
Specific emissions calculated with benefit allocation method (Energy Statistics Finland 2008)

20. Just use average specific emission factors?
• Average specific CO2-emissions 2000-2007:
- 273 kg(CO2)/MWh) for electricity
- 217 kg(CO2)/MWh) for district heat
• Or average relative energy carrier factors (previous ones divided by
reference specific emission of oil 267 kg(CO2)/MWh)):
- 1.0 for electricity
- 0.8 for district heat
- (reference: 1.0 for oil)
• These average factors would probably lead to increased use of
electricity in buildings (electrical heating etc.) as 1.0 is very low
compared to common primary energy factor of 2.5 for electricity
• What was not taken into account?
Jarek Kurnitski 11.5.2010
© Sitra 2010

21. Higher factor for electricity in winter?
• Hypotheses: peak loads cause higher specific emissions in the
production
• Can be easily tested with hourly data
Jarek Kurnitski 11.5.2010
© Sitra 2010

22. Specific CO2 emissions of total electricity generation
as a function of outdoor temperature 2006–2008
450
Specific CO2 emissions, kg(CO2)/MWh 400
350
300
250
200
150
100
50
0
-26 -22 -18 -14 -10 -6 -2 2 6 10 14 18 22 26 30
Outdoor temperature at Helsinki, °C
• Generation of separate conventional thermal power in Finland can be high in
summer period due to shortage of hydro power and lack of CHP which is generated
against heat load of district heating + service breaks of nuclear power plants
Jarek Kurnitski 11.5.2010
© Sitra 2010

23. Demand change analyses (emissions response to a
step change in the demand)
+ or – step
change in Change in
electricity or emissions ?
district heat
• In the electricity production especially carbon-neutral capacity is limited
• District heat CHP is produced against heat load without similar lack of
capacity (demand change has no effect on the specific emission)
• Construction of new buildings or renovation of existing ones means
changes in the demand responded by electricity market
• To account emissions of the step change we need to know a link between
a new or non-appearing energy use in a building and energy production
source (i.e. which type of plant will generate or is cutting down this
energy production)
Jarek Kurnitski 11.5.2010
© Sitra 2010

24. Demand change of electricity: allocation according to
variable cost
• The change in the demand is allocated typically to the production
source with highest variable cost as production sources have limited
generation capacity and different variable cost
• Similar order of variable costs for the whole EU and Finland
• Hourly calculation: if enough generation capacity with lower variable cost is
available, then the demand change will be allocated to that capacity (CHP or
hydro).
Jarek Kurnitski 11.5.2010
© Sitra 2010

25. Results for current situation (2007)
Specific CO2 emissions by new or non-appearing electricity use (demand change)
for current situation
Current situation (year 2007) Total Separate CHP electricity Industrial Weighted
electricity conventional generation CHP average specific
generation thermal power emission
Specific emission
279 893 439 190 814
kg(CO2)/MWh
Share of the demand change 90 % 2% 0%
• Results show that during 90% of the time of the year the demand change
will be allocated to the separate conventional thermal power, 2% to CHP
and the rest for carbon-neutral production (not shown in the Table).
• This means that an hourly weighted specific emissions by new or non-
appearing electricity use is as high as 814 kg(CO2)/MWh that is average
emission of total generation by factor 3.
Jarek Kurnitski 11.5.2010
© Sitra 2010

26. Scenario of 1600 MW new nuclear energy
• We calculated a simple scenario, where new 1600 MW of nuclear energy
will replace only separate conventional thermal power with no
changes in energy demand structure (calculated with 2007 data)
Specific CO2-emissions of the demand change for the scenario where 1600 MW
new nuclear energy replaces only separate conventional thermal power
1600 MW new nuclear Total Separate CHP electricity Industrial Weighted
power replaces only separate electricity conventional generation CHP average specific
conventional thermal power generation thermal power emission
Specific emission
137 893 439 190 466
kg(CO2)/MWh
Share of the demand change 24 % 57 % 0%
• 1600 MW new nuclear power decreased an average specific emission
by almost of factor 2, but the ratio of the demand change and average
specific emission values even increased to 3.4.
Jarek Kurnitski 11.5.2010
© Sitra 2010

27. Energy carrier factors for demand change relative to
specific CO2-emission of oil
Specific CO2-emissions of district heating and electricity (weighted average)
relative to light fuel oil (heating fuel oil) CO2-emission factor
Light fuel oil Electricity District
(heating fuel oil) (weighted average heating
specific emission)
Specific emission
267 814 219
kg(CO2)/MWh
Current situation (year 2007)
Energy carrier factor 1 3.0 0.8
Specific emission
267 466 219
1600 MW new nuclear power kg(CO2)/MWh
replaces only separate
conventional thermal power Energy carrier factor 1 1.7 0.8
• When calculated with 2006 data, the emissions are slightly higher for electricity,
leading to factor of 2.1 instead of 1.7 (and 3.2 instead of 3.0)
Jarek Kurnitski 11.5.2010
© Sitra 2010

28. Energy carrier factors for selected scenarios
900
800
Specific emission, kgCO2/MWh 700
600
500
400
300
200
100
0
2005 2010 2015 2020 2025 2030
Electricity, basic scenario Electricity, "less nuclear"
Electricity, "more nuclear" District heat estimate
Demand change of electricity
How to quantify the factors between average and demand change values?
Jarek Kurnitski 11.5.2010
© Sitra 2010

29. Demand change in district heating energy use
• The total CO2 emissions of Finnish electricity generation and district heating
production if electricity use is kept constant, but district heating is
reduced (e.g. additional insulation of existing multi-storey buildings) or
increased
• ⇒ Due to CHP, the total emissions do not depend on the amount of district
heat used
Total emissions of electricity and district heat 30
25
production, milj. t CO2
20
15
10
5
0
0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.295 1.3 1.4 1.5
Ratio of the district heat demand change (1 = current situation,
0.5 = 50% reduction, 1.5 = 50% increase) Jarek Kurnitski 11.5.2010
Electricity generation District heat production
© Sitra 2010

30. District heat replacing electricity use or vice versa
• The total use of electricity and district heat is kept constant:
- The ratio of 1 corresponds to the current situation, the ratio 0.5 means that half of
current district heating energy used is replaced by electricity use and 2 that the
current district heating use is doubled and electricity use reduced correspondingly
• ⇒ Replacing district heat by electrical heating drastically increases total
emissions
Jarek Kurnitski 11.5.2010
© Sitra 2010

31. Demand change analyses with flexible capacity
• Main principle: energy system model allowing both changes in the
demand and production capacities, annual balance calculation
1. Select reference electricity and district heat production (e.g. 90 TWh el.
and 33 TWh DH, repeat the calculation for other relevant values)
2. Define rules for production sources/capacities allowing to introduce new
capacity to cover increased demand:
- production sources with fixed capacity, hydro and nuclear (fixed capacity can be
selected as input parameter)
- production sources with flexible capacity, in this case condensing power and CHP
- limits for district heat produced by CHP, 70…80% in this case
- wind power and solar electricity fixed in this case, but can be treated with similar
rules if considered flexible
3. Introduce a step change of heat and electricity demand (+3 TWh in this
case) and solve energy production balance by minimizing emissions or
production cost
4. Results: emissions and cost caused by +3 TWh electricity or heat
production ≡ specific emission factors of the studied scenario
Jarek Kurnitski 11.5.2010
© Sitra 2010

32. Finnish case study
• +3 TWh step change of heat or electricity demand
• 80 and 90 TWh reference electricity production and 33 TWh district heat
production
• Flexible capacity of separate condensing power and CHP
• Nuclear energy capacity fixed, several capacity values calculated
• Hydropower and wind power fixed
• Limits for district heat produced by CHP, to be between 70 and 80%
Specific emission (energy method) and cost data used:
Production source Fuel cost Specific emission
milj. EUR/TWh kgCO2/MWh
Nuclear energy 5 0
Separate condensing power 25 900
CHP electricity 15 300
CHP district heat 18 300
Separate district heat 22 225
Jarek Kurnitski 11.5.2010
© Sitra 2010

33. Emissions by + 3 TWh with flexible capacity
50
+3 TWh El.
+3 TWh DH
DH 33 TWh
El. 90 TWh
45
40
+3 TWh El.
DH 33 TWh
+3 TWh DH
El. 90 TWh
35
CO2-emissions, Mt
30
25
20
15
10
5
0
22,5 TWh nuclear energy 35,5 TWh nuclear energy
• + 3 TWh electricity increased emissions by factor of 4,0 relative to + 3 TWH district
heat (0.68 Mt vs. 2.7 Mt)
• This factor of 4 would change to 3, if separate district heat production is not used
• Results confirm that relevant selection of energy carrier factor for electricity should
be close to the demand change values, not average values of specific emissions
Jarek Kurnitski 11.5.2010
© Sitra 2010

34. Conclusions 1/2
• Energy carrier factors may be based on CO2-emissions, primary energy
(usually non-renewable) or on energy policy considerations
• Primary energy factors are relevant for fuels, but for nuclear energy depend
by factor 3 on the definition used
• Specific CO2-emissions factors are scientifically sound (independent on
definitions), but average factors cannot be used for regulative purposes,
because they may guide to increased electricity use, which will consequently
increase emissions as shown in the Finnish case study
• Finnish average specific emission based factors (2000-2007):
- electricity 1.0
- district heat 0.8
- oil 1.0 (reference)
• Average factors for electricity and district heat are very close, but replacing
district heat by electrical heating drastically increased total
emissions in the Finnish case study and vice versa
Jarek Kurnitski 11.5.2010
© Sitra 2010

35. Conclusions 1/2
• Hourly demand change allocation increased electricity factor from 1.0 to 3.0
and analyses both with fixed and flexible capacity showed that the factor
caused by demand change is 3 to 4 times higher than the average one
• Energy system scenario calculations confirmed that relevant selection of
energy carrier factor for electricity should be close to the demand change
values, not average values of specific emissions
• Using the rule of 3 x average specific emission, one can easily calculate
electricity factors for future scenarios, i.e. if the Finnish average factor will be
reduced to 0.6 in 2020, the electricity factor will be 1.8
• Proposed Finnish factors are: electricity 2, district heat 0.7, fossil fuels 1.0
• Higher energy carrier factor for electricity means in the energy performance
design that electricity is more valuable energy than fuel energy or district
heat. Such building regulation will generally promote for more effective
electricity use in buildings and limit wasteful use of electricity.
• Energy carrier factors are not constant, as depending on production sources,
and are subject of revision with relevant interval of about 5 years
Jarek Kurnitski 11.5.2010
© Sitra 2010