Primary Energy and CO2 Conversion Factors

Carsten Petersdorff and Alex Primas

The delivered and used energy in buildings for heating and DHW is conventionally fossil fuels (gas and oil), district heating, electricity or renewable resources that cause different CO2 emissions when converted to heat. To judge the different environmental impacts of buildings during operation, two indicators are used in this book:

1 The primary energy: this is the amount of energy consumption on site, plus losses that occur in the transformation, distribution and extraction of energy.

2 CO2 emissions: these are related to the heat energy consumption, including the whole chain from extraction to transformation of the energy carrier to heat. Using the CO2 equivalent values (CO2eq), not only CO2 but all greenhouse gases are taken into account, weighted with their impact on global warming.

To determine the primary energy use or the related CO2 eq emissions, different methodologies are common. The purpose with this appendix is to describe the definitions and boundary conditions that are assumed for the simulations in this book:

• Only the non-renewable share of primary energy is taken into account.

• All factors are related to the lower heating value (LHV), not including condensation energy. This could mean that, theoretically, the efficiency of a heating system could exceed 100 per cent if a condensing gas furnace is used. However, we use 100 per cent efficiency for gas, 98 per cent for oil and 85 per cent for pellets. For DHW, the efficiency is 85 per cent.

• As a geographical boundary, the borderline of the building plot is chosen, which means that each energy carrier that is delivered to the house is weighted with factors for primary energy and CO2eq emissions.

• For better comparison of the simulations, European average values are taken into account.

Table A1.1 presents the factors for primary energy and CO2eq that are used in the simulations in this book, based on the GEMIS tool (GEMIS, 2004).

Table A1.1 Primary energy factor (PEF) and CO2 conversion factors

Primary energy and CO2 conversion factors PEF CO2eq

Oil-lite 1.13 311

Natural gas 1.14 247

Hard coal 1.08 439

Lignite 1.21 452

Wood logs 0.01 6

Wood chips 0.06 35

Wood pellets 0.14 43

EU-17 electricity, grid 2.35 430 District heating combined heat and power (CHP) - coal condensation 70 per cent, oil 30 per cent 0.77 241

District heating CHP - coal condensation 35 per cent, oil 65 per cent 1.12 323

District heating heating plant, oil 100 per cent 1.48 406

Local district heating CHP - coal condensation 35 per cent, oil 65 per cent 1.10 127

Local district heating plant, oil 100 per cent 1.47 323

Local solar 0.00 0

Solar heat (flat) central 0.16 51

Photovoltaic (multi) 0.40 130

Wind electricity 0.04 20

Note that primary energy and CO2 conversion may differ for specific national circumstances. The different factors for electricity particularly influence the results on national levels (see Figures A1.1 and A1.2). On the other hand, the electricity market is international, which justifies average values for the EU-17 grid, for example.

3.50

EU countries

Source: Carsten Petersdorff and Alex Primas

Figure A1.1 National primary energy factors for electricity; the line represents the EU-17 mix that is used in this book

1000.0 900.0 800.0 700.0

S 500.0

g 400.0

1000.0 900.0 800.0 700.0

S 500.0

g 400.0

1

1

1

1

_ i

i 1

1

11

1

1 ■

1

1

1

11 n 1

_

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EU countries cc O

Source: Carsten Petersdorff and Alex Primas

Figure A1.2 National CO2 equivalent conversion factors for electricity; the line represents the EU-17mix that is used in this book

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