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6.3 Glossary

CO2 emission factor

The CO2 emission factor is the sum of all the CO2 emissions linked to the production and usage of a product.

CO2 emissions

To simplify the term “greenhouse gas emissions measured in kg of CO2 equivalents” the term “CO2 emissions” is used as an equivalent in this users’ guide.

CO2 equivalents

CO2 equivalents are a metric measure used to compare the emissions from various greenhouse gases based upon their global warming potential (GWP). Carbon dioxide equivalents are commonly expressed as “million metric tonnes of carbon dioxide equivalents (MMTCDE)”. The carbon dioxide equivalent for a gas is derived by multiplying the tonnes of the gas by the associated GWP. MMTCDE = (million metric tonnes of a gas) x (GWP of the gas). For example, the GWP for methane is 21 and for nitrous oxide 310. This means that emissions of one million metric tonnes of methane and nitrous oxide respectively is equivalent to emissions of 21 and 310 million metric tonnes of carbon dioxide. On the Display™ poster the emissions are shown in kilogrammes of CO2 equivalents.

CO2 ratio

The CO2 ratio describes the emission of greenhouse gases expressed in CO2 equivalents per square metre of the internal gross floor area of the building and per year.

Cogeneration plant

A cogeneration plant is a thermal power station in which all the steam generated in the boilers passes to turbo-generators for electricity generation, but designed so that steam may be extracted at points on the turbine and/or from the turbine exhaust as back-pressure steam and used to supply heat.

Cumulative energy demand (CED) factor

The CED factor is defined in the German guideline VDI 4600 and is equal to the sum of all primary energy inputs of a product or a service. This contains its production, usage, and disposal. It contains not only the energy demand of the process necessary to provide a service or to produce a product but also the energy that remains in a product, e.g. the lower heating value of mineral oil in plastic products.

Cumulative energy use factor

The cumulative energy use factor describes the overall primary energy consumption which is linked with the creation or use of a product or a service, including all preproduction chains but without primary energy used as materials such as mineral oil in plastic products. Furthermore, the energy utilised for the disposal is not taken into account. Since there is not a widely used abbreviation for this factor in English so far we use the German abbreviation KEV in this users’ guide


Efficiency is defined as the ratio of the energy output to the energy input of a machine.

Final energy

(also: energy supplied) Final energy is the part of the secondary energy that is available to the consumer. It equals the secondary energy less losses such as transmission and transformation losses and is finally converted into useful energy.

Greenhouse gases

Greenhouse gases are gaseous pollutants released into the atmosphere through the burning of fossil fuels and through other avenues, which amplify the greenhouse effect. The Kyoto protocol includes the following greenhouse gases: Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), and Sulphur hexafluoride (SF6)

Gross internal floor area

The gross internal floor area of a building is the area measured to the internal face of the perimeter wall at each floor level. It includes areas occupied by internal walls and partitions, columns, piers and other internal projections, internal balconies, stairwells, toilets, lift lobbies, fire corridors, atria measured at base level only, and covered plant rooms. It excludes the perimeter wall thickness and external projections, external balconies and external fire escapes. Furthermore, unused areas such as unheated cellars or lofts are not included in the gross internal floor area. Its unit is m².

Lower heating value (LHV)

(also: net calorific value, lower calorific value, net heating value) The lower heating value is the total heat produced on the complete combustion of a fuel less the energy in the uncooled products of combustion. Among these is uncondensed water vapour.

Primary energy

Primary energy is the energy that has not been subjected to any conversion or transformation process. It is contained in fossil fuels and energy derived from renewable sources such as the sun, wind and waves. All the energy which we use comes from these primary sources, though very often the energy may be supplied in the form of secondary fuels such as electricity, manufactured gas, or coke.

Primary energy ratio

The primary energy ratio describes the consumption of primary energy per square metre of the internal gross floor area of the building and per year.

Secondary energy

Secondary energy is the energy produced by the conversion of primary energy, e. g. electricity, hydrogen, or petrol.
Upper heating value (UHV)
(also: gross calorific value, higher calorific value) The higher heating value of a fuel is the total heat developed after the products of a complete combustion are cooled to the original fuel temperature.

Useful energy

Useful energy is the portion of final energy which is actually available after final conversion to the consumer for the respective use. In final conversion, electricity becomes for instance light, mechanical energy or heat.

Water ratio

The water ratio describes the consumption of water per square metre of the internal gross floor area of the building and per year. For swimming
pools, it’s more pertinent to speak about water consumption per swimmer/user.

Weather correction factor

The weather correction factor is supposed to take into account the climatic difference between the year your data is from and an average year. Please note that this factor does not take into account climatic differences between two different climatic zones.

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