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Primary energy – quantifying sustainability

The primary energy demand determines the impact on the environment. To be more exact:

  • The total primary energy demand from non-renewable energy sources that is supplied to the building 68)
  • for all energy uses arising in the building,
  • thus also for the household electricity in a residential house (shown in “yellow” in the following illustration).

Note 1: the current calculation method of the Energy Saving Regulations (EnEV) does not take the domestic electricity into account.
Note 2: The world is furtunately substituting more and more not renewable energy sources by renewable energy sources. These source do have much less dangerous environmental impacts; but these also need some limited resources (e.g. land use). In the future, it will become more and more important, to design an energy system in a way, that the renewable energy generation can be kept within sustainable limits. This is, what the new "primary energy renewable" PER method has been developed for.

Comparison of the primary energy demand of various energy standards (based on the living area)||

What is being compared?
For the “existing building“ category with the average consumption of buildings from the construction year categories before 1984.
For the “WschVO 84” category (Thermal protection regulation) with the requirement standard set there (unfortunately there are no statistics for the actual consumption values, these are presumably higher because the regulations haven not taken into account some important facts and because construction is simultaneously becoming more “complicated”). [Eschenfelder 1999]
For the “WSchVO 1995” category with the requirement standard set there (same problem with statistics here).
For the “EnEV 2002” category with the requirement standard set there (same problem with statistics here).
The stacking columns for the Passive House represent the measured values of the Passive House in Darmstadt-Kranichstein. These match the statistics from built Passive House developments [AkkP 28] . If energy efficient household appliances are used, the values shown here are typical for modern Passive Houses.69)

Two important stages can be identified:

  • The first stage of heating energy savings from a typical old building to the “EnEV”, which was divided into three separate steps (1984, 1995 and 2002).
  • And the second stage of heating energy savings from the EnEV house to the Passive House, which is particularly interesting because not only is energy being saved, but also the whole system becomes more simpler, more comfortable and crisis-proof. Of course, also domestic electricity should be efficiently used in a Passive House.

Heating comes first...

The illustration shows that in existing buildings it is mainly the heating energy which affects the environment (64% of the primary energy demand). The Thermal Protection Regulations (WSchVO) and the Energy Saving Regulations (EnEV) have taken this into account - the requirements set by them are mainly regarding the thermal protection of the building, which is reasonable. With the EnEV quality standard the heating energy demand decreases to less than half of the average value of old buildings. Now the primary energy consumption for domestic electricity is as high as that for the heating (more than 40 % respectively). With the EnEV, the total primary energy consumption is reduced by about 40 % altogether in contrast with old existing buildings.

In the Passive House

The heating demand is reduced even further, this also makes sense, as it still represents the largest single item. What is even more important - heating is concentrated during the winter months, a time, where substituting it by renewables is much more expensive. Better insulation on the other hand is economically very attractive – it also improves the protection of the building and the thermal comfort. However, domestic electricity also needs to be considered; by using efficient electrical appliances, effective control and energy-efficient lighting, it was possible to reduce the electricity consumption by more than 50 % in the Passive House in Darmstadt-Kranichstein, without any impairment in comfort. Due to insulation of the water carrying pipes and the use of a solar collector, the requirement for domestic hot water, which is not as significant as the requirement for heating or domestic electricity, could be reduced by over 75% in the Passive House in Kranichstein, in comparison with existing buildings.

Altogether the Passive House standard reduces the total primary energy demand of a building by more than 70 % in contrast with an ordinary new construction (EnEV). This is about twice the savings achieved by the EnEV standard in contrast with old buildings. What remains is a primary energy demand which is reduced by a factor of 6 (17%) in contrast with an average old building. The deciding factor is that because the primary energy demand is so small, it can be covered in a lasting and environmentally-friendly way through renewable sources which are regionally available. The Passive House is sustainable – it can be part of a circular flow economy which remains stable for generations. And it functions at reasonable cost.

Better than a Passive House ...

is when the remaining largest part of the consumption, which is the domestic electricity, is reduced even more. Technically, this is possible – and implies advanced development of household appliances by manufacturers. The diagram shows clearly that it doesn't make sense to concentrate on reducing the heating demand even further, as the Passive House has only a small heating demand. From the environmental protection point of view, “zero-heating houses” are not an important objective, neither are they financially viable, because starting with the Passive House, not much money can be saved in terms of heating – and there are no further simplifications of the system possible.

Energy autarchy

Energy autarchy is technically possible, but at the moment, it is still extremely expensive. And what are the benefits for the environment? Wherever a mains supply system exists, electricity generated elsewhere from renewable energy sources can be transported to the building without much effort - and surplus electricity that is generated on the premises can be fed into the network. This makes much more sense for the environment than an autarchic building.

Embodied energy

Grey energy has not been dealt with here. Of course, energy expenditure also plays a role for the creation of a building: the primary energy input for production (PEI). This has been systematically examined in two publications and set in relation to the operating energy input [Feist 1997] , [Mossmann, Kohler 2005] . This has been put together on the following internet page: Life Cycle energy balances, Embodied energy and the Passive House Standard. This much in advance:

  • Most of the grey energy is used for the production of the building materials. Lasting and continuing usability are the main factors for the energy efficiency of building performance.
  • The energy expenditure for the production of a (otherwise identical) Passive House is not necessarily greater than that of an ordinary new construction; it can even be less. The “primary energy investment” amortises very quickly, in less than a year as a rule. The additional financial investments don't pay back so quickly unfortunately, but they are still worth it. See Affordability.

The Passive House Planning Package

The Passive House Planning Package (PHPP) is a comprehensive tool for determining energy balances for buildings, that identified the complete primary energy demands already in its first edition in 1997. Like concepts, tools must also be helpful for the designer, otherwise they fall short of their purpose. See PHPP – Passive House Planning Package.


[AkkP 28] Wärmeübergabe- und Verteilverluste, Protokollband Nr. 28 des Arbeitskreises kostengünstige Passivhäuser Phase III; Passivhaus Institut; Darmstadt 2004.
(Thermal transmission and distribution losses, Protocol Volume No. 28 of the Research Group for Cost-efficient Passive Houses Phase III; Passive House Institute; Darmstadt 2004)

[Eschenfelder 1999] Eschenfelder, D., Das Niedrigenergiehaus in NRW – Test; Bauphysik 21/1999, Heft 6, S. 260-267.
(The low-energy house in NRW - Test; Bauphysik 21/1999, Issue 6, pages 260-267.)

[Feist 1997] Feist, Wolfgang: Lebenszyklusbilanzen im Vergleich: Niedrigenergiehaus, Passivhaus, Energieautarkes Haus, In: Arbeitskreis Kostengünstige Passivhäuser, Protokollband Nr. 8: “Materialwahl, Ökologie und Raumlufthygiene“, Hrg.: Wolfgang Feist, Passivhaus Institut, Darmstadt, 1997, S. V/1 – V/11.
(Life-cycle balances in comparison: Low-energy house, Passive House, Energy-autarchic house, in: Research Group for Cost-efficient Passive Houses, Protocol Volume No. 8: “Material selection, ecology and indoor air hygiene“: Wolfgang Feist, Passive House Institute, Darmstadt, 1997, pages V/1 – V/11)

[Mossmann, Kohler 2005] Mossmann, Cornelia; Kohler, Nikolaus; Jumel, Stéphanie: Lebenszyklusanalyse von Passivhäusern; Im Tagungsband der 9. Passivhaustagung, Ludwigshafen-Darmstadt 2005, S. 333-338
(Life cycle analysis of Passive Houses; in the Conference Proceedings of the 9th International Passive House Conference, Ludwigshafen-Darmstadt 2005, pages 333-338)

[PHPP 2007] Feist, W.; Kah, O.; Kaufmann, B.; Pfluger, R.; Schnieders, J.: Passivhaus Projektierungs Paket 2007, Passivhaus Institut Darmstadt, 2007.
(Passive House Planning Package 2007, Passive House Institute, Darmstadt 2007)

There are many environmental effects of the use of not renewable energy: consumption of limited resources, pollution of the atmosphere with harmful substances (e.g. CO2, other greenhouse gases), contamination of the water and soil (e.g. with radioactive waste materials), damage to the environment etc. At the moment, it is not possible to weigh up the various effects against one another and to adjust the risks quantitatively in relation to each other. It is undoubtedly indisputable that there are very serious risks involved in each case (climate change, proliferation of nuclear weapons, safety of future generations with regard to storage of nuclear waste).
With renewable energy sources and energy efficiency, there are no risks of this magnitude - at least, as long as attention is focussed on sustainable use (no deforestation for the purpose of obtaining fuel). Within this context, the non-renewable demand for primary energy is currently a good quantifying factor for the overall damage to the environment through conventional energy use. Using solely CO2 as a parameter for this purpose plays down the other risks and the significance of the resource situation. Incidentally, this quantification approach has also become increasingly popular with other authors. The fact that non-renewable energy sources are, to a great extent, usually quickly substitutable by each other also speaks for this assessment– if certain risks become apparent, a widespread substitution effect should be expected. Today we do not know exactly which primary energy carriers (oil, gas, coal or uranium) actually will be used predominantly in the next decades – evaluation of the total primary energy applied will provide security against this additional uncertainty. In the future, however, at some time the energy will be generated more and more from renewable sources - and this will change the picture completely. After all, the risks and the environmental damage from renewable energy is far lower than these from fossil or nuclear sources - but we can not neglect, that renewable energy also needs resources (e.g. land use). The impact can be kept really small, as long as the overall renewable energy to be used is in a fair relation to the planetary resources. To have a measure for this, the passive house institute introduced the "primary energy renewable" PER as a new assessment method.
Primary energy savings from the far left (existing buildings, based on average statistics) to the far right (Passive House, as demonstrated by statistics from around 300 properties, the average measured values accurate to ±1.5 kWh/(m²a)) are statistically significant. These are 83%, or 5/6 of the average consumption of primary energy today. The information for other standards is not statistically relevant. From the effectiveness of the energy efficiency measures for Passive Houses, it can be inferred that the computed values were also achieved.
All values are based on the heated living space. The area reference had to be converted because the statistics were always based on the living area while regulations refer to a (20 to 30% larger) useable area AN.
basics/energy_and_ecology/primary_energy_quantifying_sustainability.txt · Last modified: 2020/08/09 13:50 by wfeist