Implementation of energy efficiency in old buildings

Positioning in the pattern of energy consumption
Fig. 1 shows the current total energy use in Germany, subdivided into combustibles (hydrocarbon fuels), district heating and electricity [Arge 2001]). Combustibles and hydrocarbon fuels contribute the main share (78%) of German energy supply, followed by electricity with a share of 18 % and and district heating with 4 %. For a better distinction, the respective share of renewable energy has been highlighted in the diagram using some colour. Nowadays, the percentage of electricity generated by renewable energy sources is after all about 9%. A much higher share of renewable energy than in the field of substituting combustibles, with only one per cent of firewood and thermal utilisation of solar energy (water heating) still in a very low range. Even optimistic future estimations of increasing the use of renewable energy sources in this field by 6 to 9 % is not sufficient in compliance with climate protection goals. At least, as long as today`s level of consuming combustibles and hydrocarbon fuels is taking into acccount. That is precisely where energy efficiency technology can make a vital contribution to increasing the share of renewable energy sources- by increasing the efficiency of energy usage.

Improved energy efficiency in the field of heating
The basic approach of modernising existing buildings by means of highly efficient elements, has already been presented at the 3rd Conference on Passive Houses in Bregenz. It is of utmost importance to significantly improve the energetic quality of each component that is being modernised. Always acting on the maxim “if you’re going to do something at all, you might as well do it properly”.

Passive House technology mainly pushed the development of new, energy-saving components in the last ten years. The importance of such new components according to energy saving potentialities in already existing buildings is shown in figure 2. Here, multi family residences in the period of 1919-1948 and 1949-1957 (former FRG ) have been singled out.

Up to the year 1990, it was possible with the availabe technologies to achieve economically sound energy saving potentialities (costs of saved energy about 0,065 €/kWh) of approximately 60 %, compared to the actual state of the buildings. Carefully taken measures led to annual heat reqirements of 65 to 90 kWh (m²a). Thereby meeting the standard of low energy houses.
The green columns in in figure 2 on the far right show the possible annual heat requirement after modernising the respective building by means of today’s Passive House technology. With only 25 to 35 kWh/(m²a), the annual heat requirement was again reduced to less than half of what it has been before. Thereby achieving possible energy savings of 80 to 90 %.

Updated scenarios as shown in figure 3 result from estimations on further high rates of implementation and modernisation, based on the total heating demand of reunited Germany in the year 2000. The old “trend-scenario” (see Ebel 2000) needs to be compared to the effects of new terms and regulations in the EnEV 2002 (energy saving ordinance). Due to higher demands on windows, thermal insulation and re-fitting duties, we are forecasting an already noticable reduction of the energy requirement in comparison to the old trend-scenario. Thanks to the availability of Passive House elements ( “new technology”), this potential will be more than doubled again.

Conclusion
The results of realised projects demonstrate that with today’s available Passive House components it is possible to achieve annual heat requirements of 25 kWh/(m²a) even in the stock of already existing buildings [AkkP24]. If visual cladding or regulations of monumental protection make an insulation at the external surface impossible, 60 kWh/(m²a) can still be achieved by internal insulation. Thereby, acting on the maxim that a carefully planned inner insulation is better than no insulation at all. Such measures have been the topic of the research group’s 32nd meeting [AkkP 32 (German)] . Dabei gilt der Grundsatz, dass eine sorgfältig geplante Innendämmung besser ist als keine Dämmung.

The existing potentialities make clear that it is possible to improve the quality of the building stock immensely in the decades to come, provided that an engaged programme of modernisation is initiated. Thus making it possible to reduce the heating energy consumption in total to less than 50 % of what it is today. Already taking into account the small stock of buildings, where modernisation is not possible. Against the background of immensely improved energy efficiency, potentialities of renewable energy sources (see Fig. 1) can now be newly judged. More efficient systems (buildings, facilities and vehicles) lead to strongly reduced energy demands. Thus, renewable energy sources can reach a significant share in total energy supply ( see Fig. 4).

The utilisation of the potentialities takes place at a local and regional level. What are suitable instruments to proceed further on this road, what are model projects and examples and what experiences have been made. These questions will be subject of

Working group no. XIV: Implementation within the region and the municipalities.

Literature:

[Arge 2001] Arbeitsgemeinschaft Energiebilanzen: Auswertungstabellen zur Energiebilanz für die Bundesrepublik Deutschland 1990 bis 2000, Ausgabe 2001. (German)

[Ebel 2000] Ebel, W.; Eicke-Hennig, W.; Feist, W.; Groscurth, Helmuth-Michael: Energieeinsparung bei Alt- und Neubauten, 1. Auflage, Heidelberg, 2000. (German)

[AkkP 24] Passivhauskomponenten im Gebäudebestand , Protokollband Nr. 24 des Arbeitskreises kostengünstige Passivhäuser Phase II, Passivhaus Institut (German)

[AkkP 32] Passivhauskomponenten und Innendämmung, Protokollband Nr. 32 des Arbeitskreises kostengünstige Passivhäuser Phase II, Passivhaus Institut (German)

(Author: Dr. Wolfgang Feist; abstract derived from [AkkP 24])


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Time schedule of the 10th International Conference on Passive Houses in Hannover

2005 Dezember 1st: Deadline for abstracts
2006 February 1st:    Notification on acceptance of abstracts
2006 March 1st:         Registration period for reduced fee ends
2006 March 15th:       Deadline for the written contributions of the preceedings

2006 May 19th and 20th   10. Conference on Passive Houses HCC Hannover with Exhibition on Passive House Components and manufacturers session

May 21st field trip to the most interesting Passive House projects and construction sites incl. refurbishment in the region near Hannover.

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