Installing the additional thermal insulation required for Passive House level of performance level. (photo: Schulze Darup). Here, the insulation thickness is 20 cm.

If a house is already insulated, then renovate it correctly - even an old house. If the work is done properly, the building will not have to be refurbished again for many years into the future. Adding insulation to the Passive House level is economically optimal under the present and future economic conditions. The results of using less thermal insulation are already expensive - and will only get worse in the future.

Preserving older heritage buildings, while renovating to Passive House levels is important, as discussed by Ludwig Rongen at the 10^thAnnual Passive House Conference (Working group V). Also, the architecture of recent buildings may not always be valued as highly. This was a central topic of interestat the 11^th Passive House conference.

Old house reborn- basic renovation of a terraced house with vacuum insulation to "factor 10" objective by Florian light-blue. Vacuum insulation was a central topic at the 10th Passive House Conference.

How does a featureless building develop into a representative seat for the Suedtiroler National Council for Energy? Michael Tribus modernized this building in Bozen to the Passive House Standard.

The measurements below were taken from Jean-Paul-Platz in Nurenberg, one of the first modernizations of old buildings using Passive House components. Above is a view of the modernized facade.
(Project of Burkhard Schulze Darup)

Results of the consumption measurements from Nurenberg/Jean-Paul-Platz: the heating amount determined by PHPP (bar) predicts the energy requirement. The measurements (red squares) verify this: consumption was reduced by nearly a factor 10. (i.e. 26.9 kWh/(m²a) was measured, originally approximately 200 kWh/(m²a)).

A 1960's apartment building became a Passive House. André Zaman of the GAG Ludwigshafen presented the experiences in working group 10 of the 10th Passive House Conference. The apartment complex under construction was part of the tour during the 9^thPassive House Conference. The renovation was finished in 2006. Energy consumption is being systematically monitored in this complex. First results were available in 2007.

The modernization of the existing building stock is the most important task in the future for the building sector. Presently all of those involved emphasize this, from housing policymakers to builders and building industry. And they are correct, it is important that rennovations be done.

No-one agrees, however, on how to do this. Specifically, there are questions about the necessary quality level of long-overdue renovations to the building envelope, windows, and mechanical systems. The majority of owners still believe that it is necessary just to put in a slightly more efficient mechanical system, and perhaps stop up some of the air leakage in the structure. But even amongst building physicists and HVAC engineers there is a strong tendency to encourage only moderate renovations to existing energy performance.

• Eberhard Jochem has already shown, at the 9^th Passive House Conference, why owners are well-advised to correctly compute the economics of efficiency measures. Presently, investments into good energy efficiency are uniquely attractive, especially with the favorable incentives from KfW Foerderbank.
  
• The oft-repeated phrase when building new or renovating is "if already, because already". But building envelopes are long-lived economic goods, and a qualitative improvement omitted today will hurt the owner for decades. There already owners who are annoyed that they spent so much money on their new building or renovation but got only a moderate increase in energy efficiency.
  
• Mark Zimmermann (EMPA, Duebendorf, Switzerland), showed at the 10^thPassive House Conference that with energy targets which don't reach the Passive House level, energy sustainability will never be attained. Although even the Passive House level may not even be good enough, it (and existing Passive House Components) is an excellent basis on which to build energy sustainability.
  
• Burkhard Schulze Darup discussed the improvements to numerous old buildings in order to meet the "factor 10" objective, and contributed important experience to economics and to strategies for further implementation.

The specialists described above are members of the Passive House Conference advisory committee. Working groups of the 11th Passive House Conference with the topic of the inventory reorganization will be discussed in detail.

The crucial steps for energy conservation in existing buildings are:

• Very good thermal insulation
• Minimization of Thermal Bridges
• Airtightness
• Balanced Ventilation with heat recovery
• highly efficient Windows
• Innovative mechanical systems

You may notice that these are the exact same elements that work so effectively with new low energy buildings. In particular the energy-saving components developed for new construction Passive Houses can be utilized successfully in old buildings - with energy savings of 75% to over 90%.

The energy savings potential of using Passive House components is very high: the leftmost graph in the chart above shows an uninsulated old building with a heating energy consumption of around 240 kWh/(m²a). The rightmost graph shows the result of renovating using only Passive House components: heating energy consumption decreases to one tenth of its original value (therefore "factor 10"), and this has been proven often through implementation (see the pictures on the left side). If it is only possible to add insulation to the interior, but Passive House components are used, it is still possible to reach a 75% reduction in energy consumption. This shows that the best market-ready Passive House components are viable solutions well into the future.

Here you can find to more information on modernization with concrete examples. (German)

Here you can find further examples of successful renovations using Passive House components.

Link to the main page for information about the Passive House: Passive House Fundamentals.

Link to the homepage of the Passive House conference:
Passive House Conference.

Go to the Passive House Institute homepage:

(updated: February 24^th 2009 /author Wolfgang Feist Passive House Institute;
unchanged copy permitted - please give reference to the source
thanks to Malcolm Isaacs for proof reading)