Refurbishment boosts efficiency
How refurbishment worked in one German house
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One of the BuildDesk team on Germany, Markus Schröder, owns one of country’s most energy efficient houses. In 2006, when the Schröder family took over the house, which was originally built in 1952, neither the 135 m2 floor plan nor the energy usage level satisfied their expectations. With a yearly energy demand of 26,000 kWh and a yearly primary energy demand of approximately 620 kWh/m2, the house belonged to the lowest energy efficiency class "I" - if not even lower. From energy efficiency class 'I' to 'A' in 11 months
The overriding goal for the renovation project was to reduce the energy consumption. The house was renovated from roof to basement and the result was a 70% saving in energy costs. One focal point was the heating system: the original heating system (a combination of an electrical floor heating system and electrical night storages) was replaced by a modern wood pellet heating system. Another focal point of the renovation project was airtightness: a mechanical ventilation system was installed throughout the house and the entire building envelope was insulated from top to bottom. The roof was insulated with 360 mm stone wool, the old windows were replaced with new, double-glazed, low energy windows, the horizontal division between basement and ground floor was insulated and finally 180 mm external wall insulation was installed.
The renovation project took several months and the result of all the various measures were tested right after the completion of the project. The future, yearly heating demand of the house was calculated to decrease from 193 kWh/m2 to 38 kWh/m2 and the yearly energy demand was calculated to decrease from 26,000 kWh to approximately 12,500 kWh. The yearly primary energy demand was calculated to decrease from 620 kWh/m2 to 26 kWh/m2. This all means that the house now belongs to energy efficiency class "A".
The Schröder family moved into their new house around Christmas 2006. Getting used to living in their new house also involved getting used to new routines. As an example, the new ventilation system saves a lot of energy and ensures the indoor climate is always pleasant, but only when windows are kept closed. Having lived in there for almost a year now, the Schröder family is very happy with the changes.
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The renovation project was part of an ongoing dena (Deutsche Energie Agentur - German Energy Agency) scheme and thus had to follow a renovation concept. As part of the scheme, subsidies and favourable interest rates has been offered to house owners bringing their houses up to the latest low energy standard: the greater the energy saving, the higher the subsidy available. Since the completion of the house, the project has been mentioned and described in various German trade magazines and even made The Wall Street Journal.
