Cutting Home Energy Consumption by 80%
Freiburg’s energy efficient housing standard has lead to reductions of up to 80% in average household energy consumption. Moreover, the standard has influenced the development of two attractive districts - Vauban and Rieselfeld - that are setting new standards for energy-efficient housing in Europe. The standard had been improved in 2008 towards a general passiv-house-standard. Low energy housing in Vauban is estimated to reduce CO2 emissions by 2100 tonnes per year in 270 residences. Furthermore energy aspects are considerated in each new development plan since 2005 in a consistent way.
What is it?
Introduced in 1992, the “Low-energy Housing Construction” standard was incorporated into all lease and purchase contracts for City property and stated that no more than 65 kWh/m2 of energy may be used for heating purposes in households. Following amendments to national legislation, the standard has subsequently been revised to ensure that Freiburg remains at the forefront of low-energy development in Germany. The latest - a two step revision towards a nearly Passiv-House-Standard 2009/2011 - was adopted by the city council in 2008. From 2011 on all new housing buildings in Freiburg will be built in a high energy efficient standard.
The standard is not a building ordinance, but a matter of civil law applying to public land that is sold by the city to private investors. Since 2005 the standard is also operated in new development plans. The Vauban and Rieselfeld districts are large-scale showcases of Freiburg’s achievements.
Freiburg has pursued a programme of retro-fitting old buildings with renovations and upgrades to make the high potential in the existing building stock accessible for energy saving and energy efficiency.
How does it work?
Contractors are obliged to build according to low-energy guidelines, to orient buildings so that they optimise their capacity for use of passive solar energy, and to make roofing available for solar collectors. Lease and bills of sale contain rulings that specify about 5,000 m2 must be kept clear for solar collectors, yielding around a 40% reduction in the use of warm water in new districts.
The entire Vauban and Rieselfeld districts have been constructed to the 65kWh/m2 low energy building standard, comprising a population of 18,000 people. Around 270 units have been constructed to “passive house” (15kWh/m2) or “plus energy” (houses producing energy surpluses) standards. Additional energy for passive houses is required for only a few weeks each year – a wood chip biomass combined heat and power (CHP) plant provides this energy.
The integrated design concept of the Vauban district also means that a traffic concept has been development, leading to reduced use of private vehicles; the number of solar installations is constantly increasing; and rainwater is collected (for example, for use in school toilets). A biogas plant has also been introduced to the district. Freiburg has achieved high-quality housing for young families, with green spaces and good social infrastructure, whilst reducing energy consumption and CO2 emissions.
2007 the city council adopted a consistent procedure – developed by the planning and environmental department - integrating energy aspects for all future development plans. Each new development plan includes:
- Early consideration of energy aspects in target definition for new building areas
- Consideration of passive solar aspects in draft plan
- Freiburg building standard in all new building areas
- Energy concepts with variant verification central/decentral, CHP (combined heat/power), early involvement of renewable energies. The implementation is based on agreements on urban development between the city and private owners.
Annual savings and CO2 reductions
Low-energy housing costs around 2% more to build than traditional housing, yet energy consumption falls by up to 80% compared to existing building stock and CO2 emissions are reduced by 30%. Consumption of oil for heating purposes is more than halved, from 12-15 litres to 6.5 litres per square metre heated. The rising price of oil means low-energy housing is even more effective and the houses in Vauban save residents more than €1,000 a year per dwelling.
Annual savings of 1,900 litres are heating oil in a single family home are achieved and emission reductions are: 6,5 kg sulphur dioxide (SO2); 3,4 kg nitrogen; 3,1 kg carbon; 0,3 kg hydrocarbons; and 001, kg dust. Around 2100 tonnes CO2 equivalent are reduced by the passive housing development and is going to increase with the new building standards from 2009 on.
Construction costs for multi-unit buildings are lower. Costs associated with energy efficient construction are initially added directly to the purchase price, but the public has accepted these additional costs, in the anticipation of reduced running costs. Costs associated with new local government buildings are of course paid by the municipality.
Application – Development of Vauban City Quarter
There has been wide public acceptance of the development programme with significant interest throughout Germany and other European countries. Dozens of cities have indicated interest in implementing a similar programme.
An important element of success in the implementation of a programme aimed at low-energy housing construction is to have building contractors and architects accept the programme. This requires keeping these people well informed and overcoming the stereotyped view that low-energy construction involves increased financial burdens.
The programme has also benefited from making use of an existing resource pool of architects and administrative officials from other communities who are implementing similar programmes. For instance, creative examples of low-energy housing construction in Scandinavia demonstrated to local architects lead to the result that this type of construction created new opportunities in housing design in the city of Freiburg.