Narrow floor plans, small rooms, sparse daylight, outdated radiators: an unmodernized 1950s house is a relic of days gone by. Almost all residential buildings constructed before 1980 to 1990 have major shortcomings in terms of energy consumption. It is not unusual for older properties to use up to 4,000 liters of heating oil a year and have a primary energy demand of almost 60,000 kilowatt hours. (Consumption is normally expressed in terms of primary energy, such as solar energy or crude oil.)

But recent years have witnessed previously unheard-of innovations in building and energy technology. A new home constructed in 2014 requires seven times less energy for the same living space as half a century ago. Fossil fuels are no longer needed, and the CO2 emissions from running and maintaining the building drop to a fraction of their previous value. The condition of the building is key to achieving a complete energy turnaround. The fact is, around 40 to 50 percent of total energy requirements and harmful CO2 emissions in Switzerland are attributable to buildings.

Ambitious targets for 2050
“Zero-energy houses will be possible in the future,” explains Urs Rieder, Professor of Building Technology at the University of Lucerne. We have to bear in mind that every building still needs an external power supply to operate the heating system or heat pump, building installations and lighting. However, energy can be generated directly on site using efficient heat pumps that run on a minimum of electricity along with photovoltaic or hybrid collectors. Heat pumps use energy derived from water or the ground, and photovoltaics convert solar energy into power. So zero net energy should be possible in the future: the building would produce the same amount of energy over the year as it gets from external sources.

Rieder is convinced that “this is how the trend is going.” In the EU, from 2020 all new buildings will have to be designed to zero-emission standards. Switzerland’s energy policy also calls for buildings to use much less energy and cut back on harmful CO2 emissions. Cantonal requirements for new buildings will be considerably tightened by 2020, and older buildings will have to be fully renovated by 2050. While great progress has already been made on new homes thanks to technical innovations, old buildings still have a long way to go. “Especially when it comes to facades, the renovation and renewal rate is still too low for all old buildings to be converted within 50 years,” reports Thomas Ammann, head of the Energy and Building Technology section of the Swiss Homeowners’ Association (HEV).

Heat pumps instead of huge heating systems
When dealing with older buildings, which make up the majority of properties in Switzerland, a clear strategy is required. Typically people take uncoordinated individual measures instead of considering the complex interplay between the various elements such as windows, roof, facade, insulation and heating. “If an old heating system breaks down, you have to keep your future options open when it comes to repairs or replacement,” recommends Urs Rieder. It makes little sense to install a large-scale heating system if the facade insulation will be improved in a few years’ time, lowering the demand for heating energy.

If work cannot be avoided on the heating system, it’s the ideal opportunity to switch to a modern heat pump, which draws energy for heating or cooling from the environment (air, water or soil). These systems have been tried and tested in Switzerland thousands of times and have proven sturdy and cheap to operate and maintain. With a longer-term renovation plan, the building can be modernized in stages: windows, facade, insulation and roof. “From a long-term perspective, every home – including older buildings – should be moving toward the 2000-watt society,” Rieder emphasizes. It’s crucial to avoid planning mistakes. “If a refurbishment is planned in any case and various measures are coordinated and implemented, energy renovations will pay off fi nancially over time,” states the HEV’s Ammann. In the interest of sustainability and cost-effi ciency, the building’s different lifecycles need to be understood and taken into account.

Beyond minimal renovation
A heating system has a life expectancy of around 20 to 25 years, windows of 25 to 30 years, facades usually even longer. “But there’s no point replacing functioning parts of the building not yet amortized in ecological terms,” fi nds Rieder. That’s why it’s often worthwhile seeking expert advice. Energy consultants, architects and planners of building technology and heating systems are the right people to talk to.

Where a building application has to be submitted for a new construction or renovation project, the current Energy Act already sets certain standards. “In the long run, it makes no sense to settle for the absolute minimum investment,” says Ammann. When planning, take into account your personal aims in life, your future space requirements or, in the case of rental properties, the future demand on the rental market. Rieder has no doubt that the energy turnaround can match your personal needs. “Today we can engineer buildings that produce more net energy than they need to run, and cause almost no CO2 emissions.”

23.04.2014, Jürg Zulliger (text) and Luca Schenardi (illustrations)