Energy-efficient renovation

The federal government has an ambitious plan: all building stock in Germany will be climate-neutral by 2050. This excludes any new buildings whose technical design specifications are already energy-efficient.

The situation is more difficult when it comes to old buildings because they are based on construction techniques dating back many decades. Read on to find out all you need to know about the federal government’s climate change package.

The government offers grants in the form of funding programmes to assist consumers with the energy-efficient renovation of their old buildings.

The spectrum of energy-efficient renovation options for old buildings is broad, ranging from insulating the building to installing new windows and doors right up to fitting new heating systems or installing solar plants.

We can provide you with an overview of the various measures that are best suited for modernisation projects.

When undertaking the energy-efficient renovation of an old building, please note that the various measures should not be implemented separately: rather they must be sensibly coordinated. Every building has its own character, different structural engineering and individual heating requirements.

Are you thinking about renovating your heating system or even installing a new heating system? Good idea! It is less complex than external wall insulation and, best of all, renovation usually greatly reduces your fuel bills.

A modern condensing boiler can use fossil energy efficiently and lower fuel costs. It will also improve your environmental footprint by reducing your consumption of fossil fuels and production of harmful emissions.

Prices for new heating systems vary according to output and fuel type. Gas condensing boilers start at €3000. However, the price depends on the building’s structural characteristics. Oil condensing boilers are a little more expensive in comparison.

But when is it worth investing in a new heating system? Depending on the building’s state of renovation and current energy prices, the payback period is around 7 to 10 years per accommodation unit.

Proper insulation of the old building’s envelope from the cellar to the roof greatly reduces the heat transfer coefficient: heat is stored for longer and consumption of finite resources drops.

The aim of energy-efficient renovation is to minimise the thermal permeability of exterior walls using certain insulating materials.

The costs largely depend on the substance of the building, the structural engineering, the construction materials used and other particular conditions. The following table shows prices that can be used as approximate values for rough calculations.

The individual composition of the building will also affect how cost-effective insulation measures of this kind will be for your home. For instance, the construction year and insulation standard are of great importance. But energy prices also affect the payback period. On average, we can say that insulating the façade will pay for itself after around 10 years and insulating the roof after around 16 years.

Replacing old windows is another advisable method of minimising thermal losses from the building envelope. The German Energy Saving Ordinance (EnEV) 2009 states that the heat transfer coefficient of modern windows must not exceed Uw=1.3 W/(m²*K) or Uw=1.1 W/(m²*K) for the glass itself.

Modern, triple-glazed thermal insulation windows lose up to 80% less heat. When combined with façade insulation, these measures can have a major impact.

The cost of replacing windows depends on the window frame material and the surface area of the windows. The table shows figures obtained from the Bavarian Environment Agency. They refer to triple-glazed thermal insulation windows 1.3 x 1.3 metres in size.

Further costs are incurred by fitting and sealing the windows. The installation costs amount to an average of 30 to 40% of the overall costs, so keep an eye on this expense. If you engage a company to install new windows, check that they are certified in line with RAL quality criteria and that they work in line with the appropriate standard procedures.

The payback period for new windows in old buildings is around 8 to 15 years and depends on the type of window and building insulation. In this way, you can lower heating costs by up to 20%.

Admittedly, installing solar equipment is not a renovation measure per se. However, it supports your heating system and helps you to make it more energy efficient. Solar thermal technology systems use solar radiation and solar collectors located on the roof through which water flows. Solar radiation heats the circulating water,

which is then used to heat the building and to supply hot domestic water. When using one of these systems, it makes sense to purchase a buffer cylinder to ensure that you can collect and use as much solar energy as possible.