How to go about an energy-efficient renovation

Energy-efficient renovation includes all building-related measures that reduce the energy consumption of your home. By replacing windows and the heating system or renewing the façade or building envelope, you can save a considerable amount on heating costs and help the environment. You can carry out the measures together, individually or in stages. Old buildings usually consume significantly more energy than new ones. In particular, energy for heating is often generated inefficiently and offers potential for savings.

Energy-efficient renovations are an important way of improving the sustainability of the real estate sector and achieving climate protection targets. In Switzerland, CO2 emissions are to be halved by 2030 and reduced to zero by 2050. Because greenhouse gas emissions are largely attributable to the construction and operation of buildings, the adaptation measures of the Swiss Climate Protection Act are particularly aimed at the real estate sector.

For building owners, making the switch to economical energy use should be worthwhile.

With rising energy prices and no shortage of available subsidies, it makes sense to invest in energy efficiency for economic reasons alone. Then there is also the long-term perspective: future-proof properties are more likely to satisfy legal and political requirements and meet the needs of tenants or buyers for decades to come. Buildings with better energy performance could be more in demand, while those with a poor energy balance and air quality could become less attractive. Ideally, modern technology will also allow maintenance costs to be reduced.

Energy-efficient renovation covers a range of different measures:

Window modernization

Replacing old windows with modern, thermally insulated windows is worthwhile if the lower heating bills over a period of years outweigh the one-time costs of replacement. Replacing single-glazed windows with modern, triple-glazed equivalents offers the highest potential savings. Other pleasant benefits are improved living comfort, higher security and better sound insulation. In addition, there is a lower risk of mold, which can form on windows due to condensation.

Roof renovation

In an unrenovated single-family house, around 17% of energy is lost via the screed floor and roof. Renovating the roof to make it more energy efficient reduces heating costs through improved insulation. This is achieved by fixing insulating material above, below or between the rafters, which are the load-bearing beams in the roof. An even better result can be obtained by combining all three methods. Depending on the type of construction, the room volume is slightly reduced by the insulating materials. Insulating the screed floor is less complex but just as effective.

Basement insulation

Insulating the basement walls can further reduce heating bills and improve the energy balance. If you also want to use your basement as a living space, insulation is essential to make it pleasant to be in. This way you can prevent it from getting cold. Although the external insulation of basements in old buildings is effective, it is also very complex, because the outer walls are exposed. For this reason it can also make sense to insulate the basement walls on the inside.

Installing a new heating system

In principle, modern heating systems are more efficient, meaning you can obtain the same amount of heat from less fuel. In most cases, the replacement of an old, oil-fired heating system in unrenovated single-family homes should pay for itself within 10 years. If you want to renew your heating system, you have several options, technically speaking. One option is to replace the gas- or oil-fired heating system with a new appliance that uses condensing technology. Condensing boilers consume much less gas or oil because they also use the heat from the exhaust gases for heating. In simple terms, this means that the water circulating in the radiators also absorbs the thermal energy of the exhaust gases in the boiler. This works all the better the greater the temperature difference between the two media, i.e., the cooler the water. The next technical measure then comes into play: low-temperature radiators. While the water in conventional radiators flows at 70 to 90 degrees Celsius, in low-temperature systems, 40 to 50 degrees Celsius is sufficient. However, before replacement, please note that these radiators are somewhat larger and won’t always fit seamlessly into the current space.

Using renewable energy with solar power

Solar thermal systems use the sun’s energy to generate hot water. Even a comparatively small system can supply around two-thirds of the hot water required by a single-family home. More complex solar thermal systems not only heat potable water and water for showering and bathing, but also support the heating system. This means solar energy can also be used to heat your home.

Fitting a ventilation system

A central ventilation system allows you to save a lot of energy.

Whereas window ventilation wastes energy and increases heating costs, central ventilation systems with heat recovery are more economical. They suck the warm air out of indoor spaces. Up to 98% of this heat is mixed in a heat exchanger with the fresh air drawn from outside and returned to the interior.

Sustainable renovation through upcycling

Renovation often involves the removal and disposal of certain fixtures and fittings. However some, like doors, are still worth money and can be sold secondhand on online platforms. Upcycling is a form of sustainable renovation in which existing parts of the building are upgraded instead of replaced. Some things can be reused once they have been repaired or restored. If new seals for the windows are sufficient to minimize energy loss, you will avoid having to install new plastic windows, which is good for both your wallet and the environment.

Renovations take time. It usually takes 6 to 12 months from the initial contact with consultants to the first contracts for work and services. It also takes time to find tradespeople for the job. There may also be shortages of various building materials. For these reasons, projects can rarely be completed in less than a year.

When it comes to energy-efficient renovations of old buildings, many owners initially only think about the costs. Although these are usually high, it can still make sense to do the work. If renovations strongly reduce ongoing energy costs, then a lot of renovations will pay for themselves over a period of years. And the longer energy prices remain high, the more quickly these costs will be amortized. In addition, a renovation can improve the resale price of your property – a good argument if you plan to sell it in future. A renovation will also usually make your home more comfortable to live in.