Fluctuating energy prices, uncertainty about subsidy programs and high investment costs for energy-efficient renovations are causing uncertainty and putting many homeowners under pressure. In addition, it is foreseeable that fossil fuels will become more expensive. The gradual increase in the CO₂ price is making heating with gas and oil in particular more expensive. Owners must therefore expect permanently higher burdens. But which renovation measures noticeably reduce running costs, pay off the fastest and increase the value of the property at the same time? Aroundhome, the leading independent placement platform for specialist companies for house projects, investigated these questions in its current study. The result: Without the correct order, the renovation will come to nothing. Those who reduce heat losses first permanently reduce energy consumption and create the basis for more efficient heating technology. This saves investment and operating costs. The following measures show which financial effects are realistic. The basis is a typical single-family house with around 140 square meters of living space and gas heating. With a share of 63.7 percent, gas continues to be the most common energy source in German residential buildings and therefore forms the basis of the model calculation.
1. Insulate the top floor ceiling
The insulation of the top floor ceiling is one of the most economically sensible renovation measures. The reason is simple. Warm air rises to the top. If the ceiling is uninsulated, a relevant part of the heating energy is lost through the roof. At the same time, the measure can often be implemented quickly and is relatively inexpensive compared to other renovation steps.
Costs
For insulation, owners should expect roughly 30 to 120 euros per square metre, depending on the type of insulation. In addition, there are labor costs for the specialist company, which are often between 40 and 60 euros per hour, depending on the region and company.
Example calculation
Suppose 70 square meters of top floor ceiling are insulated.
- Costs: 50 euros per square metre, for 70 square metres = 3,500 euros
- Own contribution for 20 percent funding: 2,800 euros
- Savings: 10 kWh per square metre per year, with 70 square metres = 700 kWh per year
- Energy price: 0.15 euros per kWh. This results in an annual saving of 105 euros.
- Amortization: around 27 years
Monthly savings
Based on the example calculation, this corresponds to about 9 euros per month.
Disclaimer: The direct financial relief is therefore manageable for the time being. Nevertheless, the measure makes economic sense, as it creates the basis for further energy optimization.
Added value
If the energy performance visibly improves as a result of the insulation, an increase in value of one to three percent is possible. With a property value of 400,000 euros, this corresponds to about 4,000 to 12,000 euros. The greatest financial effect occurs when a better energy class is achieved as a result.
2. Renew windows
Windows are among the largest heat loss points in existing buildings, mainly in old double glazing or leaking frames. Replacement reduces energy requirements, improves living comfort and reduces draughts. At the same time, another aspect is becoming increasingly important: summer thermal insulation. With rising temperatures and increasingly frequent heat waves, buildings heat up faster, especially attics and rooms with large windows. Modern windows with good thermal insulation glazing and suitable shading keep heat out much more effectively and reduce the need for fans or air conditioning units. Financially, the measure is particularly worthwhile if the windows are in need of renovation anyway or if the building envelope is improved overall in the course of further renovations.
Costs
Depending on the type of window, installation effort and building, the costs are often between 500 and 1,000 euros per window. For a single-family house with around twelve windows, this results in roughly 6,000 to 12,000 euros. In addition, there may be work on reveals, roller shutter boxes or window sills.
Example calculation
Suppose twelve windows are replaced in a single-family house.
- Costs: 800 euros per window, for 12 windows = 9,600 euros
- Own contribution for 20 percent funding: 7,680 euros
- Savings: 10 kWh per square metre and year
Assumption: Total window area approx. 20 square metres
20 square metres × 10 kWh = 200 kWh per year - Energy price: 0.15 euros per kWh
- Savings: 200 × 0.15 = 30 euros per year
- Amortization: 7,680 ÷ 30 = around 256 years
Disclaimer: The calculated amortization period of around 256 years shows that a window replacement usually pays off not only through saved heating costs, but above all through better energy efficiency, higher living comfort, better sound insulation and a possible increase in the value of the property.
Monthly savings
Based on the example calculation, about 2.50 euros per month.
Added value
New windows practically do not pay for themselves purely through heating costs. Their economic logic lies primarily in comfort, appearance and value stability – not in short-term energy returns. New, energy-efficient windows can increase in value by two to four percent, depending on their initial condition. For a property worth 400,000 euros, this corresponds to 8,000 to 16,000 euros. The effect is particularly strong if it improves the energy efficiency class or creates a visible push for modernization.
3. Façade insulation
The insulation of the outer walls permanently reduces heat loss over the largest surface component of the building. This significantly reduces the heating energy requirement. At the same time, the measure is investment-intensive and often pays off financially in the long term. It makes economic sense mainly when plastering, painting or façade work is pending, because then part of the costs are incurred anyway.
Costs
For a thermal insulation composite system, the costs are often 120 to 180 euros per square metre of façade area. For a single-family house with a façade area of about 150 square meters, this results in between 18,000 and 27,000 euros.
Example calculation
Suppose 150 square meters of façade are insulated.
- Costs: 150 euros per square metre, for 150 square metres = 22,500 euros
- Own contribution for 20 percent funding: 18,000 euros
- Savings: 15 kWh per square metre per year
150 square metres × 15 kWh = 2,250 kWh per year - Energy price: 0.15 euros per kWh
- Savings: 2,250 × 0.15 = 337.50 euros per year
- Amortization: 18,000 ÷ 337.5 = around 53 years
Monthly savings
Based on the example calculation, about 28 euros per month.
Added value
If the façade insulation leads to a better energy class, a five to ten percent price surcharge is realistic. With a property value of 400,000 euros, this corresponds to 20,000 to 40,000 euros. The increase in value is particularly significant if the property improves from a weak to a medium or good efficiency class.
4. Heat pump
A heat pump can reduce running costs, but only if the building is suitable for it. The better the insulation and the lower the flow temperatures, the more efficiently the system works. From a financial point of view, the heat pump is therefore typically not a first step, but a later building block after measures have been taken on the building envelope.
Costs
Depending on the system, building and effort, the total conversion costs from gas heating to heat pumps are on average between 20,000 and 40,000 euros. For the example calculation, the basic funding rate of 50 percent is used. A total of up to 70 percent or 30,000 euros is currently possible for the first residential unit.
Example calculation
Suppose an existing gas heating system is converted to a heat pump with an annual heat requirement of 20,000 kWh. For gas heating, a gas price of 0.10 euros/kWh and 130 euros maintenance costs per year are assumed. For an efficient heat pump, an annual performance factor (COP) of four as well as an electricity price of 0.25 euros/kWh and 140 euros maintenance costs are assumed.
- Costs: a total of 30,000 euros
- Own contribution for 50 percent basic funding: 15,000 euros
- Gas heating costs: 2,130 euros per year
- Heat pump costs: 1,390 euros per year
- Savings: 740 euros per year
- Amortization: 15,000 ÷ 740 = around 20 years
Monthly savings
Based on the example calculation, about 62 euros per month. Especially in view of the prospect of rising CO₂ prices for fossil fuels, the heat pump is an investment that pays off in the long term.
Added value
The installation of a modern heat pump can increase the market value by three to eight percent. For a property worth 400,000 euros, this corresponds to 12,000 to 32,000 euros. The effect increases if the energy efficiency class is improved at the same time and the property is thus considered future-proof.
“The right sequence plays a central role in energy-efficient renovations,” says Jannis Mischke, expert for energy-efficient living at Aroundhome. “In many cases, it makes sense to first reduce heat losses and then modernize the heating technology, as this reduces the overall energy requirement and the new system can be dimensioned more efficiently. Against the backdrop of rising CO₂ prices in the future, this step is also economically advisable in most cases, as inefficient buildings will be subject to greater strain in the future. However, the individual condition of the building is always decisive. If a house is already at a good energy level, it can also make sense to switch directly to a heat pump. Energy-efficient renovation is therefore primarily an economic decision on a case-by-case basis, which takes into account not only running costs but also the long-term value development of the property.”
About the study
For the analysis, Aroundhome compared typical energy-efficient renovation measures in existing buildings. The basis of the example calculations is a single-family house with around 140 square meters of living space and gas heating. Investment costs, possible subsidy shares, annual energy savings, amortization period and potential effects on the property value were calculated.
The applied energy prices, savings potentials per square metre and the typical costs per measure are based on market averages. The calculations serve as a guide and represent simplified model calculations. Individual factors such as the condition of the building, regional price differences, initial energy condition and actual subsidy amount can have a significant influence on profitability in individual cases.
