Energy-efficiency renovation: planning beats overpaying

The right sequence for renovating

Many renovations end up costing more than necessary because the measures are tackled in the wrong order. The classic example: the heating system is replaced first, and insulation and new windows follow a few years later. The result is a system that is oversized for the renovated building. Those who sequence the steps correctly get more out of every euro invested. The proven rule of thumb is easy to remember: analysis first, then the envelope, and the technology last.

The analysis comes first

It all starts not with a construction site but with a qualified energy consultation. It looks at the building as a whole: where is heat being lost, which measures work together, what takes priority? This forms the basis for a roadmap that puts the measures into a sensible order (more on this in the next section). The big advantage: from then on you no longer decide by gut feeling but on the basis of an expert analysis, and before the first quote is even obtained.

Then the envelope

The second step is the building envelope: the top-floor ceiling or the roof, the windows, the facade and the basement ceiling. Only once the envelope is insulated is it clear how much heat the building actually still needs. That very information is worth its weight in gold later, when the new heating system is being designed.

The technology comes last

The final step is the building systems, above all the heating. The reason for this order: the new system is sized to match the renovated building. An insulated building needs less heating capacity; replacing the heating first and insulating later risks an oversized and therefore unnecessarily expensive system. There are exceptions, of course, for instance when the old heating system suddenly fails. All the more valuable is a roadmap that thinks such cases through in advance.

The individual renovation roadmap (iSFP)

The most important tool for renovating with a plan is the individual renovation roadmap, or iSFP for short. It is drawn up by the energy consultant and puts the measures for your building into a sensible, coordinated order. It gives you a document that serves as a common thread for years: every individual measure fits into an overall picture instead of being planned in isolation.

The iSFP is attractive twice over: its preparation is itself subsidised by the state. And it additionally brings a subsidy bonus of 5 percentage points on many individual measures on the building envelope and building systems. Only heating replacement is excluded from this bonus.

Subsidies at a glance: BAFA, KfW and the tax bonus

The German state subsidises energy-efficiency renovations through the federal funding scheme for efficient buildings (BEG). Depending on the measure, the route runs through the federal office BAFA or the state development bank KfW; owner-occupiers also have a tax-based alternative. One important note up front: all figures are given as of July 2026. Funding programmes change, so check the conditions again immediately before commissioning any work.

As of July 2026. Programmes change, so check the current conditions before commissioning.

In practice this means: individual measures such as new windows or basement ceiling insulation run as BAFA grants, and with an iSFP many of these measures get 5 percentage points on top. Heating replacement has its own funding world at KfW: a 30 percent basic subsidy, plus various bonuses, capped at 70 percent in total. Which bonuses exist and which deadlines apply is covered in our guide to Germany's heating law (GEG). Those who bring the entire building up to an efficiency-house standard in one go use a KfW loan with a repayment grant: part of the loan then does not have to be repaid.

The alternative for owner-occupiers: the tax bonus under Section 35c EStG

If you live in your own home, you have a second option: instead of the subsidies, you can deduct 20 percent of the costs of energy-efficiency measures on your owner-occupied home from your taxes, spread over 3 years (Section 35c of the German Income Tax Act, EStG). Important: the tax bonus cannot be combined with the subsidies. For each measure, you decide which route works out better for you, grant or tax bonus. A quick comparison of both routes before commissioning is therefore part of any good plan.

Obligation to renovate? What actually applies

No general renovation obligation

First, the reassuring news: there is no obligation to bring an entire building up to a particular energy standard. The EU Buildings Directive (EPBD), adopted in 2024, does not fundamentally change this either: it sets average targets per member state; it does not mandate the forced renovation of individual residential buildings. Germany has yet to transpose the directive into national law (as of July 2026). In all honesty: the requirements for buildings will keep evolving. But those who renovate with a plan do so on their own initiative and to their own advantage, not under compulsion.

These GEG obligations apply nonetheless

Regardless of any renovation plans, Germany's Building Energy Act (GEG) already requires a few things today:

• Top-floor ceiling: the ceiling towards unheated attics must be insulated (minimum thermal protection).
• Pipes: accessible heating and hot water pipes in unheated rooms must be insulated.
• Change of ownership: after a change of ownership, certain retrofit obligations must be fulfilled within 2 years.
• Renovations happening anyway: if a building component is being renovated anyway, for example the facade is being re-rendered, minimum energy requirements apply to that component.

How the WEG approves an energy-efficiency renovation

In a condominium owners' association, insulation, windows and the heating system almost always concern the common property. That puts the owners' meeting in charge, and the bar is lower than many think: the meeting approves energy-related measures on the common property with a simple majority (Section 20 of the German Condominium Act, WEG).

The more interesting question is who pays. Here Section 21 WEG applies: if the resolution achieves a doubly qualified majority, meaning more than two thirds of the votes cast and at the same time more than half of the co-ownership shares, all owners bear the costs. The same applies if the measure pays for itself within a reasonable period. In all other cases, only the owners who voted in favour pay. How resolutions, majorities and challenges work in general is explained in our guide WEG and the law.

Three funding routes in the WEG

Little can be said about costs in general terms: the range runs from a few thousand euros for individual measures to six-figure sums for full renovations of large buildings. What matters is that the funding fits the measure. The association has three routes available:

In practice, combinations are common: part from the reserve, the rest via a special levy or a loan. The basics of loans and terms are covered in our guide to property financing.

The role of the property manager

An energy-efficiency renovation is a project with many parties involved: energy consultants, specialist contractors, funding bodies, owners. This is exactly where a good property management company shows its value. It coordinates the energy consultation, obtains quotes, prepares the resolutions for the meeting, supports the subsidy applications (often together with the energy consultant and the contractors) and keeps track of the implementation. For you as an owner, this turns an intimidating major project into a sequence of well-prepared decisions.

Renovation experience is not standard, however: 202 of the 2,176 property management companies in our directory state that they support energy-efficiency renovations (as of July 2026, our own analysis of our directory). So it pays to ask about it specifically when choosing one.

Frequently asked questions about energy-efficiency renovation

This guide was prepared with great care (last updated: July 2026) but does not replace energy, legal or tax advice for your individual case. Funding programmes change; the funding bodies' current conditions always prevail. For special situations, an energy consultant, a tax advisor or a law firm specialising in German condominium law can help.