Is it worth renovating before a sale — and what does the GModG require?

As at: June 2026

The answer first. Before any sale, it is worth looking at renovation and funding. An older house often loses considerable value without proper assessment — at the same time, not every measure pays off. The Building Modernisation Act (GModG, until July 2026 the Building Energy Act) sets requirements that can be triggered on a change of owner; funding programmes can carry part of the cost. This weighing belongs in the first conversation, not at the end.

The building-modernisation law — until July 2026 the building-energy law — brings together the requirements for the energy efficiency of buildings. On a change of owner through sale or inheritance, insulation duties can apply: for the top-floor ceiling and for accessible heating and hot-water pipes outside heated rooms. A two-year deadline runs from the transfer of ownership. What applies in an individual case depends on the building, its age and the timing — an energy adviser will assess this reliably.

For families taking over an inherited or long-occupied house, one thing above all matters: these duties are no cause for haste and no reason for worry, but a point on the list that can be checked calmly. Many requirements apply only in certain cases, allow for transitional periods, or take effect only when something is done to the building anyway. What is actually binding for your house depends on its year of construction, its condition and the occasion of the change of owner. Blanket statements from the internet often mislead here; a professional assessment by an energy adviser creates clarity before anyone advises on measures.

Anyone selling or letting must present a valid energy certificate and show it to interested parties — this is required by the GModG. The certificate describes the energy condition of the house and influences how buyers assess its value. It is worth having it ready early rather than supplying it under time pressure. A soberly documented condition guards against the blanket markdowns that buyers otherwise apply “just to be safe”.

Energy-efficient renovations are supported nationwide through the Federal Funding for Efficient Buildings (BEG): grants for single measures run through the Federal Office for Economic Affairs and Export Control (BAFA), loans and the heating subsidy through the KfW. The conditions and rates change from time to time, and much must be applied for before a measure begins. An energy-efficiency expert plans the measures and the applications — we name no fixed rates but point to the programmes in force at the time.

Not every euro invested comes back as more than a euro. Sometimes the calmer and better path is to sell the house as it is, with a fair, transparent market and price assessment; sometimes a targeted measure — a new heating system, say, or a current certificate — lifts the value more than it costs. The point is to decide with a market and price assessment in hand, not under pressure. That way you do not sell below value merely because time was short.

Take an older family home that is to be sold after a move into care or an inheritance. The first reflex is often either to renovate everything at once or to touch nothing at all. Both can be a mistake. Set in order, the path looks different: first the energy condition is recorded factually — a valid energy certificate belongs to the sale in any case. Then, with professional help, it is checked which duties the GModG triggers for precisely this house and which of them have time to spare. Only after that can one weigh whether a single, well-funded measure noticeably raises the value, or whether selling in the present condition is the calmer path. Thus a decision arises from an overview rather than from gut feeling — and no one invests in a measure that does not pay off in the end.

We bring the three threads — condition, duties and funding — together into one picture before a sale is decided. We make sure a valid energy certificate is in place and record where the house stands energetically, so that buyers need not apply blanket markdowns. We name the bodies that give binding information: an energy adviser for the duties under the GModG and for planning the measures, the respective programmes for the funding conditions in force, those entitled to advise for tax questions. And we calculate soberly with you whether a measure before the sale is worthwhile or not. We do not take a renovation or sale decision for you, and we do not replace legal, tax or energy advice; we ensure that you decide with a clear view and without time pressure.

This article provides orientation and does not replace legal, tax or energy advice. Duties under the GModG and funding conditions are clarified by an energy adviser and the respective programmes.