5 min read
Renovation Obligations: Understanding the GEG (Heating Law) in Germany
Since 29 July 2026 the GEG is the Building Modernisation Act. What buyers of older German houses must still retrofit after purchase, with deadlines.
Table of Contents
Germany's Building Energy Act (Gebäudeenergiegesetz, GEG) has been called the Building Modernisation Act (Gebäudemodernisierungsgesetz, GModG) since 29 July 2026, following the amending act of 23 July 2026 (Federal Law Gazette 2026 I No. 226). The 65 % renewable rule and the 30-year boiler ban are gone. If you buy an older house, you may still have two retrofit duties with a two-year deadline: insulating the top floor ceiling and insulating exposed heating and hot-water pipes in unheated rooms.
What the 2026 reform removed
In the official text, sections 47 to 55 and 71 to 73 are now marked "weggefallen" (repealed), and several other sections have new numbers. There is no longer a duty to use 65 % renewable energy when replacing a heating system, and no duty to shut down oil and gas boilers after 30 years. You may keep running a working system, and sections 42 to 46 GModG govern any replacement.
Test this investment idea on your own address
Pick a location and enter the purchase price. We'll prepare rental yield, cash flow, tax impact, and the cost breakdown as a private report.
What still applies after you buy
Two retrofit duties apply to all residential buildings. For houses with one or two dwellings where the owner lived in one of them on 1 February 2002, the duties only apply to the new owner after a sale. The deadline is two years from the first transfer of ownership after 1 February 2002.
Top floor ceiling (section 35 GModG): if the top floor ceiling does not meet the minimum thermal protection of DIN 4108-2, it must be insulated to a heat transfer coefficient (U-value) of no more than 0.24 W/(m²K). Insulating the roof above it to the same standard also satisfies the rule.
Heating and hot-water pipes (section 69 GModG): accessible pipes in unheated rooms, such as a cellar, that have never been insulated must be insulated to the standard in Annex 8 of the act.
How this plays out depends on the house's history:
The seller lived there on 1 February 2002 and yours is the first sale since: your two years start when ownership passes to you on entry in the land register.
The house has been sold before since 2002: the deadline ran for that earlier buyer. If the work was never done, the duty is already overdue when you buy.
The house was rented out on 1 February 2002: the duty already applied to the owner at the time, with or without a sale.
Owner-occupiers of one- and two-dwelling houses can skip the ceiling insulation if energy savings would not recover its cost within a reasonable period (section 35(4)); landlords cannot.
Ask the seller for the contractor's declaration (Unternehmererklärung). A contractor must issue one after insulating a ceiling or pipes (section 96 GModG). If there is none, budget for the work; the cash flow calculator lets you add the cost as a renovation item.
Energy certificate and the buyer consultation
The seller or agent must show you the energy certificate (Energieausweis) at the viewing at the latest, and hand it over after the purchase contract (section 80(4) GModG). If you buy a residential building with no more than two dwellings, you must then have an informational consultation about the certificate with a person licensed to issue energy certificates. The duty applies where such a consultation is offered free of charge.
Have the German certificate and its modernisation recommendations explained before the notary appointment; they help you set a realistic maintenance reserve.
If you install a new gas or oil heating system
A new gas, oil or liquefied-gas heating system installed in an existing building after 29 July 2026 must get a rising share of its heat from biomethane, bio-oil, biogenic liquefied gas or hydrogen (section 43 GModG):
From | Minimum share |
|---|---|
1 January 2029 | 10 % |
1 January 2030 | 15 % |
1 January 2035 | 30 % |
1 January 2040 | 60 % |
Section 42a announces a separate law on a green gas and green heating oil quota, which the federal government is to present by 1 December 2026. That law has not been adopted yet.
Apartment buildings: heating check by September 2027
In a building with at least six units, a water-based heating system installed before 1 October 2009 must be checked and optimised by 30 September 2027; later systems (other than heat pumps) within a year after they turn 15 (section 60b GModG).
Who checks, and what it costs to ignore
The district chimney sweep checks at the regular inspection whether pipes that had to be insulated are still bare, sets a deadline and reports you to the state authority if nothing happens (section 97 GModG). Not insulating the ceiling or pipes is an administrative offence (section 108).
Subsidies for a new heating system
KfW, the federal development bank, pays a 30 % base grant for climate-friendly heating in residential buildings, landlords included. Only owner-occupiers can add bonuses; the total is generally capped at 70 %, or 80 % for low-income owner-occupiers. For a single-family house, eligible costs are capped at €28,000 (KfW programme 458). As a landlord you can therefore receive at most €8,400.
Note the order: you need a contract with a contractor that is conditional on the grant before you apply, and you must apply before work starts. KfW will lower the cap and the owner-occupier speed bonus in steps from 1 February 2027.
Frequently asked questions
Do I have to replace an old oil or gas boiler after buying?
No. The operating ban for old boilers was repealed with effect from 29 July 2026. A change of ownership alone no longer triggers a replacement duty.
Does the two-year deadline apply when I buy an apartment?
No. That rule only covers buildings with at most two dwellings; in larger buildings the duties apply regardless of a sale. Check the minutes of the owners' meetings to see whether the work has been done.
This article is not tax, legal or investment advice.
