Building Modernization Act passed: What happens next for energy certificates?

Joost Jansky

Energieberater, Blogger

This article follows a simple line: It starts with the vote and timelines (Article 9), then turns to certificate content in practice — consumption versus demand, the norm change, Smart, and issuing “in advance”. It closes with a compact overview and an outlook for owners and API partners.

What happened? Bundestag and Bundesrat pass the GModG

On Friday, 10 July 2026, the Bundestag adopted the legislative package amending the German Building Energy Act (GEG) in a roll-call vote — 323 to 271, according to the Bundestag voting page. The basis was the committee version in recommendation 21/7009 building on the cabinet draft 21/6278. On the same day the Bundesrat approved it in agenda item 84 — the parliamentary process is complete (BBSR GModG news).

Press coverage often focuses on heating: the former 65-percent renewable-energy requirement on heating replacement is dropped, replaced by a “bio ladder” with rising biofuel shares from 2029 (Bundestag, calendar week 28/2026). In parallel, the same act implements the EPBD transposition 2026 — with the new DIN/TS 18599 norm, an A–G scale for non-residential buildings, stricter consumption data, and extended duties on sale, letting, and lease renewal (lease renewal and certificate duty).

The new statutory title: Act to Save Energy and Modernise Heat Supply in Buildings (Building Modernisation Act – GModG). Anyone who followed the cabinet draft in spring will find the core certificate points largely unchanged in the passed version — Article 9 on entry into force remained unchanged according to recommendation 21/7009.

Parliament also adopted a resolution: the federal government should push for simplification of the Buildings Directive at EU level (Bundestag, kw28/2026). For your immediate certificate planning that is mostly background — what matters is the national statute and when it takes effect.

Blanket formulas like “with immediate effect” or “all energy certificate rules apply from January 2027” are both wrong. Promulgation will likely follow in a few weeks — then certificate rules from Article 1 can apply very quickly, with no transition period for software vendors, issuers, and platforms. At the same time, not every rule waits until 2027. Article 9 is decisive; the next section walks through it step by step.

What happens next? From promulgation to entry into force

After the GModG vote on 10 July 2026, enactment by the Federal President and promulgation in the Federal Law Gazette remain — only then does Article 9 apply. The legislative chain:

Bundestag ✓ → Bundesrat ✓ → Federal President (enactment) → promulgation in BGBl → Article 9

Typically promulgation comes one to three weeks after the parliamentary vote — there is no fixed date. As of 12 July 2026 the act had not yet appeared in the Federal Law Gazette.

Article 9 of document 21/6278 sets four stages:

The BBSR GEG information portal summarises briefly: Article 1 = “heating replacement” immediately after promulgation, Article 2 = EPBD rules six months later. In the statutory text, the main transposition for energy certificates is already in Article 1 — not Article 2. Article 2 mainly adds renovation requirements for non-residential buildings and further GModG parts.

What this means for energy certificates — three stages

For energy certificates, three stages can be distinguished:

Stage 1 (day after promulgation): New §§ 79–88, DIN/TS 18599:2025-10, Annex 10a (A–G scale for non-residential buildings), digital issuance, stricter requirements for 24 months of consumption data under § 82, extended mandatory disclosures under § 85, fines up to €10,000 under § 108.

Stage 2 (six months after promulgation): Minimum standards under § 40/41 (MEPS) and charging infrastructure under GEIG — mostly secondary for certificate issuance, relevant for owners of office and commercial property.

Stage 3 (2028 and 2030): Zero-emission buildings and life-cycle assessment are long-term topics; you can read more in the Pillar fact check and the overview of all changes.

If promulgation comes in summer 2026 — expected within weeks of the parliamentary vote — Stage 2 would fall in spring 2027. That does not blanket all certificate content from Article 1. Anyone reading “from 2027” should check whether Article 1 or Article 2 is meant — and how quickly things move for software vendors, issuers, and API providers: Article 1 applies the day after promulgation, with no transition period for software vendors.

Example: promulgation on 15 August 2026 → new certificate §§ from 16 August (Article 1). Articles 2 and 7 would apply on 1 February 2027 (sixth calendar month after promulgation). The core rules for consumption and demand certificates therefore do not start only at that February cut-off — but within weeks of the vote on 10 July.

Energy certificates in the GModG: key changes at a glance

The Building Modernisation Act reforms energy certificates on several fronts at once. The table below bundles the main topics by stage. For detailed scale and EPBD context, see the fact check on A–G.

What differs for residential and non-residential buildings

Non-residential and mixed-use buildings will receive only the demand certificate (balance under § 81) — the consumption certificate no longer applies there. For purely residential buildings the choice remains: consumption under § 82 or demand under § 81, provided the respective conditions are met.

At the same time, the former link to the 1977 thermal insulation ordinance for small older buildings drops (§ 80 para. 3 sentences 2–3 GEG today). The consumption certificate becomes selectable for all residential buildings — if 24 months of consumption data are available monthly and by energy carrier. The article on consumption certificate freedom of choice explains the details.

The next section covers which certificate type fits your building — and which data you actually need to obtain.

Consumption or demand certificate — what changes for you

Under the GModG the basic decision remains: consumption certificate (§ 82) or demand certificate (§ 81). For residential buildings there will be freedom of choice — provided 24 months of consumption data are available.

The consumption certificate reflects what was actually consumed — efficient use can yield a better class than demand on an unsanitised envelope. The demand certificate calculates energetic condition independent of heating behaviour — important for buyers comparing building fabric.

Take a rented three-unit house: the heating cost ordinance (HKVO) often already provides structured consumption data — a consumption certificate becomes realistic. In a owner-occupied single-family home without central billing those series are often missing; then the demand certificate is the pragmatic route unless you document 24 months manually.

Under § 82 para. 3 recorded consumption must be weather-adjusted — under DIN/TS 18599-10:2025-10 Table 5, including user behaviour and longer vacancy. The most recent billing period may be at most 15 months old (§ 82 para. 4).

The 24-month requirement in everyday practice

If you cannot provide 24 months of consumption data — recorded monthly and split by energy carrier — you effectively choose the demand certificate. Typical data sources:

• Heating cost statements under HKVO (centrally heated rented MFH),
• utility portals and bills,
• smart meters / intelligent metering systems — optional, not required in all duty cases,
• for owner-occupied SFH without tenant billing, gaps are common — then manual recording or a demand certificate.

You will find a detailed checklist for building your data in the article 24 months of data before the GModG.

Photovoltaics affects consumption and demand certificates differently — you can read more in the article on PV and energy certificate.

DIN/TS 18599 — why efficiency classes can shift

From Article 1 (day after promulgation) DIN/TS 18599:2025-10 replaces DIN V 18599:2018 — for demand certificates, reference buildings, and balance logic (overview of DIN/TS 18599). Main shifts:

• Constructible reference buildings (Annexes 1 and 2) instead of the previous reference building,
• total primary energy including renewable shares (Annex 4),
• new primary energy factors — e.g. electricity 1.5 instead of 1.8, GHG reference 100 g/kWh instead of 560 g/kWh,
• revised calculation for heat pumps, PV yield, and building automation.

In substance: a house rated class C today can slide to D under the new norm without renovation — not because it got worse, but because reference values and calculation rules changed. The BfEE validation report on DIN/TS 18599 (2023 version, final report 09/2024) documents such model-building effects for SFH, MFH, and office use.

For weather adjustment in the consumption certificate Table 5 of the norm applies; for reference buildings and usage zones in balancing Tables 6 and 7 are used — two different tables, two different purposes.

You can read more about MWh mandatory disclosures on the certificate in the article on absolute energy indicators.

The norm change is not only theoretical — it can shift your visible efficiency class on sale or letting before you implement any measure.

Energyausweis Smart™ — why automatic type selection gains importance

Four developments hit owners at once:

1. Freedom of choice for the consumption certificate — but only with reliable 24-month data.
2. Data gaps for many owners who previously relied on demand.
3. Class uncertainty through DIN/TS 18599 — demand and consumption can diverge.
4. Transaction pressure from extended duties (lease renewal) and fines up to €10,000 (§ 108).

Energyausweis Smart™ calculates demand and consumption certificates from one dataset and checks which variant delivers the better efficiency class — the more favourable of the two is issued, not two separate documents. This requires a reliable data base: for the consumption part you need 24 months of consumption data; without them, only the demand certificate can be evaluated.

Energy certificate “in advance” — sensible strategy or risk?

An energy certificate issued in advance — i.e. before GModG entry into force — can be an option for some owners. In principle every energy certificate is valid for ten years from issuance (§ 113 GEG). Anyone who issues before entry into force still under the current GEG receives a document under today’s rules — unchanged for the certificate’s lifetime in principle (validity and EU rules).

When “in advance” is worth considering:

• unclear effect of DIN/TS 18599 on your demand class,
• missing 24-month data but sale planned soon,
• transaction in the coming months and no valid certificate yet.

Example: you plan to sell in autumn 2026, promulgation comes in August — a certificate issued in July under the old GEG remains valid for ten years, but after entry into force you must observe new mandatory disclosures in listings (§ 112 para. 3). Whether “in advance” pays off depends on your class under DIN/TS 18599 and your sale timing.

Limitation: on sale or letting after entry into force, new presentation and disclosure duties apply — even if the certificate itself is still valid. § 112 para. 3 governs old mandatory listing disclosures for certificates issued before the six-month cut-off (Art. 9 para. 2). That does not make the certificate worthless — only that listings may require different information.

Whether “in advance” fits your case cannot be answered in the abstract. When in doubt, ask your issuer or energy adviser.

Overview — the essentials at a glance

• Status: Bundestag and Bundesrat passed on 10 July 2026 — promulgation in the BGBl still pending (as of 12 July 2026).
• Certificate entry into force: core rules (Article 1, §§ 79–88) day after promulgation — expected within weeks, no software transition period; Articles 2/7 six months later.
• Consumption vs. demand: residential freedom of choice with 24 months of monthly consumption data; non-residential demand only.
• Norm: DIN/TS 18599:2025-10 — efficiency classes can shift without renovation.
• Existing certificates: valid 10 years; “in advance” possible, but watch listing duties on transactions.
• Software/API: no transition period for vendors; platforms can connect an issuer backend via API.

Outlook and conclusion

What still follows promulgation

After promulgation, notices in the Federal Gazette typically follow: new templates under § 85 para. 3 and data formats under § 88b. Until then software providers and issuers face a practical gap — the law applies, forms are not yet available everywhere.

The BBSR GEG information portal will publish cut-off dates and guidance. Sample checks under § 99 can still run for certificates until 31 July 2027 (issued after Art. 9 para. 2) after the cut-off — that concerns enforcement, not a software moratorium.

For owners and sellers: a valid certificate does not automatically satisfy new listing and presentation duties. Check early whether your 24 months of consumption data suffice for a consumption certificate — and whether your demand class shifts under DIN/TS 18599 before you plan transactions.

Energyausweis.de tracks promulgation and cut-off dates and prepares the DIN/TS switch, digital certificates, and workflows for 24 months of consumption data — concrete go-live dates depend on template notices.

API partners — outsourcing regulation

Property management platforms, PropTech, and estate-agent software often want energy certificates as a feature — without in-house energy advisers or norm software. For API partners the offer from Energyausweis.de is: “Energyausweis.de handles timely implementation and keeps the regulatory burden off your desk.”

Concretely on the issuer side Energyausweis.de takes on: monitoring promulgation and cut-offs, adapting API schema and validation, DIN/TS calculation, digital output including registration, validation of § 82 consumption data, and current mandatory fields under § 85/87. Partners supply structured payloads and their own UI — UI, data collection, consents, and contract law stay with you. “Off your desk” means: no in-house compliance tracking for GModG, DIN/TS, and templates — not “no data duty”.

Read more for platforms in the articles on GModG for property management platforms and Energy certificate API for online portals. You will find the technical documentation at energyausweis.de/api.

Software vendors vs. API partners

The explanatory memorandum to 21/6278 assumes €380 software adaptation cost per office — routine maintenance. The act provides no explicit transition period for vendors; Article 1 applies the day after promulgation — and because promulgation is expected within weeks, the implementation deadline is closer than it first appears. Anyone implementing DIN/TS and templates in-house faces time pressure. API partners connect one stable interface to a backend that absorbs norm and template updates — without in-house DIN/TS development.

What to do next — six steps after the GModG vote

The parliamentary vote alone does not require a new energy certificate — but anyone planning to sell, let, or issue anew should clarify legal status, timelines, and data now:

Conclusion

Parliament has set the course — for energy certificates the clock starts only with promulgation. Core changes (24 months of consumption data, DIN/TS 18599, A–G for non-residential buildings, extended duties) arrive with Article 1 already the day after promulgation. Because promulgation is expected within weeks, things can move very quickly and put software vendors, issuers, and platform providers under pressure — with no statutory transition period.

In practice: review your consumption data, plan transactions ahead, and when unsure check which certificate variant delivers the better class — e.g. via Smart certificate, if the data base allows, or in separate commissions. Anyone who can still issue under the current GEG should weigh “in advance” with the limitations above. No need to panic — but if a sale or new letting is coming, plan now rather than under time pressure after promulgation.

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