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

Joost Jansky

Energy consultant, 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 “all energy certificate rules apply immediately” remain wrong. Article 1 (renaming, heating) has applied since 29 July 2026; the EPBD energy certificate rules sit in Article 2 and start on 1 January 2027. Article 9 remains decisive; the next section walks through it with the now-known cut-off dates.

What happens next? From promulgation to entry into force

After the GModG vote on 10 July 2026, enactment and promulgation in the Federal Law Gazette followed on 28 July 2026 (BGBl. 2026 I No. 226). Article 9 therefore applies. The legislative chain:

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

Article 9 of document 21/6278 sets four stages — with promulgation on 28 July 2026, the calendar dates for paras. 1 and 2 are now fixed:

The BBSR GEG information portal summarises briefly: Article 1 = “heating replacement” immediately after promulgation, Article 2 = EPBD rules at the six-month cut-off — here concretely 1 January 2027. In the statutory text, the main transposition for energy certificates is in Article 2 — not Article 1. Article 1 renames the GEG as GModG and mainly covers heating and structural changes; for §§ 79–88 it contains only cross-references (e.g. § 48→§ 36). The revised certificate sections follow in Article 2.

What this means for energy certificates — three stages

For energy certificates, three stages can be distinguished:

Stage 1 (29 July 2026, Article 1): GEG→GModG renaming, heating reform, building automation — for energy certificates only editorial adjustments in §§ 80–85 and new § 108 (fine framework). Not yet the final § 82 data rule, no DIN/TS 18599 switch, no new § 87 listing duty.

Stage 2 (1 January 2027, Article 2): The EPBD core rules apply: new §§ 79–88, DIN/TS 18599:2025-10, Annex 10a (A–G scale for non-residential buildings), digital issuance, annual consumption data over two years under § 82 (latest period ≤ 18 months), extended mandatory disclosures under § 85, new § 87 listing duties, MEPS under § 40/41. Transitional rules in § 112 expressly tie to Article 9 para. 2.

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.

Anyone reading “from 2027” usually means Article 2 — the certificate core rules from 1 January 2027. Software vendors, issuers and API providers therefore have the window until end-2026 for the EPBD rollout. For the current overview see the hub GModG promulgated: the new energy certificate arrives on 1 January 2027.

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 remains selectable only for exclusively residential use — if annual consumption data over two years (§ 82) are available; even a small commercial share excludes the consumption certificate (then demand § 81). 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 exclusively residential use there is freedom of choice — provided annual consumption data over two years 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 build annual data over two years manually.

Under the final § 82, 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 18 months old.

The consumption-data requirement in everyday practice

If you cannot provide annual consumption data by energy carrier over two years (or you miss the 18-month limit), 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 consumption data before the GModG (historical title; align content with the final § 82).

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 2 (1 January 2027) 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 for exclusively residential use and with reliable annual data over two years.
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 annual consumption data over two years; 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 annual data over two years but sale planned soon,
• transaction in the coming months and no valid certificate yet.

Example: you plan to sell in autumn 2026 — a certificate still issued in 2026 under the interim regime remains valid for ten years, but from 1 January 2027 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 from Article 2, 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 1 January 2027 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: Passed on 10 July 2026, promulgated on 28 July 2026 (BGBl. 2026 I No. 226).
• Certificate entry into force: EPBD core rules (Article 2, §§ 79–88) from 1 January 2027; Article 1 (renaming, heating) since 29 July 2026.
• Consumption vs. demand: consumption certificate only for exclusively residential use with annual data over two years (latest period ≤ 18 months); mixed use and non-residential → demand § 81.
• Norm: DIN/TS 18599:2025-10 — efficiency classes can shift without renovation.
• Existing certificates: valid 10 years; issuance until 31 Dec 2026 under the interim regime possible, but watch listing duties from Article 2.
• Software/API: no transition period for vendors; platforms can connect an issuer backend via API.
• Current overview: GModG promulgated — energy certificate from 1 January 2027.

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 — Article 2 is set, forms are not yet available everywhere.

The BBSR GEG information portal publishes 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 from 1 January 2027. Check early whether your annual consumption data over two years suffice for a consumption certificate — and whether your demand class shifts under DIN/TS 18599 before you plan transactions.

Energyausweis.de prepares the DIN/TS switch, digital certificates, and workflows for § 82 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 2 applies from 1 January 2027. Anyone implementing DIN/TS and templates in-house has the window until end-2026. 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 and promulgation have set the course: promulgated on 28 July 2026, Article 1 since 29 July 2026, certificate core rules from 1 January 2027 (Article 2). Core changes (annual consumption data over two years, DIN/TS 18599:2025-10, A–G for non-residential buildings, extended duties) arrive with Article 2 — not already the day after promulgation.

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 interim regime until 31 December 2026 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 shortly before 1 January 2027.

Note: This article documents the post-vote status and was updated in August 2026 to the promulgated law. The statutory text is authoritative (BGBl. 2026 I No. 226); current overview in the hub GModG promulgated: the new energy certificate arrives on 1 January 2027. Not legal advice.

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