GModG for marketing agencies: the energy performance certificate as lead lever and service stack for real-estate clients

Joost Jansky

Energieberater, Blogger

Note — cabinet draft, not yet binding law. Status: cabinet decision of 13 May 2026. Entry into force only after Bundestag, Bundesrat and promulgation. Specific section references relate to the cabinet draft; the likely wording is quoted in detail in the overview fact-check.

Three levers solve this, in order: lead liberation on the landing page, service card stacked alongside GDPR and BFSG, and mandate protection before the first UWG cease-and-desist letter hits your client. The fine cap of EUR 10,000 under § 108 GModG draft hits the advertiser, not you — but if you do not act, the economic pain ends up in your ROAS dashboards and in your retainer.

What § 87 GModG changes for your real-estate clients' listings

One section carries the whole article. § 87 GModG draft replaces the final energy demand in the mandatory listing text with the primary energy demand and adds the date of issue as a new mandatory disclosure. § 108 (fine offences) and annex 4 (primary energy factors) flank the rule — but the economic risk is rarely the fine; it is the UWG cease-and-desist letter. The Federal Court of Justice settled that constellation in 2017 (BGH I ZR 232/16): mandatory energy-certificate disclosures in listings are market-conduct rules under § 3a UWG; breaches can be cease-and-desisted. The full client-side mechanism — §§ 80, 87 and 108 side by side, with the three-offence list and a four-week roadmap — is described in the sister article GModG for estate agents.

Primary energy instead of final energy

The switch sounds like a wording change but is a metric change. Final energy is what arrives at the building — electricity, gas, wood. Primary energy multiplies that figure by a factor that captures upstream losses. In annex 4 of the GModG draft, the factor for electricity (heat-pump heating) drops from 1.8 to 1.5; for wood and pellets it rises from 0.2 to 0.7. Consequence: a heat-pump house tends to move into a better class in the listing, a pellet house into a worse one — without any change to the building. Copy, briefings and listing templates of your clients that still display final energy values become factually wrong on the day after promulgation.

The residential A+ to H scale stays final-energy-based under § 86 (2) GModG draft; that is a structural weakness that may yet be adjusted in the parliamentary process. The listing now carries the primary energy value alongside it — and that value moves as soon as the new factors apply. Existing certificates retain the final-energy disclosure in the listing under § 112 (3) GModG draft until they expire — both paths must be representable in listing back-ends and CMS templates.

The cease-and-desist letter is the costlier pain

Enforcement of § 108 is restrained. Where fines are imposed for listing breaches, they tend to sit in the low three- to four-digit range; Deutsche Umwelthilfe speaks of enforcement deficits. The economically real lever is the UWG cease-and-desist letter from competitors, qualified associations or the Wettbewerbszentrale. A signed cease-and-desist undertaking typically costs your client 3,000 to 5,000 EUR per breach as a contractual penalty; warning costs come on top. The Ingolstadt Regional Court ruled in June 2023 that mandatory disclosures in the exposé alone are not enough — the listing itself must carry them.

Lever 1 — Lead liberation: what listing stand-still costs your clients

The German property portals already validate mandatory disclosures in the publishing back-end. ImmoScout24 requires certificate type, final energy consumption, efficiency class, energy carrier and year built; Immowelt validates similarly. Listings without those disclosures are returned for correction or rejected — they simply do not go live. Once § 87 GModG takes effect, a back-end migration of the portals is to be expected: final energy turns into primary energy as the mandatory disclosure, the date of issue becomes its own mandatory field. Your clients' existing listings inevitably end up in the re-validation loop during the transition. That is not a compliance detail; it is directly visible in every ROAS dashboard.

A worked example (conservatively scoped)

Picture a mid-sized property developer as an existing mandate: 25 active listings, EUR 5,000 weekly budget on performance search campaigns, blended CPL at EUR 80 — the upper end of the DACH range that agencies such as ostend.digital cite for developer setups. If, after the GModG enters into force, one fifth of those listings has no § 87-compliant certificate — expired certificate, missing primary energy disclosure or annex 4-shifted class — roughly EUR 1,000 of weekly media budget burns. Over twelve weeks that is about EUR 12,000 of wasted budget; the five missing certificates would cost between EUR 2,000 and 3,000 to procure at EUR 400–600 apiece.

The 20 % gap rate is an example, not a measurement. Any agency that inventories its real-estate mandates — expiry dates, final-energy versus primary-energy status, certificate type — gets its real rate. That becomes the first sentence of the account review: "We have run your 25 active listings against § 87. In five, the mandatory disclosure no longer matches the wording that applies from day one — that is roughly EUR 1,000 of media budget per week. Two days of preparation per mandate clears it."

The clean operational answer is not a spreadsheet but an order embed directly on the client landing page. The client sees the status of their certificates, orders what is missing in three clicks, and the result flows back into the listing back-end as structured data.

Lever 2 — Stack-the-brick: the energy certificate as the next service card

Lever 1 saves media budget. Lever 2 changes the agency's revenue model. Marketing agencies with real-estate clients have monetised compliance cards for years — GDPR privacy notices, cookie-consent reseller deals (Cookiebot, Usercentrics, OneTrust), legal-notice and T&C audits, and since 2025 BFSG audits including WCAG 2.1 remediation. Energy certificate compliance slots seamlessly into that line-up. The BFSG is the right model: the addressee is the website operator, not the web agency — and a service business of its own has emerged from exactly that constellation since June 2025.

Web agencies are not directly addressed by any of these obligations — the obligation always sits with the client offering the service. Even so, hundreds of agencies have built BFSG audit packages, WCAG remediation and maintenance retainers since 2024: the client carries the obligation, but only the agency can deliver the solution. § 87 GModG follows the same logic — § 87-compliant listing templates, an inline ordering process for missing certificates and structured JSON-LD all come from the agency. The Datenschutz-Generator guide describes this indirect tying of web agencies in detail.

The mandatory metrics from § 87 are clean, well-researched data points anyway. Embedding them as JSON-LD into the listing makes life easier for crawlers. Schema.org has no official energy-class property on RealEstateListing for residential buildings; the established pattern uses LocationFeatureSpecification inside the Accommodation block — as documented in the WP-ImmoMakler schema docs. When the ordering process delivers structured API responses, the block fills itself — including the DIBt registration number as an E-E-A-T anchor. That is not a ranking promise but clean data hygiene for SEO and content teams.

Lever 3 — Mandate protection: the real agency risk

Lever 2 builds revenue; lever 3 protects the book of business. The UWG cease-and-desist letter formally targets your client — § 87 GModG draft names sellers, landlords, lessors, finance lessors and estate agents as advertisers. At first glance the agency seems out of harm's way. In practice the risk runs along two legal tracks — and a third, operational pain point sits at the heart of the matter.

External: § 8 (2) UWG pulls the agency into the client's risk

§ 8 (2) UWG makes the advertising company — your client — liable, regardless of fault, for unfair-competition breaches by its agents. Advertising agencies, performance marketing providers, affiliate partners and platform operators all fall into that category under settled case law. The Federal Court of Justice reaffirmed the reach of this agent liability with its judgment of 11 March 2026 — I ZR 28/25. The claim formally targets the client, but the agency's conduct is attributed to them — and the second track opens automatically.

Internal: the agency's contractual duty of care

If the agency delivers a performance ad or landing page that is unusable because of § 87 GModG, the work is contractually defective (§§ 633, 634 BGB). The client may refuse acceptance, claim a price reduction or demand damages. Settled case law since BGH VII ZR 49/71 holds that the agency must warn the client about legal concerns regarding advertising; even a pure execution mandate carries an advisory duty (OLG Hamm 26 U 198/86). Consequence: a UWG contractual penalty of 3,000 to 5,000 EUR plus warning costs can be passed on by the client to the agency — unless the client carries predominant contributory negligence (§ 254 BGB), for example because they supplied faulty data.

The account-review question

Both legal tracks rarely produce the acute pain. The acute pain hits during the account review after the first cease-and-desist letter. The client asks — rarely in this exact form, but in this spirit: "Why did this take us by surprise? You have been running our listings for three years." The answer determines whether the agency stays positioned as a trusted advisor or becomes interchangeable at the next contract renewal. Real-estate retainers typically range between EUR 12,000 and 60,000 per year per client; a lost retainer is economically much more expensive than any contractual penalty.

The pitch for your next account review

Three slides, five minutes, a clear plan — that structure works in every real-estate account review between now and entry into force. It makes the client the hero of the story, the agency the trusted advisor, and avoids compliance-anxiety tonality.

Slide 1 — Status quo (90 seconds): an inventory of your client's advertising. How many active listings? Which mandatory metric is on file? Which certificates expire in the next twelve months? Which heating mix dominates the portfolio? Data-driven, about 30 minutes of preparation per mandate.

Slide 2 — Risk and opportunity (90 seconds): the worked example from lever 1, with the client's real numbers. Weekly budget × gap rate = burned media budget per week. Next to it the UWG contractual penalty range and the annex 4 PEF shift with the properties that move into a different class. One slide, three columns.

Slide 3 — Two-phase plan (60 seconds): a four-week pilot with one chosen mandate (embed module, inventory, JSON-LD block); then an eight-week rollout to further mandates, optionally with a reseller model as recurring revenue.

Talk-track sample: "We took a look at the GModG for you. Today you have X listings, Y of them with expiring certificates or outdated mandatory disclosures. In a four-week pilot we will deliver this for your flagship properties — we handle the ordering and maintenance, you keep data accuracy and briefing. Which account is the right pilot?"

What does not belong in this pitch: fine threats, compliance anxiety, blanket urgency formulas. The carrying argument is commercial — saved media budget, a new service card, an extended retainer.

How do you plan today?

Seven steps for the next six to twelve weeks before the GModG is promulgated:

1. Take stock of the real-estate client — active listings, expiry dates of the certificates, final-energy versus primary-energy status. Also list templates that hard-code "final energy demand" or "final energy consumption" as a column heading; they will be factually wrong on the day after promulgation.
2. Calculate risk and opportunity — CPL × gap rate shows the burned media budget; alongside, the UWG contractual penalty range and the annex 4 PEF shift per property.
3. Set up a four-week pilot with one existing mandate — preferably a mid-sized, communicative client whose listings are actively marketed.
4. Integrate the embed module into the pilot landing page — ordering, certificate status and data return, all via the API.
5. Move the mandatory disclosures into structured JSON-LD — LocationFeatureSpecification with the DIBt registration number as an E-E-A-T anchor.
6. Sharpen T&C and engagement clauses on data accuracy — who delivers the § 87 data, who checks it, who is liable for errors; this reduces the agency's contractual liability for defective work via § 254 BGB contributory negligence.
7. Eight-week rollout — the same setup applied to further real-estate mandates; optionally with a reseller model as recurring revenue.

This sequence is the script for the pilot rollout — and at the same time the HowTo schema block that search engines use for voice assistants and featured snippets.

Certificate ordering as a platform feature: the energyausweis API for agencies

Do not build your own certificate generator. The building physics behind it — DIN V 18599, annex 4 primary energy factors, plausibility-checked consumption values from three heating periods — is not in the wheelhouse of a marketing agency. The operational answer is an API that delegates issuance to certified energy auditors and returns the result as structured JSON.

The lead touchpoint stays with the agency. Instead of redirecting your client to an external provider, the ordering process runs on the agency-owned landing page: status, re-order, lead time and pricing — all in the same frame. Three trust signals carry over 1:1: certified energy auditors who personally review every certificate, the DIN V 18599 quality seal, and the DIBt registration number as a verifiable entry in the federal register. The client's compliance pressure becomes trust.

Once the API integration is in place, the GModG switch is an event, not a project: from the day of promulgation the API delivers the new mandatory text, the new primary energy factors and the date of issue as a mandatory field — the agency does not have to maintain anything. Referral commissions per certificate are available through the energyausweis partner programme; we discuss the specific terms individually. More on the API itself, OpenAPI 3.1.2 and the Scalar sandbox in the API pillar article.

FAQ

We are only a marketing agency — do we have to deal with § 87 GModG at all? You are not the direct addressee — § 87 GModG draft addresses the advertiser. Even so: when paid clicks land on listings that are not approved, ad budget burns. When landing pages display outdated mandatory disclosures, those are attributed to the client through § 8 (2) UWG. When the client asks after a cease-and-desist letter why the agency was not prepared, the retainer is on the line. Your clients carry the obligation, the operational solution comes from you.

What changes for our real-estate clients on the day after promulgation of the GModG? The listing duty switches from final energy demand to primary energy demand, the date of issue becomes a new mandatory disclosure, and the primary energy factors in annex 4 shift individual classes. The fine offences in § 108 (presentation, handover, listing duty) apply from stage 1 (the day after promulgation); the renaming GEG → GModG follows only six months later in stage 2. Existing certificates retain the final-energy disclosure in the listing under § 112 (3) GModG draft — until they expire.

How high is a UWG cease-and-desist letter for faulty mandatory disclosures? In practice, contractual penalties for UWG cease-and-desist letters over energy certificate disclosures typically run from 3,000 to 5,000 EUR per breach. Warning costs come on top. After a signed cease-and-desist undertaking, the contractual penalty falls due for each further faulty advertisement. The penalty assessment follows § 13a UWG (nature, scope, consequences, size of the addressee); the Act itself sets no fixed amounts.

Can we embed the energy certificate ordering process into a client landing page? Yes — that is the standard solution. The energyausweis API offers embed modules for landing pages and CMS templates; status, re-order and data return stay in your UI. Reach the partner team via /kontakt.

Which revenue model makes sense for the agency? Three streams that combine well: a one-off setup fee per mandate (inventory, embed integration, JSON-LD, T&C update — volume comparable to a BFSG audit), a recurring compliance retainer for monitoring and disclosure updates, and a referral commission from the API partner programme. We discuss specific margins individually.

What changes for SEO content with energy metrics? Copy that references final energy values as a mandatory metric becomes factually wrong from stage 1. Briefing templates must be migrated to primary energy and the date of issue. Structured JSON-LD via LocationFeatureSpecification can be auto-populated — the DIBt registration number as an E-E-A-T anchor.

Does the A+ to H scale stay in place for residential buildings? Yes. § 86 (2) GModG draft keeps the residential-building classification unchanged; it is still calculated from the final energy value. The listing now shows the primary energy value alongside it. This split is a structural weakness of the draft that may still be adjusted during the parliamentary process. More detail in the pillar fact-check.

Conclusion: three levers for your next account review

Lever 1 — lead liberation: the inventory plus the worked example shows how much media budget your real-estate clients lose without preparation. Lever 2 — stack-the-brick: stack certificate compliance as the next service card, with BFSG as the operational model and JSON-LD as the SEO bonus. Lever 3 — mandate protection: § 8 (2) UWG on the outside, contractual diligence on the inside, account-review credibility on top.

If you do not pull these three levers, the inverse picture awaits: media budget drifts unused through listings that were not approved, competing agencies claim the new service card first, and the first real-estate client with a UWG cease-and-desist letter asks the awkward question in the account review. The preparation effort is modest — the consequences of skipping it are not.

This week, set up an account-review meeting with your largest real-estate client. Three slides, five minutes, a clear plan — the template is in the pitch section above.

Three next steps:

1. API documentation and try-it — OpenAPI 3.1.2, Scalar sandbox.
2. Bespoke package solutions — reseller terms, custom setup.
3. Pillar fact-check — the deep context for §§ 79–88, annex 4 and the A–G scale.

Legal note. This article refers to the cabinet draft of the Building Modernisation Act of 13 May 2026. Bundestag and Bundesrat may make changes before promulgation. Phrases such as "draft", "envisaged" and "after entry into force" used in the text are to be understood in that sense. Specific section references may differ slightly in the final statute.