Consumption or demand certificate: which one do you actually need?

You want to sell or let a property and are faced with two certificate types with very similar names. This article is written for owners of residential buildings who have to decide exactly once and never want to think about it again. The answer hangs on two numbers: the number of flats and the date of the building application.

One thing first: in many cases there is no choice at all. Where there is one, the two certificates do not differ in legal status but in their data basis — and therefore in what they say about your building. The article first names the criteria, then shows the statutory assignment, compares both types, explains what changes on 1 January 2027, and closes with a recommendation for the case that you may choose freely.

#What this comparison is based on

The comparison runs along five criteria that have proved decisive in practice: the data basis, the statement about the building fabric, the dependence on occupant behaviour, the effort of preparation and the price. Everything else — validity period, efficiency class, duty to present — is identical for both certificate types and therefore useless for telling them apart.

What both certificates cost and where the difference comes from is explained in detail under energy performance certificate costs. This article is about the question that comes before it: which of the two is even permitted for your building. If you first want to know what an energy performance certificate is and what it is needed for, the German overview article covers that.

A word on the name of the law: since 29 July 2026 the Building Energy Act (Gebäudeenergiegesetz, GEG) has carried the title Building Modernisation Act (Gebäudemodernisierungsgesetz, GModG). The title changed, the numbering did not — the sections on the energy performance certificate are still where they were. Wherever you still read “GEG”, the same law is meant.

#When you have the choice and when you do not

The assignment is laid down in § 80 (3) of the Building Modernisation Act.2 It hinges on two characteristics: the number of flats in the building and the date of the building application. Both apply to certificates issued up to 31 December 2026 — what applies afterwards is explained further down.

There is one practically important exception to the rule in the first row: if the building meets the requirement level of the 1977 Thermal Insulation Ordinance (Wärmeschutzverordnung) — either from the outset or through later modernisation — a consumption certificate is sufficient there too. Anyone who can prove such a measure should keep the documents to hand.

Two further cases lead to the demand certificate regardless: the new building, for which § 80 (1) GModG requires a demand certificate to be issued immediately after completion, and the building without consumption data — without bills, the consumption certificate simply has no basis.

How much “enough bills” is, is defined in § 82 (4) GModG,4 and it is often reproduced too loosely. What is required is 36 consecutive months, and the most recent billing period must not be more than 18 months old when the certificate is issued. Taken together this means: a gap of one quarter in the middle makes the series unusable, and so does a pile of old bills from a house that has stood empty for two years.

Read in sequence, these are four questions, and the first applicable answer decides:

With these details the question can be answered — and once you know the certificate type, ordering it online takes about a quarter of an hour.

#Method: where the information comes from

All legal statements in this article are taken from the Building Modernisation Act in its current version; the sections relied on are named in the text, and the small superscript numbers lead to the list of sources at the end of the page, where every section is linked. The classification into efficiency classes follows Annex 10 of the Act. The legal position from 1 January 2027 comes from Article 2 of the amending Act of 28 July 2026, also linked at the end.

The prices are our own and apply to online preparation without a site visit. Statements about how meaningful the two procedures are rest on their calculation basis, not on a survey of our own — the consumption certificate evaluates measured consumption, the demand certificate calculates according to DIN V 18599, from 2027 according to DIN/TS 18599: 2025-10.

#The result at a glance

#What the consumption certificate does

The consumption certificate evaluates what was actually used: the bills for heating and hot water from 36 consecutive months, weather-adjusted and related to the building’s usable floor area. It therefore describes how the building is run, not its structural condition.

Two corrections are built into this figure: the weather adjustment removes the effect of a mild or a hard winter, so that a certificate from a warm year does not look better than one from a cold year. The hot-water share is added as a flat rate where the bills do not include it.

That is its strength and its weakness at the same time. A frugal household in a poorly insulated house produces a good figure; a family with small children in a well-insulated house a worse one. Anyone who wants to judge a building’s energy performance learns little from the consumption certificate — anyone who wants to know what a tenant can expect to pay day to day learns a lot.

Vacancy shows through as well: if part of the building stands empty for a longer period, consumption falls without anything about the house having changed. That is what the vacancy correction is for — it removes the unused share, but it presupposes that the share was stated correctly.

#What the demand certificate does

The demand certificate calculates. Its basis is the components of the building envelope — walls, roof, windows, basement ceiling — and the technical systems for heating, hot water and ventilation. From these the energy demand under standardised conditions is derived, independent of who lives in the house and how they heat.

That makes it the only one of the two that says something about the fabric. It shows where the building loses energy and carries the modernisation recommendations that § 84 GModG requires to be attached,6 as far as they are possible. For prospective buyers this is the more reliable information, because it describes the house and not its previous occupants.

That the two procedures arrive at different figures for the same house is therefore not an error but the design of the two certificates: one measures an inhabited house over three past years, the other calculates a notional house under standard conditions. Neither figure takes legal precedence; every certificate therefore states which procedure was applied.

The price for this is the greater effort: more details are needed, and every one of them goes into the calculation. That is exactly why it costs 119.90 € with us instead of 69.90 €.

#If you may choose freely

Then what you need the certificate for decides. Three rules of thumb from practice:

The last point is regularly underestimated. Anyone who has just insulated the façade or replaced the heating will only see this in the consumption certificate once 36 new billing months are available — until then the certificate carries the figures from before. From 2027 this waiting time shortens to 24 months; it does not disappear.

#What applies to both

Regardless of the certificate type: an energy performance certificate is always issued for the whole building, never for an individual flat. Under § 79 (3) GModG it is valid for ten years.1 And it places the building in one of the nine efficiency classes from A+ to H laid down in Annex 10 of the Act7 — the same scale for both procedures.

This scale remains in place for residential buildings even after the amendment. The Europe-wide uniform scale A to G, which currently haunts many guides and newspaper articles, is set out in the new Annex 10a and, via § 86 GModG,5 applies from 1 January 2027 exclusively to non-residential buildings.8 Your detached house will continue to be classified from A+ to H.

When you need the certificate at all, which buildings are exempt and what happens in the event of a breach is covered in the article on the duty to have an energy performance certificate.

#If part of the building is used for work

Everything said so far applies to residential buildings. As soon as part of the house is used commercially — a practice, a shop, an office in an extension — the commercial share decides whether a residential certificate is still an option or whether the residential and non-residential parts are considered separately.

“Flat-like” means a use that behaves like living in energy terms: practice or office rooms with the same temperatures and operating hours, not a workshop and not a restaurant kitchen. The boundary is a professional judgement, not an arithmetic exercise — in case of doubt we clarify it before issuing.

#What changes on 1 January 2027

The Building Energy Act was amended and promulgated on 28 July 2026 as the Building Modernisation Act. For the energy performance certificate this changes nothing for the time being: the new rules are in Article 2 of the Act and only enter into force on 1 January 2027.8 Certificates already issued keep their full ten years.

For the question of this article, one of these changes is the decisive one: the assignment by number of flats and building application disappears.

The other changes do not affect the choice: the scale for residential buildings stays A+ to H, and the certificate will in future be issued digitally and machine-readable, on request still on paper. What that means for prices is covered under energy performance certificate costs.

In practice this means: anyone selling a two-family house from 1965 today needs a demand certificate. Anyone who postpones the same sale to next year may choose and would get away more cheaply. But the sums only add up if the sale has time — the certificate must be available at the viewing at the latest.

Two points belong here because they are often reported wrongly. The certificate types get new statutory names: the demand certificate will then be called “energy performance certificate based on an energy balance” (§ 81 GModG),3 the consumption certificate “energy performance certificate based on measured final energy consumption” (§ 82 GModG). The same procedures are meant; the short names remain common in everyday use. And for non-residential buildings the consumption certificate is abolished entirely — anyone who owns a predominantly commercially used building no longer has the cheaper route from 2027.

#Conclusion: the choice is rarely free

First check the two hard criteria — fewer than five flats and a building application before 1 November 1977 means demand certificate, everything else leaves you the choice. Then check the bills: 36 consecutive months, the most recent no older than 18 months — otherwise it stays with the demand certificate. Where you may choose, the purpose decides: the consumption certificate is the faster and cheaper statement about running costs, the demand certificate the more reliable statement about the building itself.

From 1 January 2027 the question becomes simpler for residential buildings, but not superfluous — the statutory assignment disappears, the professional one remains. You cannot go wrong with either certificate as long as the underlying details are correct; you are liable for those, not the issuer.