The PENB: why a Czech energy certificate describes a model, not your bills

A buyer opens an advert for a flat in a brick building and sees a small coloured bar, with the letter D picked out. Another flat, in a newer block, shows B. The reader can guess which one is cheaper to heat, and the guess is mostly right. It is also an over-simplification. The certificate behind the letter is a technical document with a specific purpose, and its limits are as useful to know as its contents.

What the PENB is

The PENB (průkaz energetické náročnosti budovy, energy performance certificate of a building) is a document that rates how much energy a building needs under standard conditions. It is required by the Czech Act on energy management, No. 406/2000 Coll., and detailed in a government decree on the energy performance of buildings (as of 2026; check the current texts on e-Sbírka). The system implements the EU's directive on the energy performance of buildings.

The certificate does two things. It gives a class from A to G, shown on a graphic scale, and it provides the underlying figures: the calculated energy needed for heating, cooling, ventilation, hot water and lighting where relevant, and indicators that express how much of that comes from non-renewable sources. It also lists recommendations for improving the building. Our companion explainer, energy classes A to G decoded, goes through the scale.

When a certificate is required

The rules distinguish situations. A new building needs one, and so does a building after a major renovation, as part of showing that it meets the requirements. When a building or a unit, such as a flat, is sold or let, the seller or landlord must show the certificate and hand it over, and the energy class is stated in adverts (as of 2026; check Act No. 406/2000 Coll., and check the advert rule for lettings with the Ministry of Industry and Trade). For a flat in an apartment block, energy bills for the last three years can replace the certificate in some cases. Larger public buildings must display their certificates visibly.

There are exceptions. Certain small buildings and some other categories, such as buildings protected for their heritage where compliance would alter their character, are excluded. For flats in an apartment block, the certificate can be that of the whole building or a separate one for the unit, depending on what exists. Check the exact scope with the authority, since the rules for letting differ in details from those for sale.

Compliance is supervised by the State Energy Inspectorate, which can impose fines for failures (as of 2026; check the Inspectorate). For a seller or landlord, a missing certificate is a practical and legal risk. For a buyer, it is a prompt to ask.

Who issues it

A certificate is prepared by an energy specialist (energetický specialista), a professional who holds authorisation from the Ministry of Industry and Trade and appears in the Ministry's list. The specialist collects the building's details, such as walls, roof, windows, floors, technical systems and the heated area. Then they run a calculation according to the method set in the decree and issue the certificate, which is entered in a state register of certificates.

The calculation uses the building's documentation, a site inspection and standard assumptions about use. Two features follow.

First, the result describes the building, not the household. A household that keeps the flat cool uses less than the model, and one that keeps it very warm uses more.

Second, quality depends on the inputs. A certificate based on full documentation and a careful inspection is more reliable than one based on guesses about hidden structure. If an owner has replaced windows or insulated a roof, the certificate should reflect it, and the owner needs the invoices and datasheets to prove it.

How long it lasts

A PENB is normally valid for ten years from issue, unless a change in the building makes it out of date (as of 2026; check the decree). If you carry out work that changes the energy performance, such as insulating, replacing windows or changing the heating source, a new certificate is needed to show the new class. Owners who plan to sell soon after a renovation often commission an updated one, since the better class is a selling point.

Certificates in blocks of flats

A flat in an apartment building raises a practical question: whose certificate is it? Where the building as a whole has been assessed, the flat can rely on that building certificate, and the class is the same for every flat in the block. Where a flat has been assessed separately, perhaps because its owner renovated it or because the building has no certificate, the unit's own figures apply. The difference matters because a flat on the top floor, at the corner of a block or above an unheated passage loses more heat than one in the middle, yet a whole-building certificate averages these differences away.

For owners' associations, the building certificate is also a planning tool. It lists the measures that would raise the class and can serve as a starting point for the energy audit that precedes a renovation. When an association applies for a subsidy, a certificate before and after the works is usually part of the file. A block that has kept its old certificate in a drawer has one more reason to ask for a fresh one if major work is under way.

What to look for as a buyer

A certificate is easiest to use as a comparison tool and a to-do list.

The advice in the last step is the most useful. A seller can show the building's service-charge settlements, which record what was actually paid for heating and hot water. Service charges and building funds shows how those statements work.

Why the class matters beyond the advert

The class has consequences. It is a signal of running costs, and a building in a low class will usually be costlier to heat than a similar one in a high class. It is a signal of future spending: a low class suggests that insulation, windows or the heating system may need to be upgraded, which affects how much the owners' fund must hold. And it is a signal of policy risk: EU and national rules are moving towards higher efficiency standards, and the recast directive of 2024 makes renovation of the worst-performing buildings an aim of policy. How and when this translates into Czech obligations for owners should be checked with the Ministry of Industry and Trade. Panel blocks are the obvious test case; see panel block renovation.

Some lenders also take energy performance into account in their lending products. Terms differ and change, so check with the bank rather than assume.

Frequently asked questions

Do I need a PENB to sell my flat?

Generally yes: the seller shows and hands over the certificate, and the energy class is stated in the advert. For a flat in a block, recent energy bills can replace it in some cases, and there are other exceptions, so check Act No. 406/2000 Coll. or ask the State Energy Inspectorate.

How long is a PENB valid?

Normally ten years from issue, unless changes to the building make it out of date (as of 2026; check the decree).

Does class A mean low bills?

It means the building is calculated to need little energy under standard use. Your own bills depend on how you live, the weather and prices.

Who can issue a PENB?

An energy specialist authorised by the Ministry of Industry and Trade and listed by it.

When a certificate is offered, ask for the energy specialist's name and the date, and match both against the Ministry's list.

This is a general explainer, not legal or tax advice.