Energy performance certificate: when you need one and what class D means
“An energy performance certificate (průkaz energetické náročnosti, PENB) is just extra paperwork” — that is the objection we hear most often when selling a flat, and there is some truth in it: the certificate on its own will not insulate the building or lower the advance payments. But it has one field with a letter that the buyer remembers, and another field with a number that the buyer converts into money. This text is about the difference between the two.
When you need an energy performance certificate and when you do not
The obligation is framed as an obligation to hand the certificate over, not as an obligation to have one. The owner hands the certificate over to the buyer or tenant (nájemce) at the latest when the contract is signed, but the advertising must already state the class from it. The deadline is therefore not the day of signing but the day you put the flat on the market.
There are exceptions to the obligation. Two of them matter for flats: the building is a cultural monument (kulturní památka) or stands in a heritage reserve (památková rezervace), or it was built before 1 January 1947 with no later major change (větší změna) and the parties agree in writing that no certificate will be obtained. The exemption for buildings under 50 m² of energy reference area (energeticky vztažná plocha) is assessed for the building as a whole. The energy reference area is not the same as the floor area (podlahová plocha) stated in the owner’s declaration (prohlášení vlastníka), and it is calculated from external dimensions; so the 50 m² threshold does not help even with studio flats (garsoniéra) in a block of flats.
The sanction is real. The unit owner, whether a natural or a legal person, faces a fine of up to CZK 200,000. Compliance is checked, and offences are heard, by the State Energy Inspectorate (Státní energetická inspekce). In practice the omission does not come to light at the sale but later — typically when the buyer is dealing with a subsidy or a renovation and finds out that they never received a certificate.
The certificate is valid for ten years from its issue. The date it was prepared is therefore the first thing we look for on it, even before the letter.
The purchase agreement (kupní smlouva) should contain a separate clause on the handover. A sentence saying that the buyer has been made aware of the certificate is not enough. We state the certificate’s registration number (evidenční číslo), the date it was prepared and a statement that the seller handed the certificate over to the buyer at signing; the certificate itself is then a numbered annex to the agreement and appears in the list of annexes.
Who obtains the certificate for a flat and what to do if the owners’ association does not have one
The certificate is as a rule prepared for the building, not for the unit. For a flat in a block of flats, it is therefore obtained by the owners’ association (společenství vlastníků jednotek, SVJ), not by you. A certificate “just for your own flat” can be prepared only for a flat with its own heat source or with a separately metered and centrally regulated energy supply.
The procedure we use has three steps. First, we ask the owners’ association in writing, at the address entered in the register of owners’ associations (rejstřík společenství vlastníků), and we date the request. By data box (datová schránka) or registered letter, because an e-mail without confirmation is not a provable request. Then we have the date of delivery confirmed. Only if the owners’ association does not supply the certificate does the substitute solution come in: the owner meets the obligation by handing over the billing statements for energy supplies (vyúčtování dodávek energií) for the last three years.
The substitute has a catch that is worth knowing in advance. Statements for three years are data about a specific flat and a specific household. The buyer will see from them how the previous owner heated the flat, which is sometimes a better and sometimes a much worse calling card than the modelled figure from the certificate. When the seller heated little and let the flat go cold, the flat looks economical on paper and the buyer is surprised after the first winter.
The price of preparing a certificate for a block of flats rises with the size of the building, and only a quote from an energy specialist (energetický specialista) gives a concrete figure. Divided per unit, it is a small item — an argument worth having ready at the owners’ association meeting.
What we read on the certificate and in what order
The graphic part of the certificate (grafická část průkazu) looks like a single label, but it is four separate figures, one below the other.
At the top is a coloured A–G scale with an arrow. It classifies non-renewable primary energy (primární energie z neobnovitelných zdrojů) — a quantity that takes into account where the energy comes from, not how much of it flows into the building.
Below it is total delivered energy (celková dodaná energie) in kWh per m² per year. That is the amount of energy that actually enters the building. This is the number that converts into money.
Then the building envelope (obálka budovy), that is, the average heat transfer coefficient (průměrný součinitel prostupu tepla). A figure for how well the building holds heat, regardless of what it is heated with.
Finally, partial delivered energies (dílčí dodané energie) broken down by system: heating, cooling, ventilation, humidity control, hot water preparation, lighting. This is where you can tell whether the building is expensive because of heating or because of hot water preparation.
We read the letter last. First comes the date of preparation, second the total delivered energy, third the envelope.
Into the title block (popisové pole) of the property sheet (list nemovitosti) we take three figures: the class, the total delivered energy in kWh per m² per year and the year the certificate was prepared. The certificate itself goes into the annex as a numbered image. We do not reproduce it in full in the text, because a coloured scale without the number below it tempts the buyer to fill in the rest themselves.
Class D is not a number of kilowatt hours
This is where mistakes are made most often. The energy performance class (klasifikační třída) is not an absolute value. The class boundaries are set from the reference value of the classified indicator (referenční hodnota klasifikovaného ukazatele), designated ER, and the class is a multiple of this reference value.
Under Annex 2 to Decree No. 264/2020 Coll. (vyhláška), the boundaries for non-renewable primary energy are as follows:
| Class | Verbal designation | Boundary |
|---|---|---|
| A | exceptionally efficient (mimořádně úsporná) | up to 0.8 × ER |
| B | very efficient (velmi úsporná) | up to 1.2 × ER |
| C | efficient (úsporná) | up to 1.6 × ER |
| D | less efficient (méně úsporná) | up to 2.3 × ER |
| E | uneconomical (nehospodárná) | up to 3.0 × ER |
| F | very uneconomical (velmi nehospodárná) | up to 3.7 × ER |
| G | exceptionally uneconomical (mimořádně nehospodárná) | over 3.7 × ER |
Class D therefore means “up to 2.3 times the reference value”. Not “150 kWh”. Two buildings in class D can differ in consumption by tens of per cent, because one lies just above the C boundary and the other just below the E boundary.
In addition, the table has its own columns with different multiples for total delivered energy and for partial delivered energies. One building can therefore have one class by primary energy and another by delivered energy, and the certificate shows both.
Older certificates cannot be compared with new ones. Until 31 August 2020, Decree No. 78/2013 Coll. applied, with different boundaries, and it determined the class for advertising from total delivered energy. The letter from a certificate prepared in 2014 and the letter from 2026 are not the same information, even though they look the same.
The same building can have two different letters
Non-renewable primary energy is calculated by multiplying delivered energy by a factor according to the type of source. Electricity has a high factor; district heating has a lower one, depending on what it is produced from.
In practice this means that changing the source moves the letter without anything changing in the flat. A building that switches from electric heating to district heating can gain a letter one class better with the same envelope, the same windows and the same heat consumption.
That is why at the owners’ association meeting we ask about two things separately: what is planned for the envelope and what is planned for the source. The first changes comfort and consumption; the second mainly changes the letter.
What we do with class D when selling a flat
Class D is common in Prague blocks of flats from the eighties and nineties, and in itself it does not hold up a sale. What holds it up is uncertainty about what follows from it.
That is why, alongside the certificate, we file three documents from the owners’ association: the minutes of the last meeting, the repair plan (plán oprav) and the balance of the repair fund (fond oprav). The class is usually a proxy for the question the buyer is really interested in — when external thermal insulation (zateplení) will come and how much their share of it will cost. The answer “the building is in class D” does not reassure them. The answer “as at date X the fund holds this much, and the repair plan provides for insulation in year Y” does. This ties in with preparing the documents, which we describe in the text on how to sell a flat in Prague.
We will admit the drawback of our approach straight away. When we put both the modelled cost from the certificate and the actual billing statement into the property sheet, the two figures commonly differ by tens of per cent — the certificate assumes standardised operation, not the way the flat is really heated. We then explain the difference at every viewing, and some buyers conclude that the figure is unreliable. The number that was meant to be an argument thus sometimes works against us. We accept this as the price of the buyer getting more than just a letter.
The second drawback: for buildings whose certificate is more than five years old, we recommend having a new one prepared, even if the existing one is still valid. The seller thereby pays for a document the law does not require of them at that moment.
With new builds (novostavba) the situation is different. Under the requirements in force from 1 January 2022, a new building must not exceed the reference value of primary energy from which the class boundaries are also calculated, so it comes out at class B at worst, and the certificate there tends to be a confirmation rather than an issue — more on this in the text on buying a flat from a developer.
Annex: calculation of the annual costs of a model flat by class
Model: a flat with 68 m² of energy reference area in a Prague block of flats, district heating for space heating and hot water, electricity for lighting and appliances.
Inputs:
- heat price CZK 4.71/kWh including VAT (Pražská teplárenská, price list from 1 January 2026, rate PM2, band A; sum of the variable and fixed components)
- electricity price CZK 5.57/kWh including distribution and VAT (PRE, rate D02d, 2026)
- model consumption split of 80 % heat and 20 % electricity
- blended price: 0.8 × 4.71 + 0.2 × 5.57 = CZK 4.88/kWh
Model values of total delivered energy for the individual classes in a Prague block of flats. Calculation: kWh per m² per year × 68 m² × CZK 4.88.
| Class | Delivered energy (kWh/m²/year) | Flat consumption (kWh/year) | Annual cost |
|---|---|---|---|
| A | 45 | 3,060 | CZK 14,900 |
| B | 75 | 5,100 | CZK 24,900 |
| C | 105 | 7,140 | CZK 34,800 |
| D | 145 | 9,860 | CZK 48,100 |
| E | 190 | 12,920 | CZK 63,000 |
| F | 235 | 15,980 | CZK 78,000 |
| G | 290 | 19,720 | CZK 96,200 |
What follows from this:
In the model, the difference between class C and class D is CZK 13,300 a year, i.e. roughly CZK 1,110 a month. The difference between D and G is CZK 48,100 a year.
And now the part the calculation is done for. If the buyer reflected the C → D difference in the price as ten years’ worth of savings, they would arrive at CZK 133,000. For a model 68 m² flat valued at CZK 150,000 per m², i.e. CZK 10,200,000, that is 1.30 % of the purchase price.
Just over one per cent. Through the energy bill, the class on its own hardly moves the price of a flat at all.
What does move the price is the investment the class anticipates. How much insulation costs is shown only by a budget for the specific building; in the model we assume a share of CZK 150,000–250,000 per flat. That is roughly 1.1 to 1.9 times the entire ten-year energy saving — and it comes as a one-off increase in the contribution to the repair fund, not as an item that slowly builds up in the billing statements.
That is why, with class D, we do not ask how much the buyer will save. We ask when and how much they will pay.
Frequently asked questions
How long is an energy performance certificate valid? Ten years from its issue. When that period expires, a new one has to be prepared. Validity also ends earlier if the building undergoes a major change or a change in the method of heating, cooling or hot water preparation.
Who pays for the energy performance certificate when a flat is sold? For a flat in a block of flats, it is arranged and paid for by the owners’ association as the administrator of the building, because the certificate is prepared for the whole building. The seller obtains a certificate for the unit themselves only if the flat has its own heat source or a separately metered and centrally regulated energy supply.
What if the owners’ association does not have a certificate? Request it in writing and in a provable way. If the owners’ association does not supply it upon such a request, you meet the obligation by handing over the billing statements for energy supplies for the last three years.
Is class D bad? It is average, and usual in Prague buildings from the eighties and nineties. Its verbal designation is “less efficient”, and it means up to 2.3 times the reference value. More important than the letter is the total delivered energy figure below it and the building’s repair plan.
Must the property’s energy label be in the advert? Yes — the energy label (energetický štítek), i.e. the energy performance class, is stated in the listing (nabídka). If the broker (zprostředkovatel) does not receive the graphic part of the certificate, they state the worst class, which is a worse starting position for the seller than the actual letter.
Key takeaways
The energy performance certificate is as a rule a document about the building, not about the flat, and its most useful part is not the coloured one. The letter is a ratio to a reference value, so two identical letters can mean different consumption; the total delivered energy figure, by contrast, converts directly into Czech crowns. Our model calculation shows that a difference of one class corresponds to something of the order of one per cent of the purchase price, while the investment that a worse class signals can exceed the entire ten-year saving. Anyone who knows this stops treating the certificate as extra paperwork and starts asking about the repair plan.