District heating in 49 Romanian towns, 2021‑2025

Heat lost in the ground: how much of each Romanian town's district heating never reaches the buildings

Many Romanian flats are still heated by hot water piped from a town plant. Of every 10 gigacalories that leave the plant, on average 6.4 reach the buildings they heat, most of them apartment blocks. The rest is lost on the way, in a network of pipes almost all buried under the streets. In Brașov, Constanța and Bacău, more than half is lost. Pick a town to see where its 10 gigacalories end up.

Of 10 gigacalories: 6.4 reach the buildings, 3.6 are lost on the way.

Map: where the heat leaks#

Each dot is a town that sold district heat in 2025. The size shows how much heat enters its network; the colour shows the share that never reaches a building, averaged over five years, 2021–2025.

The loss is the difference between the heat the operator sends into its network, from its own plant or bought, and the heat it sells to customers: heat lost on the way or never billed. Of the 4,135 kilometres of network, 93% are underground. Losses inside the blocks, in risers and radiators, are not included.

Click a dot on the map to pick that town.

10%70% of the heat lost (2021–2025)no loss reported

The ranking: 30 towns, one measure#

The ranking covers towns with at least 10,000 megawatt-hours entering the network in 2025 that report a loss and still have homes connected. Each bar shows the share of heat lost over the five years taken together.

In 4 towns, half or more was lost. In 10, at least 40% was lost. The national figure was 36.4%. In Brașov, Constanța, Bacău, Motru and Vatra Dornei, by an estimate that splits the loss in proportion to sales, the network lost more heat in 2025 per connected home than each home received.

reaches the buildingsis lost

Five years, the same hole#

Nationally, the loss was between 35.6% and 36.9% every year from 2021 to 2025. It did not fall. In 2025, 3,841 gigawatt-hours were lost, or 3,302,432 gigacalories: roughly a year's heat for 690,700 connected homes, at the average use of a connected home (5.56 MWh). Outside Bucharest, 469,749 homes remain connected in the whole country.

Bucharest alone accounts for 48% of all the heat lost. The chart shows the national line and, once you pick a town, its own.

Share of heat that does not reach a building, by year

Source: ANRE (Romania's energy regulator), annual district-heating reports, annex 5. Loss = 1 − heat sold ÷ heat entering the network.

Pipes too big for the heat they still carry#

The networks were built for towns in which far more blocks were connected. The heat they distribute has since fallen several times over, by the national statistics office's figures: in Brașov, from 1,165,364 gigacalories in 1999 to 26,572 in 2025; in Bacău, from 674,098 in 2001 to 66,067. One possible explanation for the losses: a pipe left too big carries less heat, but its loss per kilometre does not fall at the same pace.

The test was fixed before it was run: the less heat a kilometre of network sells, the larger the share lost? The answer: yes, moderately. The rank correlation across 30 towns is −0.42 (p = 0.025). Brașov, Constanța and Bacău sell around 570–600 megawatt-hours per kilometre and lose more than half. Bucharest, Ploiești and Oradea sell more than four times as much per kilometre and lose less. The test shows an association, not a cause, and not the whole story: Motru and Timișoara lose a lot although they sell a fair amount per kilometre.

Loss (2021–2025) against heat sold per kilometre of network (2025)

The horizontal axis is logarithmic. Each dot is a ranked town. Network length: ANRE, annex 1, transmission and distribution routes.

Who pays for the lost heat#

The price families pay for a gigacalorie is set by the town council and, in many towns, is below cost. The town hall covers the gap from the local budget, which means also from residents who are not connected. In 2025, subsidies and transfers for district heating came to 2.15 billion lei (Romanian lei, RON; about €430 million) across the towns here, of which 1,016 million in Bucharest.

A simple calculation, with one assumption: if all costs are spread evenly over every megawatt-hour entering the network, the share of the money that corresponds to lost heat is the loss share itself. On that assumption, in Brașov, Constanța or Bacău, of every 100 lei spent heating homes, bills and subsidy together, more than 50 would correspond to heat that reached no one. The amounts for the town you pick are in its card. Investment (budget titles 56, 58 and 71) is shown separately and is not included here.

District-heating subsidy per resident, 2025 (lei)

Ploiești1,175 lei
Timișoara825 lei
Constanța655 lei
Bucharest592 lei
Brad553 lei
Rădăuți526 lei
Arad486 lei
Bacău476 lei
Oradea354 lei
Focșani272 lei
Craiova243 lei
Cluj-Napoca228 lei
Pitești218 lei
Tulcea190 lei
Suceava169 lei
Miercurea Ciuc142 lei

Source: Ministry of Finance, local budget execution, chapter 81.06 Thermal energy, titles 40 (subsidies) and 51 (transfers); residents: 2021 census. Towns where the network is run by the town hall itself are left out, because its cost also sits in other budget lines. Oradea includes Sânmartin commune, served by the same network.

Towns that report no loss#

In 9 places, the operator reports selling 99% or more of the heat it sent into the network. Under the rule fixed in advance, these towns are not compared with the others: they are grey on the map, as "no loss reported", and are not ranked.

Tulcea and Bârlad appear in the regulator's annex with zero connected homes at the end of 2025, although during the year they still sold heat to households. In 2025, Tulcea lost 36% of the heat it sent into its network.

No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
Zero homes connected at the end of 2025. Loss 2021–2025: 13.7%.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others. Zero homes connected at the end of 2025.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others.
No loss reported: the operator reports selling 99% or more of the heat it sends into the network, so the town is not compared with the others. Zero homes connected at the end of 2025.

Method#

The data come from the annual reports of ANRE, Romania's energy regulator, on the public district-heating service, for 2021–2025. Annex 5 gives, for each operator and town, the heat produced in its own plants and delivered to the network, the heat bought from other producers, and the heat sold, by type of customer. The loss is 1 minus sold divided by heat in. The five-year figure adds up all the megawatt-hours lost and divides by all those that went in.

The figures match those published separately by the towns: for Bucharest in 2024 the calculation gives 36.9%, against 37.73% reported by City Hall; for Arad in 2021 it gives 42.1%, against 42.13% in the city's heating strategy. Heat sold matches, for most towns, the "thermal energy distributed" in the national statistics office's data (INS), which has no figure for heat in and so cannot show the loss.

Connected flats come from annex 3 (end of 2025), network length from annex 1. Loss per home is an estimate: it takes the part of the lost heat that corresponds to sales to households and divides it by the number of connected homes (flats and houses). In Râmnicu Vâlcea and Oradea, much of the heat goes to companies as steam or hot water, so their share is not fully comparable.

The money comes from local budget execution published by the Ministry of Finance: town-hall payments under chapter 81.06 Thermal energy, title 40 (subsidies) and title 51 (transfers). Investment (titles 56, 58 and 71) is shown separately. Where the network is a service of the town hall itself (Iași, Brașov, Drobeta-Turnu Severin, Vatra Dornei, Gheorgheni, Făgăraș, Întorsura Buzăului, Călimănești), its cost also sits in other budget lines, so those towns are not compared per resident; their card shows the chapter's total.

The network-density test, the definitions and the stopping rules were written down before the calculation. The descriptive ranking had been seen before they were written.