Konstantin Kholodilin (St. Petersburg, 1973) grew up in one of the communal homes expropriated after the Bolshevik Revolution of 1917. Crowded hives, which still exist, in which each family occupies a room and shares a bathroom and kitchen. His grandmother, he remembers, paid a "very affordable" rent: 2% of her income. There he learned a saying: "In Russia we say that every drop of water destroys the stone. One drop will not do it, but if a million drops fall, in the end the stone..."
That is the burning nail that this economist from the German Institute for Economic Research in Berlin is clinging to. It is the great academic reference in the study of the effects of rent control. His 2024 paper in the Journal of Housing Economics, titled The Effects of Rent Control through Empirical Research: A Near-Exhaustive Review of the Literature, concludes that although these policies benefit the tenants they directly affect in the short term, their secondary effects can offset the desired ones. Among them: inflating prices in unregulated areas, deterioration in the quality of housing, decrease in residential mobility, stopping new construction...
It is the Bible of the matter. An examination of hundreds of scientific studies that analyze the effects of these types of measures over the last six decades. Since its publication, in just two years, it has been cited 159 times in other research, according to Google Scholar. Kholodilin is mentioned as an authority by the OECD and also by the Bank of Spain in its latest Annual Report when he talks about the negative impacts of rent controls.
And yet... the stone remains intact.
RENT CONTROL: THE SAME RECIPE SINCE JULIUS CAESAR
The 'Maricarmen decrees' that overturned the Congress of Deputies, and that Pedro Sánchez will recover in the Permanent Deputation, reproduce measures previously applied in almost a hundred countries since at least 2,073 years ago, when Emperor Julius Caesar froze rents during his Civil War with Pompey. In 48 BC it was prohibited for any citizen to pay more than 2,000 sesterces in rent in the city of Rome. In the rest of Italy, there were always classes, the cap remained at 500. The measure was short-lived and forgotten for 300 years, until Valeriano briefly reintroduced the prohibition on increasing prices in 253 AD during the validity of the contracts.
Then came the Byzantine Empire and many other examples until the measure became massively popular due to the destruction and shortages caused by the First World War. "Surprisingly, the effects are very similar," Kholodilin confirms to Crónica about the results of his historical comparison. "There are some differences in the intensity or size of the effect but in general, since human behavior is the same throughout the world, it reacts to similar stimuli in a fairly similar way," he adds.
His analysis makes many stops in our country. The longest in Madrid, where rent control lasted for almost three centuries, from 1564 to 1842, following the transfer of the capital from Valladolid. With quite a few updates along the way to adapt the price calculation formulas. "In Spain you have a very long history with rent control, much longer than in Germany," jokes the doctor from Berlin, the great laboratory city.
"NO MATTER WHAT WE SAY ABOUT THE HARMFUL EFFECTS..."
Kholodilin is one of two economists on the German Justice Ministry's expert commission studying future reform of housing policies and rental price controls. It shares space with "representatives of tenants, builders, owners, unions, workers and judges." Above all of them is Minister Stefanie Hubig, of the Social Democratic Party, determined not to dismantle such a controversial and discussed measure, but to delve deeper into it. "The result is quite sad," summarizes the economist. His frustration is evident: "It doesn't matter what we say about the harmful or negative effects of rent control. It will not affect the result. The decision has already been made. Our presence there is a pro forma, and then we say that we have consulted with a group of experts."
The drop, the stone... "I still believe that more studies could clarify things even more and help decision-making," Kholodilin consoles himself.
In addition to Germany, in recent weeks he has been contacted by the Welsh authorities to obtain his opinion on a future regulation. In the Netherlands, his studies were already used in the political discussion on the matter, but rent control ended up being tightened in the summer of 2024. Since then, the Dutch Central Statistics Office has observed effects in line with those pointed out by Dr. Kholodilin's research: the reform has contained prices in homes directly affected by the regulation, but supply stagnated and more than 30,000 homes left the rental stock. According to data from Pararius, the country's main real estate portal, prices in the market have continued to rise by 7.3% year-on-year per square meter in the first quarter of 2026.
It is a scenario that seems to be repeated tirelessly from Antiquity until today. Berlin, Catalonia... "It continues to be a very popular measure during housing crises. When there is a large deficit and rental prices rise, governments almost immediately begin to intervene with these measures," summarizes the economist.
EVIDENCE AGAINST, BUT 70% OF CITIZENS IN FAVOR
The data proves him right. In the housing barometer published this week by the Center for Sociological Research (CIS), with field work carried out between June 22 and 30, 70.6% of respondents in Spain support freezing rents for two years. What is it about housing that makes scientific data impermeable to both the voter and the politician?
"It seems like a very obvious measure and it is also not expensive. The Government does not need to spend billions of euros on housing construction or subsidies for tenants," reasons Kholodilin. But the main problem is electoralism. The political omnipresence of these measures, despite the more than studied adverse effects, has to do, according to the expert, "with the electoral cycle."
Actions such as rent freezes have, according to Kholodilin, "a very short planning horizon, four or five years, while the housing market is, by definition, a long-term market." "If we build now, these constructions will survive 100 years and will affect the housing market a few generations later. But decisions are made based on myopic, very short-sighted policies," he criticizes.
ELECTORALISM AND CONSEQUENCES
It is a problem of electoral incentives. "A law that freezes rents is proof for the voter that the politician has done something. Afterwards, he does not have to pay for it, but it is society that pays for his decision with less construction, less quality of housing, less residential mobility..." he lists.
Kholodilin, who left Saint Petersburg for Barcelona at the beginning of the century to pursue his doctorate at the Universitat Autònoma de Barcelona, does not hesitate if asked about the origin of price increases. "The problem is always more or less the same. A population increase that happens very quickly and a much more limited supply of housing. Whenever there is a rapid increase in demand, it ends in a housing crisis," he says.
In Spain, immigration has caused the population to go from 46.4 million inhabitants in 2016 to 49.8 million in the latest count by the National Institute of Statistics (INE). In that time, just 800,000 new homes have been completed. The deficit grows daily: in the first half of 2026, 51,406 homes were completed, according to the Ministry of Housing, while in the same period 107,688 new homes were created among newcomers, independents, new coexistence centers...
"Each factor that increases demand affects the balance in the housing market. And migration is one of those phenomena. When masses of population move from one place to another, they create additional pressure on the market in the place where they arrive," he analyzes a debate that is increasingly gaining more space in Spanish politics. Kholodilin looks at it without the glasses of polarization: "Most studies show a strong relationship between migration and prices. But it can be different depending on the level of analysis. At the macro level, the effect in most cases is that the more migration, the higher the prices will be. At the micro level it can be different, if there is a massive flow of immigrants with a low income level to a neighborhood, the prices of that neighborhood can decrease because people with more resources can leave."
Konstantin Kholodilin is an academic. He emphasizes that he does not have the magic wand for the problem. Also, unlike in Germany or Wales, he has never been contacted from Spain for political advice. And despite the enormous academic impact of his work, his profile is discreet and he does not lavish himself on social networks. On X, at the time of going to press, he only had 144 followers. Only one of them with a record in the recently dissolved Congress: Carlos Hernández Quero, Vox Housing spokesperson.
"SCEPTIC" ABOUT LARGE-SCALE CONSTRUCTION
Unlike Quero, however, Kholodilin is "skeptical" that mass construction of new housing is the solution to any problem. He is critical of urban concentration, the excessive expansion of large cities and the densification that he experienced when he was young in Russia. In his studies, he has also placed a lot of emphasis on the Not In My Backyard (NIMBY) phenomenon, which states that even people who defend a very expansive construction policy do not want it to occur near their home.
The paradoxes of the housing market are endless. In Berlin, where he lives, the old Tempelhof airport survives in the middle of the city as a huge 350-hectare void that citizens have turned into a park. In 2014, it was proposed in a referendum to use part of that land to build new housing: it was rejected. "In 2021, seven years later, the same people who decided not to build at the airport decided to nationalize housing," underlines Kholodilin about a measure that has once again been Die Linke's star proposal to win the mayor's office in the recent local elections. He, who began studying the phenomenon of rent freezing in 2014, has been caught by the succession of crises as a landlord.
