The mortgage that makes your home worth more

Energy efficiency increases the value of Spanish homes. Specifically, a grade improvement in energy efficiency increases house prices by an average of 1.3% and can exceed 4% in northern Spain, according to the IESE business school, the real estate valuation firm Tinsa by Accumin, and the market data and analysis platform Accumin Intelligence.

This means that energy efficiency is beginning to be considered among the factors when purchasing a home, and that the idea that energy savings is and will continue to be a factor in price formation is slowly gaining ground among citizens. "The market positively values ​​properties with higher levels of efficiency, as they incorporate both future energy cost savings and their contribution to environmental sustainability," says Cristina Arias, director of the Research Department at Tinsa by Accumin. Its direct impact on prices is, for now, moderate, but with a clear upward trend in the coming years.

This is because that 1.3% is the result of focusing solely on energy efficiency without taking into account other construction variables, something that had not been done until now. The most energy-efficient homes are also usually more modern, with better construction quality and higher prices. For example: the average increase in value for a home that improves one letter in its energy rating is around 9.4%. However, this figure is falsified because the quality of the construction, which is more modern and expensive, is also being taken into account. "This result leads to erroneous conclusions. Therefore, it is important to differentiate whether the market values ​​a home for its attribute of, for example, modernity or whether it does so because it values ​​its greater energy efficiency," adds Arias.

This is the exercise carried out by IESE, Tinsa by Accumin, and Accumin Intelligence in an analysis—with a sample of 243,000 homes collected between 2012 and 2024—which, for the first time, statistically demonstrates how energy efficiency is becoming "a relevant tool not only for increasing but also for maintaining the financial value of residential properties," concludes Arias, one of the authors.

The price increase is greater when the letter rating is improved in the most efficient homes (CA) and somewhat lower in the least efficient homes (GD). For example, the price increases by 1.2% when moving from letter E to D; by 2.1% when B becomes A; and up to 3.3% when changing from C to B. In other words, there is a green premium in the Spanish residential market where better CO2 emission ratings translate into higher home values, the report states.

To achieve this, the owner must address three factors: "reinforcing insulation, replacing air conditioning systems with more efficient ones, and installing renewable energy," says Arias.

The appreciation in housing values ​​is not restricted to luxury properties, single-family homes, or specific locations; rather, it is an attribute valued by citizens across all market categories. However, the price increase is greater in regions with colder climates, such as Asturias (4.5%) and Cantabria (4.8%), due to the importance the Technical Building Code attributes to reducing heating costs. In warmer regions, such as Andalusia, Madrid, and the Canary Islands, the green premium is lower (from 1% to 1.1%). The price increase is higher for single-family homes (1.5%) than for apartment blocks (1.3%), and for homes built after 2006 (1.7%) than for older properties (between 1.1% and 1.2%).

In the coming years, the economic impact is expected to become more significant. "Based on increased environmental awareness and, above all, increased regulation to achieve energy transition goals, we expect it to continue to increase and accelerate in the coming years," says Arias.

There's plenty of room for improvement. The energy efficiency of Spain's housing stock is quite low. Most homes have ratings indicating high energy consumption and poor insulation and air conditioning performance (they have an energy rating between D and G). Reversing this situation is one of Spain's major challenges, a country where a large percentage of buildings predate the approval of the Technical Building Code (which came into force in 2006) and 60% of homes were built without any energy efficiency regulations (they predate the implementation of the NBE-CT 79 standard), according to the Institute for Energy Diversification and Savings (IDAE).

The label

Buyers and sellers can find out about the energy efficiency of their homes through the certificate, a mandatory document for selling or renting. It includes a letter scale: from A (most efficient) to G, similar to the labels on household appliances. It's mandatory in theory because, last March, the consumer association CECU reported Idealista, Fotocasa, and Alquiler Seguro for irregularities with this label on their listings : one in three failed to display it and stated that it was "in process."

In 2026, Spain must adapt its energy efficiency certification system to the new EU scale, which aims to ensure uniformity across all countries. According to European Directive 2024/1275, by 2030, buildings with the lowest rating (G) must be renovated to at least an E rating, and by 2033, all buildings must achieve at least a D rating. By 2050, all buildings must be zero-emission.

The cost of the certificate in Spain remains stable and does not vary significantly from year to year. "For apartments up to 250 square meters, the price of a certificate, in accordance with Royal Decree 390/2021 and duly registered with the competent authority, ranges between 90 and 135 euros. In the case of single-family homes, the cost usually starts at 150 euros, depending also on the location and characteristics of the property," says Lucía Martínez, technical director of Agentia R+ by Accumin. It's worth remembering that issuing this document requires an in-person visit to the interior of the home by a qualified technician. This inspection guarantees the veracity of the data collected and the legal validity of the document.