## 1 Introduction
### Past Research in Spain  
In Spain, the effect of energy performance over the dynamics of the residential market has been researched from the perspective of revealed and stated preferences. In the first body of work, the research of [PERSON] [32] based on a hedonic price analysis for Barcelona uncovered a small but positive correlation between EPC ratings and listing prices. Similarly, other works have identified specific hedonic agendas across the country and time: [PERSON] and [PERSON] [33] indicated the effect is larger in cities where efficient homes are scarce, while [PERSON] and [PERSON] [4] concluded that within the same city it is larger in the low-quality home tier, while being null in the case of high efficient state-of-the-art ones, suggesting a misunderstood role of such ratings since they are probably understood as general quality indicators. [PERSON] et al. [34] found, also, a small effect on home prices when controlling for an extensive location and architectural attributes in Alicante. As well as [PERSON] et al. [35] who report that owners have no incentives to disclose EPC ratings at property advertisements allowing them to sell low-tier EPC homes at the price of up-tier ones. While the best rated homes (i.e., \"A\" \"B\") exhibit prices comparable to those rated as less efficient. Figure 2: Perceived co-benefits or energy performance before and after the retrofit program. Source: Own elaboration using [PERSON] et al. [30] data. Interestingly, the aforementioned misperception of the role of EPC ratings is not exclusive to households. [PERSON] et al. [8] surveyed a sample of real estate agents across the country to learn the awareness level on EPCs and the effect that EPC ratings have on home marketing. They found that some of such property professionals do also misunderstand the role of the EPCs, since they are perceived as general indicators of home quality or comfort instead of what they are; that is, indicators of energy consumption (to reach a standard comfort level) and CO\({}_{2}\) emissions. They also found that, in the opinion of realtors, energy performance is not a key element in home pricing, speed to market nor price negotiation. Which is in line with the small, and possible incorrectly, marginal price found in hedonic price studies. From the stated preferences techniques [PERSON], [PERSON] and [PERSON] [5] used a contingent valuation to learn whether households are willing to make an extra payment for top-efficient homes in Barcelona. Their conclusions suggest that people are willing to pay a similar quantity to the indicated monthly energy savings, coming from improved energy-performance conditions. They found that personal respondents' attributes such as income, environmental awareness, awareness of the EPC scheme or the fact that the use of efficient homes can be seen as a socially responsible behavior do increase the aforesaid extra payment. Interestingly, the perceived co-benefits such as energy savings as well as the living conditions were also correlated with prices: The worse the living conditions, the larger the willingness to pay (WTP) for efficient homes. Moreover, respondents willing to buy the offered home (instead of leasing it) said they were ready to pay more. In a further work, [PERSON], [PERSON] and [PERSON] [6] using a larger and more recent sample, in the context of a contingent valuation, also in Barcelona, were able to segment it in order to identify sociodemographic specific reasons to be ready to make an extra payment for efficient homes. Their results suggest that young respondents whose education is in progress, seem to have developed an environmental concern that renders a larger WTP when they come from affluent families, although such payment is lower in the case of women, especially in the case of young women.