## 4 Results and Discussion
### Factors Influencing the Perception of Energy Efficiency Benefits  
Figure 7 illustrates the coefficients of the multiple regression analysis aimed at isolating the marginal contribution of sociodemographic and living conditions over the intensity in which respondents perceive the assessed co-benefits of energy efficiency. Such a model is specified only with the variables statistically significant at 95% confidence. One of these values is beta coefficient, which allows to compare the relative importance of the independent variables on the variation of the dependent variable. Such a procedure consists of regressing the dependent variables on the standardized scale of the independent variables. Typically, z-values procedure is used to standardize the variables getting as a result a distribution whose average value is zero and standard deviation is one. According to the beta coefficient, calibrated using the standardized variables, the following findings can be extracted:  
1. The main explanatory attribute is the priority to insulate respondents' present home windows. The higher such priority, the larger the composite co-benefits associated with energy efficiency. It is worth recalling that window transmittance is the largest among enveloping elements in multifamily housing where poor-quality windows imply airflow infiltrations and external noise transmission. In that, the benefits of upgrading this element are of a multidimensional nature, as discussed in Section 2.2. 2. The second explanatory attribute concerns the socioeconomic context. The lower the respondent socioeconomic level, the less aware of the energy efficiency co-benefits. It is worth recalling the strong association in Spain between disposable family income and educational attainment, in that, well educated respondents do have better cognitive resources to understand the benefits of efficient premises even when they are not specialists. 3. The third most important explanatory factor is the indirect indicator of willingness to pay for efficient homes. In turn, respondents that think that efficient homes pursue a higher market value are also the most aware of energy efficiency implications. This finding is relevant since it empirically endorses the core hypothesis of the EPC scheme, regarding the relationship between energy transparency and prioritization of efficient premises in the form of a larger willingness to pay for them. 4. The fourth explanatory element is related to the priority to implement energy-efficient retrofits in heating/domestic hot water and air-conditioning systems. Respondents who consider this a priority in their current home are more aware of the composite benefits of energy efficiency. 5. Regarding demographic profiles, after having controlled for income, women are less aware of energy efficiency benefits as well as young respondents. These findings are a clear target for tailoring specific policies aimed at increasing energy performance awareness. The same is true regarding the role within the residential market, since the findings confirm that owners do place a large value on the benefits of energy efficiency in relation to tenants. It is worth recalling that women said in a larger proportion that their home does not require the assessed retrofits (i.e., their homes exhibit better living conditions in relation to male respondents' home), so as suggested before, it is possible that this fact has influenced their response; although it is also possible that female respondents have a more optimistic perception of their homes in relation to male respondents. In the model, interaction variables between gender and living conditions were introduced, but none resulted statistically significant. 6.