###### Abstract
Among the energy saving measures in buildings, the most effective in the long term are those that reduce the need to consume energy, since they do not depend on any equipment that must be monitored for its proper operation and maintenance. These types of measures are known as passive measures, and mainly comprise the insulation of facades and roofs, the use of windows with low thermal transmittance and the proper use of solar gains. [PERSON] et al. [12] performed a review of these types of passive techniques, as well as more special ones, such as Trombe Walls, Double Skin Walls, and Green Walls. In the scientific literature, we found numerous case studies in which the main proposal for the energy renovation of a building is the incorporation of insulation in facade walls. [PERSON] et al. presented as a case study the deep renovation of a residential building in the Province of Milan through the placement of prefabricated panels of thermal insulation on the exterior layer of the facade walls [13]. [PERSON] and [PERSON] also presented as the main measure of renovation of buildings the use of insulation, and focuses their study on comparing different types of insulation from the point of view of environmental performance. They concluded that the highest eco-efficient performance corresponds to sheep wool and recycled cotton, jointly with traditionally used mineral and glass wool [14]. Among conventional thermal insulation materials, [PERSON] and [PERSON] highlight mineral wool as the most efficient option [15]. In addition, [PERSON] and [PERSON] say that adding insulation is an efficient way to upgrade an existing building into a nearly zero-energy building, and present a Case Study for which a 70% reduction in the energy demand is reached [16]. Other researchers, such as [PERSON] et al., proposed to optimize the necessary insulation thickness depending on the use of the building and the climate [17]. At the same time, it should be noted that the insulation that reduces heat losses in winter has the same effect in summer, in this case being an unintended drawback that contributes to overheating [18]. This overheating, more common in well-insulated homes [19], has been observed mainly in top-floor homes of apartment blocks with high solar gains and low ventilation. Thus, the risk of overheating when retrofitting existing homes is especially high, mainly when insulation is placed as the interior layer of facade walls and roofs [20]. In addition, increasing the thermal inertia of the building envelope is known to reduce the energy required for cooling, as well as the peak cooling load [21]. This is a serious problem highlighted by institutions such as the Building Research Establishment Ltd. (BRE) in the United Kingdom, which has recommended that more should be done to address the growing risk of overheating in dwellings and other buildings [22]. A risk that according to CIBSE TM59 occurs in summer when a dwelling fails more than 3% in the number of hours that exceed the comfort temperature in living rooms, kitchens, and bedrooms, or when indoor temperatures in bedrooms exceed 26 \({}^{\circ}\)C for more than 1% of the annual hours. This same report points out one of the causes of overheating as the combination of the increase in the facade glazing area along with the use of wall insulation. In fact, it can occur with an outdoor air temperature that is not necessarily high. The problem arises from the solar gains that enter the building and that fails to get out through insulated walls [23]. The same trend was observed by [PERSON] et al. in a monitoring study of 122 social housing units in central England to investigate the overheating risk [24]. On the other hand, it is known that the layers of a wall that are useful for inertia are those that remain from the insulation material to the inside of the building. Thus, if the insulation layer is placed on the outside side of the wall, all its layers are useful as thermal inertia.