Quantification of the Improvement in Sustainability after a Comparative Experimental Study of Single-Family Homes with Façade Rehabilitation Using the External Thermal Insulation Composite System

Abstract

This study emerged from the necessity to analyze the most effective energy-saving strategies within the current real estate market and substantiate their application with empirical data. Undoubtedly, the adoption of External Thermal Insulation Composite Systems (ETICSs) stands out as one of the prevalent approaches. This article presents temperature-monitoring data collected on-site from the facades of two single-family homes initially constructed with identical compositions, materials, construction dates, locations, and orientations. The thermal envelope of one home underwent rehabilitation using the ETICS, while the other remained in its original state. Continuous temperature recordings on the southern and northwestern facades of both homes were conducted using thermocouples over a 15-day period. The data analysis yielded insights into facade performance before and after this rehabilitation approach. The findings suggest that the implementation of ETICS results in more stable interior temperatures, significantly reducing indoor temperatures in comparison to outdoor conditions, leading to a notable decrease in heat energy loss. Consequently, this research underscores the tangible benefits of employing ETICS in building rehabilitation, emphasizing its role as a passive energy-saving strategy. By demonstrating the positive impact on thermal performance and energy efficiency, this study reinforces the vital connection between research endeavors and sustainability objectives.

1. Introduction

Buildings represent approximately 40% of total final energy use and 36% of all CO₂ emissions in the European Union (EU) [1,2]. Therefore, the EU climate and energy policy from the 2030 Agenda emphasizes that the majority of the energy-saving potential in the EU lies in the construction sector [3].

Given this problem, the EU has established a legislative framework consisting of the Energy Performance of Buildings Directive (EPBD) of 2010 [4], which consolidated the EPBD of 2002 [5], and the Energy Efficiency Directive of 2012 [6]. Currently, the EPBD Directive 2018 [7] is in effect. It applies a long-term strategy intended to create a highly energy-efficient and decarbonized real estate park by 2050.

In Spain, the EPBD has been transposed into national legislation through the Basic Energy Savings Document of the Technical Building Code (CTE-DB-HE 2019) [8], which includes a series of basic requirements. The six requirements cataloging buildings as second-generation NZEB (almost zero energy) are energy consumption limitations (CTE-DB-HE0 2019); conditions for controlling energy demand (CTE-DB-HE1 2019); thermal installations performance (CTE-DB-HE2 2019), developed in the Building Thermal Installations Regulation [9]; the conditions of the lighting installations (CTE-DB-HE3 2019); minimum contributions of renewable energy to satisfy domestic hot water demands (CTE-DB-HE4 2019); and the minimum generation of electrical energy (CTE-DB-HE5 2019) [10].

To assist with all of this, the EU declared that all new buildings must have almost zero energy consumption (NZEB) as of 31 December 2020, and all public buildings should be NZEB as of 31 December 2018 [5], but the greatest concern currently focuses on existing buildings and their high energy consumption, given that 35% of all EU buildings are over 50 years old and 90% were built before 1990 [11]. On the other hand, renovations of NZEB are not defined in terms of a specific threshold of primary energy savings, but rather, with the official national definitions of NZEB, which verify the importance of having special NZEB definitions for existing buildings. Therefore, in Spain, there continues to be room for more ambitious limitations, in line with the conclusions made by the Buildings Performance Institute Europe (BPIE) in its last report, offering detailed analysis of the ambition levels of new construction standards across the EU [12].

We can install different systems to reduce building consumption, such as ceiling fans that can reduce energy by up to 32% in a zero-energy building, while maintaining high thermal comfort [13]. Some studies have shown that one of the best ways to contribute to energy savings and improve comfort inside existing buildings is to improve the insulating capacity of their envelopes [14,15,16,17,18]. Currently, one of the most frequently used strategies to improve the thermal behavior of facades is the use of ETICSs (External Thermal Insulation Composite Systems), since not only do they mitigate thermal bridges and condensation [17,19,20,21], but they also have the advantage of not reducing the apartment’s useable area, improving the aesthetic appearance of the buildings [22]. ETICSs are construction systems composed of multiple layers: the external wall, the insulation material, adhesive, the base coat, the reinforcing mesh, and a decorative finishing layer [23]. This technique may vary depending on the insulation manufacturer, since different types of insulating materials can be placed: expanded polystyrene (EPS) plates, extruded polystyrene (XPS) plates, or ETICS with mineral wool plates. When applying it, there are different techniques: In some products, a perimeter cord and strips are spread centered on the back of the insulating plate, and in others, the adhesive is spread over the entire back of the plate with a notched trowel. Even for large surfaces, you can choose to extend a cord with the help of a spraying machine and place the insulating plates on it. The ETICS tends to have good mechanical resistance, CO₂ permeability, impermeability to water and water vapor [24], and along with these benefits, diverse studies have shown that the systems really do contribute to improving the thermal behavior of buildings [25,26,27,28,29].

In this experimental study, monitoring was used to compare the thermal performance of the envelope of two single-family homes built on the same date, having the same initial construction typology, the same orientation, and both located on Calle Tarancón (numbers 7 and 15, respectively) in Valdemoro (Madrid). The first construction, referred to in this work as the “Tarancón 7 home” was renovated using a 10 cm ETICS in 2021, while the second home, referred to as the “Tarancón 15 home” was not renovated. The primary aim was to measure the energy efficiency enhancements achieved by implementing a rehabilitation system in the “Tarancón 7 home” compared to the non-rehabilitated “Tarancón 15 home”. The data analysis highlights the positive impact of External Thermal Insulation Composite Systems (ETICSs) on the energy efficiency of this building type, considering the specific conditions examined.

The construction of two simultaneous dwellings, erected in the same year, under the same standards, using the same construction system and sharing a similar orientation, provides an ideal scenario for meaningful comparisons between the two structures. The similarity in these essentially controlled conditions allows us to more accurately analyze the impact of specific variables and evaluate the effectiveness of different components on the performance and efficiency of the buildings. The goal is to provide a holistic approach that combines quantitative data with qualitative experiences to provide a complete picture of the benefits of retrofitting with SATE compared to a non-retrofitted home.

2. Methodology

A comprehensive overview of local climatic conditions is provided to offer a contextual backdrop for the findings; this includes an in-depth exploration of factors such as temperature variations, humidity levels, and prevailing weather patterns, all of which can significantly influence the performance of the facades under scrutiny. Understanding these climatic nuances is crucial for interpreting the recorded data accurately and drawing meaningful conclusions regarding the efficacy of the adopted energy-saving strategies.

Furthermore, the technical specifications of both the initial and rehabilitated facades are elucidated in detail. This encompasses a thorough examination of the materials used, structural compositions, and architectural elements employed in the construction of each facade. By delineating these technical aspects, a comprehensive understanding of the baseline conditions is established, serving as a crucial reference point for evaluating the impact of the ETICS rehabilitation.

In conjunction with the facade specifications, the parameters set for measurement are expounded upon. This includes a detailed explanation of the instrumentation utilized, the locations of thermocouples, and the specific variables monitored throughout the study duration. Clearly defining these measurement parameters ensures the precision and reliability of the data collected, facilitating a robust analysis of the thermal performance before and after the rehabilitation process.

In essence, this expanded section not only provides a thorough insight into the local climatic context but also delves into the technical intricacies of the facades and the meticulous parameters guiding the measurement process, all of which are imperative for a comprehensive understanding of the research findings.

2.1. Description

Two isolated, single-family homes located at Calle Tarancón 7 and 15 of Valdemoro (Madrid), built at the same time and completed in 2009, having the same building composition and the same spatial orientation. In 2021, the facade of the “Tarancón 7 home” was renovated, consisting of covering the envelope with 10 cm of 20 kg/m³ expanded polystyrene of the Weber brand, “weber.therms etics” model. The “Tarancón 15 home”, on the other hand, was not renovated. This, and the highly similar characteristics of the homes in all senses (location, age, construction type, and orientation) permitted the collection and comparison of data on surface and environmental temperature of their facades. It should be mentioned that, during the measurements, the “Tarancón 7 home” was occupied by a family with four household members while the “Tarancón 15 home” was occupied by a family with three members, in both cases, the homeowners.

The climate in Madrid (Spain) is characterized as mild (Mediterranean, continental), with temperatures ranging from 0° to 18 °C during the winter months. The classification of this climatic zone corresponding to Spain according to the Köppen-Geiger system (AEMET—State Meteorology Agency and IM—Portuguese Meteorological Institute) is Csa (mild, dry, hot in the summer) [23].

The study was conducted at the end of April and the beginning of May, a period coinciding with spring in Madrid. Both the average temperatures and the variation in day and night readings make the selected period suitable for monitoring ETICS thermal activity.

The average temperature in Valdemoro (Madrid) during April and May of 2023 was 15 °C (7.5 °C and 10 °C minimum in April and May, respectively; 17.5 °C and 22.5 °C maximum in April and May, respectively; and the relative humidity was 56% in May and 52% in April, with an average of 6.4 days with over 1 mm of rain [30].

Valdemoro is a municipality located in the south of the Madrid community (Latitude: 40°11′20″ N—Longitude: 3°40′43″ O). The two single-family homes are individual constructions built in 2009. They both have a basement (used as a garage and storage room), ground floor and first floor (where the other rooms are located). They have facades in all four orientations, but the main facades correspond to the north and south (Figure 1 and Figure 2).

For the purpose of this study, the locations indicated in

Table 1. Locations and nomenclature of dataloggers and thermocouples used in “Tarancón 7 home” and “Tarancón 15 home”.

Name	Orientation	Floor	Datalogger (Serial Number)	Indoor Thermocouple	Outdoor Thermocouple	Nomenclature in Graphics
“Tarancón 7 home”—living room	South	Ground floor	7895	Opus 200-6 (1)	Opus 200-12 (2)	7S_…
“Tarancón 7 home”—office	Northwest	First floor	7974	Opus 200-14 (3)	Opus 200-31 (4)	7NW_…
“Tarancón 15 home”—living room	South	Ground floor	7892	Opus 200-8 (5)	Opus 200-16 (6)	15S_…
“Tarancón 15 home”—child’s bedroom	Northwest	Ground floor	7973	Opus 200-0 (7)	Opus 200-28 (8)	15NW_…

and the representations in Figure 3 and Figure 4 were used.

The original facade (Figure 5), having a thickness of 28.75 cm, consisted of perforated ceramic brick with a thickness of 12.25 cm, finished on the outside with 2 cm of acrylic mortar, 5 cm of mineral wool, and 7.5 cm double hollow brick partition finished on the inside by 2 cm of plaster. The U-value of the enclosure in the unrenovated state is 0.42 W/(m²·K), calculated with the Basic Energy Savings Document of the Technical Building Code [10,31]. Windows were low thermal emissivity PVC tilt-and-turn double-glazed windows (4 + 4/14/6), having an average transmittance of 1.3 W/(m²·K).

The renovation of the facade carried out in 2021 was only conducted on the opaque part of the “Tarancón 7 home”; the exterior carpentry was not renovated. As previously mentioned, the Weber brand, therms etics model ETICS was used, having the following recognized European technical sheet: ETA 03/0058 [32]. This system (Figure 6) consists of adding stabilized expanded polystyrene (EPS) plates of 20 kg/m³ (to avoid dimensional losses) attached to the support with polymer mortar, Weber-therm.base, single-compound, transpirable and impermeable, armed with HD fibers (high dispersion glass fiber) in its composition, pre-dosed (with the necessary thickness for suitable alignment); reinforced with fixings on polypropylene mechanical anchors (spikes of 50 mm of Ø) measuring 90–110 mm in 7 units per/m², subsequent plastering of the EPS plates with two coats of Weber-therm.base (3 mm thickness), reinforced with fiberglass mesh (160 g/m² and 4 × 4 mm grid and 4% deformability); and the placement of system accessories (start profiles and mesh corners, drip corners, expansion joints, etc.); roller application of Weber PRIMER color regularization and background absorption primer as required by the system; and final coating with high-performance mineral acrylic mortar Weber.tene CLASSIC L black and white color.

The insulating panels used in the construction of “Tarancón 7 Home” are made of 10 cm EPS and cover the entire surface of the vertical facing, with a screen thickness of 38.75 cm. One of the objectives of this type of renovation is to maintain the aesthetics of the home. Because it has a smooth and uninterrupted finish, the thickness of the panels must be adapted to the shape of the surface [29]. Therefore, in the case of the jambs and lintels, 5 cm thick panels were used. After the rehabilitation, the theoretical thermal transmittance of the facades was 0.17 W/(m²·K), calculated based on the Basic Energy Savings Document of the Technical Building Code [10] and the UNE-EN ISO 6946 international standard [33].

The color of the facades was white for most of the surfaces, with some small areas in black, in accordance with the initial aesthetic, in an attempt to avoid higher surface temperatures resulting from colored facades [34].

The use of each of the homes did not change during the study period. The “Tarancón 7 Home” was occupied by four individuals, two of whom were between 40 and 50 years of age and two between the ages of 10 and 12; the “Tarancón 15 Home” was occupied by three people, two between the ages of 40 and 50 years and one 9 year old. Depending on the daily use conditions, both may be classified as low internal charge spaces with an internal source density of less than 6 W/m² [10,31]. The indoor environment was maintained between 22 °C and 24 °C during the day and 18 °C and 20 °C at night.

2.2. Experimental Setup

The temperatures of the southern and northwestern facades were recorded and compared to evaluate the influence of the ETICS. For this, contact-type surface temperature measurement instruments were used (thermometers (thermocouples)), in accordance with UNE-EN ISO 7726 [35] and ISO 9869-1:2023 standards [36].

Thermocouples were placed to ensure that results were as representative as possible of the entire construction element. Therefore, they were arranged on the facades as shown in Figure 7 and Figure 8, at an approximate height of between 1 and 1.3 m above the home’s floor level, as this is the most representative area of the facade, according to ISO standard 9869-1:2023 [36] and taking into account the possibilities of manual placement within and outside of the homes. The nomenclature of each control area is shown in Table 1.

To validate the temperature measurements, instructions from the ISO 9869-1:2023 standard [33] were followed. Therefore, the values obtained by the sensors were recorded continuously or fixed for a period of entire days and a minimum of 72 h (in this case, for 15 full days, from 24 April to 8 May 2023). An average interval of 10 min was used for the reading of the registers.

Type k thermocouples were used, having a precision of ±0.2 °C. It connected to the surface and connected to the OPUS 200 data logger. This data logger records the temperature every 2 min and the average every 10 min. Since heat transfer occurs between the sensor and the surface, it is important to insulate the thermocouple from adverse weather conditions (sun damage, rain, wind), as shown in Figure 9.

3. Results and Discussion

The results obtained from the analysis of the monitored values of the thermocouples from 24 April to 8 May 2023 are described below. The variables examined were indoor and outdoor wall surface temperatures (T, in °C) and heat flux (q, in W/m²). Differences in surface temperatures and heat flux between the facades of “Tarancón 7 home” (rehabilitated with ETICS) and “Tarancón 15 home” (not rehabilitated) were compared.

3.1. Database Selection

Data for both homes were systematically recorded during the same timeframe, ensuring identical external conditions and facilitating a meaningful comparison. Outdoor temperature data were sourced from the Spanish Meteorology Agency (AEMET), utilizing information from the nearest meteorological station located in Getafe (Madrid), approximately 21 km north of Valdemoro (Madrid). The meteorological station at Getafe is situated at an altitude of 620 m, with a latitude of 40°17′58″ N and a longitude of 3°43′20″ W.

Analysis of the meteorological station data revealed that, throughout the duration of the study, the average maximum environmental temperature, derived from the recorded maximum daily temperatures, stood at 20.8 °C. Concurrently, the average minimum temperature, calculated based on the minimum daily temperatures, was recorded at 8.7 °C. The overall average temperature for the study period was determined to be 12.5 °C.

These meticulously recorded meteorological conditions provide a robust foundation for assessing the thermal performance of the facades in both homes, as any observed variations can be attributed to the rehabilitation process rather than external climatic disparities.

3.2. Analysis of the Thermal Behavior of the Facades

The received temperature data are uploaded to the average temperature database every 10 min, making 144 measurements per thermocouple per day, for a total of 1152 data collected.

First, the data obtained from the unrenovated “Tarancón 15 home” were analyzed. As seen in the following graph (Figure 10), the surface temperatures inside the facades (south “15S_indoor”, as well as in the northwest “15NW_indoor”) had minimum temperature ranges, as compared to the data recorded in the outdoor thermocouples (south “15S_outdoor” and northwest “15NW_outdoor”). demonstrating higher and lower values compared to the indoor temperatures.

The table below shows the difference between the temperatures of the indoor and outdoor surface of the different facades, with the difference in average temperatures being −0.6 °C on the south facade and 1.9 °C on the northwest facade (

Table 2. Minimum, maximum, and average temperatures obtained in the “Tarancón 15 home”.

Name	Maximum T	Minimum T	Average T	Standard Deviation
15S_Outdoor	76.0 °C	8.0 °C	22.8 °C	1.14
15S_Indoor	27.2 °C	18.1 °C	23.4 °C	10.62
ΔTª Out-Ind_S	48.8 °C	−10.1 °C	−0.6 °C
15NW_Outdoor	39.6 °C	11.3 °C	22.9 °C	0.89
15NW_Indoor	24.5 °C	20.6 °C	21.0 °C	4.92
ΔTª Out-Ind_NW	15.1 °C	−9.3 °C	1.9 °C

).

In addition, comparing the average indoor surface temperature of the south facade “15S_Indoor” of 23.4 °C and northwest “15NW_indoor” of 21.0 °C, a difference of 2.4 °C was observed between 2 facades of the same building.

Second, the data obtained from the “Tarancón 7 home” were analyzed. This building was renovated using an ETIC-type outdoor insulation system described above. As seen in the graph below (Figure 11), the surface temperatures inside the facades (south “7S_indoor” and northwest “7NW_indoor”) presented minimum temperature ranges, as occurred in the other home. The data collected in the outdoor thermocouples (south “7S_outdoor” and northwest “7NW_outdoor”) reveal fluctuations, with higher and lower values compared to the indoor temperatures.

In the table below, it is possible to see the difference between the temperatures of the indoor and outdoor surfaces of the distinct facades, with the temperature differences averaging −1.2 °C in the southern facade and 4.2 °C in the northwest facade (

Table 3. Minimum, maximum, and average temperatures obtained in the “Tarancón 7 home”.

Name	Maximum T	Minimum T	Average T	Standard Deviation
7S_Outdoor	63.3 °C	7.5 °C	22.6 °C	0.84
7S_Indoor	24.7 °C	20.0 °C	23.8 °C	11.08
ΔTª Out-Ind_S	38.6 °C	−12.5 °C	−1.2 °C
7NW_Outdoor	36.3 °C	8.2 °C	23.9 °C	1.13
7NW_Indoor	26.4 °C	20.9 °C	19.7 °C	5.24
ΔTª Out-Ind_NW	9.9 °C	−12.7 °C	4.2 °C

). The result obtained in this home is double that found in the “Tarancón 15 home”.

In addition, comparing the average indoor surface temperature of the south facade “7S_Indoor” of 23.8 °C and northwest facade “7NW_indoor” of 19.7 °C, a difference of 4.1 °C is found between the two facades of the same building. This value is also double that obtained in the “Tarancón 15 home”.

Thirdly, the data from both homes are compared to obtain the difference in the indoor and outdoor surface temperatures of the original facade and of the one rehabilitated with the ETICS (Figure 12 and Figure 13). Analyzing the average temperature difference between the outdoor and indoor sensors, that of the rehabilitated south facade is 50.0% lower than that of the facade in its original state. Moreover, on the rehabilitated northeast facade, it is 54.8% lower than that of the original facade.

To measure the effect of the ETICS on interior surface temperatures, statistical analysis of the data was performed using Stargraphics, using a simple regression model to compare interior and exterior surface temperatures for each facing before and after renovation (

Table 4. Correlation between indoor and outdoor surface temperatures of both homes.

Name	Northwest	South
Tarancón 15 Home (not renovated)	Correlation Coef. = 0.0256	Correlation Coef. = 0.2117
	R-squared = 0.1%	R-squared = 4.5%
Tarancón 7 Home (renovated)	Correlation Coef. = 0.3585	Correlation Coef. = 0.3303
	R-squared= 12.8%	R-squared = 10.9%

).

The correlation coefficient between indoor and outdoor temperatures is lower in the unrenovated home (Tarancón 15), so there is less of a relationship between the values collected by the thermocouples. The same occurs with the R-squared coefficient of determination, where the results obtained indicate a lower value in the unrenovated facade.

The resulting results are similar to the data presented in the previous figure. The correlation between interior and exterior surface temperatures is lower than in the unmodified home. In the renovated façade, the R-squared coefficient of determination is greater than that of the unrenovated home, showing a larger correlation between the data collected.

There is also a difference between the west and south sides, the correlation being higher for the surface on the west side than for the south side.

3.3. Analysis of Changes in Heat Flux

The heat flux (q) was calculated per unit area considering a steady state where the power transmitted per unit area is the same for all layers of the composite wall as given by Equation (1) and is defined as the internal temperature of the facade (Ti), the temperature of the external surface of the facade (Te), and the thermal resistance of the facade (RT).

q = (Ti − Te)/RT (W m⁻²)

(1)

where RT (m² KW⁻¹) is the total thermal resistance of all materials in the opaque part of the facade, calculated according to the CTE [10,31] as shown in

Table 5. Theoretical conditions of the elements of the facades studied, according to the CTE’s building elements catalog.

	Unrehabilitated “Tarancón 15” Facade			Rehabilitated “Tarancón 7” Facade
	w (m)	l (W/mK)	R (m2K/W)	w (m)	l (W/mK)	R (m2K/W)
Cement mortar				0.020	0.073	0.274
Expanded polystyrene EPS				0.100	0.029	3.448
Acrylic mortar	0.020	0.350	0.057
½ Foot of perforated ceramic brick	0.123	0.350	0.350	0.123	0.350	0.350
Mineral wool thermal insulation	0.050	0.031	1.613	0.050	0.031	1.613
Double hollow brick partition wall	0.075	0.320	0.234	0.075	0.320	0.234
Gypsum plaster	0.020	0.200	0.100	0.020	0.200	0.100
Total R of the enclosure (m2K/W)			2.354			6.020

.

Figure 14 shows the heat flow changes in the Tarancón 15 home (unrenovated) and the Tarancón 7 home (renovated). Efficiency is as expected, one that releases heat during the coldest hours of the day and absorbs heat at midday. With the original facade, the heat flow to the south is 2.00% greater than to the north (yellow and orange lines). On the renovated facade, the heat flow is more stable (blue and gray lines) and the difference between south and north is only 0.15%. In both cases, the southern facades are the highest fluctuations.

When both facades are considered the amount of heat and energy was saved in the home before and after renovation is 5 W/m² and 1884.0 W/m². This amount of energy is lost during the coldest hours of the day. But during the middle of the day, when temperatures are warmer, energy flows from outside to inside the home, as shown in the following

Table 6. Heat losses and gains in different homes and in different orientations.

Name	Northeast (W/m2)		South (W/m2)
	Losses	Gains	Losses	Gains
Tarancón 15 (not rehabilitated)	−1160.5	2983.5	−3971.4	3471.0
Tarancón 7 (rehabilitated)	−232.3	1718.5	−1718.7	1321.6

.

This means that in the south direction, the opaque part of the renovated facade of the home reduces energy losses by 56.7% and energy gains by 61.9% compared to the facade of the original house. As for the northwestern orientation, the energy losses of the rehabilitated facade are reduced compared to the original facade by 80% and the energy gains by 42.4%.

Moreover, both facades have a greater difference between the maximum and minimum heat flow on the non-renovated facade because the difference between the internal and external temperatures is smaller. On the ETICS facade, where the temperature difference between the internal and external surfaces is greater, the heat flow is more stable.

4. Conclusions

The current literature on energy retrofitting of existing building facades is cited in the present paper, which brings together previous studies based on experimental data. Specifically, it reveals the benefits of using ETICS in the rehabilitation of facades of single-family homes in hot climates. Sufficient data were collected during the study period to permit an in-depth analysis of facade performance before and after the renovation, assisted by the fact that both homes were built on the same date, location, and orientation and with the same starting materials.

On a facade renewed with the ETICS, the temperatures of the internal surfaces are more stable all the time and close to the average indoor air temperature. Although external surface temperatures affect internal surface temperatures of the original facade (12.8% [Northeast] and 10.9% [South]), this effect is minimal (0.1% [North] and 4.5%) for the facade restored with ETICS. [South]. The data show that an ETICS installation achieves internal surface temperatures that are more independent of external surface temperatures compared to an unrenovated facade. Therefore, the outdoor ambient temperature will have less of an impact on the indoor temperature.

However, the temperature differential between the north and south facades of the internal surface was decreased by 69.2% compared to the same difference of the building with the original facade. This means that the rehabilitation solution minimizes the differences and unifies the behavior of the surface temperatures in both orientations of the same building. Moreover, the increase in average temperature improvement between the outdoor and indoor was 50% on the southern facade and 54.8% on the northwestern one, using the original facade as a reference, as compared to the rehabilitated one.

This study focuses on the role of ETICS in controlling heat flow within the envelope’s opaque region. The installation of ETICS reduces power losses by 56.7% and power gains by 61.9% as compared to the facade in its original state. In particular, the heat energy lost before and after the renovation is 2323.5 W/m² in the original state, as compared to 1884.0 W/m² in the renovated state.

The findings from this study underscore the significance of conducting on-site trials to precisely quantify the enhancements in the thermal behavior of facades. This is crucial, given that variables like orientation and fluctuations in outdoor temperatures exert a direct influence on thermal performance, as convincingly demonstrated by the outcomes.

Taking into account all the aforementioned factors, it can be firmly concluded that, for comparable homes situated in the continental Mediterranean climate of Madrid, the rehabilitation process involving External Thermal Insulation Composite Systems (ETICS) emerges as a pivotal solution. By augmenting the insulation capacity of facades, ETICS not only showcases a remarkable ability to reduce heat loss but also contributes significantly to the overarching goal of sustainability. This sustainable approach aligns with the imperative need to enhance energy efficiency in the built environment, ultimately fostering a more environmentally responsible and resource-efficient architectural landscape. Therefore, the study advocates for the adoption of ETICSs as a strategic measure to harmonize building rehabilitation efforts with the broader objectives of sustainable and energy-efficient construction methods.

Some limitations encountered in the development of the research are the specific climatic conditions of the building environment, which pose a geographical limitation, as well as, the unique constructive geometry of the building and the temporal limitations, together with the need to consider the representativeness of the sample and the possible technological restrictions in the equipment used for monitoring.