Hygrothermal and environmental performance of a perlite-based insulating plaster for the energy retrofit of buildings

Accepted Manuscript

Hygrothermal and environmental performance of a perlite-based insulating plaster for the energy retrofit of buildings Elisa Fenoglio , Stefano Fantucci , Valentina Serra , Corrado Carbonaro , Riccardo Pollo PII: DOI: Reference:

S0378-7788(18)30543-7 https://doi.org/10.1016/j.enbuild.2018.08.017 ENB 8753

To appear in:

Energy & Buildings

Received date: Revised date: Accepted date:

14 February 2018 3 August 2018 12 August 2018

Please cite this article as: Elisa Fenoglio , Stefano Fantucci , Valentina Serra , Corrado Carbonaro , Riccardo Pollo , Hygrothermal and environmental performance of a perlite-based insulating plaster for the energy retrofit of buildings, Energy & Buildings (2018), doi: https://doi.org/10.1016/j.enbuild.2018.08.017

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ACCEPTED MANUSCRIPT Highlights 

An experimental assessment of the impact of the perlite content on the thermal performance of plaster is here presented

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Analyses have been carried out through laboratory, in-situ measurements and heat and moisture transfer simulations on a real case study

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The embodied energy and embodied carbon have been assessed for different percentages of perlite

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content

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Hygrothermal and environmental performance of a perlite-based insulating plaster for the energy retrofit of buildings Elisa Fenoglio a, Stefano Fantucci a, Valentina Serraa*, Corrado Carbonarob, Riccardo Pollob a

Department of Energy, TEBE Research Group, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino

b

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10129, Italy Department of Architecture and Design, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129,

Italy * Corresponding author: Valentina Serra

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Tel.: +39 011 0904431; fax: +39 011 0904499 E-mail address: [email protected] Abstract

In the last few years, thermal insulating plasters have started to be an attractive solution for the insulation of

the replacement of damaged plasters.

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already existing wall structures, especially old masonry ones, where refurbishment interventions can involve

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Intensive research efforts are being made to reduce the thermal conductivity and the environmental impact of these materials by optimizing their mixtures (combination of lightweight aggregates, binders and additives).

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In the present study, the hygrothermal performance and environmental impact of the different perlite-based plasters that are currently being developed have been investigated.

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A series of analyses has been carried out, at a material scale, by means of heat flow meter apparatus, to determine the relationship between the perlite content and the thermal properties. Moreover, the effect of the

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moisture content on λ has been analyzed, and the embodied energy and embodied carbon of the four mixtures have been assessed using both the cradle-to-gate and the cradle-to-site approaches. Furthermore, in-situ measurements have been conducted at a demonstration site, at a component scale, and a series of heat and moisture transfer simulations has been carried out to evaluate the actual thermal behaviour of the plaster under real operating conditions. The thermal conductivity values of the four plaster mixtures ranged from between 0.118 W/mK and 0.059 W/mK, thus demonstrating that the perlite concentration had a significant impact on the reduction of thermal conductivity and that the embodied energy of the applied material (5 cm thickness) decreased as the perlite content increased. Moreover, the results of the measurements on the demonstration building and the

ACCEPTED MANUSCRIPT hygrothermal simulations have revealed that the thermal insulating plaster is able to reduce the U-value of the wall. However, an increase of 26-30% of the actual thermal conductivity should be considered when the material is exposed to real operating conditions. Keywords: Thermal insulating plaster

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Building energy retrofit Thermal conductivity Rendering coat

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Embodied energy

Nomenclature: Thermal conductivity

U

Thermal transmittance

R

Thermal resistance

C

Thermal conductance

Rsi

Interior surface resistance factor

[m2K/W]

Rse

Exterior surface resistance factor

[m2K/W]

Tai

Indoor air temperature

[°C]

Tae

Outdoor air temperature

[°C]

Tsi

Indoor surface temperature

[°C]

Tse

Outdoor surface temperature

[°C]

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q

[W/mK] [W/m2K] [m2K/W] [W/m2K]

Heat flux density

[W/m2]

Dry bulk density

[kg/m3]

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ρ

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λ

Acronyms: LWA

Light weight aggregates

HFM

Heat flow meter

HMT

Heat and moisture transfer

EPS

Expanded polystyrene

PE

Polyethylene

GWP

Global Warming Potential

EE

Embodied Energy

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Embodied Carbon

1 Introduction Most of the building stock in Italy was built before 1970 [1], during years in which no laws concerning energy savings in buildings were inforced. Moreover, the primary causes of energy consumption were related to civil use, and space heating/cooling represented the most significant part of the final energy demand [2]. The most critical elements were the installed opaque components, which contributed to a higher energy loss of the building [3]. Therefore, the energy retrofitting of existing buildings should be considered a

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good approach to reduce the overall building energy consumption. Since most of the building stock is made up of masonry, thermal insulating plasters can be considered suitable materials for energy retrofitting. These materials are made up in the same way as traditional plasters, but sand is replaced by different types of lightweight aggregates (LWA) that contribute to reducing the thermal conductivity. This retrofitting technique is preferable to the current solutions, due to the higher hygrothermal compatibility and easier

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application to irregular supports that can be achieved. Thanks to the good thermal properties achievable using LWA to produce plasters, several studies have analysed the variations in the thermal and mechanical behaviour as a function of the LWA content [4]. The aims of this study have been:

to assess the thermal and environmental performance variations of a set of thermal insulating plasters

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that have been improved by the addition of variuos percentages of perlite; to analyse the variation of the actual thermal performance of thermal insulating plaster exposed to

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real operating conditions and compare the resultswith the results of laboratory tests.

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To achieve the above-metioned objectives, a series of thermal conductivity measurments was carried out together with embodied energy and embodied carbon analyses to determine the influence of the perlite

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content on both the thermal conductivity and the environmental behaviour of the plasters; in addition, the thermal conductivity tests were repeated under water saturated conditions on a previously chosen mixture.

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This formulation was also applied to the interior side of the external vertical walls of a XIX century rural house in Italy that had been selected as a case study and which was monitored to determine the thermal performance of the thermal plaster at a component scale. The insulated walls were monitored and compared with non-insulated walls in the building (the unheated rooms were not insulated), to identify the benefits achievable through the application of thermal plaster. The monitored data were then used to calibrate an HMT simulation model in WUFI Pro software [5], and the model was used to evaluate the changes in the hygrothermal behaviour of the wall over the long term. Analyses of the embodied energy and embodied carbon were conducted to assess how the perlite content can affect the environmental behaviour of the materials.

ACCEPTED MANUSCRIPT Attention was in particular focused on the conductivity relation as a function of the moisture content. A similar study was developed in 2014 [6], but no evaluation or simulation of the moisture content was reported. 2 State of the art on mineral-based thermal plasters Thermal insulating plasters are made by adding various types of Light Weight Aggregates (LWA) to a matrix, which can be made of cement, gypsum, natural hydraulic lime or hydraulic lime. A widely diffused

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type of LWA is mineral aggregates, including perlite, vermiculite, diatomite, zeolite and pumice. Different studies have been developed on plasters made up of these different types of aggregates.

In 2009, L.M. Silva et al. [7] developed a study on a series of plaster mixtures packed with perlite and vermiculite. The study highlighted that the mineral content led to a decrease in the mechanical properties. Another study [8] focused on the mixing of cement mortars and expanded perlite, polystyrene, expanded

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glass and hollow microspheres. That study also highlighted that polystyrene and perlite were the LWAs that affected the mechanical properties the most. S. Abidi et al. [9] developed a series of biphasic plasters made of gypsum, perlite and vermiculite. His numerical and experimental results showed that the addition of a mineral aggregate led to an increase in porosity and a decrease in thermal conductivity. A percentage of perlite and vermiculite of 25% was found to reduce thermal conductivity: 0.23 W/mK for vermiculite and

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0.16 W/mK for perlite (from an initial value of 0.50 W/mK). A cement-based plaster, to which perlite and different types of pumice, such as LWAs, polypropylene (PP) fibres, a foam agent, adhesive polymer and lime, had been added, was investigated in [10]. The addition of these LWAs reduced thermal conductivity

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from an initial value of 0.87 W/mK to a value of about 0.08 W/mK. Perlite led to a greater decrease of λ than pumice, while pumice showed better compressive strength. Other studies focused on mixing mineral

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aggregates and fibres to improve both the mechanical and the thermal properties. O. Gencela et al. [11] developed a series of specimens made up of gypsum with vermiculite (10-20%) and PP fibres (0.5-1.0%).

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The results showed that vermiculite and the PP fibres contributed by decreasing the unit weight; vermiculite led to an increment in porosity, but also determined a loss of the mechanical resistance; thermal conductivity was found to be influenced by the presence of vermiculite and, to a lesser extent, by PP fibres. A similar

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plaster, in which PP fibres were added to a mixture of gypsum and diatomite, was also studied [12]. The effect of diatomite was found to be more relevant, than that of fibres, on reducing the unit weight, while no effect on the porosity was observed. An increase in bending strength was observed, thanks to the presence of the PP fibres, and diatomite contributed by improving the compressive strength. The thermal conductivity decreased according to the diatomite concentration, and reached a final value of 0.384. K. Sedan et al. [13] developed a series of plaster mixtures containing both pumice and sunflower stalks. The results of their tests showed good thermal properties, but also increases in the content of the LWA density and decreases in the compressive strength. In [14], a decrement in thermal conductivity was obtained for two plaster mixtures: the first one, which was based on NHL, zeolite, vermiculite perlite and granular corncob, was used to produce plaster, while the second one was made with the addition of NHL, Portland cement, perlite, corncob and

ACCEPTED MANUSCRIPT wheat straw. The results of tests showed decreases in the λ value to 0.101 and 0.086 W/mK, respectively. The material developed in that study was also analysed for a real case application, and the results showed a reduction in the energy loss through the wall. However, no evaluation of the thermal behaviour was made as a function of the moisture content [6]. J. Zach et al. [15] developed a thermal plaster using expanded obsidian, with the addition of lime hydrate, cement and metakaolin. The lowest thermal conductivity obtained was about 0.07 W/mK. The addition of metakaolin was found to improve the mechanical strength, while discrete thermal properties were maintained. The final product showed a good ratio between the

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thermal insulation and mechanical resistance. Mineral binders were also used as a container for PCM and to produce gypsum plaster, which showed good thermal properties [16]. Using this LWA to produce plaster allowed a higher internal temperature to be maintained for a longer period. Mineral aggregates allow good thermal properties to be obtained, but it is necessary to improve plaster with nanomaterials, such as aerogels, to achieve a better thermal insulation level. The thermal conductivity obtained using this LWA was very low (about 0.027 W/mK [17][18][19]), this thermal plaster did not show any significant thermal performance

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variation when exposed to an aging process, and only a high humidity level was found to affect the λ-value, albeit only slightly [20] [21]. However, the final product is not always economically viable [22] as a result of the high production cost of aerogel.

Another factor that affects thermal conductivity is the presence of moisture in plaster. In [23], changes were made to the thermal conductivity as a function of the moisture content for a traditional plaster made up with

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different types of lime: a series of specimens were tested, and numerical models were developed. The results showed a large increment of the λ-value for all the considered types of lime (from 0.5 W/mK to 2 - 2.5

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W/mK). A study on the hygrothermal performance of a wall with thermal insulating plaster, based on aerogel, was conducted by M. Ibrahim et al. [24]: a WUFI simulation analysis was performed after in-situ

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measurements. In that case, no evaluation of the variations in thermal conductivity was conducted, but a series of evaluations on the mould growth, water content and condensation risk was carried out. The same

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material was investigated in [25], and better results were obtained than for the material with mineral aggregates. The results showed a conductivity of about 0.027 W/mK. All the tests carried out with different types of LWA used to produce thermal plasters showed good results, regarding the thermal properties, and a

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value of ~0.08 W/mK was reached, but the mechanical behaviour was very poor for all the mineral compounds, except for those made of diatomite. Furthermore, the addition of PP fibres enhanced the flexural strength. A few studies ([6],[25]) have focused on in-situ thermal performance assessments. Although several studies have analysed the thermal performance of insulating plasters, less research has been done on the variations of their thermal properties as a function of the moisture content. The behavioural changes, due to the presence of moisture, can be analysed through Heat and Moisture Transfer simulations. An experimental validated HMT simulation was used in [24] on a building wall with different types of external/internal coatings to evaluate the risk of mould growth. T. Stahl et al. [26] investigated the moisture accumulation in hystoric walls retrofitted with an aerogel-based rendering on the external side. S. J. Chang et

ACCEPTED MANUSCRIPT al. [27] investigated the impact of the boundary conditions, exposure and the humidity level on the hygrothermal performance (condensation risk and mould growth) of two envelopes used in Korea (wood and concrete). Another study [28] reported the results of HMT simulations that had focused on the risk of mould growth on a typical thermal bridge and on the advantage achievable through the application of different thicknesses of the thermal coating. A coated wall, compared to an uncoated one, showed an increase in the surface temperature and a decrease in the mould index. K. Ghazi Wakili et al. [29] performed preliminary HTMs to identify any possible risks (water uptake) and to prevent damage to the building element, in a

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prefabricated concrete panel building retrofitted with an aerogel-based rendering coat. Scientific interest in materials and buildings for LCA has almost doubled in the last five years [30]. As a result of the growing interest in the use phase of buildings and in the materials applied in architecture, LCA studies have begun to take into account the embodied energy and the embodied carbon [31][32]. Several studies have focused on an LCA analysis on thermal plasters in which the embodied energy and embodied

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carbon of different plaster mixtures, made up of both natural and artificial aggregates, have been evaluated [33][14][34]. 3 Methodology

The analyses reported in this study were conducted at the material and component scales.

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A first series of laboratory test was conducted, at a material scale, by means of heat flux meter apparatus, to determine the thermal properties of plaster mixtures containing different quantities of a lightweight aggregate

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(perlite).

The environmental impact indicators (i.e. embodied energy and embodied carbon) were determined for each

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plaster mixture.

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Two different analyses were carried out at a component scale: An in-situ monitoring campaign was performed to determine the thermal transmittance of a component; two different walls were compared (retrofitted wall vs non-insulated wall); a series of heat and moisture transfer simulations was carried out to analyse the changes in the thermal

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performance of the component exposed to real operating conditions.

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The embodied energy and the embodied carbon of the applied materials were determined using the cradle-to-site approach.

3.1. Experimental analysis As mentioned before, the experimental analyses were performed at both a material scale (laboratory tests) and a component scale (in-situ measurements).

ACCEPTED MANUSCRIPT The laboratory tests were performed to measure the thermal conductivity of four mixtures of Natural Hydraulic Lime (NHL2 between 60% and 70%) and cement (<7.5%) mixed with different concentrations of perlite (from 25 to 40%). The analyses allowed the impact of the perlite content on the final thermal conductivity and the embodied energy to be identified. In a second step, one of the four analysed mixtures was applied to the case study building, and the thermal transmittance of the walls was measured, with and without the thermal insulating plaster, by means of the

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heat flux meter method, according to ISO 9869-1:2014 [35]. 3.1.1 Laboratory tests

The features of the four different analysed plaster samples (perlite mass fraction and dry bulk density) are summarised in Table 1, while a photographic survey showing the physical appearance of each sample is

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reported in Fig.1.

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Fig. 1: Photographic survey of the plasters under investigation.

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Table 1. Perlite aggregate mass fraction and dry bulk density of the four analysed plaster specimens. Perlite mass fraction

ρ (dry bulk density)

name

[%]

[kg/m3]

P25

25%

617

P30

30%

394

P35

35%

325

P40

40%

248

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Sample

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Fig. 2: a) Drying process: climatic chamber (ACS DM 340); b) HFM measurement (Lasercomp FOX 600). The specimens, made by means of manual mixing to achieve a size of almost 40x40x5 cm, were preliminary dried in a climatic chamber (ACS DM 340 Fig. 2a) at 100°C. Samples were considered dry when a constant mass was reached (weight variation <0.2% after two consecutive weighings, according to UNI EN 101510:2007 [36]), and the dry bulk density was then determined as the ratio between the dry mass and the net

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volume of the sample.

The equivalent thermal conductivity, λeq, was determined by means of a Heat Flux Meter (HFM), according

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to EN ISO 12667-2002 (Fig. 2b). Measurements were performed at two different set-point temperatures (10°C and 25°C) with a temperature difference between the instrument plates of 20°C. A measurement was also performed on P30 under a moisture saturated condition, which was reached by immersing the samples in

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a basin filled with water for 24h. Two additional rubber mats (2 mm each) were used for the test to reduce the contact thermal resistance between the samples and the plates and to avoid damage due to the imperfect

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planarity of the sample surfaces. Furthermore, the thermal resistance of the samples was determined by subtracting the thermal resistance of the two rubber mats (0.031 m2K/W, previously determined). The samples were sealed in a polyethene envelope (PE) to prevent any variations of the moisture content during

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the tests. Moreover, in order to verify that the specimens had not been affected by water vapour permeation, their weights were checked before and after each measurement. 3.2. In-field measurements 3.2.1. The case study The in-situ monitoring campaign was carried out on a rural house, built between the XIX and XX centuries, in south Piedmont (Dogliani) (Fig. 3); the site falls into climatic zone ―E‖ and is characterised by 2.681 heating degree days (HDD). After a period of abandonment, the building was subjected to a detailed refurbishment that also involved the opaque building envelope. The external wall was made up of solid fired

ACCEPTED MANUSCRIPT clay bricks and was subjected to energy retrofitting measures that involved the use of a thermal insulating plaster with perlite on the inside (thickness ~5 cm). The insulating plaster was considered a better solution than the commonly used ETICS technique for the following reasons: 

one of the goals of the refurbishment project was that of preserving the original aspect of the building;

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the plaster that was present was damaged and needed to be replaced, and the use of this thermal insulating plaster would increase the thermal resistance of the wall; this material was considered more compatible with the existing wall than other solutions that adopt

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material with a higher vapour resistance value (e.g. EPS panels); 

the thermal plaster was applied internally in order to preserve the duration of the material, because, if the plaster had been applied to the external surface of the wall, atmospheric agents could reduce the duration of the material;

the building was only used occasionally, and the use of plaster internally would allow the time

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necessary to heat the ambient to be minimised.

The monitoring campaign was carried out over a period of two years after the end of the refurbishment, with

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the main goal of analysing the thermal behaviour of the insulating plaster under actual operating conditions.

Fig. 3: The case study building during the refurbishment

3.2.2. In-field thermal transmittance measurments In order to assess the actual thermal performance of a retrofitted wall under real operating conditions, an in-field experimental campaign was performed on the case study house presented in section 3.2.1 (see Fig. 4). The measurements were carried out in two rooms, one on the ground floor (without insulating plaster) and the other on the first floor (retrofitted with the P30 insulating plaster). Measurements were performed simultaneously on two different oriented walls (north-east and north-west) in order to check

ACCEPTED MANUSCRIPT whether the external envelope presented a homogeneous structure and performance. The exterior walls were made of solid fired clay brick masonry (~50 cm thickness) and finished off on the external side with ~2 cm

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of Natural Hydraulic Lime plaster (NHL2).

Fig. 4: Plans of the ground and first floors of the case study building, with indication of the positions of the sensors. T-type thermocouples (accuracy ± 0.25°C) were adopted for the air temperatures measurements (internal and external). Moreover, four heat flux meter plates (HFP01) were placed on the inner surface of the walls. Before selecting the area where the sensors were to be placed, an infrared thermographic survey of the wall temperature distribution was carried out (Fig. 5) to identify an area that was not disturbed by 2D heat fluxes (thermal bridges). The sensors were taped to the wall at a height of 1.70 m from the floor to avoid any rising

ACCEPTED MANUSCRIPT damp effects (ground floor), as well as at a distance of 1 m from the window and from the corner of the two walls. The sensors were connected to a data logger (datataker DT 85) that acquired the data with a time-step

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of 15 minutes.

Fig. 5: a) The sensors placed on the wall; b) the infrared thermographic image of the selected wall Since the measurements were carried out between 21-30 March (spring season, characterised by high-

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temperature fluctuations), the monitored rooms were heated to 24°C to reduce the measurement uncertainty in order to guarantee a significant temperature difference (Tin-Tout >5°C). Nevertheless, the temperature difference was only slightly below 5°C for a few hours (less than 5% of the time). Fig. 6 reports the temperature difference between the monitored indoor and outdoor temperatures in the two rooms; the highlighted area (characterised by the maximum temperature difference 24 – 28 March) was selected for the

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analyses.

Fig. 6: Difference between the internal and external temperatures The collected data allowed the transmittance U (eq.1) and the conductance C (eq.2) of the monitored walls to be calculated through the use of the average method, according to ISO 9869-1:2014 [35].

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(

(1)

)

∑

where:

(

(2)

)

is the heat flux measured through the walls (W/m2);

surface temperatures of the walls (°C), respectively; temperatures, respectively.

and

and

are the internal and external

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∑

are the internal and external air

It was also possible to calculate the internal heat resistance factor, Rsi , from the data collected during the

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measurement campaign as follows:

(3)

Moreover, the external resistance factor Rse can be calculated according to eq. (4):

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3.3. Heat and moisture transfer simulations

(4)

The thermal resistance of multilayer components is mainly influenced by their moisture content, and for this

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reason, numerical coupled one-dimensional Heat and Moisture Transfer (HMT) simulations were performed, using WUFI® Pro [5], to investigate the annual thermal performance of the reference wall (Ref_wall) and

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the retrofitted wall (Tpl_wall).

A period of two years, with a time step of an hour, was considered for the numerical simulation, that is, from

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March 2015 (date of the wall refurbishment) to March 2017 (date of the monitoring campaign). EN 15026 [37] (medium moisture load) was adopted (Fig. 7) for the boundary conditions on the internal

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side, while a climatic file was created from data recorded by the ARPA meteorological station in Cuneo (~35 km from the case study building) for the external condition. The wall was modelled as a multilayer structure. The Masea Database (Belgian Brick) was used to model the brick construction and the plaster layer, and ―mineral reinforced plaster‖ data were adopted. Insulating plaster P30 was defined by modifying the ―interior plaster with perlite‖ (perlite-based plaster with a comparable dry bulk density) and adopting the moisture dependent thermal conductivity, retrieved from the experimental results (section 4.2), as input. Furthermore, rain exposure was assumed to be low, due to the presence of the protruding roof.

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Fig. 7: Internal air temperature and moisture level (EN 15026 [37]) 3.4. Embodied energy analysis

An analysis of the environmental impacts was carried out with the aim of supporting the mixture design

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phase and of finding answers concerning the environmental impact of each compared prototype. The adopted method complies with the ISO 14040 family rules [38], which regulate the four main phases of the analysis process: goal and scope definition, Inventory Analysis, Life Cycle Impact Assessment and interpretation.

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The research has had the aim of triggering the design phase of a thermal plaster innovation process through a multidisciplinary approach. Four blend prototypes were developed during the design phases: the differences

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in the experimental mixtures pertained to the percentage by weight of the three main ingredients: Natural Hydraulic lime, cement and perlite (Table 2). Each blend has another kind of material, which is generally

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called ―Additive‖. Since the characteristics and the amount (0.4 – 0.6 % by weight) of the additives used in the blend did not affect the environmental results, the LCA analysis only considered the binders and

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aggregates as blend ingredients. Table 2: Raw materials of the four analysed plaster mixtures

Raw material of the blend

Binders (Natural hydraulic lime, cement) Aggregate (Perlite)

P_25 [%] 75 25

P_30 [%] 70 30

samples P_35 [%] 65 35

P_40 [%] 60 40

According to the LCA approach, an analysis may include different life-cycle stages of a product. Since the general aim of LCA studies of traditional plaster is to identify the most environmentally friendly blend from among all the prototypes, the ―Cradle-to-Gate‖ assessment appeared to be the most significant. The ―Cradleto-Gate‖ assessment includes all the operations connected to the materials of blends, starting from the raw

ACCEPTED MANUSCRIPT material extraction up to the manufacturing and packaging phases. A ―Cradle-to-Gate‖ assessment is also adopted in the environmental product declaration method (EPD) for the environmental certification of building materials. Although the "Cradle-to-Gate" analysis is sufficient for the analysis and comparison of traditional plasters, it may not be for thermal plaster. In fact, during the design phase of a thermal plaster blend, it is essential to maximize its lightness and thermal resistance, since they affect the application stage and the operational phase, respectively, as already shown in similar LCA studies on thermal plasters [14].

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A ―Cradle-to-site‖ assessment is therefore more suitable for the analysis of the environmental quality of thermal plasters, if subsequently compared with the thermal-resistance performance indicators that are representative of the operating stage.

In order to guarantee the best support for the design of the thermal plaster mixture, the LCA analysis was developed in two progressive steps, in which the system boundary and the functional unit were changed: 

Step 1: A Cradle-to-gate assessment, based on the analysis of raw material extraction, transport,

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storage, transformation, mixing and packaging. The aim of the analysis was to compare the composition of the experimental mixtures. The adopted functional unit was 1 kg of packed blend, including the palletizing phase. Fig. 8 illustrates the flow chart of a functional unit of an industrial production in a factory plant; 

Step 2: A ―Cradle-to-Site‖ assessment that included the results of the step 1 analysis. The aim of

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this second LCA study was to verify whether the environmental results would be confirmed during the life stages. The functional unit of the LCA stage was 1 m2, with 5 cm of thickness,

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which is the same amount of blend that was applied to the demonstration building. This choice made it possible to evaluate both the embodied energy and the thermal performance indicator (thermal conductivity), and to highlight which of the prototypes would have the best

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environmental quality throughout its life cycle up to the use phase.

Fig. 8: Flow chart of the Cradle-to-Gate assessment of the thermal plaster

ACCEPTED MANUSCRIPT Both Primary and Secondary data were used in the LCA study. The Ecoinvent database (version 3.2) was used to adapt the Secondary data provided by the plaster manufacturer: both raw material extraction and primary energy production (thermal and electrical) were considered, starting from the Ecoinvent database codes. The data related to the transport, to the transformation phase and to the packaging phase were provided by the manufacturer, according to their production line data, with reference to the year 2016. The manufacturing phase electricity data referred to the energy mix of the factory plant, of which 38% came from self-produced photovoltaic energy and 62% from the national electricity grid.

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The on-site application phase data (Table 3) were derived from data collected directly during the construction site operations, and they took into account the electricity used for the plaster machine, the amount of water in the mixture and the packaging wastes. Transportation between the plaster company plant and the construction site in Dogliani (CN, Italy) was taken into account in the study.

The Life Cycle Impact assessment was developed, according to the ISO 14044 standard [38], through two

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single issue methods: the cumulative energy demand (CED version 1.09) [39] and IPPC 2013 (GWP 100) [40]. The first one, which was split into renewable and non-renewable resources, was used to quantify the embodied energy (EE), while the second one was used to evaluate the embodied carbon (EC). Table 3: Input data of the application phase related to 1m2 of wall and a plaster thickness of 5 cm Plaster powder:

Water:

Waste:

Waste:

Energy:

from the plant to Dogliani (tkm)

amount for the blend (kg)

amount for the blend (kg)

Plaster bag (kg)

LDPE packaging (kg)

p 25

1,296

30,85

20,67

0,005

0,007

plastering machine application (kWh) 0,598

p 30

0,827

19,70

20,44

0,008

0,011

0,382

p 35

0,683

16,25

20,22

0,010

0,013

0,315

p 40

0,521

12,40

20,00

0,013

0,017

0,240

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Transport:

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Sample

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4 Results and discussion

4.1 The effect of the perlite content on the thermal properties of plasters

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The laboratory analyses were aimed, at a material level, at identifying the thermal conductivity of the different plaster mixtures, each of which was characterised by a different LWA content and a different dry bulk density. Table 1 report the influence of the perlite content on the material density. It is possible to observe that an increase in the perlite content (from 25% to 40%) determined a relevant decrease in the density, that is, from ~600 kg/m3 to ~250 kg/m3. A roughly linear increment of the plaster thermal conductivity, according to the increase in density, can be noted in Fig.9a. Moreover, Fig. 9b shows the reduction in thermal conductivity as a function of the perlite content (grey curve), while the dashed line represents the thermal conductivity of the raw perlite. These results show that any further increment in the perlite content (above 40%) would not determine a significant

ACCEPTED MANUSCRIPT increase in the thermal performance, since it is not possible to decrease the thermal conductivity below a value of 0.045 W/mK (100% perlite). The obtained results are in line with those reported in [41], where a cement compound showed a linear decrease in density as the perlite content increased. Although a low value of thermal conductivity is particularly suitable for insulating purposes (P40 reach a λ=0.059 W/mK), it should be underlined that, because of the high perlite concentration, the decay of the mechanical properties is relevant, as shown in [41]

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and as confirmed by the manufacturer (data not available).

Fig.9: a) decrease in the conductivity as a function of the density; b) decrease in the conductivity as a

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function of the perlite mass fraction in the samples.

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4.2 Influence of temperature and water content on the thermal conductivity A series of tests was performed on dry and wet plaster P30 specimens ( the formulation chosen for the case

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study in Dogliani) in order to investigate the impact of the moisture content. The resulting water content, under saturation conditions, was 304 kg/m3, and a variation of the thermal

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conductivity (Table 4), from dry to saturated conditions of between 325-350%, was observed for test temperatures of 10°C and at 25°C, respectively. Furthermore, the results of the thermal conductivity at 25°C was 0.002-0.003 W/mK higher than the results obtained at 10°C (Table 5) for all the specimens. For this

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reason, this effect was considered negligible for the building operation temperatures. Table 4: Thermal conductivity of the plaster (P30) with different water contents

Test type

Sample

Water content 3

conditions

[kg/m ]

Test 1

dry

0

Test 2

wet

304

Test temperature [°]

λ [W/mK]

10

0.084±0.002

25

0.087±0.002

10

0.272±0.005

25

0.306±0.006

ACCEPTED MANUSCRIPT Table 5: Results of the HFM measurements λeq [W/mK]

Sample

Tavg =25 °C

P25

0.118±0.004

0.12±0.004

P30

0.084±0.002

0.087±0.002

P35

0.072±0.002

0.074±0.002

P40

0.059±0.001

0.061±0.001

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Tavg =10 °C

4.3. Embodied energy results

The LCA analysis of the ―Cradle-to-Gate‖ assessment has highlighted how the choice of raw materials is of fundamental importance. The materials in the thermal plaster mixtures that affect the environmental impact the most are normally the aggregates, even though, on one hand, they have a higher primary energy content,

feature in reducing impacts during the use phase.

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on the other, they make the mixture very light, thus increasing the thermal resistance, which is a relevant

In step 1 of the LCA analysis, the sample with the highest perlite content (40%) was characterized by an E.E. value of 3.33 kWh/kg, of which 61% was derived from perlite. The lowest impact, in terms of CED, was that of the P_25 sample, which had an Embodied Energy value of 2.59 kWh / kg, of which 47% was perlite

than the blend with less perlite (P25).

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(Fig.11a). In the comparison of the experimental mixtures, the P_40 sample had a 28.3% higher value of E.E.

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The analysis of the impacts related to the Embodied Carbon of 1 kg of thermal plaster showed less difference between the two mixtures, but confirmed the growth trend in relation to the quantity of perlite: the amount of

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equivalent CO2 incorporated in the P_40 mixture was 7.9% higher than that of the P_25 sample (Fig.11b). It is interesting to note that, in the analysis of the production processes of 1 kg of plaster, the value of

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Embodied Energy, due to the presence of the raw materials, had a value that varied between 91% (P_25) and 87% (P_40), while the value increased from 8.4% to 12.5% (Fig.11) for the packing operations (including

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the raw materials for the plaster bag and for the palletizing). Step 2 of the LCA analysis also included the application phase, in which the amount of mixture necessary for 1 m2 of wall was evaluated for a plaster thickness of 5cm. The analysis of the energy content for 1m2 of wall showed values that were in contrast with those highlighted in step 1 of the analysis: the P_40 sample was the best, as far as both the Embodied Energy value (42.2 kWh/m2 for a plaster thickness of 0.05m) and the Embodied Carbon value (14.98 kg CO2 eq./m2 for a plaster thickness of 0.05m) are concerned. The P_40 prototype values were 48.7% lower for the Embodied Energy and 56.7% lower for the Embodied Carbon (Fig 13a and Fig 13b) than for the P-25 prototype values.

ACCEPTED MANUSCRIPT Since the density of the binders was greater than that of the expanded perlite, the mixture that contained the lighter aggregates had less weight for the same volume (first column in Tab. 3). The reason for the change in the ranking of the environmental performances lies in the density of the mixtures: the mixture with the largest amount of perlite was lighter, and the weight of the functional unit considered in the E.E. assessment (1m2 wall area, 5cm plaster thickness) was therefore much lower in the application phase. In fact, the weight of the raw materials was the environmental indicator that had the most effect on the environmental impact of the 5 cm thick thermal plaster applied to one square meter of wall: the embodied energy of the raw material

mixtures.

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ranged from between 87% and 82% of the total energy consumed for the preparation and application of the

The behaviour of the prototypes changed when different life cycle stages were analyzed: when only the ―Cradle to Gate‖ method was considered, with 1 kg as the functional unit, the E.E increased as the perlite content in the blend increased (Fig. 10). When the ―Cradle-to-Site‖ assessment was considered, the E.E.

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decreased as the perlite content increased. (Fig. 12).

The increase in perlite is clearly limited by the mechanical resistance that the plaster has to satisfy, in order

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to support its own weight and to prevent the detachment of the perlite from the binder.

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Fig.10: a) Embodied energy of the thermal plasters (CED method); b) Embodied Carbon of 1kg of thermal plaster (IPCC GWP 100a method)

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Fig.11: Embodied Energy in the Cradle-to-gate assessment: percentage incidence of the impacts related to

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the manufacturing processes and the raw materials in each prototype

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Fig.12: a) ―Cradle to Site‖ Assessment: Embodied Energy of 1 m2 of 5 cm thick thermal plaster; b) Embodied Carbon of 1 m2 of 5 cm thick thermal plaster (IPCC GWP 100a method)

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4.4. In situ measurement

The data collected during the monitoring period allowed the thermal transmittance U and the conductance C

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of the walls to be determined. It is possible to observe, from Fig. 13, that there is a negligible difference between the results of U and C in the two differently orientated walls. This demonstrates that the measured wall structures present homogeneous sections and layers. The wall retrofitted with the P30 insulating plaster (the Tpl_wall) shows a significant reduction, in both the thermal transmittance and conductance, with respect to the reference wall (Ref_wall): 

A decrease of about 60% of the thermal conductance C (from 2.25 W/m2K to 1.02 W/m2K)



A reduction of about 45% of the thermal transmittance U (from 1.43 W/m2K to 0.79 W/m2K)

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Fig. 13: Transmittance and conductance of the walls in the case study 4.5. Simulation results

Since the water content dramatically reduces the thermal performance of a plaster and can fluctuate during

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the operational phase of a building element, a series of numerical HMT analyses was carried out. These analyses allowed the behaviour of the thermal plaster applied to the case study building to be assessed for the

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different periods of the year.

As a first step, a comparison between the simulated and the measured thermal performance of the two investigated components was carried out to verify the reliability of the simulation model. Fig. 14a and Fig.

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15b show the comparison of the U value and the C value of the two analysed components, and highlight that the results obtained from the numerical model are in agreement with the values measured in-situ; the

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maximum error is found for the conductance of the reference wall (about 20%, Fig. 14).

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The difference between the simulated and the monitored values could be the result of several factors : -

The plaster layers (internal and external) were applied to an irregular support that did not allow a thick homogenous layer to be applied, and the declared plaster thickness and the wall thickness could therefore have been affected by high uncertainty;

-

The physical properties of all the materials, except those of the internal insulating plaster, were retrieved from a database and they may therefore have differed from the actual physical properties.

A further consideration that supports these assumptions is that the retrofitted wall, whose thermal resistance is mainly due to the thermal plaster, which has measured and well-known properties, allows the discrepancy between the measured and simulated results to be significantly reduced.

ACCEPTED MANUSCRIPT As reported in the ISO 9869 thermal insulation standard [35], several factors can affect the numerical model (uncertainty about the layer thickness and unknown thermal properties of the materials) and this can determine a difference of up to 20%. Moreover, the in-situ measurements can be influenced by errors from different sources: errors in the calibration of the sensors, accuracy of the data logging system, variations of the thermal contact between the surface and sensors, variations of the temperature and heat flux, differences between the air temperature and space, etc. However, the expected total uncertainty can range between 14 – 28% (ISO 9869).

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For the all the above mentioned reasons, the differences highlighted in Fig. 14a and Fig. 14b can be considered acceptable.

It is possible to note, from Figs. 14a and 14b, that the transmittance has a rather stable trend over the year, with a maximum variation of about 10%.

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The U and C values obtained from the retrofitted wall are more in line with the simulated values (within an error of 5%) because the thermal performance of the component is mainly influenced by the presence of the

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insulating plaster (the thermal properties are known since they were measured in the laboratory).

Fig. 14 a) Transmittance and conductance of the Ref_wall (North-East facing); b) Transmittance and

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conductance of the Tpl_wall (North-East facing) Fig. 15 reports the moisture content results of the two simulated configurations. The high amount of moisture in the retrofitted configuration is mainly in the plaster layer (~ 34–38 kg/m3), because of the low temperature of the interface between the plaster and the clay bricks and because of the high capability of the plaster to absorb the moisture from the indoor environment.

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Fig. 15: Water content in different wall layers

Since the presence of moisture can affect the thermal performance of the insulating plaster to a great extent,

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other investigations were carried out to find out whether the presence of moisture could affect the thermal conductivity of the plaster layer.

The trend of the values is in agreement with the water content (Fig. 16), and it is in fact possible to see a

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slight increase in the plaster conductivity as the water content rises.

Fig.16: Water content and conductivity of the P30 layer Fig. 17 shows the winter monthly boxplot results of the simulated thermal conductivity of the insulating plaster (P30). The results highlight that the in-field λ presents median monthly values of between 0.106 W/mK (January) and 0.109 W/mK (October), respectively, that is, 26% and 30% higher than the λ determined in the laboratory. This data can be used to determine the actual thermal conductivity under real operating conditions for energy calculation purposes.

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Fig. 17: Boxplot of the thermal conductivity trend of the plaster during the heating season 5 Conclusions

In this study, the thermal conductivity of a lime-based thermal insulating plaster has been assessed for different concentrations of Light Weight Aggregates (LWA). The HFM measurements show a decrease in

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the thermal conductivity as a function of the increase in the perlite content; the results range from between 0.118 W/mK (25% of perlite) to 0.059 W/mK (40% of perlite). Nevertheless, the reduction in λ obtained by

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increasing the perlite concentration from 25% to 30% is almost the same as the one obtained by increasing the concentration from 30 to 40%. For this reason, it is possible to assume that an increase in the perlite concentration to higher values than 40% can only determine a marginal reduction of the thermal

(raw perlite).

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conductivity. In fact, an ideal plaster containing 100% of perlite can reach a λ value of about 0.045 W/mK

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The thermal conductivity of a sample containing 30% of perlite (P30) was assessed at different temperatures and for different moisture contents (dry and saturated conditions). An increase in the thermal conductivity

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from 325 to350% was observed for the moisture saturated sample, while the effect of temperature on the thermal conductivity can be considered negligible. The results of the embodied energy and the embodied carbon analysis highlighted that the impact of packed plaster (Cradle-to-Gate assessment) grows according to the increase in the perlite aggregates. On the contrary, the ―Cradle-to-Site‖ analysis that considered a 5 cm thick thermal plaster applied to 1 m2 of wall revealed that the embodied energy decreased as the perlite content in the mixture increased. As expected, the study has demonstrated that the limit of the analysis is only at the material level (cradle-to-gate) as misleading results can be determined that could drive designers towards questionable choices. These results affect both the design phase of the blend made by the producers and the choice of the building product made by the designer:

ACCEPTED MANUSCRIPT 

the designer of the plaster blend has to take into account the whole life cycle, including the application and operational stages;



the building designer should consider the proprieties of the thermal plaster during the application phase, in which the lightness of the plaster is the most important quality to minimize the environmental impacts.

The external walls of a case study building were retrofitted on the interior side by applying the P30 plaster. The thermal performance of two wall typologies was assessed (retrofitted wall and reference wall) by means

decrease of the thermal transmittance of about 50%.

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of heat flux measurements. The results show that the application of the thermal insulating plaster led to a

Furthermore, the data collected from the in-situ measurements were used to validate a heat and moisture simulation analysis, with the aim of evaluating the variations of the thermal conductivity of insulating plaster

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exposed to actual operating conditions for an extended period.

As expected, the simulation results revealed that the actual conductivity values of the P30 thermal plaster resulting from the simulations were higher than those reached by the dry specimens in the laboratory test (0.084 W/mK). The analysed material (P30 plaster) presented a 26% to 30% higher thermal conductivity than the λ determined in the laboratory. This increment can be considered acceptable. Nevertheless, it should

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be carefully considered to better quantify the real benefits that can be achieved by adopting thermal insulating plaster.

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The comparison of the four mixtures has highlighted that the plaster that shows the best thermal performance and the lowest environmental impact is the P40 mixture (40% of perlite). Nevertheless, the study has demonstrated that the thermal conductivity of 0.059 W/mK represents the top value, and only a marginal

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reduction can be achieved by using only perlite as an aggregate. A non-negligible improvement could still be achieved by modifying the mixture and the LWA type to reduce both the thermal conductivity and the

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environmental impact, and strategies to limit the decay of the thermal conductivity of the material exposed to real operating condition are currently under investigation.

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Acknowledgements

The authors would like to thank Vimark Srl for providing the necessary data for the environmental analyses. Marco Dutto and Cinzia Ferrua are kindly acknowledged for their support during the preparation of the specimens. Francesco Isaia and Ylenia Cascone helped during the experimental and the simulations phase, Mr. Maurizio Cappa and Mrs. Elena Cappa made the case study building available for the experimental tests and Mrs. Manuela Bassi (ARPA Piemonte) supplied the climate data. The authors also wish to acknowledge Fraunhofer IBP for providing the WUFI© Pro license that was adopted within the framework of Elisa Fenoglio’s master thesis. References

ACCEPTED MANUSCRIPT [1]

A.N.C.E., Lo stock abitativo in Italia, 2015.

[2]

E.N.E.A., Rapporto annuale efficienza energetica (RAEE) 2017: analisi e risultati delle policy di efficienza energetica del nostro Paese, 2017.

[3]

U.S. Department of Energy, Windows and Building Envelope Research and Development: Roadmap for Emerging Technologies, 2014

[4]

S. Gutiérrez-González, J. Gadea, A. Rodríguez, C. Junco, V. Calderón, Lightweight plaster materials with enhanced thermal properties made with polyurethane foam wastes, Construction and Building Materials 28 (2012) 653–658, https://doi.org/10.1016/j.conbuildmat.2011.10.055 WUFI Pro ©, Fraunhofer Institute for Building Physics IBP, https://wufi.de/en/

[6]

L. Bianco, V. Serra, S. Fantucci, M. Dutto, M. Massolino. Thermal insulating plaster as a solution for

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[5]

refurbishing historic building envelopes: First experimental results. Energy and Buildings 95 (2015) 86–91. https://doi.org/10.1016/j.enbuild.2014.11.016 [7]

L.M. Silva, R.A. Ribeiro, J.A. Labrincha, V.M. Ferreira. Role of lightweight fillers on the properties of a mixed-binder

mortar,

Cement

&

Concrete

Composites,

[8]

(2010)

19–24,

AN US

https://doi.org/10.1016/j.cemconcomp.2009.07.003

32

M. Lanzón Torres, P.A. García-Ruiz. Lightweight pozzolanic materials used in mortars: Evaluation of their influence on density, mechanical strength and water absorption, Cement & Concrete Composites 31 (2009) 114–119, https://doi.org/10.1016/j.cemconcomp.2008.11.003

[9]

S. Abidi, B. Nait-Ali, Y. Joliff, C. Favotto. Impact of perlite, vermiculite and cement on the thermal conductivity of a plaster composite material: Experimental and numerical approaches, Composites: Part B 68

M

(2015) 392–400 https://doi.org/10.1016/j.compositesb.2014.07.030

[10] M. Davraz, L. Gunduz, E. Baspınar. Lightweight Aggregated Foam Plaster for Thermal Insulation in

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Buildings, Journal of Engineering Science and Design Vol:1 No:3 pp.150-155, 2011 [11] O.Gencel, J. Jose del Coz Diaz, M.Sutcu, F. Koksal, F.P. Alvarez Rabanal, G. Martinez-Barrera, W. Brostow. Properties of gypsum composites containing vermiculite and polypropylene fibers: Numerical and

PT

experimental results, Energy and Buildings 70 (2014) 135–144. DOI 10.1016/j.enbuild.2013.11.047 [12] O. Gencel, J. Jose del Coz Diaz, M. Sutcu, F. Koksal, F. Pedro Álvarez Rabanal, G. Martínez-Barrera. A novel lightweight gypsum composite with diatomite and polypropylene fibers, Construction and Building Materials

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113 (2016) 732–740. https://doi.org/10.1016/j.conbuildmat.2016.03.125 [13] K. Sedan, S. Sirri, G. Hikmet, O. Ibrahim e E. Sabit. Use of sunflower stalk and pumice in gypsum composite

AC

to improve thermal properties, Journal of applied sciences, 2006. [14] C.Carbonaro, S.Tedesco, F. Thiebat, S. Fantucci, V.Serra, M. Dutto. An integrated design approach to the development of a vegetal-based thermal plaster for the energy retrofit of buildings, Energy and Buildings 124 (2016) 46–59, https://doi.org/10.1016/j.enbuild.2016.03.063

[15] J. Zach et al., Utilization of Lightweight Aggregate from Expanded Obsidian for Advanced Thermal Insulating Plasters

Production,

Advanced

Materials

Research,

Vols.

335-336,

pp.

1199-1203,

2011

DOI10.4028/www.scientific.net/AMR.335-336.1199 [16] A. Karaipekli e A. Sar. Development and thermal performance of pumice/organic PCM/gypsum composite plasters for thermal energy storage in buildings, Solar Energy Materials & Solar Cells, 2016. https://doi.org/10.1016/j.solmat.2015.12.034

ACCEPTED MANUSCRIPT [17] T. Stahl, S. Brunner, M. Zimmermann e K. Ghazi Wakili. Thermo-hygric properties of a newly developed aerogel based insulation rendering for both exterior and interior applications, Energy and Buildings, 2012. https://doi.org/10.1016/j.enbuild.2011.09.041 [18] M. Ibrahim, E. Wurtz, P. Achard e P. H. Biwole. Aerogel-based coating for energy-efficient building, 9th International Energy Forum on Advanced Building Skins, 2015. [19] U. Berardi, The benefits of using aerogel-enhanced systems in building retrofits, Energy Procedia, Volume 134, October 2017, Pages 626-635 [20] U. Berardi, R. Nosrati, Long-term thermal conductivity of aerogel-enhanced insulating materials under

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different laboratory aging conditions, Energy, Volume 147, 15 March 2018, Pages 1188-1202. [21] R. Nosrati, U. Berardi, Long-term performance of aerogel-enhanced materials, Energy Procedia, Volume 132, October 2017, Pages 303-308.

[22] C. Buratti, E. Moretti, E. Belloni e F. Agosti, Aerogel Plasters for Building Energy Efficiency, Nano and Biotech Based Materials for Energy Building Efficiency, 2016.

[23] Z. Pavlík, E. Vejmelková, . Fiala, R. Cerný, Effect of Moisture on Thermal Conductivity of Lime-Based

AN US

Composites, International Journal of Thermophysics, 2009

[24] M. Ibrahim, P. Henry Biwole, E. Wurtz, P. Achard, Hygrothermal performance of exterior walls covered with aerogel-based

insulating

rendering,

https://doi.org/10.1016/j.enbuild.2014.07.039

Energy

and

Buildings

84

(2014)

241–251

[25] M. Ibrahim, P. Henry Biwole, E. Wurtz, P. Achard. A study on the thermal performance of exterior walls covered with a recently patented silica-aerogel-based insulating coating, Building and Environment 81 (2014)

M

112e122, https://doi.org/10.1016/j.buildenv.2014.06.017

[26] T. Stahl, K. Ghazi Wakili, S. Hartmeier, E. Franov, W. Niederberger, M. Zimmermann. Temperature and

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moisture evolution beneath an aerogel based rendering applied to a historic building. Journal of Building Engineering 12 (2017) 140–146. https://doi.org/10.1016/j.jobe.2017.05.016 [27] S. Jin Chang , S. Kim. Hygrothermal performance of exterior wall structures using a heat, air and moisture

PT

modeling, Energy Procedia 78 ( 2015 ) 3434 – 3439 https://doi.org/10.1016/j.egypro.2015.12.328 [28] S. Fantucci, F. Isaia F., V. Serra , M. Dutto Insulating coat to prevent mold growth in thermal bridges, Energy Procedia 134 (2017) 414–422. https://doi.org/10.1016/j.egypro.2017.09.591

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[29] K. Ghazi Wakili, C. Dworatzyk, M. Sanner, A. Sengespeick, M. Paronen, T.Stahl. Energy efficient retrofit of a prefabricated concrete panel building (Plattenbau) in Berlin by applying an aerogel based rendering to its

AC

façades. Energy & Buildings 165 (2018) 293–300. https://doi.org/10.1016/j.enbuild.2018.01.050 [30] C. Anand, B. Amor, 2017. Recent developments, future challenges and new research directions in LCA of buildings: a critical review. Renewable and Sustainable Energy Reviews. 67, 408e416.

[31] P. Chastas , T. Theodosiou ,D. Bikas . Embodied energy in residential buildings towards the nearly zero energy building: A literature review. Building and Environment 2016; 105:267–82 [32] MK Dixit, JL Fernández-Solís, S. Lavy, CH Culp. Need for an embodied energy measurement protocol for buildings: A review paper. Renewable and Sustainable Energy Reviews 2012; 16:3730–43 [33] R. Garrido, J. Silvestre, D. Silvestre e I. Flores-Colen, Economic and Energy Life Cycle Assessment of aerogel-based thermal renders, Journal of Cleaner Production, 2017.

ACCEPTED MANUSCRIPT [34] C. Carbonaro, Y. Cascone, S. Fantucci, V. Serra, M. Perino, M. Dutto, Energy Assessment of A Pcm– Embedded Plaster: Embodied Energy Versus Operational Energy, Volume 78, November 2015, Pages 32103215, https://doi.org/10.1016/j.egypro.2015.11.782. [35] ISO 9869-1:2014 Thermal insulation - Building elements - in situ measurement of thermal resistance and thermal transmittance - Part 1: Heat flow meter method. [36] UNI EN 1015-10:2007 Methods of test for mortar for masonry - Part 10: Determination of dry bulk density of hardened mortar [37] EN 15026:2007, Hygrothermal performance of building components and building elements - Assessment of moisture transfer by numerical simulation.

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[38] UNI EN. ISO 14040/44:2006. Environmental management—Life cycle assessment. [39] R. Frischknecht, N. Jungbluth, H.J. Althaus, G. Doka, R. Dones, R. Hischier, S.Hellweg, S. Humbert, M. Margni, T. Nemecek, M. Spielmann. Implementation of Life Cycle Impact Assessment Methods: Data v2.0 ecoinvent report No. 3,Swiss centre for Life Cycle Inventories, Dübendorf, Switzerland, 2007.

[40] Climate Change 2013 The Physical Science Basis. IPCC Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, 2013.

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[41] O. Sengul, S. Azizi, F. Karaosmanoglu, M. Ali Tasdemir. Effect of expanded perlite on the mechanical properties and thermal conductivity, of lightweight concrete, Energy, and Buildings 43 (2011) 671–676.

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https://doi.org/10.1016/j.enbuild.2010.11.008