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21 pages, 7452 KiB

Open AccessArticle

Assessment of the Effect of Phase Change Material (PCM) Glazing on the Energy Consumption and Indoor Comfort of an Office in a Semiarid Climate

by Daniel Uribe and Sergio Vera

Appl. Sci. 2021, 11(20), 9597; https://doi.org/10.3390/app11209597 - 15 Oct 2021

Cited by 14 | Viewed by 2241

Abstract

Office buildings are usually characterized by low thermal inertia, which could cause underperformance in terms of energy consumption. Moreover, the use of large glazed façades in office buildings can cause thermal and visual discomfort due to high solar heat gains and excessive daylight [...] Read more.

Office buildings are usually characterized by low thermal inertia, which could cause underperformance in terms of energy consumption. Moreover, the use of large glazed façades in office buildings can cause thermal and visual discomfort due to high solar heat gains and excessive daylight transmitted into the office space. Phase Change Materials (PCMs) integrated into glazing have arisen as an innovative strategy to increase thermal inertia and improve office buildings’ energy performance and indoor comfort at a low cost. This paper aims to analyze the impact of PCM glazing on buildings’ energy performance and occupants’ thermal and visual comfort. The analysis is performed through a one-year real-scale experiment in two offices in Santiago, Chile, with an east-oriented façade and a window-to-wall ratio (WWR) of 56%. The results are analyzed on two timescales: seasonally and daily. Representative days in each season were selected to carry out the analysis. Regarding the energy consumption of the HVAC system, PCM glazing reduces energy consumption during summer and mid-seasons and significantly reduces the peak loads in summer. A meaningful improvement in thermal comfort is achieved due to the control of the mean radiant temperature for the whole year. Considering visual comfort, there is an improvement in the luminance distribution in winter and mid-season cold conditions. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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18 pages, 6669 KiB

Open AccessFeature PaperArticle

Evaluating the Impact of Indoor Insulation on Historic Buildings: A Multilevel Approach Involving Heat and Moisture Simulations

by Ivana Mattea Lisitano, Deborah Laggiard, Stefano Fantucci, Valentina Serra and Elisa Fenoglio

Appl. Sci. 2021, 11(17), 7944; https://doi.org/10.3390/app11177944 - 27 Aug 2021

Cited by 5 | Viewed by 1703

Abstract

The energy refurbishment of historic buildings is a complex task for building envelope designers who need to carefully consider building conservation guidelines and principles. In most cases, external wall insulation techniques can determine an unacceptable alteration of the historical value of a building. [...] Read more.

The energy refurbishment of historic buildings is a complex task for building envelope designers who need to carefully consider building conservation guidelines and principles. In most cases, external wall insulation techniques can determine an unacceptable alteration of the historical value of a building. For this reason, internal wall insulation techniques have been used widely in the last few decades. Nevertheless, dealing with internal wall insulation requires a complex design to avoid the risk of condensation and moisture-related pathologies. Moreover, an internal wall insulation may have a relevant impact on indoor comfort conditions. In this paper, the Monastery of Santa Maria de Monfero in Galicia (Spain) has been adopted as a building case study to compare different technological solutions based on: (i) an insulating plaster layer, (ii) dry counter wall systems. In the first step, heat and moisture transfer simulations of the wall components were performed to analyze the hygrothermal behavior of the different alternatives considering two different climate conditions. In a second step, a simulation of the whole building was performed to analyze the impact of the retrofitting strategies on the indoor climate and on the building heating and cooling demand. The obtained results show that the counter wall solution leads to higher energy savings during the heating season in the colder winter climate. However, the use of insulating thermal plaster could also be a viable solution since they lead to several advantages in summer because of their higher thermal inertia. Therefore, the selection of the most appropriate insulation technique has to be evaluated carefully considering the outdoor/indoor climate and using a case-by-case approach. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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18 pages, 4988 KiB

Open AccessArticle

Systematic Analysis of Micro-Fiber Thermal Insulations from a Thermal Properties Point of View

by Ákos Lakatos, István Csarnovics and Attila Csík

Appl. Sci. 2021, 11(11), 4943; https://doi.org/10.3390/app11114943 - 27 May 2021

Cited by 5 | Viewed by 2220

Abstract

In the European Union, almost 40% of all energy consumption comes from buildings, while another 20–25% comes from transport. In the European Union, including Hungary, only buildings with almost-zero energy demand could be built after 2020, and the use of renewable energies must [...] Read more.

In the European Union, almost 40% of all energy consumption comes from buildings, while another 20–25% comes from transport. In the European Union, including Hungary, only buildings with almost-zero energy demand could be built after 2020, and the use of renewable energies must be strengthened. The Renewable Directive stipulated that by 2020, the share of renewable energy in buildings must be 25%, and in transport it must be 10%; the use of electric vehicles is vital. There are about four million dwellings in Hungary, of which approximately three million need to be renovated, and only some of these (a few hundred) meet the cost-optimized level of the 2020 directive. The use of insulation materials is very important in the transport sector, too. Insulation materials are also used by aircraft and electric vehicles. To reduce the energy loss from buildings, different insulation materials can be used; investigations of insulation materials are very important. This paper presents a comprehensive research report on insulation materials which could be used for building elements, HVAC (heating, ventilation, and air conditioning appliances) equipment, and vehicles. In this paper, laboratory investigations will be presented along with calculations to better understand the properties and behavior of these materials. For this, firstly structural analysis with scanning electron microscope will be presented. Moreover, the paper will present thermal conductivity and combustion heat measurement results. The sorption and hydrophobic behavior of the materials will be also revealed. Finally, the article will also display differential scanning calorimetry measurements and Raman spectroscopy results of the samples. The research was conducted on four different types of colorized microfiber lightweight wool insulation. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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14 pages, 1712 KiB

Open AccessFeature PaperArticle

Preparation and Characterization of a Selective Polymer-Based Solar Absorber for Building Integration

by Miroslav Čekon, Karel Struhala and Daniel Kopkáně

Appl. Sci. 2020, 10(21), 7861; https://doi.org/10.3390/app10217861 - 06 Nov 2020

Cited by 9 | Viewed by 1825

Abstract

Recent technological advances in solar absorber production may have created opportunities for new applications of these materials in buildings. A low-emissivity enhanced polymer-based absorber foil was developed and prototyped to demonstrate feasibility of the concept. This paper describes key development factors leading to [...] Read more.

Recent technological advances in solar absorber production may have created opportunities for new applications of these materials in buildings. A low-emissivity enhanced polymer-based absorber foil was developed and prototyped to demonstrate feasibility of the concept. This paper describes key development factors leading to a particular composition of the prototype and its testing, specifically spectroscopy measurements (both for shortwave and longwave regions) and environmental impact assessment of its production. It also provides comparison of the tested parameters with commercially available absorbers. The results show that the developed absorber has relatively good thermal emissivity (approx. 0.3), high solar absorption (0.95) and selectivity (3.2), and significantly lower (up to 98%) environmental impacts compared to the commercially available metal-based solar selective absorbers. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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19 pages, 3793 KiB

Open AccessArticle

Influence of Exposure to Elevated Temperatures on the Physical and Mechanical Properties of Cementitious Thermal Mortars

by Manuel Cunha Pereira, António Soares, Inês Flores-Colen and João Ramôa Correia

Appl. Sci. 2020, 10(6), 2200; https://doi.org/10.3390/app10062200 - 24 Mar 2020

Cited by 20 | Viewed by 3079

Abstract

Thermal mortars incorporating insulating aggregates are a possible solution to ensure good thermal performance and thermal comfort in buildings due to their low thermal conductivity coefficient. Under some circumstances, namely for particular in-service conditions in industrial applications and/or accidental actions (such as fire), [...] Read more.

Thermal mortars incorporating insulating aggregates are a possible solution to ensure good thermal performance and thermal comfort in buildings due to their low thermal conductivity coefficient. Under some circumstances, namely for particular in-service conditions in industrial applications and/or accidental actions (such as fire), it is important to quantify the retention of their properties after exposure to elevated temperatures, however this information is not yet available in the literature. This study aims to characterize the physical and mechanical behavior of thermal mortars incorporating expanded clay, granulated expanded cork and silica aerogel as aggregates after exposure to elevated temperatures. To this end, five types of mortars were produced in laboratory conditions—three thermal mortars, one reference sand mortar and one sand mortar with admixtures—and then exposed to different elevated temperatures (from 20 °C to 250 °C) in a thermal chamber. After thermal exposure, the following properties were assessed: bulk density; ultrasonic pulse velocity; dynamic elasticity modulus; dynamic shear modulus; Poisson coefficient; compressive strength; and thermal conductivity. The results obtained show that residual properties present a very high dependence on the reactions that take place in the cement paste when the mortars are exposed to elevated temperatures. After such exposure, all mortars with thermal insulating aggregates were able to maintain their insulating characteristics, but experienced internal damage and degradation of their mechanical properties. Results obtained also showed that insulating aggregates allowed to produce mortars with higher aggregate-cement paste compatibility at elevated temperatures compared to conventional mortars, resulting in less micro-cracking of the mortar, and leading to lower reductions in thermal conductivity with increasing temperature. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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16 pages, 4160 KiB

Open AccessArticle

Experimental Assessment of the Effects of Low-Emissivity Paints as Interior Radiation Control Coatings

by Stefano Fantucci and Valentina Serra

Appl. Sci. 2020, 10(3), 842; https://doi.org/10.3390/app10030842 - 24 Jan 2020

Cited by 15 | Viewed by 4618

Abstract

Radiation Control Coatings (RCC) are commonly recognised as paints, in which the long-wave radiation emissivity can be dramatically reduced from 0.9 to below 0.25 due to the dispersion of aluminium flakes inside the base paint. The low emissivity (Low-E) feature makes these materials [...] Read more.

Radiation Control Coatings (RCC) are commonly recognised as paints, in which the long-wave radiation emissivity can be dramatically reduced from 0.9 to below 0.25 due to the dispersion of aluminium flakes inside the base paint. The low emissivity (Low-E) feature makes these materials particularly suitable for reducing the radiative heat exchange in building components and worthy of being used in roof attics, pipes, heat storage tank, etc. However, in the last few years, the application to the indoor surfaces of the building envelope has become quite popular, because the reflective properties can be exploited to increase the thermal comfort and reduce the winter heat losses. Except for aluminium based paint, that, for their strong metallized effect, suffer from some aesthetical limitation, the claimed performance of most of the other commercially available reflective paints are not universally recognized and in most of the cases their properties are misled, referring to visible and short wave infrared reflectivity. In this paper, a new methodology for assessing the long-wave thermal emissivity by using a heat flow meter apparatus is proposed. Moreover, the thermal emissivity of different paint mixtures with reduced metallised effect is assessed. The results allow for affirming that paints with acceptable aesthetic value (limited metallized effect) can reach an emissivity of ~0.60 instead of a typical emissivity of paint between 0.85–0.90. Furthermore, the partition wall of a double climatic chamber apparatus was painted with different low-E paints to evaluate whether an increase of the indoor operative temperature would have been observed. A slight, but not negligible, increase was shown of up to 0.3 °C and 0.6 °C for paint with an emissivity of ~0.6 and ~0.4, respectively. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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14 pages, 2146 KiB

Open AccessArticle

Experimental and Numerical Energy Assessment of a Monolithic Aerogel Glazing Unit for Building Applications

by Cinzia Buratti, Elisa Moretti, Elisa Belloni and Michele Zinzi

Appl. Sci. 2019, 9(24), 5473; https://doi.org/10.3390/app9245473 - 13 Dec 2019

Cited by 13 | Viewed by 1957

Abstract

In the last few decades, the attention of researchers has been focused on the characterization of aerogels in order to improve the thermal performance of transparent building envelopes. Granular aerogel is already spread in the market thanks to the easy manufacturing system, whereas [...] Read more.

In the last few decades, the attention of researchers has been focused on the characterization of aerogels in order to improve the thermal performance of transparent building envelopes. Granular aerogel is already spread in the market thanks to the easy manufacturing system, whereas the difficulty in producing monoliths without defects, cracks, and inhomogeneity limited the diffusion of monolithic aerogel systems. A new production process for the monolithic panels was developed at Union College (Schenectady, NY, USA); it is a rapid supercritical extraction technique which allows a reduction in production time (only a few hours) and results in less solvent waste. Panes with maximum dimensions of about 100 × 100 mm were fabricated and composed in a unique glazing system, with external dimensions 300 × 300 mm. The thermal characterization of the innovative monolithic aerogel glazing system (simple float glazing 4.7-mm-thick monolithic aerogel pane 15-mm-thick simple float glazing 4.7 mm thick), which was carried out by means of a Small Hot Box apparatus, showed a thermal transmittance value of about 1.1 W/(m²K). Data was used in dynamic simulations of a typical non-residential building. They showed that the new investigated solution allows a valuable reduction with respect to a low-e double glazing system in terms of heating energy demand (about 5–7% for Helsinki, 8–12% for Paris, and 10–15% for Turin), for different window-to-wall ratios. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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12 pages, 1744 KiB

Open AccessArticle

Numerical Analysis of Building Envelope with Movable Phase Change Materials for Heating Applications

by Alvaro de Gracia

Appl. Sci. 2019, 9(18), 3688; https://doi.org/10.3390/app9183688 - 05 Sep 2019

Cited by 9 | Viewed by 2298

Abstract

Latent heat storage materials have been tested by several researchers for decades to be used as passive heating and cooling systems in buildings but their implementation into building components is still stacked as is facing specific technical limitations related to difficulties to be [...] Read more.

Latent heat storage materials have been tested by several researchers for decades to be used as passive heating and cooling systems in buildings but their implementation into building components is still stacked as is facing specific technical limitations related to difficulties to be charged both in heating and cooling periods. This paper presents a numerical analysis to evaluate the potential of a disruptive system, which is designed to solve the main drawbacks and to convert phase change materials (PCM) passive heating technology into a competitive solution for the building sector. The novel technology moves PCM layer with respect to the insulation layer inside the building component to maximize solar benefits in winter and be able to actively provide space heating. Design variables such as PCM melting point and control schemes were optimized. The results demonstrated that this technology is not only able to limit heat losses towards outdoors but it can provide space heating from stored solar energy when required. The promising numerical results endorse the possibility to build a future experimental prototype to quantify more in detail the benefits of this system. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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Review

Jump to: Research

34 pages, 3218 KiB

Open AccessReview

Titanium Dioxide in Chromogenic Devices: Synthesis, Toxicological Issues, and Fabrication Methods

by Valeria De Matteis, Alessandro Cannavale and Ubaldo Ayr

Appl. Sci. 2020, 10(24), 8896; https://doi.org/10.3390/app10248896 - 13 Dec 2020

Cited by 3 | Viewed by 5379

Abstract

The use of titanium dioxide (TiO₂) within two specific classes of devices, namely electrochromic and photoelectrochromic, is described hereafter, with respect to its inherent properties and chromogenic features within architectures that have appeared so far, in this field. The new research [...] Read more.

The use of titanium dioxide (TiO₂) within two specific classes of devices, namely electrochromic and photoelectrochromic, is described hereafter, with respect to its inherent properties and chromogenic features within architectures that have appeared so far, in this field. The new research trends, involving the applications of TiO₂ in chromogenic materials are reported, with particular attention paid to the techniques used for film deposition as well as the synthesis of nanoparticles. Furthermore, the main studies concerning its chemical-physical properties and approaches to its chemical syntheses and fabrication are reviewed, with special regard to “green” routes. In addition, the main aspects relating to toxicological profiles are exposed, with reference to nanoparticles and thin films. Full article

(This article belongs to the Special Issue Energy Efficient Envelope Technologies for Green, Healthy and Comfortable Buildings)

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