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16 pages, 3123 KiB

Open AccessArticle

Experimental and Numerical Assessment of the Thermal Bridging Effect in a Reinforced Concrete Corner Pillar

by Gianpiero Evola and Antonio Gagliano

Buildings 2024, 14(2), 378; https://doi.org/10.3390/buildings14020378 - 01 Feb 2024

Viewed by 512

This paper discusses experimental and simulated data regarding the thermal bridging effect in a reinforced concrete corner pillar, which belongs to a building dating back to the 1980s and located in Southern Italy. The thermal field determined by the concrete pillar corner has [...] Read more.

This paper discusses experimental and simulated data regarding the thermal bridging effect in a reinforced concrete corner pillar, which belongs to a building dating back to the 1980s and located in Southern Italy. The thermal field determined by the concrete pillar corner has been evaluated, introducing an experimental procedure based on both direct measurements and indirect observations of the inner superficial temperature by means of thermal imaging techniques and surface temperature probes. Moreover, indoor and outdoor air temperature and relative humidity were measured to provide suitable boundary conditions in the numerical simulations, performed with a commercial software tool widely used in Italy based on 2D finite element techniques. The experimental measurements show that, at more than 50 cm from the corner, the surface temperatures become almost constant, meaning that the thermal bridging effect becomes less evident. However, the surface temperature in the corner is around 1.5 °C lower than in the undisturbed flanking walls. In terms of local heat flux, the discrepancy between simulations and measurements is below 3%. Finally, this paper verifies the effectiveness of External Thermal Insulation Composite System (ETICS) renovation in reducing the thermal bridging effect of the corner pillar. The results also include the calculation of the linear thermal transmittance with a series of relations available in well-known atlases for thermal bridges and show that these relations are more reliable in the case of uninsulated pillar than for the insulated one. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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16 pages, 53050 KiB

Open AccessArticle

Early-Age Cement Paste Temperature Development Monitoring Using Infrared Thermography and Thermo-Sensors

by Nevena Živanović, Marina Aškrabić, Aleksandar Savić, Miša Stević and Zoran Stević

Buildings 2023, 13(5), 1323; https://doi.org/10.3390/buildings13051323 - 19 May 2023

Viewed by 938

Abstract

Infrared thermography is an advanced technique usually applied for the assessment of thermal losses through different elements of the building envelope, or as a method for detection of damage (cracks) in reinforced concrete elements, such as bridges. Use of this method for the [...] Read more.

Infrared thermography is an advanced technique usually applied for the assessment of thermal losses through different elements of the building envelope, or as a method for detection of damage (cracks) in reinforced concrete elements, such as bridges. Use of this method for the investigation of temperature development during early cement hydration is still an evolving area of research. For the purpose of verifying the reliability of the method, two types of cubic samples of different heights were prepared using a cement-based paste, with 20% of cement (by mass) replaced with fly ash. Temperature development was measured in two ways: using infrared thermography and thermo-sensors embedded in the samples. Additionally, the obtained results were modeled using the asymmetric Gaussian function. Peak temperatures in the middle of each sample were higher than the peak temperatures measured on the sample surface, with differences ranging between 2 °C and 4 °C. Differences between the temperature measurements of the thermo-sensors placed on the surface of the sample and thermal camera were lower than 2 °C. Very good compliance of the results was obtained for both the camera and the surface sensors measurements, as well as for the modeling coefficients. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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17 pages, 2614 KiB

Open AccessArticle

Optimal Insulation Assessment, Emission Analysis, and Correlation Formulation for Indian Region

by Mehmet Ali Kallioğlu, Ahmet Yılmaz, Ashutosh Sharma, Ahmed Mohamed, Dan Dobrotă, Tabish Alam, Rohit Khargotra and Tej Singh

Buildings 2023, 13(2), 569; https://doi.org/10.3390/buildings13020569 - 20 Feb 2023

Cited by 3 | Viewed by 1630

Abstract

The current study depicts the effects of different insulation materials and fuel types on the cooling and heating performance of buildings situated in hot and dry, warm and humid, composite, and cold climatic conditions in India. Ten different locations chosen from diverse climatic [...] Read more.

The current study depicts the effects of different insulation materials and fuel types on the cooling and heating performance of buildings situated in hot and dry, warm and humid, composite, and cold climatic conditions in India. Ten different locations chosen from diverse climatic regions were selected, and various potential parameters for expanded polystyrene and extruded polystyrene insulation materials were evaluated. Potential parameters, such as optimal insulation thickness, annual savings, and payback period, were computed for cooling and heating requirements and were found in the ranges of 0.0428–0.891 m, 10.83–19.19 $/m², and 1.49–2.36 years for cooling, as well as 0.0063–0.1522 m, 0.29–55.92 $/m², and 0.95–6.52 years for heating, respectively. An emission analysis was also carried out for the estimation of greenhouse gas (GHG) emissions by the engagement of optimal insulation thickness for heating. The GHG emissions from natural gas, coal, and diesel by the employment of various insulating materials were found in the ranges of 5.39–11.28, 9.47–32.68, and 2.26–4.51 kg/m²-year, respectively. A correlation formulation (power) for optimal insulation thickness was also carried out. For checking the preciseness of the developed mathematical models, statistical tools were utilized, and their obtained values in the satisfactory range signified the accurateness of the developed models. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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21 pages, 3048 KiB

Open AccessArticle

Evaluation of Building Energy Savings Achievable with an Attached Bioclimatic Greenhouse: Parametric Analysis and Solar Gain Control Techniques

by Dimitrios Kaliakatsos, Francesco Nicoletti, Francesca Paradisi, Piero Bevilacqua and Natale Arcuri

Buildings 2022, 12(12), 2186; https://doi.org/10.3390/buildings12122186 - 09 Dec 2022

Cited by 7 | Viewed by 1547

Abstract

Bioclimatic solar greenhouses are passive solar systems of relevant interest in the building sector, as they allow the reduction of energy needs related to air-conditioning. The aim of this work is to analyze the thermal behavior of a bioclimatic solar greenhouse attached to [...] Read more.

Bioclimatic solar greenhouses are passive solar systems of relevant interest in the building sector, as they allow the reduction of energy needs related to air-conditioning. The aim of this work is to analyze the thermal behavior of a bioclimatic solar greenhouse attached to a residential building. It is equipped with photovoltaic solar blinds (SPBs) to manage solar inputs and produce electricity. Automated control systems are implemented to activate the vents and SPBs. The parametric performance analysis conducted using the dynamic simulation software EnergyPlus allowed the evaluation of the influence of glass type, thermal mass, size, ventilation and location. The results show how the automation of the vents allows the maximization of heat exchange throughout the year, leading to a reduction in consumption even during the summer period. Analyses conducted for some cities in the Mediterranean area show that the maximum energy saving obtained is greater than 13%; in addition, photovoltaic solar shading contributes to the production of more than 1000 kWh/year of electricity. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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16 pages, 3839 KiB

Open AccessArticle

CFD Analysis of Different Ventilation Strategies for a Room with a Heated Wall

by Y Quoc Nguyen, Viet T. Nguyen, Long T. Tran and John C. Wells

Buildings 2022, 12(9), 1300; https://doi.org/10.3390/buildings12091300 - 25 Aug 2022

Cited by 4 | Viewed by 1851

Abstract

Solar chimneys can help to reduce solar heat gain on a building envelope and to enhance natural ventilation. In this work, we proposed three configurations of two solar chimneys combined with a heated wall for the natural ventilation of a room: (I) the [...] Read more.

Solar chimneys can help to reduce solar heat gain on a building envelope and to enhance natural ventilation. In this work, we proposed three configurations of two solar chimneys combined with a heated wall for the natural ventilation of a room: (I) the chimneys are connected serially, (II) the chimneys are parallel and exhaust air at two separate outlets, and (III) the chimneys are parallel, but the outlets are combined. The airflow rate achieved with each configuration was predicted with a Computational Fluid Dynamics model. The results show the effects of the heat flux in each channel and the geometries of the channels. Configuration (II) shows the highest flow rate. Particularly, the proposed configurations enhance the flow rate significantly and up to 40% when compared to the typical setup with a single channel solar chimney. The findings offer a novel design option for building façades for reducing solar heat gain and enhancing natural ventilation. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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13 pages, 5923 KiB

Open AccessArticle

Experimental and Numerical Performance Evaluation of Bio-Based and Recycled Thermal Break Strips in LSF Partition Walls

by Paulo Santos, David Abrantes, Paulo Lopes and Diogo Mateus

Buildings 2022, 12(8), 1237; https://doi.org/10.3390/buildings12081237 - 14 Aug 2022

Cited by 5 | Viewed by 1358

Abstract

The thermal performance of Lightweight Steel Framed (LSF) walls could be strongly compromised due to steel’s high thermal conductivity and their related thermal bridges. In this paper, the performance of bio-based (pine wood) and recycled (rubber–cork composite) Thermal Break Strip (TBS) materials, to [...] Read more.

The thermal performance of Lightweight Steel Framed (LSF) walls could be strongly compromised due to steel’s high thermal conductivity and their related thermal bridges. In this paper, the performance of bio-based (pine wood) and recycled (rubber–cork composite) Thermal Break Strip (TBS) materials, to mitigate the thermal bridge effect originated by steel profiles in LSF partition walls, is evaluated. This assessment was achieved by measurements under controlled laboratory conditions and by predictions using some numerical simulation models. Regarding the measurements, two climatic chambers (cold and hot) were used to impose a nearly constant temperature difference (around 35 °C), between the LSF partition test samples’ surfaces. To measure the overall surface-to-surface thermal resistance (R-value) of the evaluated LSF wall configurations, the Heat Flow Meter (HFM) method was used. Moreover, the measured values were compared with the calculations by 2D (THERM models) and 3D (ANSYS models) numerical simulations, exhibiting an excellent agreement (less than ±2% difference). Three TBS locations and three materials are evaluated, with their thermal performance improvement compared with a reference interior partition LSF wall, having no TBS. The top performance was accomplished by the aerogel super-insulating TBS material. The bio-based material (pine wood) and the recycled rubber–cork composite present quite similar results, with a slight advantage for the pine wood TBSs, given their higher thickness. Considering the TBS location, the inner and outer side present comparable performances. When using TBSs on both sides of steel profile flanges, there is a relevant thermal performance improvement, as expected. The thickness of the TBS also presents a noteworthy influence on the LSF partition thermal resistance. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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20 pages, 5841 KiB

Open AccessArticle

FEM-Based Evaluation of the Point Thermal Transmittance of Various Types of Ventilated Façade Cladding Fastening Systems

by Fanni Petresevics and Balázs Nagy

Buildings 2022, 12(8), 1153; https://doi.org/10.3390/buildings12081153 - 02 Aug 2022

Cited by 1 | Viewed by 3441

Abstract

The prevalence of ventilated façade systems is not only due to their aesthetic properties but also due to the fact they provide mechanical and acoustic protection for the façade and reduce the energy demand of the building. However, it is essential to mention [...] Read more.

The prevalence of ventilated façade systems is not only due to their aesthetic properties but also due to the fact they provide mechanical and acoustic protection for the façade and reduce the energy demand of the building. However, it is essential to mention that the point thermal bridges of the fastening system with brackets and anchors are often neglected during simplified energy performance calculations and practical design tasks. The reason practitioners do not consider the brackets in the calculation is the lack of standards for the simplified calculation of point thermal transmittances, or there being no comprehensive, manufacturer-independent thermal bridge catalogue available. This study aims to evaluate the point thermal transmittances created by the brackets and anchors of the ventilated façade claddings by using 3D numerical thermal modelling. A broad point thermal bridge catalogue was created, considering multiple factors of the ventilated facades. The FEM-based results show that thermal breaks/isolators could reduce the point thermal transmittances by only 2 to 28%, depending on the material of the brackets and the isolators. The brackets’ material and geometrical properties/parameters could cause up to 70% of difference between corrected and uncorrected thermal transmittance values, as well as significant differences between the results if the brackets were applied to different kinds of masonry walls or reinforced concrete walls. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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17 pages, 1288 KiB

Open AccessArticle

BECOP: A New Metric for Measuring the Energy Performance of the Building Envelope

by Samir E. Chidiac and Ghassan E. Marjaba

Buildings 2022, 12(5), 553; https://doi.org/10.3390/buildings12050553 - 26 Apr 2022

Viewed by 1604

Abstract

Thermal properties of the building envelope (BE) prescribed by codes and standards do not provide a consistent and comprehensive measure of its performance. Qualitative comparative analysis employed by the codes to assess energy savings is deterrent to technology development as the potential energy [...] Read more.

Thermal properties of the building envelope (BE) prescribed by codes and standards do not provide a consistent and comprehensive measure of its performance. Qualitative comparative analysis employed by the codes to assess energy savings is deterrent to technology development as the potential energy savings are never realized. A new metric, referred to as the building envelope coefficient of performance (BECOP), is proposed, which compares the BE performance to an ideal system. BECOP, which is invariant to calculation methods and applicable to all building types and climate zones, is a comprehensive metric for assessing the thermal performance of building envelopes while accounting for the various building characteristics. The sensitivity and range of BECOP were assessed for Canadian climate and construction methods. Using case studies, BECOP results revealed that current practices and regulations pertaining to the building envelope are inconsistent and fail to provide any measure of efficiency. It was also found that current building envelope technologies are not energy efficient. A max BECOP value of 35% is obtained for the best building envelope technology, revealing inefficiencies and energy saving potentials. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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26 pages, 8457 KiB

Open AccessPerspective

Renewable Energies and Architectural Heritage: Advanced Solutions and Future Perspectives

by Elena Lucchi

Buildings 2023, 13(3), 631; https://doi.org/10.3390/buildings13030631 - 27 Feb 2023

Cited by 21 | Viewed by 2684

Abstract

The current legislative framework and the recent energy crisis ask for massive applications of renewable energy sources (RES) in the built environment to reduce energy demand, environmental emissions, and energy costs. The uncritical application of these policies, especially on architectural heritage, could generate [...] Read more.

The current legislative framework and the recent energy crisis ask for massive applications of renewable energy sources (RES) in the built environment to reduce energy demand, environmental emissions, and energy costs. The uncritical application of these policies, especially on architectural heritage, could generate serious conservation issues, compromising their heritage values, biodiversity, traditional appearance, and materiality. Thus, there is an urgent call to balance architectural heritage preservation with energy production using clear rules, policies, criteria, and heritage-compatible technologies. The present study aims at defining an updated overview of the application of solar, wind, geothermal energy, and bioenergy on architectural heritage. A deep literature review of the studies published in the years 2020–2023 has been performed, identifying main topics, challenges, advanced solutions, and future perspectives. Acceptability, design criteria, and cutting-edge technologies are also illustrated through case studies to better understand practical approaches. Full article

(This article belongs to the Special Issue Thermal Performance of the Building Envelope—Original Methods and Advanced Solutions)

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