energies-logo

Journal Browser

Journal Browser

Building Thermal Envelope

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "G: Energy and Buildings".

Deadline for manuscript submissions: closed (30 November 2019) | Viewed by 58176

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors


E-Mail Website
Guest Editor
Department of Civil Engineering, Architecture and Georresources, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
Interests: CIB—International Council for Research and Innovation in Building and Construction; durability of building elements, maintenance of buildings; rehabilitation of buildings; building life cycle assessment
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Civil Engineering, Architecture and Georesources, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
Interests: Building physics; Thermal and energy performance of buildings (laboratory and field experiments; modelling and simulation); Sustainable and energy efficient materials and solutions; Wind action and natural ventilation of buildings
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The increasing requirements in building thermal and energy performance standards and the need for designing net-zero energy buildings, while still enhancing indoor comfort conditions, lead to a demand for more efficient thermal building envelope solutions. In fact, the effective use of building thermal envelopes, as an interface between outdoors and indoors, plays a key role in sustainable and energy-efficient building design. Therefore, there is a need for a continuous search for innovative materials, construction solutions, and technologies that manage the energy and mass transfer between buildings and the external environment, taking into account not only climatic changes but also user preferences. Knowledge concerning the performance of building thermal envelope solutions and existing design support tools, such as building performance simulation, is crucial for stakeholders to make informed decisions with respect to the definition and implementation of energy-efficient strategies for new and refurbished buildings.

This Special Issue intends to provide an overview of existing knowledge related to various aspects of building thermal envelopes.

Original research (theoretical and experimental), case studies, and comprehensive review papers are invited for possible publication in this Special Issue. Relevant topics to this Special Issue include but are not limited to the following subjects:

  • Building envelope materials and systems envisaging indoor comfort and energy efficiency;
  • Building thermal and energy modelling and simulation;
  • Lab test procedures and methods of field measurement to assess the performance of materials and building solutions;
  • Smart materials and renewable energy in building envelopes;
  • Adaptive and intelligent building envelopes;
  • Integrated building envelope technologies for high-performance buildings and cities.

Prof. Dr. Jorge de Brito
Prof. Dr. Maria da Glória Gomes
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • building envelope materials and systems envisaging indoor comfort and energy efficiency
  • building thermal and energy modelling and simulation
  • lab test procedures and methods of field measurement to assess the performance of materials and building solutions
  • smart materials and renewable energy in building envelopes
  • adaptive and intelligent building envelopes
  • integrated building envelope technologies for high-performance buildings and cities

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (14 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Editorial

Jump to: Research

5 pages, 204 KiB  
Editorial
Special Issue “Building Thermal Envelope”
by Jorge de Brito and M. Glória Gomes
Energies 2020, 13(5), 1061; https://doi.org/10.3390/en13051061 - 28 Feb 2020
Cited by 3 | Viewed by 1774
Abstract
The increasing requirements in building thermal and energy performance standards and the need to design nearly zero-energy buildings, while still enhancing the indoor comfort conditions, have led to a demand for more efficient thermal building envelope solutions [...] Full article
(This article belongs to the Special Issue Building Thermal Envelope)

Research

Jump to: Editorial

17 pages, 21291 KiB  
Article
The Application of Courtyard and Settlement Layouts of the Traditional Diyarbakır Houses to Contemporary Houses: A Case Study on the Analysis of Energy Performance
by İdil Ayçam, Sevilay Akalp and Leyla Senem Görgülü
Energies 2020, 13(3), 587; https://doi.org/10.3390/en13030587 - 27 Jan 2020
Cited by 10 | Viewed by 4163
Abstract
Conventional energy use has brought environmental problems such as global warming and accelerated efforts to reduce energy consumption in many areas, particularly in the housing sector. For this purpose, bioclimatic design principles and vernacular architecture parameters have started to be examined in residential [...] Read more.
Conventional energy use has brought environmental problems such as global warming and accelerated efforts to reduce energy consumption in many areas, particularly in the housing sector. For this purpose, bioclimatic design principles and vernacular architecture parameters have started to be examined in residential buildings nowadays. Thus, the demand for less energy-consuming houses has started to increase. In this study, we aimed to specify the significance of traditional architectural parameters for houses in the hot-dry climatic region of Diyarbakır, Turkey. Within the scope of the study, a case was based on the urban fabric of the traditional houses in Historical Diyarbakir Suriçi-Old Town settlement and the Şilbe Mass Housing Area was discussed. The courtyard types, settlement patterns, and street texture of traditional Diyarbakır houses were modeled by using DesignBuilder energy simulation program for the case study. Annual heating, cooling, and total energy loads were calculated, and their thermal performances were compared. The aim is to create a less energy-consuming and sustainable environment with the adaptation of traditional building form-street texture to today’s housing sector. Development of a settlement model, which is based on traditional houses’ bioclimatic design for hot-dry region, was intended to be applied in the modern housing sector of Turkey. Moreover, adapting local forms, urban texture, and settlement patterns to today has significant potential for sustainable architecture and energy-efficient buildings. According to this study, the optimum form and layout of traditional houses, which are one of the climate balanced building designs, provide annual energy savings if integrated and designed in today’s building construction. As a result of this study, if the passive design alternatives such as building shape, layout, and orientation were developed in the first stage of the design, energy efficient building design would be possible. The study is important for the continuation of traditional sustainable design. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

22 pages, 8661 KiB  
Article
Envelope Thermal Performance Analysis Based on Building Information Model (BIM) Cloud Platform—Proposed Green Mark Collaboration Environment
by Ziwen Liu, Qian Wang, Vincent J.L. Gan and Luke Peh
Energies 2020, 13(3), 586; https://doi.org/10.3390/en13030586 - 27 Jan 2020
Cited by 26 | Viewed by 9271
Abstract
Building Information Modeling (BIM) and sustainable buildings are two future cornerstones of the Architectural, Engineering and Construction (AEC) industry. In Singapore’s context, the Green Mark (GM) scoring system is prevalently used to assess the sustainability index of green buildings. BIM provides the semantic [...] Read more.
Building Information Modeling (BIM) and sustainable buildings are two future cornerstones of the Architectural, Engineering and Construction (AEC) industry. In Singapore’s context, the Green Mark (GM) scoring system is prevalently used to assess the sustainability index of green buildings. BIM provides the semantic and geometry information of buildings, which is proliferated as the technological and process backbone for the green building assessment. This research, through vast literature reviews, identified that the current procedure of achieving a Green Mark score is tedious and cumbersome, which hampers productivity, especially in the calculation of building envelope thermal performance. Furthermore, the project stakeholders work in silos, in a non-collaborative, manual and 2D-based environment for generating relevant documentation to achieve the requisite green mark score. To this end, a cloud-based BIM platform was developed, with the aim of encouraging project stakeholders to collaboratively generate the project’s green mark score digitally in accordance with the regulatory requirements. Through this research, the authors have validated the Envelope Thermal Transfer Value (ETTV) calculation, which is one of the prerequisite criteria to achieve a Green Mark score, through a case study using the developed cloud-based BIM platform. The results indicated that using the proposed platform enhances the productivity and accuracy as far as ETTV calculation is concerned. This study provides a basis for future research in implementing the proposed platform for other criteria under the Green Mark Scheme. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Graphical abstract

13 pages, 2359 KiB  
Article
Energy Retrofitting of a Buildings’ Envelope: Assessment of the Environmental, Economic and Energy (3E) Performance of a Cork-Based Thermal Insulating Rendering Mortar
by José D. Silvestre, André M. P. Castelo, José J. B. C. Silva, Jorge M. C. L. de Brito and Manuel D. Pinheiro
Energies 2020, 13(1), 143; https://doi.org/10.3390/en13010143 - 27 Dec 2019
Cited by 8 | Viewed by 2785
Abstract
This paper presents an environmental, economic and energy (3E) assessment of an energy retrofitting of the external walls of a flat of an average building with the most current characteristics used in Portugal. For this intervention, a cork-based (as recycled lightweight aggregate) TIRM [...] Read more.
This paper presents an environmental, economic and energy (3E) assessment of an energy retrofitting of the external walls of a flat of an average building with the most current characteristics used in Portugal. For this intervention, a cork-based (as recycled lightweight aggregate) TIRM (Thermal Insulating Rendering Mortar) was considered. The declared unit was 1 m2 of an external wall for a 50-year study period and the energy and economic costs and savings, as well as the environmental impacts, were analytically modelled and compared for two main alternatives: the reference wall without any intervention and the energetically rehabilitated solution with the application of TIRM. Walls with improved energy performance (with TIRM) show lower economic and environmental impacts: reductions from 6% to 32% in carbon emissions, non-renewable energy consumption and costs during the use stage, which depends on the thickness and relative place where TIRM layers are applied. A worse energy performance is shown by reference walls (without TIRM) during the use stage (corresponding to energy used for heating and cooling), while the improved walls present economic and environmental impacts due to the application of TIRM (including the production, transport and application into the building) that do not exist in the reference walls. The comparison between reference walls and energy-retrofitted ones revealed that reference wall become be more expensive when more demanding operational energy requirements are analysed over a 50-year period, even if renewable materials are more expensive. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

17 pages, 12922 KiB  
Article
Experimental Studies Involving the Impact of Solar Radiation on the Properties of Expanded Graphite Polystyrene
by Paweł Krause and Artur Nowoświat
Energies 2020, 13(1), 75; https://doi.org/10.3390/en13010075 - 22 Dec 2019
Cited by 18 | Viewed by 3397
Abstract
This article presents the research studies aimed at identifying the behavior of expanded polystyrene with the addition of graphite in the conditions of exposure to solar radiation. For this purpose, a series of in situ tests and laboratory studies were carried out. Three [...] Read more.
This article presents the research studies aimed at identifying the behavior of expanded polystyrene with the addition of graphite in the conditions of exposure to solar radiation. For this purpose, a series of in situ tests and laboratory studies were carried out. Three types of material were tested, i.e. expanded polystyrene (EPS) (white polystyrene), polystyrene with the addition of graphite (gray polystyrene) and two-layer polystyrene (gray bottom layer and white top layer). Temperature distributions on the surfaces of the panels in field and laboratory conditions were determined. The distributions of temperature were recorded at varied wind impact (field conditions and laboratory conditions) and at varied impact of solar radiation (laboratory conditions). Based on the conducted experiments, differences in temperature distribution on the surfaces of the tested panels were determined. In addition, geometric changes and deformation levels of the tested white and gray expanded polystyrene panels exposed to artificial sun radiation were determined in laboratory conditions. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

11 pages, 3724 KiB  
Article
Effects of the Aspect Ratio of a Rectangular Thermosyphon on Its Thermal Performance
by Chia-Wang Yu, C. S. Huang, C. T. Tzeng and Chi-Ming Lai
Energies 2019, 12(20), 4014; https://doi.org/10.3390/en12204014 - 22 Oct 2019
Cited by 2 | Viewed by 2374
Abstract
The natural convection behaviors of rectangular thermosyphons with different aspect ratios were experimentally analyzed in this study. The experimental model consisted of a loop body, a heating section, a cooling section, and adiabatic sections. The heating and cooling sections were located in the [...] Read more.
The natural convection behaviors of rectangular thermosyphons with different aspect ratios were experimentally analyzed in this study. The experimental model consisted of a loop body, a heating section, a cooling section, and adiabatic sections. The heating and cooling sections were located in the vertical portions of the rectangular loop. The length of the vertical cooling section and the lengths of the upper and lower adiabatic sections were fixed at 300 mm and 200 mm, respectively. The inner diameter of the loop was fixed at 11 mm, and the cooling end temperature was 30 °C. The relevant parameters and their ranges were as follows: The aspect ratios were 6, 4.5, and 3.5 (with potential differences of 41, 27, and 18, respectively, between the cold and hot ends), and the input thermal power ranged from 30 to 60 W (with a heat flux of 600 to 3800 W/m2). The results show that it is feasible to obtain solar heat gain by installing a rectangular thermosyphon inside the metal curtain wall and that increasing the height of the opaque part of the metal curtain wall can increase the aspect ratio of the rectangular thermosyphon installed inside the wall and thus improve the heat transfer efficiency. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

17 pages, 5821 KiB  
Article
A Study on Changes of Window Thermal Performance by Analysis of Physical Test Results in Korea
by Seok-Hyun Kim, Hakgeun Jeong and Soo Cho
Energies 2019, 12(20), 3822; https://doi.org/10.3390/en12203822 - 10 Oct 2019
Cited by 5 | Viewed by 3454
Abstract
The interest in zero energy buildings is increasing in South Korea. Zero energy buildings need to save energy by using passive technology. The window performance is important to the thermal insulation of the building. Also, the government regulates the window performance through regulation [...] Read more.
The interest in zero energy buildings is increasing in South Korea. Zero energy buildings need to save energy by using passive technology. The window performance is important to the thermal insulation of the building. Also, the government regulates the window performance through regulation and standards. However, it is difficult to predict window performance because the components of the window have become complicated due to the various materials used in the glass and frame. Based on window performance standards and regulations, the quality of window performance was managed. In this research, to consider thermal performance in proper window design in South Korea, we confirmed the impact on the thermal performance of the window through various kinds of materials and shapes. The authors also propose a window shape classification and frame calculation method based on actual test results. The authors analyzed the thermal performance data of the windows provided by the Korea Energy Agency and confirmed the change in the thermal performance of the windows by year and by frame material. The average U-value of the window decreased from 2012 to 2015 and maintained similar values until 2017. In 2018, this value was decreased to comply. Also, the authors confirmed the U-value of the windows through actual physical experiments and confirmed the change in thermal performance by the construction of the windows based on the results. The results show, in the case of aluminum windows, the U-value corresponding to Grade 3 (1.4–2.1 W/m2·K) was as high as about 60%. Regarding the analyzed results of the U-values of PVC windows, Grade 3 (U-value of 1.4–2.1 W/m2·K) accounted for about 35%, and Grade 2 (U-value of 1.0–1.4 W/m2·K) for about 29%. This paper also confirmed that the frame U-value of the PVC windows is lower than the frame U-value of the aluminum windows. Therefore, the authors proposed the performance index of the glazing part in PVC and aluminum window design. The results of this research can be used as basic data to identify problems in the method of determining the performance of windows in Korea. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

15 pages, 5876 KiB  
Article
Thermally Anisotropic Composites for Improving the Energy Efficiency of Building Envelopes
by Kaushik Biswas, Som Shrestha, Diana Hun and Jerald Atchley
Energies 2019, 12(19), 3783; https://doi.org/10.3390/en12193783 - 5 Oct 2019
Cited by 18 | Viewed by 3259
Abstract
This article describes a novel application of thermal anisotropy for improving the energy efficiency of building envelopes. The current work was inspired by existing research on improved heat dissipation in electronics using thermal anisotropy. Past work has shown that thermally anisotropic composites (TACs) [...] Read more.
This article describes a novel application of thermal anisotropy for improving the energy efficiency of building envelopes. The current work was inspired by existing research on improved heat dissipation in electronics using thermal anisotropy. Past work has shown that thermally anisotropic composites (TACs) can be created by the alternate layering of two dissimilar, isotropic materials. Here, a TAC consisting of alternate layers of rigid foam insulation and thin, high-conductivity aluminum foil was investigated. The TAC was coupled with copper tubes with circulating water that acted as a heat sink and source. The TAC system was applied to a conventional wood-framed wall assembly, and the energy benefits were investigated experimentally and numerically. For experimental testing, large scale test wall specimens were built with and without the TAC system and tested in an environmental chamber under simulated diurnal hot and cold weather conditions. Component-level and whole building numerical simulations were performed to investigate the energy benefits of applying the TAC system to the external walls of a typical, single-family residential building. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

14 pages, 13088 KiB  
Article
Natural Ventilation Effectiveness of Awning Windows in Restrooms in K-12 Public Schools
by Sung-Chin Chung, Yi-Pin Lin, Chun Yang and Chi-Ming Lai
Energies 2019, 12(12), 2414; https://doi.org/10.3390/en12122414 - 23 Jun 2019
Cited by 10 | Viewed by 6696
Abstract
Using computational fluid dynamics (CFD), this study explores the effect of a different number of awning windows and their installation locations on the airflow patterns and air contaminant distributions in restrooms in K-12 (for kindergarten to 12th grade) public schools in Taiwan. A [...] Read more.
Using computational fluid dynamics (CFD), this study explores the effect of a different number of awning windows and their installation locations on the airflow patterns and air contaminant distributions in restrooms in K-12 (for kindergarten to 12th grade) public schools in Taiwan. A representative restroom configuration with dimensions of 10.65 m × 9.2 m × 3.2 m (height) was selected as the investigated object. Based on the façade design feasibility, seven possible awning window configurations were considered. The results indicate that an adequate number of windows and appropriate installation locations are required to ensure the natural ventilation effectiveness of awning windows. The recommended installation configuration is provided. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

20 pages, 11280 KiB  
Article
The Application of Building Physics in the Design of Roof Windows
by Jan Tywoniak, Vítězslav Calta, Kamil Staněk, Jiří Novák and Lenka Maierová
Energies 2019, 12(12), 2300; https://doi.org/10.3390/en12122300 - 16 Jun 2019
Cited by 8 | Viewed by 4369
Abstract
This paper deals with a small but important component in a building envelope, namely roof windows in pitched roofs. Building physics methods were used to support the search for new solutions which correspond to the maximum extent for requirements for passive house level [...] Read more.
This paper deals with a small but important component in a building envelope, namely roof windows in pitched roofs. Building physics methods were used to support the search for new solutions which correspond to the maximum extent for requirements for passive house level design. The first part of the paper summarizes the key phenomena of heat transfer, mainly based on a comparison of vertical windows in walls. The results of repeated two-dimensional heat transfer calculations in the form of parametric studies are presented in order to express the most important factors influencing thermal transmittance and minimum surface temperatures. Several configuration variants suitable for technical design are discussed. It was found that a combination of wood and hardened plastics in the window frame and sash is the preferred solution. The resulting thermal transmittance can be up to twice as low as usual (from 0.7 down to 0.5 W/(m2·K), with further development ongoing. Surface temperature requirements to avoid the risk of condensation can be safely fulfilled. Concurrently, it is shown that the relative influence of thermal coupling between the window and roof construction increases with the improvement of window quality. Specific attention was given to the effect of the slanting of the side lining, which was analyzed by simulation and measurement in a daylight laboratory. The increase in thermal coupling due to slanting was found to be negligible. Motivations for specific building physics research are mentioned, such as the need to study the surface heat transfer in the case of inclined windows placed in a deep lining. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

22 pages, 6681 KiB  
Article
Integrated Measuring and Control System for Thermal Analysis of Buildings Components in Hot Box Experiments
by Tullio de Rubeis, Mirco Muttillo, Iole Nardi, Leonardo Pantoli, Vincenzo Stornelli and Dario Ambrosini
Energies 2019, 12(11), 2053; https://doi.org/10.3390/en12112053 - 29 May 2019
Cited by 28 | Viewed by 4240
Abstract
In this paper, a novel integrated measuring and control system for hot box experiments is presented. The system, based on a general-purpose microcontroller and on a wireless sensors network, is able to fully control the thermal phenomena inside the chambers, as well as [...] Read more.
In this paper, a novel integrated measuring and control system for hot box experiments is presented. The system, based on a general-purpose microcontroller and on a wireless sensors network, is able to fully control the thermal phenomena inside the chambers, as well as the heat flux that involves the specimen wall. Thanks to the continuous measurements of air and surfaces temperatures and energy input into the hot chamber, the thermal behavior of each hot box component is analyzed. A specific algorithm allows the post-process of the measured data for evaluating the specimen wall thermal quantities and for creating 2D and 3D thermal models of each component. The system reliability is tested on a real case represented by a double insulating X-lam wall. The results of the 72 h experiment show the system’s capability to maintain stable temperature set points inside the chambers and to log the temperatures measured by the 135 probes, allowing to know both the U-value of the sample (equal to 0.216 ± 0.01 W/m2K) and the thermal models of all the hot box components. The U-value obtained via hot box method has been compared with the values gathered through theoretical calculation and heat flow meter measurements, showing differences of less than 20%. Finally, thanks to the data postprocessing, the 2D and 3D thermal models of the specimen wall and of the chambers have been recreated. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

18 pages, 5031 KiB  
Article
Analysis of Convergence Characteristics of Average Method Regulated by ISO 9869-1 for Evaluating In Situ Thermal Resistance and Thermal Transmittance of Opaque Exterior Walls
by Doo Sung Choi and Myeong Jin Ko
Energies 2019, 12(10), 1989; https://doi.org/10.3390/en12101989 - 24 May 2019
Cited by 20 | Viewed by 3719
Abstract
In the last few decades, an average method which is regulated by ISO 9869-1 has been used to evaluate the in situ thermal transmittance (U-value) and thermal resistance (R-value) of building envelopes obtained from onsite measurements and to verify [...] Read more.
In the last few decades, an average method which is regulated by ISO 9869-1 has been used to evaluate the in situ thermal transmittance (U-value) and thermal resistance (R-value) of building envelopes obtained from onsite measurements and to verify the validity of newly proposed methods. Nevertheless, only a few studies have investigated the test duration required to obtain reliable results using this method and the convergence characteristics of the results. This study aims to evaluate the convergence characteristics of the in situ values analyzed using the average method. The criteria for determining convergence (i.e., end of the test) using the average method are very strict, mainly because of the third condition, which compares the deviation of two values derived from the first and last periods of the same duration. To shorten the test duration, environmental variables should be kept constant throughout the test or an appropriate period should be selected. The convergence of the in situ U-value and R-value is affected more by the length of the test duration than by the temperature difference if the test environment meets literature-recommended conditions. Furthermore, there is no difference between the use of the U-value and R-value in determining the end of the test. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

12 pages, 4378 KiB  
Article
Experimental Observation of Natural Convection Heat Transfer Performance of a Rectangular Thermosyphon
by C. S. Huang, Chia-Wang Yu, R. H. Chen, Chun-Ta Tzeng and Chi-Ming Lai
Energies 2019, 12(9), 1702; https://doi.org/10.3390/en12091702 - 6 May 2019
Cited by 6 | Viewed by 2903
Abstract
This study experimentally investigates the natural convection heat transfer performance of a rectangular thermosyphon with an aspect ratio of 3.5. The experimental model is divided into a loop body, a heating section, a cooling section, and two adiabatic sections. The heating section and [...] Read more.
This study experimentally investigates the natural convection heat transfer performance of a rectangular thermosyphon with an aspect ratio of 3.5. The experimental model is divided into a loop body, a heating section, a cooling section, and two adiabatic sections. The heating section and the cooling section are located in the vertical legs of the rectangular loop. The length of the vertical heating section and the length of the upper and lower horizontal insulation sections are 700 mm and 200 mm, respectively, and the inner diameter of the loop is 11 mm. The relevant parameters and their ranges are as follows: the input thermal power is 30–60 W (with a heat flux in the range of 60–3800 W/m2); the temperature in the cooling section is 30, 40, or 50 °C; and the potential difference between the hot and cold sections is 5, 11, or 18 for the cooling section lengths of 60, 45, and 30 cm, respectively. The results indicate that the value of the dimensionless heat transfer coefficient, the Nusselt number, is generally between 5 and 10. The heating power is the main factor affecting the natural convection intensity of the thermosyphon. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

22 pages, 11270 KiB  
Article
Study on the Thermal Performance of a Hybrid Heat Collecting Facade Used for Passive Solar Buildings in Cold Region
by Xiaoliang Wang, Bo Lei, Haiquan Bi and Tao Yu
Energies 2019, 12(6), 1038; https://doi.org/10.3390/en12061038 - 18 Mar 2019
Cited by 9 | Viewed by 4179
Abstract
Passive solar technologies are traditionally considered as cost-effective ways for the building heating. However, conventional passive solar buildings are insufficient to create a relatively stable and comfortable indoor thermal environment. To further increase the indoor air temperature and reduce the heating energy consumption, [...] Read more.
Passive solar technologies are traditionally considered as cost-effective ways for the building heating. However, conventional passive solar buildings are insufficient to create a relatively stable and comfortable indoor thermal environment. To further increase the indoor air temperature and reduce the heating energy consumption, a hybrid heat collecting facade (HHCF) is proposed in this paper. To analyze the thermal performance of the HHCF, a heat transfer model based on the heat balance method is established and validated by experimental results. Meanwhile, the energy saving potential of a room with the HHCF is evaluated as well. When the HHCF is applied to places where heating is required in the cold season while refrigeration is unnecessary in hot season, the HHCF can reduce the heating need by 40.2% and 21.5% compared with the conventional direct solar heat gain window and the Trombe wall, respectively. Furthermore, a series of parametric analyses are performed to investigate the thermal performance of the room with HHCF under various design and operating conditions. It is found that the thermal performance of the HHCF mainly depends on the window operational schedule, the width and the absorptivity of heat collecting wall, and the thermal performance of the inner double-glass window. The modeling and the parametric study in this paper are beneficial to the design and the optimization of the HHCF in passive solar buildings. Full article
(This article belongs to the Special Issue Building Thermal Envelope)
Show Figures

Figure 1

Back to TopTop