| 1. |
- Allard, Ingrid, 1986-, et al.
(författare)
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Energy performance criteria for residential buildings : A comparison of Finnish, Norwegian, Swedish, and Russian building codes
- 2021
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 250
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Tidskriftsartikel (refereegranskat)abstract
- Building code are considered to be an effective policy tool to reduce energy use in buildings. In practice, national priorities influence the indicators and criteria adopted in the building codes. Consequently, neighbouring countries with similar climate conditions may use different criteria in their building codes to regulate the energy performance. In this paper, the energy performance criteria and their relative stringency in the latest residential building codes of Finland, Norway, Sweden and Russia are compared. The study is based on energy performance evaluations of one single-family building and one multi-family building, located in the north of Sweden. Both buildings complied with the Norwegian and Russian building code. However, the buildings did not comply with the specific fan power and heat loss criteria in the Finnish building code. Additionally, the single-family building did not comply with the specific primary energy and electric powerdemand criteria in the Swedish building code when heated by an electric heater. The national standard input data were found to have a large influence on the buildings’ compliance with the studied energy use criteria. Policy implications of the results are discussed.
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| 2. |
- Allard Stolterman, Ingrid, 1986-
(författare)
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Regulating energy performance of residential buildings in cold climate : a study of indicators, criteria, and evaluation methods
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Building energy performance has been important in Fennoscandia ever since the early vernacular houses, to combat the cold climate. Due to EU directive 2010/31/EU on the energy performance of buildings (EPBD recast), building energy performance has become even more relevant in northern Europe the last decade. Objectives for improving building energy performance may include reducing cost and CO2-emissions, increasing energy independency, and improving the indoor climate. Different indicators, criteria, and evaluations methods may be used to reach these objectives. This dissertation addresses indicators, criteria, and evaluation methods used to regulate energy performance of residential buildings in Sweden, Norway, Finland, and Russia. Four research objectives are covered: (RO1) comparing criteria and evaluation methods used to regulate energy performance of residential buildings in Sweden, Norway, and Finland, (RO2) studying the perspective of professionals with experience in building energy performance evaluation on (a) methods for evaluating envelope air leakage of residential buildings in Sweden and Finland and (b) potential energy performance indicators in the Swedish procurement process of multi-family buildings, (RO3) developing an approach for analysing the performance gap between design predictions and measurements that can be used to verify compliance with requirements on building energy use in practice, and (RO4) comparing the stringency of the energy performance criteria for residential buildings between the Swedish, Norwegian, Finnish, and Russian national building code. Many differences were found between how energy performance of residential buildings was regulated in the four countries. In Sweden, measurements were used more for evaluating building energy performance than in the other countries. As of 1st January 2020, the Finnish building code was characterized by its focus on the building heat loss and stringent energy performance criteria compared to the other countries. The Norwegian building code was characterized by a relatively narrow system perspective on energy performance, with no regulation of the energy production efficiency or energy source. The Russian building code also had a narrow system perspective but was also characterized by its focus on the form factor – the relationship between building volume and enclosing area. The practitioners wanted to minimize the influence from building operation and user behaviour on energy performance evaluations in the Swedish building procurement process of multi-family buildings. Hence, they preferred component-focused indicators or indicators with a narrow system boundary. An approach has been developed for analyzing the performance gap between design phase predictions and measurements. The approach can be used to verify the finished building’s energy performance, with minimal influence from occupant behavior and building operation.
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| 3. |
- Azizi, Shoaib, 1989-
(författare)
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A multi-method assessment to support energy efficiency decisions in existing residential and academic buildings
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rapid decarbonization of building stock is essential for the energy transition required to mitigate climate change and limit the global temperature rise below 1.5 °C. The decision-making for the adoption of energy efficiency measures (EEMs) is often complex and involves lasting consequences and risks. The strategy to direct and support the decision makers can significantly increase the adoption rate of EEMs in buildings. This Ph.D. project focuses on facilitating sustainability improvement in buildings by supporting the decision makers who are accountable for the consequences of adopting the EEMs. Energy efficiency improvement is decided and managed differently in various types of buildings and contexts and encounters different challenges and opportunities. Accordingly, it is required to understand the needs to select adequate strategies and to devise effective supporting interventions for energy efficiency improvement.The owners of single-family houses are often the occupants who are in charge of the most decisions to improve energy efficiency in their dwellings. The situation is rather different in multi-family buildings and academic buildings in which organizational management adds more complexity and the decisions affect various stakeholders. The studies in this project are based on qualitative and quantitative data collected from single-family houses, multi-family buildings, and university buildings in northern Sweden. Surveys were used to elicit the decision makers' perceptions of different types of buildings. Moreover, sensor data from university buildings were used in the case studies to develop informative metrics for space use efficiency and to analyze the effect of sensor positioning on monitored data.The initial work involved understanding the opportunities and challenges of improving energy efficiency in buildings and the tradeoffs between the perceived benefits and barriers. This part of the thesis provided the foundation and inspiration for the rest of the project, including investigating how to bundle several measures and use information and communication technologies (ICT) for building sustainability. The findings show lack of information and evidence that could justify the beneficial outcomes of EEMs is a major barrier for effective decision-making. Clear information on potential improvements allows sharing the responsibilities among different stakeholders and increases the management capacity to handle projects and adopt EEMs. Using feedback tools (for example, space use and/or energy use visualizations) might be an effective strategy to influence decision makers.Various studies incorporated in this multidisciplinary Ph.D. thesis develop and investigate strategies to support decision makers to improve energy efficiency in buildings. The findings provide insights to policymakers and businesses to devise intervention strategies for energy efficiency in buildings.
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| 4. |
- Azizi, Shoaib, 1989-, et al.
(författare)
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Adoption of Energy Efficiency Measures in Renovation of Single-Family Houses : A Comparative Approach
- 2020
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 13:22
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Tidskriftsartikel (refereegranskat)abstract
- Inclusion of energy efficiency measures (EEMs) in the renovation of the single-family housing stock can unlock the potential for much-needed energy efficiency to tackle climate change. Energy renovation (ER) in single-family houses is often promoted as an aggregate process, and EEMs are treated homogenously without sufficient attention to their differences. This study applies a comparative analysis on common EEMs using chi-square test to investigate the influence of factors already found affecting the implementation of ER. This paper addresses the “personal” and “house-related” factors influencing the adoption of EEMs regardless of motives or barriers leading the adopters’ decisions. This strategy is useful to highlight the contexts leading to an increase in the adoption rate of different EEMs. The analysis is based on a questionnaire survey mailed in spring 2017 to 1550 single-family homeowners in the northern region of Sweden. Approximately 60% of respondents showed interest in adopting at least one EEM if they implement a major renovation. About 46% of respondents stated to have at least one indoor environmental problem (IEP) in their houses, and IEPs are found to have significant relations with homeowners’ interest to adopt several different EEMs. The policy implications related to different EEMs are discussed.
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| 5. |
- Azizi, Shoaib, et al.
(författare)
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Application of Internet of Things in academic buildings for space use efficiency using occupancy and booking data
- 2020
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- Environmental sustainability in academic buildings can be improved with management interventions such as improving space use efficiency supported by large data from the Internet of Things (IoT). Due to the potentials, the interest in the use of IoT tools for facility management is high among universities. However, empirical studies on this topic are scarce. To address the knowledge gap in this area, this study proposes and examines a process model with steps to measure space use and to improve space use efficiency by IoT tools in academic buildings. The applicability of the model is investigated in 8 lecture halls in a university building by using occupancy and booking data from IoT tools. Four space use indicators are developed to visualize the data and quantify space use, and based on them, the strategies and interventions for space use efficiency are proposed and discussed.
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| 6. |
- Azizi, Shoaib, et al.
(författare)
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Application of occupancy and booking information to optimize space and energy use in higher education institutions
- 2020
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Ingår i: E3S Web of Conferences. - : EDP Sciences. - 2267-1242. ; 172
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Tidskriftsartikel (refereegranskat)abstract
- Building in higher education institutions (HEIs) are characterized as energy intensive Experience from practice showing large discrepancies between predicted and actual energy performance. The deviation can sometimes reach 100%. Explanations often originate from occupant’s behaviour along with building operation. IoT-based smart tools can provide extensive information about building usage to improve the building management, often associates with opportunities, for significant energy saving. The analysis in this study investigate space use based on occupancy and booking information in eight different lecture rooms at Umeå University. The results suggest interventions for significant saving potentials, such as modification of access permission and closing down redundant lecture rooms.
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| 7. |
- Azizi, Shoaib, et al.
(författare)
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Effects of Positioning of Multi-Sensor Devices on Occupancy and Indoor Environmental Monitoring in Single-Occupant Offices
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:19
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Tidskriftsartikel (refereegranskat)abstract
- The advancements in sensor and communication technologies drive the rapid developments in the applications of occupancy and indoor environmental monitoring in buildings. Currently, the installation standards for sensors are scarce and the recommendations for sensor positionings are very general. However, inadequate sensor positioning might diminish the reliability of sensor data, which could have serious impacts on the intended applications such as the performance of demand-controlled HVAC systems and their energy use. Thus, there is a need to understand how sensor positioning may affect the sensor data, specifically when using multi-sensor devices in which several sensors are being bundled together. This study is based on the data collected from 18 multi-sensor devices installed in three single-occupant offices (six sensors in each office). Each multi-sensor device included sensors to measure passive infrared (PIR) radiation, temperature, CO2, humidity, and illuminance. The results show that the positions of PIR and CO2 sensors significantly affect the reliability of occupancy detection. The typical approach of positioning the sensors on the ceiling, in the middle of offices, may lead to relatively unreliable data. In this case, the PIR sensor in that position has only 60% accuracy of presence detection. Installing the sensors under office desks could increase the accuracy of presence detection to 84%. These two sensor positions are highlighted in sensor fusion analysis as they could reach the highest accuracy compared to other pairs of PIR sensors. Moreover, sensor positioning can affect various indoor environmental parameters, especially temperature and illuminance measurements.
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| 8. |
- Fogelström, Frej, et al.
(författare)
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A review of possibilities and challenges of pit thermal energy storages in Swedish district heating networks
- 2024
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Ingår i: ISEC 2024. - : AEE – Institute for Sustainable Technologies.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The use of pit thermal energy storages (PTES) enables higher solar fraction in district heating networks by counteracting the mismatch between heat demand and production in solar district heating (SDH) installations. Capital costs linked to land areas with site-specific geological conditions are the deciding factors for PTES constructions. This study investigates non-technical and technical factors for the implementation of PTES in Swedish district heating networks. Having several SDH and PTES installations in operation the country of Denmark is used as a reference. This study, based on literature review, discusses the drivers and challenges for the use of PTES in district heating networks.
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| 9. |
- Mattsson, Moa, et al.
(författare)
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An Exploratory Study on Swedish Stakeholders’ Experiences with Positive Energy Districts
- 2023
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 16:12
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Tidskriftsartikel (refereegranskat)abstract
- Positive energy district (PED) is a novel idea aimed to have an annual surplus of renewable energy and net zero greenhouse gas emissions within an area. However, it is still an ambiguous concept, which might be due to the complexity of city district projects with interconnected infrastructures and numerous stakeholders involved. This study discusses various aspects of PED implementation and presents practitioners’ experiences with the PED concept, challenges, and facilitators they have faced with real projects. The study is based on interviews with ten Swedish professionals. The major challenges reported for PED implementation were local energy production and energy flexibility, sub-optimization, legislation, suitable system boundaries, and involvement of stakeholders. Most of the interviewees mentioned improved collaboration, integrated innovative technology, political support, and climate change mitigation goals as important facilitators. The interviewees highlighted the importance of a local perspective and considered each city’s preconditions when developing a PED project. The study emphasizes that to facilitate PED implementation and replication in cities, more knowledge and clarity is required about PED such as on the definition and system boundaries. © 2023 by the authors.
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| 10. |
- Mattsson, Moa, et al.
(författare)
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Challenges and drivers for Positive Energy Districts in a Swedish context
- 2022
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Ingår i: Eceee 2022 Summer Study on energy efficiency. - Stockholm : European Council for an Energy Efficient Economy (ECEEE). ; , s. 633-639
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Konferensbidrag (refereegranskat)abstract
- A Positive Energy District (PED) is an inclusive, energy efficient district with optimized energy flows and a local production of renewable energy, with an annual surplus of energy that can be exported to other areas. Most of the municipalities in Sweden have ambitious climate neutrality goals and implementing PEDs in cities could be one way to contribute to the achievement of those climate goals. However, PED is an innovative concept which is still ambiguous for many stakeholders, and many uncertainties remain. To understand the perspectives of Swedish stakeholders towards PEDs, a three hour long online workshop was organized in December 2020. Representatives from city officials, universities, energy utilities and real estate companies participated in the discussion groups. The groups discussed three topics related to PED, namely; 1) Definition of PED, 2) Challenges and drivers for PEDs and 3) Replication of PEDs.Most of the discussion groups agreed to the importance of viewing PEDs as a part of the larger energy system and to find holistic solutions and promoting collaboration between actors. Most groups considered leadership and stakeholder engagement as important drivers for PEDs. Further, participants discussed that the slow decision processes in municipalities could be a challenge for PEDs. Even though there was consensus on most challenges and drivers, one aspect where participants had conflicting opinions was the PED definition. Some groups thought that the PED definition needs to be clearer and more narrow, while others saw it as a potential barrier if it becomes too technology focused. During discussions on replication, most groups stressed the importance of knowledge sharing and the results highlight that different stakeholders can play different roles in facilitating replication for PEDs. The study highlights the importance of a regional perspective when developing the PED definition, since the Swedish stakeholders had different viewpoints on PED that could be used to adapt the definition.
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| 11. |
- Mattsson, Moa, et al.
(författare)
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Exploring the health and energy savings dilemma in swimming facilities and the potential influence of Positive Energy Districts
- 2023
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 2654:1
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Tidskriftsartikel (refereegranskat)abstract
- Positive energy districts (PED) are neighborhoods with a net positive energy balance with the main goal to create sustainable districts that contribute to the energy transition. The three pillars energy efficiency, renewable energy, and energy flexibility forms the foundation of PEDs, and ‘Quality of life’ is one of the key principles.Indoor swimming facilities for recreation and sports, also called aquatic centers or swimming halls, are important for healthy lifestyles. They are highly energy-demanding facilities due to the large volumes and strict heating- and ventilation requirements to ensure the health of staff, visitors, and bathers. The large energy consumption indicates good potential to reduce their energy use. One possibility might be to include aquatic centersin PEDs: the district could support the facility with locally produced renewable energy. There are also studies that investigates innovative solutions regarding aquatic centers that might have potential to increase resilience and flexibility in the district.However, one important aspect in studies on energy use in aquatic centers that is often neglected is the presence of disinfection by-products (DBP), which are found in the air and water of chlorinated swimming pools. Several DBPs can lead to health issues, such as asthma, eye irritation, and even cancer. There are often conflicting goals in studies on swimming halls. The connection between DBP and energy is currently missing, and it could lead to projects compromising health over energy savings. Based on a literature review, this study highlights the research gap between DBPs and energy use in swimming facilities. A suggestion is also presented to integrate swimming halls into PEDs with the aim of increasing possibilities for a healthy lifestyle, supporting the aquatic center’s energy demand with renewable energy, and exploring new solutions for flexibility and resilience in the district
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| 12. |
- Nair, Gireesh, et al.
(författare)
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A multi-stakeholder perspective on opportunities and challenges for energy efficiency improvement in university buildings
- 2021
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Ingår i: E3S Web of Conferences. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- University buildings are relatively energy-intensive. In Sweden, universities usually operate in rented buildings. In this study, interviews were carried out among three categories of stakeholders in a Swedish university to understand their perceptions of energy use and challenges to improve energy efficiency. As per most interviewees, the university's top management and Akademiska Hus, which owns the buildings, have the main responsibility to reduce the buildings' energy and carbon footprint. The heads of departments raised the concern on the non-availability of energy data to take actions to reduce energy use. The use of sensors and information technologies to monitor space use, energy use, and indoor environment are attractive to different stakeholders. The implications of the interview results are discussed.
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| 13. |
- Nair, Gireesh, et al.
(författare)
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A review on technical challenges and possibilities on energy efficient retrofit measures in heritage buildings
- 2022
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 15:20
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Forskningsöversikt (refereegranskat)abstract
- For heritage buildings, energy-efficient retrofitting cannot be applied with the same range of possibilities as with existing buildings. Applying such improvements to heritage buildings can be challenging due to their historic and/or cultural significance and non-standard construction methods. This paper reviews the technical challenges and potential of applying energy efficient retrofit elements in heritage buildings. The retrofitting measures reviewed are draught-proofing, windows, insulation, ventilation, heating, solar photovoltaics and phase change materials. It is possible to significantly reduce energy use in heritage buildings with such retrofits. However, there is no universal way to apply energy-efficient retrofitting in heritage buildings, which is apparent in the literature, where case studies are prevalent.
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| 14. |
- Nair, Gireesh, et al.
(författare)
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Energy production, efficiency and flexibility for positive energy districts : a review
- 2024
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Ingår i: ISEC 2024 – 3rd International Sustainable Energy Conference. - : TIB Open Publishing.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In 2018, EU launched the programme “Positive energy districts and neighbourhoods for sustainable urban development” with an aim to support the planning, deployment and replication of 100 Positive energy districts (PEDs) by 2025. This is an ambitious target considering the various challenges on implementing PEDs. This paper, based on literature review, provides an overview on the challenges and possibilities on the three main components of PEDs; energy production, energy efficiency and energy flexibility.
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| 15. |
- Nair, Gireesh, et al.
(författare)
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Perspectives of building professionals on the use of LCA tools in Swedish climate declaration
- 2021
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Ingår i: E3S Web of Conferences. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- From 1st January 2022, Swedish government plan to introduce the climate declarations as a legal requirement for new buildings. LCA is a method that could be used to quantify buildings' climate impact. The climate declaration in the Swedish building code expects to create interest in LCA among stakeholders. This study aims to identify and understand the challenges and opportunities of using LCA by stakeholders during the early stage of construction process. The study is based on responses from six building professionals to a questionnaire. The policy implications of the study findings are discussed.
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| 16. |
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| 17. |
- Ohlsson, K.E. Anders, et al.
(författare)
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Uncertainty in model prediction of energy savings in building retrofits : Case of thermal transmittance of windows
- 2022
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 168
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Tidskriftsartikel (refereegranskat)abstract
- Energy saving in buildings is an important measure for mitigation of climate change. There exists a large potential for energy saving in buildings by improving the thermal performance of windows. For decisions on energy saving window retrofits, accurate estimation of the energy saved and its uncertainty is of importance. The ISO 15099 standard, which is normative for thermal modelling of windows within the building sector, does not give uncertainty estimates. The main novelty of this study was to provide uncertainty analysis for model prediction of the thermal transmittance of windows, in the perspective of decisions on window retrofits. For this purpose, we proposed a new simplified model, which facilitated uncertainty analysis, and still was similar to the ISO 15099 window model. The model was validated by application of a benchmark validation procedure to a set of previously performed validation experiments. Main conclusions were: (i) The model was accurate within a prediction uncertainty equal to 0.20 Wm−2K−1; (ii) The domain where the model is valid was described using existing well-documented validation experiments. This domain was restricted to windows with glazing thermal transmittance corresponding to 2-layer glazing, and to windows where the frame area is a minor part of the total window area. (iii) The prediction uncertainty was mainly determined by the measurement uncertainty in the validation experiments; (iv) If a window retrofit is based on reduction of window thermal transmittance, then this reduction has to be larger than 0.56 Wm−2K−1 in order to yield energy savings above the uncertainty limit.
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| 18. |
- Olofsson, Thomas, 1968-, et al.
(författare)
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State of knowledge in Sweden during the Corona pandemic
- 2020
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Ingår i: REHVA Journal. - 1307-3729. ; :5, s. 69-71
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- During the ongoing Corona pandemic, a survey of Swedish authorities, industry associations, and consultancy and real estate companies summarize the need to increase competence on HVAC and indoor environment. The knowledge improvement span the entire area: from the choice of technical components to the design, operation and maintenance. A topic emphasized is the requirement of an interdisciplinary perspective related to establishing knowledge.
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| 19. |
- Olofsson, Thomas, 1968-, et al.
(författare)
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Så påverkar pandemin inomhusmiljön
- 2020
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Ingår i: Energi & miljö. - : EMTF Förlag. - 1101-0568. ; :10, s. 50-51
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Forskningsöversikt (populärvet., debatt m.m.)
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| 20. |
- Wikman, Tobias, et al.
(författare)
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A literature review on life cycle analysis of buildings
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Life cycle analysis (LCA) can be utilized to evaluate environmental impacts from the construction sector. In Sweden, from January 2022, climate declarations are mandatory when constructing new buildings. This report provides a literature review on various aspects related to LCA inbuilding, with focus on challenges and possibilities. Major challenges with LCA conductance are that buildings have long life-spans which introduce uncertainties in the LCA calculations since parameters may change over time. Choice of calculation tool, system boundaries for the LCA analysis and deviations between databases are further challenges that affect LCA results. Problems with data quality are another issue since usage of generic data may lower the accuracy of LCA studies on local level. Transparency of calculation tools, LCA methods, approximations and complexity of analysis are further challenges. Furthermore, when different LCA methods and calculation tools have been used, comparability between LCA studies can be compromised. To counteract the challenges voices have been raised to create national and even global databases to homogenize the data. Thorough and transparent communication of scope, method and system boundaries in LCA studies can counteract the problem with low transparency, deviating results and comparability issues. Using local data instead of generic data can increase data quality and therefore the quality and accuracy of the results.
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| 21. |
- Zhang, Ying, et al.
(författare)
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Cold windows induced airflow effects on the thermal environment for a large single-zone building
- 2020
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Ingår i: 12<sup>th</sup> Nordic Symposium on Building Physics (NSB 2020). - : Les Ulis EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- With access to modern building technologies and HVAC-systems, it is possible to obtain low energy use and good thermal comfort for complex design, such as large building volumes. However, the situation is different for large single zone buildings with large volumes. They often have insufficient thermal comfort. The problem could be partially attributed to the unwanted airflows due to the cold surfaces, especially the windows. With increased knowledge of the airflow, it is possible to identify suitable renovation strategies in such buildings.In this work, we study a church building with mechanical air change system and floor heating. CFD-simulations with dynamic airflow was conducted based on building geometries and technical data. The validation was based on data from the ventilation control and the space-heating system.The results show how the window-to-wall ratios and the positions of windows affect the thermal comfort. It contributes with knowledge of advantages and disadvantages of different envelope design in the existing environment with floor heating
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| 22. |
- Zhang, Ying, et al.
(författare)
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Field measurements and numerical analysis on operating modes of a radiant floor heating aided by a warm air system in a large single-zone church
- 2022
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 255
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Tidskriftsartikel (refereegranskat)abstract
- Space heating can constitute 60–80% of the total energy use of buildings in cold climates. Efficient heating techniques in buildings still rely on operating strategies. In this paper, a church with radiant floor heating in a cold climate is taken as a case of a large single-zone building to analyze the energy use for heating. Field measurements and numerical analysis are both used in the study. Different operating modes of heating, including intermittent heating and constant set-point heating, are compared for energy saving, reliability on indoor climate, and thermal comfort. The intermittent heating by an all-air system with supplied air temperature control results in the highest energy use. The constant set-point air temperature radiant floor heating aided by a warm air system (return air temperature control) is least affected by outdoor temperature with the best reliability and met the thermal comfort requirements throughout the heating season. The main novelty is that an operating mode of cyclic set-point air temperature is proposed. It is found that the small thermal inertia of heating systems should be preferred when the operating mode of cyclic set-point temperature is used to reduce the warm-up period. The results suggest how to operate and reduce the energy use of radiant floor heating systems in a large single-zone building.
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| 23. |
- Zhou, Hongxia, et al.
(författare)
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Experimental study of micro-encapsulated phase change materials’ influence on indoor temperature
- 2023
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics (IOP). - 1742-6588 .- 1742-6596. ; 2654:1
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Tidskriftsartikel (refereegranskat)abstract
- The energy use of buildings is almost one-third of the global final energy use. Phase change Materials (PCMs) are substances that undergo phase transition when the surrounding temperature reaches their phase transition temperature. PCMs are reported to be a good candidate as a thermal storage buffer in building systems. Accordingly, PCMs may be able to regulate the indoor temperature while using less energy and thereby contributing in improving the energy performance of the building. In this project a trail to analyse the effect of PCMs in indoor temperature was carried out, in an experimental set-up, using a climate chamber. The chamber temperature is regulated as a sinusoidal profile with a cycle of 24 hours, with a maximum of 40 °C and a minimum of -10 °C. A cubic-box, is placed at the centre of the chamber, and is used as a representation of “building”. A board was made by encapsulating PCMs, with a melting temperature of 24 °C, to gypsum with a fraction of 20 wt%. The influence of PCM added gypsum board on inside temperature of the box is studied. Temperatures at different locations have been measured by thermocouples. The results indicated that the presence of PCM resulted in less temperature variation inside the box with the temperature holding close to the PCM transition temperature for a long period. Also, the PCM boards shifted the temperature profile. Further results are expected to determine the location of the PCM board that is most suitable to reduce the temperature variation inside the building.
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| 24. |
- Zhou, Hongxia, et al.
(författare)
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Thermal behaviour of a gypsum board incorporated with phase change materials
- 2024
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 94
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the influence of a microencapsulated Phase Change Material (mPCM) on building systems in a subarctic climate which is not commonly studied for PCM applications. The mPCM is incorporated into gypsum to make a composite board with a volume fraction of 30 vt%. The fabricated composite board is then used to make a box model. This model along with a reference model built only with gypsum boards are placed inside a climate chamber where temperature is regulated to a summer day of a subarctic country, where large temperature variation exists between day and night. In addition, a Finite Element Method (FEM), is also used for the validation of the experimental data. The thermal-physical properties of the mPCM gypsum board including the specific heat capacity and thermal conductivity are measured. The microscopic features of the composite board are also studied. In addition, the temperature variation and the thermal energy storage of the boards of the two models have been studied. Results indicate that incorporation of mPCM into gypsum will change the thermal properties of the material. PCM can work as an additional insulation layer due to its low thermal conductivity. Further, the temperature fluctuation inside of the model with mPCM is reduced. In addition, the energy stored in the mPCM composite is around 3 times higher than that of gypsum board, making it promising for building energy improvement and load shifting.
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