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Nair, Gireesh
Publications (10 of 67) Show all publications
Fogelström, F., Danielski, I., Truong, N. L. & Nair, G. (2024). A review of possibilities and challenges of pit thermal energy storages in Swedish district heating networks. In: ISEC 2024: 3rd International Sustainable Energy Conference. Paper presented at ISEC 2024 – 3rd International Sustainable Energy Conference, Graz, Austria, April 10-11, 2024. AEE – Institute for Sustainable Technologies
Open this publication in new window or tab >>A review of possibilities and challenges of pit thermal energy storages in Swedish district heating networks
2024 (English)In: ISEC 2024: 3rd International Sustainable Energy Conference, AEE – Institute for Sustainable Technologies , 2024Conference paper, Published paper (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
AEE – Institute for Sustainable Technologies, 2024
Series
ISEC - Proceedings, E-ISSN 2976-2030
Keywords
Pit Thermal Energy Storage, District Heating Network, Solar District Heating, Benefits, Challenges
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-223875 (URN)10.52825/isec.v1i.1221 (DOI)
Conference
ISEC 2024 – 3rd International Sustainable Energy Conference, Graz, Austria, April 10-11, 2024
Available from: 2024-04-30 Created: 2024-04-30 Last updated: 2024-05-02Bibliographically approved
Nair, G., Mattsson, M., Delice, E. & Dino, I. G. (2024). Energy production, efficiency and flexibility for positive energy districts: a review. In: ISEC 2024 – 3rd International Sustainable Energy Conference: . Paper presented at ISEC 2024 – 3rd International Sustainable Energy Conference, Graz, Austraia, April 10-11, 2024. TIB Open Publishing
Open this publication in new window or tab >>Energy production, efficiency and flexibility for positive energy districts: a review
2024 (English)In: ISEC 2024 – 3rd International Sustainable Energy Conference, TIB Open Publishing , 2024Conference paper, Published paper (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
TIB Open Publishing, 2024
Series
International Sustainable Energy Conference - Proceedings, E-ISSN 2976-2030 ; 2024:1
Keywords
Climate Goals, Energy Transition, Cities
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-223473 (URN)10.52825/isec.v1i.1208 (DOI)
Conference
ISEC 2024 – 3rd International Sustainable Energy Conference, Graz, Austraia, April 10-11, 2024
Available from: 2024-04-17 Created: 2024-04-17 Last updated: 2024-05-06Bibliographically approved
Wikman, T., Olofsson, T. & Nair, G. (2023). A literature review on life cycle analysis of buildings.
Open this publication in new window or tab >>A literature review on life cycle analysis of buildings
2023 (English)Report (Other academic)
Abstract [en]

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.  

Publisher
p. 27
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-205898 (URN)
Note

This report is prepared as part of the Interreg Nord project "Enhanced Sustainability of Built Environment by Collaboration and Digitalization" (ESBE).

Available from: 2023-03-22 Created: 2023-03-22 Last updated: 2023-03-23Bibliographically approved
Mattsson, M., Olofsson, T., Lundberg, L., Korda, O. & Nair, G. (2023). An exploratory study on swedish stakeholders’ experiences with positive energy districts. Energies, 16(12), Article ID 4790.
Open this publication in new window or tab >>An exploratory study on swedish stakeholders’ experiences with positive energy districts
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2023 (English)In: Energies, E-ISSN 1996-1073, Vol. 16, no 12, article id 4790Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
positive energy district, energy transition, sustainable urban development, stakeholder perspective, replication
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-210541 (URN)10.3390/en16124790 (DOI)001014316100001 ()2-s2.0-85163812620 (Scopus ID)
Projects
RESILIENTa Energisystem Kompetenscentrum
Funder
Swedish Energy Agency, 52686-1
Available from: 2023-06-22 Created: 2023-06-22 Last updated: 2023-08-28Bibliographically approved
Zhou, H., Puttige, A. R., Nair, G. & Olofsson, T. (2023). Experimental study of micro-encapsulated phase change materials’ influence on indoor temperature. Paper presented at NSB 2023, 13th Nordic Symposium on building physics, Aalborg, Denmark, June 12-14, 2023. Journal of Physics, Conference Series, 2654(1), Article ID 012064.
Open this publication in new window or tab >>Experimental study of micro-encapsulated phase change materials’ influence on indoor temperature
2023 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 2654, no 1, article id 012064Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2023
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-212575 (URN)10.1088/1742-6596/2654/1/012064 (DOI)2-s2.0-85181174452 (Scopus ID)
Conference
NSB 2023, 13th Nordic Symposium on building physics, Aalborg, Denmark, June 12-14, 2023
Funder
Swedish Energy Agency, P2021-00248
Available from: 2023-08-06 Created: 2023-08-06 Last updated: 2024-01-29Bibliographically approved
Mattsson, M., Olofsson, T. & Nair, G. (2023). Exploring the health and energy savings dilemma in swimming facilities and the potential influence of Positive Energy Districts. Paper presented at 13th Nordic Symposium on Building Physics, NSB 2023, Aalborg, Denmark, June 12-14, 2023. Journal of Physics, Conference Series, 2654(1), Article ID 012132.
Open this publication in new window or tab >>Exploring the health and energy savings dilemma in swimming facilities and the potential influence of Positive Energy Districts
2023 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 2654, no 1, article id 012132Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2023
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-210371 (URN)10.1088/1742-6596/2654/1/012132 (DOI)2-s2.0-85181174332 (Scopus ID)
Conference
13th Nordic Symposium on Building Physics, NSB 2023, Aalborg, Denmark, June 12-14, 2023
Projects
RESILIENT Energisystem Kompetenscentrum
Funder
Swedish Energy Agency
Available from: 2023-06-21 Created: 2023-06-21 Last updated: 2024-01-25Bibliographically approved
Nair, G., Verde, L. & Olofsson, T. (2022). A review on technical challenges and possibilities on energy efficient retrofit measures in heritage buildings. Energies, 15(20), Article ID 7472.
Open this publication in new window or tab >>A review on technical challenges and possibilities on energy efficient retrofit measures in heritage buildings
2022 (English)In: Energies, E-ISSN 1996-1073, Vol. 15, no 20, article id 7472Article, review/survey (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
energy efficiency, barriers, historic buildings, decision, adoption, implementation
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-200223 (URN)10.3390/en15207472 (DOI)000872494500001 ()2-s2.0-85140797822 (Scopus ID)
Available from: 2022-10-12 Created: 2022-10-12 Last updated: 2023-08-28Bibliographically approved
Mattsson, M., Lundberg, L., Olofsson, T., Kordas, O. & Nair, G. (2022). Challenges and drivers for Positive Energy Districts in a Swedish context. In: Eceee 2022 Summer Study on energy efficiency: agents of change. Paper presented at Eceee 2022 summer Study on energy efficiency: agents of change, Hyères, France, June 6-11, 2022. (pp. 633-639). Stockholm: European Council for an Energy Efficient Economy (ECEEE)
Open this publication in new window or tab >>Challenges and drivers for Positive Energy Districts in a Swedish context
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2022 (English)In: Eceee 2022 Summer Study on energy efficiency: agents of change, Stockholm: European Council for an Energy Efficient Economy (ECEEE), 2022, p. 633-639Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: European Council for an Energy Efficient Economy (ECEEE), 2022
Series
Eceee Summer Study proceedings, ISSN 2001-7960
Keywords
positive energy district, transition, energy, workshop, challenges, drivers
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-198544 (URN)2-s2.0-85163818234 (Scopus ID)
Conference
Eceee 2022 summer Study on energy efficiency: agents of change, Hyères, France, June 6-11, 2022.
Note

ISBN: 978-91-983878-9-3 (online).

Available from: 2022-08-09 Created: 2022-08-09 Last updated: 2023-12-18Bibliographically approved
Zhang, Y., Zhao, C., Olofsson, T., Nair, G., Yang, B. & Li, A. (2022). 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. Energy and Buildings, 255, Article ID 111646.
Open this publication in new window or tab >>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
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2022 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 255, article id 111646Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Space heating, Protected building, Energy use, Simulations, Thermal comfort
National Category
Energy Systems
Identifiers
urn:nbn:se:umu:diva-190679 (URN)10.1016/j.enbuild.2021.111646 (DOI)2-s2.0-85120915380 (Scopus ID)
Projects
Energy Pathfinder
Available from: 2021-12-21 Created: 2021-12-21 Last updated: 2023-01-09Bibliographically approved
Zhang, Y., Zhao, C., Olofsson, T., Nair, G., Yang, B. & Li, A. (2022). 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. Energy and Buildings, 255, Article ID 111646.
Open this publication in new window or tab >>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
Show others...
2022 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 255, article id 111646Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Energy use, Protected building, Simulations, Space heating, Thermal comfort
National Category
Energy Systems Building Technologies
Identifiers
urn:nbn:se:umu:diva-190572 (URN)10.1016/j.enbuild.2021.111646 (DOI)000753988800002 ()2-s2.0-85120915380 (Scopus ID)
Available from: 2021-12-20 Created: 2021-12-20 Last updated: 2023-09-05Bibliographically approved
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