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Assessment and optimization of life cycle enrgy use in buildings
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.ORCID iD: 0000-0003-0907-1270
2018 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Utvärdering och optimering avlivscykelenergianvändning i byggnader (Swedish)
Abstract [en]

Buildings account for 40% of all energy use in European countries. The European Union (EU) therefore encourages member states to adopt Energy Efficiency Measures (EEMs) and implement energy-efficient practices during building design to minimize the energy use of buildings. However, recent studies have shown that energy-efficient buildings may not always outperform conventional buildings in terms of Life Cycle Energy (LCE) use. This is mainly due to the trade-off between embodied and operational energy, and a reliance on EEMs that reduce operational energy while sometimes increasing embodied energy and LCE use. To improve buildings’ environmental performance, the impact of different EEMs on buildings’ energy use needs to be assessed from a lifecycle perspective, and methods for identifying optimal combinations of EEMs that minimize LCE use should be developed. Ideally, these methods should be integrated with building information modelling (BIM) to enable seamless data exchange and to help Architecture, Engineering and Construction (AEC) practitioners make optimal design decisions relating to EEMs. The work presented in this thesis had two overall objectives: (1) to explore the scope for developing BIM-supported method(s) for assessing and optimizing the impact of EEMs on buildings’ LCE use during the design process, and (2) use the BIM-supported method(s) for exploring the impact of various EEMs that are implemented and modified during the building design process on the buildings’ LCE use.

The work presented in this thesis is based on an exploratory research design involving iterative cycles of (1) problem identification, (2) method development, (3) method examination, and (4) theory suggestion. In step 1, problems were identified by conducting literature studies and workshops with AEC practitioners, and analyzing archival data. In step 2, prototyping was used to develop methods to overcome the identified problems. In step 3, the applicability of these methods (or prototypes) was tested in case studies on actual and hypothetical building projects. Three case studies were conducted – one dealing with a low energy dwelling located in Kiruna, Sweden; another dealing with a multifamily residential building in Uppsala, Sweden; and a third dealing with a hypothetical multifamily residential building in Stockholm, Sweden. In step 4, the results were compared to existing theories to strengthen existing knowledge and identify previously unrecognized findings.

In relation to the first objective, the results obtained show that the factors and activities required to develop BIM-supported method(s) for assessing and optimizing the impact of EEMs on a building’s LCE use during the design phase are:

• A database that stores external and building project data (e.g. BIM data) and links it to be used for assessment and optimization, providing access to the data whenever needed.

• The development of interfaces using middleware applications to ensure interoperability and seamless automated exchange of information between BIM and other systems.

• Predefined objects (i.e. building part and component recipes) that are stored in a database and linked to inventories and Environmental Product Declarations (EPDs) for the relevant materials, enabling assessment of the buildings’ embodied energy and LCE use.

• The application of multi-objective optimization techniques (e.g. Pareto-based genetic algorithms) to identify optimal solution(s) for EEMs that minimize (optimize) the building’s LCE use.

In relation to the second objective of the thesis, the results obtained indicate that:

• EEMs that are implemented and modified during the detailed design phase have much less influence on the building’s LCE use than those implemented in the early design phase. Highly influential EEMs related to the early design phase which were tested herein were the building’s shape, orientation, Window to Wall Ratio (WWR), and the selection of materials used in the building envelope.

• Generally, thickening roof insulation has a strong beneficial effect on LCE use for buildings in Sweden.

• For buildings using energy sources with high primary energy factors, the most effective way to reduce LCE use may be to implement many EEMs that reduce operational energy use. However, this approach may be less helpful for buildings using greener energy sources because in such cases the embodied energy may have a greater effect on the final LCE use.

• The embodied energies of materials in the same class can vary significantly between suppliers. Such differences in embodied energy can be identified by considering the suppliers’ EPDs, the energetic contributions due to their mode of transportation from the site of production, and the distance between the site of production and the construction site.

• If the developed optimization approach is used to identify optimal combinations of EEMs in the early design phase, designers can freely choose from a wide range of building shapes without greatly affecting LCE use. However, without early phase optimization, designs that use different building shapes may exhibit significantly different LCE use values.

The results provide both theoretical and practical contributions that may be useful to researchers and AEC practitioners seeking to develop BIM-supported design processes and to reduce buildings’ LCE use by adopting appropriate EEMs. The results also show that embodied energy can be a major component of a building’s LCE use if the building’s design relies heavily on EEMs designed solely to reduce operational energy use. Policy makers and governmental bodies are thus advised to update regulations and building codes to reflect the importance of embodied energy so as to minimize the LCE use of new and retrofitting building projects.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2018.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Building Technologies Environmental Analysis and Construction Information Technology Architectural Engineering Construction Management
Research subject
Construction Management and Building Technology
Identifiers
URN: urn:nbn:se:ltu:diva-71315ISBN: 978-91-7790-244-7 (print)ISBN: 978-91-7790-245-4 (electronic)OAI: oai:DiVA.org:ltu-71315DiVA, id: diva2:1258092
Public defence
2018-12-20, E632, Luleå, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2018-10-25 Created: 2018-10-23 Last updated: 2019-01-03Bibliographically approved
List of papers
1. An integrated BIM-based framework for minimizing embodied energy during building design
Open this publication in new window or tab >>An integrated BIM-based framework for minimizing embodied energy during building design
Show others...
2016 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 128, p. 592-604Article in journal (Refereed) Published
Abstract [en]

Assessment of the embodied energy associated with the production and transportation of materials during the design phase of building provides great potential to profoundly affect the building’s energy use and sustainability performance. While Building Information Modeling (BIM) gives opportunities to incorporate sustainability performance indicators in the building design process, it lacks interoperability with the conventional Life Cycle Assessment (LCA) tools used to analyse the environmental footprints of materials in building design. Additionally, many LCA tools use databases based on industry-average values and thus cannot account for differences in the embodied impacts of specific materials from individual suppliers. To address these issues, this paper presents a framework that supports design decisions and enables assessment of the embodied energy associated with building materials supply chain based on suppliers’ Environmental Product Declarations (EPDs). The framework also integrates Extract Transform Load (ETL) technology into the BIM to ensure BIM-LCA interoperability, enabling an automated or semi-automated assessment process. The applicability of the framework is tested by developing a prototype and using it in a case study, which shows that a building’s energy use and carbon footprint can be significantly reduced during the design phase by accounting the impact of individual material in the supply chain.

National Category
Construction Management
Research subject
Construction Engineering and Management
Identifiers
urn:nbn:se:ltu:diva-14918 (URN)10.1016/j.enbuild.2016.07.007 (DOI)000382794200050 ()2-s2.0-84978842557 (Scopus ID)e5af1053-d40e-4e8e-aef4-ceecf553ce53 (Local ID)e5af1053-d40e-4e8e-aef4-ceecf553ce53 (Archive number)e5af1053-d40e-4e8e-aef4-ceecf553ce53 (OAI)
Note

Validerad; 2016; Nivå 2; 20160815 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-10-23Bibliographically approved
2. An Integrated BIM-based framework for the optimization of the trade-off between embodied and operational energy
Open this publication in new window or tab >>An Integrated BIM-based framework for the optimization of the trade-off between embodied and operational energy
2018 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 158, p. 1189-1205Article in journal (Refereed) Published
Abstract [en]

Design choices with a unilateral focus on the reduction of operational energy for developing energy-efficient and near-zero energy building practices can increase the impact of the embodied energy, as there is a trade-off between embodied and operational energy. Multi-objective optimization approaches enable exploration of the trade-off problems to find sustainable design strategies, but there has been limited research in applying it to find optimal design solution(s) considering the embodied versus operational energy trade-off. Additionally, integration of this approach into a Building Information Modeling (BIM) for facilitating set up of the building model toward optimization and utilizing the benefits of BIM for sharing information in an interoperable and reusable manner, has been mostly overlooked. To address these issues, this paper presents a framework that supports the making of appropriate design decisions by solving the trade-off problem between embodied and operational energy through the integration of a multi-objective optimization approach with a BIM-driven design process. The applicability of the framework was tested by developing a prototype and using it in a case study of a low energy dwelling in Sweden, which showed the potential for reducing the building’s Life Cycle Energy (LCE) use by accounting for the embodied versus operational energy trade-off to find optimal design solution(s). In general, the results of the case study demonstrated that in a low energy dwelling, depending on the site location, small reductions in operational energy (i.e. 140 GJ) could result in larger increases in embodied energy (i.e. 340 GJ) and the optimization process could yield up to 108 GJ of LCE savings relative to the initial design. This energy saving was equivalent to up to 8 years of the initial design’s operational energy use for the dwelling, excluding household electricity use.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Construction Management
Research subject
Construction Engineering and Management
Identifiers
urn:nbn:se:ltu:diva-66697 (URN)10.1016/j.enbuild.2017.11.017 (DOI)000428010300020 ()2-s2.0-85034624206 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-12-05 (andbra)

Available from: 2017-11-22 Created: 2017-11-22 Last updated: 2018-10-23Bibliographically approved

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Shadram, Farshid

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