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Optimal Design of District Energy Systems: a Multi-Objective Approach
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Service and Energy Systems.
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this thesis is to develop a holistic approach to the optimal design of energy systems for building clusters or districts. The emerging Albano university campus, which is planned to be a vivid example of sustainable urban development, is used as a case study through collaboration with the property owners, Akademiska Hus and Svenska Bostäder. The design addresses aspects of energy performance, environmental performance, economic performance, and exergy performance of the energy system. A multi-objective optimization approach is applied to minimize objectives such as non-renewable primary energy consumptions, the greenhouse gas emissions, the life cycle cost, and the net exergy deficit. These objectives reflect both practical requirements and research interest. The optimization results are presented in the form of Pareto fronts, through which decision-makers can understand the options and limitations more clearly and ultimately make better and more informed decisions. Sensitivity analyses show that solutions could be sensitive to certain system parameters. To overcome this, a robust design optimization method is also developed and employed to find robust optimal solutions, which are less sensitive to the variation of system parameters. The influence of different preferences for objectives on the selection of optimal solutions is examined. Energy components of the selected solutions under different preference scenarios are analyzed, which illustrates the advantages and disadvantages of certain energy conversion technologies in the pursuit of various objectives. As optimal solutions depend on the system parameters, a parametric analysis is also conducted to investigate how the composition of optimal solutions varies to the changes of certain parameters. In virtue of the Rational Exergy Management Model (REMM), the planned buildings on the Albano campus are further compared to the existing buildings on KTH campus, based on energy and exergy analysis. Four proposed alternative energy supply scenarios as well as the present case are analyzed. REMM shows that the proposed scenarios have better levels of match between supply and demand of exergy and result in lower avoidable CO2 emissions, which promise cleaner energy structures.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , 43 p.
Series
TRITA-IES, 2016:05
Keyword [en]
multi-objective optimization, robust design optimization, district energy
National Category
Architecture
Research subject
Civil and Architectural Engineering
Identifiers
URN: urn:nbn:se:kth:diva-192948ISBN: 978-91-7729-129-9 (print)OAI: oai:DiVA.org:kth-192948DiVA: diva2:974027
Presentation
2016-10-14, Sal M108, Brinellvägen 23, Kungl Tekniska högskolan, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20160923

Available from: 2016-09-23 Created: 2016-09-23 Last updated: 2016-09-23Bibliographically approved
List of papers
1. Multi-objective optimization of energy system designs for the Albano university campus in Stockholm
Open this publication in new window or tab >>Multi-objective optimization of energy system designs for the Albano university campus in Stockholm
2016 (English)Conference paper, Published paper (Other academic)
Abstract [en]

In this paper, a multi-objective optimization approach based on genetic algorithm is applied to the energy system design of a sustainable district – the new Albano university campus in Stockholm. The study aims to help district planners find optimal energy solutions that have good energy, environmental and economic performances. Three objectives are minimized: the non-renewable primary energy consumption, the greenhouse gas emissions, and the levelized life cycle cost. A wide range of energy conversion technologies and energy sources including both renewables and non-renewables have been modeled. The potential to recover waste heat from greywater and a prospective IT/Data center is analyzed. The energy system is modelled in steady-state and simulated in an hourly resolution with renewable energy production determined at real time. The optimization results are presented in the form of Pareto fronts, which helps district planners understand more clearly the trade-off between conflicting objectives and make more informed decisions.

Keyword
multi-objective optimization, district energy system, nearly zero energy
National Category
Architecture
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-192949 (URN)
Conference
iiSBE Forum of Young Researchers in Sustainable Building 2016, June 21
Note

QC 20160923

Available from: 2016-09-23 Created: 2016-09-23 Last updated: 2016-09-26Bibliographically approved
2. Multi-objective robust optimization of energy systems for a sustainable district in Stockholm
Open this publication in new window or tab >>Multi-objective robust optimization of energy systems for a sustainable district in Stockholm
2015 (English)In: Proceedings of BS2015: 14th Conference of International Building Performance Simulation Association, Hyderabad, India, Dec. 7-9, 2015., 2015Conference paper, Published paper (Other academic)
Abstract [en]

This paper applies a multi-objective robust design optimization approach to the energy system design of a sustainable district. The life cycle cost and the greenhouse gas emissions are the two objectives that are minimized. In order to investigate the possbility to implement a nearly zero energy district, the nonrenewable primary energy consumption is kept below a certain value, handled as a constraint in the optimization. Through the proposed robust design optimization methodology, the robust Pareto optimal solutions are obtained, which are less sensitive than the deterministic ones to the uncertainties assumed in the selected most influential economic and technical paramers as well as design variables.

Keyword
Design, Energy utilization, Gas emissions, Greenhouse gases, Life cycle, Optimization, Pareto principle, Design variables, Energy system design, Lifecycle costs, Multi objective, Pareto optimal solutions, Primary energy consumption, Robust design optimization, Robust optimization, Multiobjective optimization
National Category
Architecture
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-192951 (URN)2-s2.0-84976345007 (Scopus ID)
Conference
14th Conference of International Building Performance Simulation Association, BS 2015, 7 December 2015 through 9 December 2015
Note

QC 20160923

Available from: 2016-09-23 Created: 2016-09-23 Last updated: 2017-03-30Bibliographically approved
3. Multi-objective optimization and parametric analysis of energy system designs for the Albano university campus in Stockholm
Open this publication in new window or tab >>Multi-objective optimization and parametric analysis of energy system designs for the Albano university campus in Stockholm
Show others...
2017 (English)In: Procedia Engineering, Elsevier, 2017, 621-630 p.Conference paper, Published paper (Other academic)
Abstract [en]

In this study, a multi-objective optimization approach is applied to the energy system design of the Albano university campus in Stockholm. The greenhouse gas emissions, the life cycle cost and the net exergy deficit of the campus are minimized, while the nearly zero energy requirements are respected. Four optimal solutions are identified based on those under equal importance, environment-oriented, economy-oriented, and exergy-oriented scenarios. The energy components of the four scenarios are analyzed and compared. A parametric analysis is conducted to investigate the impact of the variations in a number of economic, environmental and technical parameters on the composition of the optimal solution.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Procedia Engineering, ISSN 1877-7058
National Category
Architecture
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-192952 (URN)10.1016/j.proeng.2017.04.221 (DOI)000404873600063 ()2-s2.0-85019337204 (Scopus ID)
Conference
International High- Performance Built Environment Conference – A Sustainable Built Environment Conference 2016 Series (SBE16), iHBE 2016
Note

QC 20160923

Available from: 2016-09-23 Created: 2016-09-23 Last updated: 2017-08-09Bibliographically approved
4. Cleaner energy supply structures for campus building clusters
Open this publication in new window or tab >>Cleaner energy supply structures for campus building clusters
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The comparison of building clusters based on energy and the quality of energy (exergy) is a

key aspect for determining steps towards cleaner energy supply structures. This paper

compares two building clusters based on an integrated approach that involves building and

energy system level analyses. The first cluster involves 8 buildings with diverse energy profiles

at the KTH Royal Institute of Technology campus, including faculty buildings, laboratories, and

a data center with waste heat recovery. The second cluster involves planned buildings in the

Albano district in the vicinity of the KTH campus that will be a joint area with lecture buildings

and accommodation for 3 universities in Stockholm. The present energy supply structure for

the campus and the surrounding urban area includes a local combined heat and power (CHP)

plant. The comparison of the building clusters involve analyses based on the Rational Exergy

Management Model. Four scenarios, which involve different shares for the existing CHP units,

new biofuel CHP unit, seawater heat pumps, peak load boilers, electric boilers, large scale

aquifer thermal energy storage, heat supply from solar collectors, and electricity and heat from

photovoltaic thermal arrays are devised for comparison. The scenarios have at most an exergy

match of 0.81. The paper concludes with useful results that are in line with the aims of IEA

Annex 64 on Optimised Performance of Energy Supply Systems with Exergy Principles.

National Category
Architecture
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-192955 (URN)
Note

QC 20160923

Available from: 2016-09-23 Created: 2016-09-23 Last updated: 2016-09-26Bibliographically approved

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Citation style
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Output format
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