Sustainable Software Engineering
Energy efficiency in cloud computing, architectural tactics for sustainability, and KPIs for green software. Collaboration with Vrije Universiteit Amsterdam’s S2 Group.
Lab271 Research
Peer-reviewed research at the intersection of software engineering,
sustainability, and digital transformation.
e ≈ 2.71828, the growth constant
6
publications
15
years of research
3
themes
Research themes
Section titled “Research themes”Digital Transformation
How asset-intensive industries navigate the integration of emerging technologies while managing decades-long asset lifecycles and regulatory constraints.
IT Governance & Sourcing
Multi-vendor orchestration, relationship structures in outsourcing arrangements, and governance of mission-critical IT services.
Publications
Section titled “Publications”Green LLM Techniques in Action: How Effective Are Existing Techniques for Improving the Energy Efficiency of LLM-Based Applications in Industry?
2026 IEEE/ACM 48th International Conference on Software Engineering (ICSE-SEIP '26), Rio de Janeiro, Brazil, 12 pages
Abstract
The rapid adoption of large language models (LLMs) has raised concerns about their substantial energy consumption, especially when deployed at industry scale. While several techniques have been proposed to address this, limited empirical evidence exists regarding the effectiveness of applying them to LLM-based industry applications. To fill this gap, we analyzed a chatbot application in an industrial context at Schuberg Philis, a Dutch IT services company. We then selected four techniques, namely Small and Large Model Collaboration, Prompt Optimization, Quantization, and Batching, applied them to the application in eight variations, and then conducted experiments to study their impact on energy consumption, accuracy, and response time compared to the unoptimized baseline. Our results show that several techniques, such as Prompt Optimization and 2-bit Quantization, managed to reduce energy use significantly, sometimes by up to 90%. However, these techniques especially impacted accuracy negatively, to a degree that is not acceptable in practice.BibTeX
@inproceedings{Kuran2026, author = {Kuran, Pelin Rabia and Chitakunye, Rumbidzai and Stoico, Vincenzo and Heitlager, Ilja and Bogner, Justus}, title = {Green LLM Techniques in Action: How Effective Are Existing Techniques for Improving the Energy Efficiency of LLM-Based Applications in Industry?}, booktitle = {2026 IEEE/ACM 48th International Conference on Software Engineering: Software Engineering in Practice (ICSE-SEIP '26)}, pages = {554--565}, year = {2026}, publisher = {ACM}, doi = {10.1145/3786583.3786896} }Navigating Digital Transformation in Asset-Intensive Companies: A Process Model Informed by Design Science
Designs 2025, 9(6), 136
Abstract
Companies in asset-intensive industries, such as aviation and railways, face unique digital transformation challenges due to the misalignment between the rapid evolution of digital technologies and decades-long asset lifecycles. This paper investigates how asset-intensive companies can systematically integrate digital technologies, while fully complying with regulatory constraints and safety requirements. We employ a design science approach in a study of Nederlandse Spoorwegen (NS), the Dutch national railway operator, focusing specifically on the implementation of AI-driven CCTV systems. We develop six design propositions and the Iterative Development & Adoption Model (IDAM) that operationalizes market maturity assessment through market readiness levels to guide make-or-buy transitions across four iterative phases: ideate, assess, realise, and review.BibTeX
@article{Heitlager2025, author = {Heitlager, Ilja and Jenniskens, Bernard and Romme, A. Georges L.}, title = {Navigating Digital Transformation in Asset-Intensive Companies: A Process Model Informed by Design Science}, journal = {Designs}, volume = {9}, number = {6}, pages = {136}, year = {2025}, doi = {10.3390/designs9060136} }Experimental Evaluation of Energy Efficiency Tactics in Industry: Results and Lessons Learned
IEEE 21st International Conference on Software Architecture (ICSA), Hyderabad, India, pp. 170-181
Abstract
Integrating (and evaluating) energy efficiency tactics into daily industrial practice is challenging. This paper addresses the experimental evaluation of energy efficiency tactics in industrial contexts. Based on different real-world scenarios, we assess five energy efficiency tactics for cloud-based software through individual experiments conducted across two companies. The results of the experiments show significant improvements in energy efficiency for three tactics, with two others showing enhanced efficiency albeit without statistical significance. Our results could guide practitioners in selecting and applying the most suitable tactic for their individual context.BibTeX
@inproceedings{Funke2024, author = {Funke, Markus and Lago, Patricia and Adenekan, Esther and Malavolta, Ivano and Heitlager, Ilja}, title = {Experimental Evaluation of Energy Efficiency Tactics in Industry: Results and Lessons Learned}, booktitle = {2024 IEEE 21st International Conference on Software Architecture (ICSA)}, pages = {170--181}, year = {2024}, doi = {10.1109/ICSA59870.2024.00024} }Unveiling Key Performance Indicators for the Energy Efficiency of Cloud Data Storage
8th International Workshop on Green and Sustainable Software (GREENS), at ICSA-C 2024, Hyderabad, India, pp. 222-229
Abstract
This paper explores metrics to evaluate the energy efficiency of cloud data storage and represents them as Key Performance Indicators (KPIs) for organizational monitoring. We present a framework for systematically identifying, categorizing, and applying KPIs that enable organizations to monitor and optimize the energy efficiency of their cloud storage infrastructure.BibTeX
@inproceedings{Banijamali2024, author = {Banijamali, Pouyeh and Fatima, Iffat and Lago, Patricia and Heitlager, Ilja}, title = {Unveiling Key Performance Indicators for the Energy Efficiency of Cloud Data Storage}, booktitle = {2024 IEEE 21st International Conference on Software Architecture Companion (ICSA-C)}, pages = {222--229}, year = {2024}, doi = {10.1109/ICSA-C63560.2024.00047} }Architectural Tactics to Optimize Software for Energy Efficiency in the Public Cloud
2022 International Conference on ICT for Sustainability (ICT4S), Plovdiv, Bulgaria, pp. 77-87
Abstract
From a cloud consumer perspective, migrating software to the cloud promises to improve quality attributes like availability, scalability, flexibility, and carbon efficiency. However, this migration might be misinterpreted as delegating the fulfillment of these QAs to the cloud provider. This paper started addressing this problem by defining, or rethinking, architectural tactics for energy efficiency. We provide a catalog of tactics that software architects can apply to optimize their cloud-based applications for energy efficiency.BibTeX
@inproceedings{Vos2022, author = {Vos, Sophie and Lago, Patricia and Verdecchia, Roberto and Heitlager, Ilja}, title = {Architectural Tactics to Optimize Software for Energy Efficiency in the Public Cloud}, booktitle = {2022 International Conference on ICT for Sustainability (ICT4S)}, pages = {77--87}, year = {2022}, doi = {10.1109/ICT4S55073.2022.00019} }Evolving Relationship Structures in Multi-sourcing Arrangements: The Case of Mission Critical Outsourcing
4th International Workshop on Global Sourcing, Zermatt, Switzerland. Lecture Notes in Business Information Processing, vol 55, pp. 168-185. Springer
Abstract
This paper explores the evolution of relationship structures in multi-sourcing arrangements for mission critical IT services. Based on a longitudinal case study at a major financial services provider, we analyze how relationship structures between client and multiple vendors develop over time, identifying key patterns and governance mechanisms that enable successful multi-vendor orchestration in high-stakes environments.BibTeX
@inproceedings{Heitlager2010, author = {Heitlager, Ilja and Helms, Remko and Brinkkemper, Sjaak}, title = {Evolving Relationship Structures in Multi-sourcing Arrangements: The Case of Mission Critical Outsourcing}, booktitle = {Global Sourcing of Information Technology and Business Processes}, series = {Lecture Notes in Business Information Processing}, volume = {55}, pages = {168--185}, year = {2010}, publisher = {Springer}, doi = {10.1007/978-3-642-15417-1_10} }
Graduates
Section titled “Graduates”We supervise MSc and BSc students from partner universities. Some join us after graduating.
A pathway through customer values towards loyal B2B relationships in IT outsourcing
MSc Strategic Design, TU Delft
Abstract
This thesis examines the growing importance of loyal B2B relationships between an IT outsourcer and its customers. The research investigates how loyal B2B relationships between SBP and their customers are established and sustained to facilitate a transition towards business outcome-driven partnerships. Key findings include a detailed context-driven B2B value framework, the correlation between B2B values, events, and interactions that guide the establishment of loyal relationships, and how a shared future vision enables the transition to business outcome-driven partnerships.Mission-critical workarounds: How workarounds impact mission-critical IT change processes of self-steering teams
MSc Business Informatics, Utrecht University
Abstract
This study focuses on mission-critical IT as within mission-critical IT, time is often of the essence, and there is limited room for failure. Two case studies were conducted within Schuberg Philis for customer teams that operate in the finance industry and postal service industry. Results show that in most cases, mission-critical workarounds relate to the administrative part of the process or the approval mechanisms. The majority of workarounds have a positive impact on time, costs and flexibility of the process.
Collaborations
Section titled “Collaborations”Lab271’s research is conducted in collaboration with academic partners:
- Vrije Universiteit Amsterdam — S2 Group (Software and Sustainability)
- Eindhoven University of Technology — Department of Industrial Engineering & Innovation Sciences
- Utrecht University — Department of Information and Computing Sciences
- TU Delft — Faculty of Industrial Design Engineering
About Lab271
Section titled “About Lab271”Lab271 is the innovation lab of Schuberg Philis, located at Boeingavenue 271 in Schiphol-Rijk, The Netherlands. We combine academic research with hands-on engineering to advance the state of the art in mission-critical IT.