Power Assumptions Matter: Evaluating End-user Laptop Energy Models for Sustainability Reporting of Browser-Based Web Services

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Hauptverfasser: Kirkeby, Maja H., Lagermann, Timmie
Format: Preprint
Veröffentlicht: 2025
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author Kirkeby, Maja H.
Lagermann, Timmie
author_facet Kirkeby, Maja H.
Lagermann, Timmie
contents Sustainability reporting for web-based services often relies on simplified end-user energy models that assume constant laptop power during browser interactions. Energy models such as Digst and DIMPACT apply fixed power values (15-22W), yet the validity of this approach for realistic browsing remains underexplored. We empirically evaluate constant-power assumptions in a controlled user study where ten participants repeatedly complete eight representative user flows across shopping, booking, navigation, and news services on four laptop platforms, while device energy is measured. Typical power is 9--13~W, substantially below current reporting standards, implying systematic overestimation. Moreover, the error scales proportionally with task duration, indicating systematic bias rather than random noise. Comparing progressively refined constant-power models, we find that category-specific parameters improve accuracy more than hardware-only parameters and approach flow-specific performance. The best fit is obtained by combining category (or flow) with hardware, while category-level models retain most of the benefit with fewer parameters, making them a practical upgrade for sustainability reporting.
format Preprint
id arxiv_https___arxiv_org_abs_2510_12566
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Power Assumptions Matter: Evaluating End-user Laptop Energy Models for Sustainability Reporting of Browser-Based Web Services
Kirkeby, Maja H.
Lagermann, Timmie
Software Engineering
Sustainability reporting for web-based services often relies on simplified end-user energy models that assume constant laptop power during browser interactions. Energy models such as Digst and DIMPACT apply fixed power values (15-22W), yet the validity of this approach for realistic browsing remains underexplored. We empirically evaluate constant-power assumptions in a controlled user study where ten participants repeatedly complete eight representative user flows across shopping, booking, navigation, and news services on four laptop platforms, while device energy is measured. Typical power is 9--13~W, substantially below current reporting standards, implying systematic overestimation. Moreover, the error scales proportionally with task duration, indicating systematic bias rather than random noise. Comparing progressively refined constant-power models, we find that category-specific parameters improve accuracy more than hardware-only parameters and approach flow-specific performance. The best fit is obtained by combining category (or flow) with hardware, while category-level models retain most of the benefit with fewer parameters, making them a practical upgrade for sustainability reporting.
title Power Assumptions Matter: Evaluating End-user Laptop Energy Models for Sustainability Reporting of Browser-Based Web Services
topic Software Engineering
url https://arxiv.org/abs/2510.12566