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Unclogging the Future
Designing a low-cost grease trap monitoring system for municipal use.
Current grease trap monitoring systems measure FOG layer thickness, which indicates when maintenance is required. Once the FOG layer reaches 80% capacity, the grease trap no longer separates FOG effectively. These systems help grease trap owners optimize maintenance schedules, as grease traps must legally be emptied at least once or twice a month unless the owner can prove that maintenance was not needed because the trap had not reached 80% capacity. However, Dutch restaurants rarely install these systems because they are not legally required. They are also unsuitable for large-scale municipal deployment, as they lack sufficient scalability and universal compatibility. In addition, municipalities lack the manpower to manually verify all grease traps, leaving them dependent on reactive FOG removal instead of preventive source control.
To reduce FOG discharge from food-service establishments, municipalities need reliable and cost-effective grease trap data acquisition. The Hague was used as the design context to explore a monitoring system that fits within its budget, with the main focus on sensor municipal dashboard development due to its complexity and novelty. The ideation phase consisted of three design processes: testing cost-effective continuous FOG output sensing, developing a municipal FOG layer-thickness sensor, and creating a central interactive dashboard that allows the municipality to quickly interpret sensor data and reduce labor needs. Since the FOG output concept was insufficiently accurate, the final concept focuses on FOG layer-thickness sensing.
The resulting concept, Grease Control, combines a low-cost capacitance sensor with an interactive municipal dashboard and business strategy. The sensor is designed for simple installation and low manufacturing cost, while the dashboard supports quick decision-making through recognizable icons and action-oriented information linked to each sensor address. Although the final designs remain proofs of concept and require validation in real grease trap environments, the project shows how combining sensor data with an interactive municipal system aids municipalities in detecting where and why FOG is discharged. If developed further, the concept is expected by the South-Holland environmental agency and The Hague to reduce municipal FOG removal costs and environmental risks while also financially benefiting grease trap owners. ...
Current grease trap monitoring systems measure FOG layer thickness, which indicates when maintenance is required. Once the FOG layer reaches 80% capacity, the grease trap no longer separates FOG effectively. These systems help grease trap owners optimize maintenance schedules, as grease traps must legally be emptied at least once or twice a month unless the owner can prove that maintenance was not needed because the trap had not reached 80% capacity. However, Dutch restaurants rarely install these systems because they are not legally required. They are also unsuitable for large-scale municipal deployment, as they lack sufficient scalability and universal compatibility. In addition, municipalities lack the manpower to manually verify all grease traps, leaving them dependent on reactive FOG removal instead of preventive source control.
To reduce FOG discharge from food-service establishments, municipalities need reliable and cost-effective grease trap data acquisition. The Hague was used as the design context to explore a monitoring system that fits within its budget, with the main focus on sensor municipal dashboard development due to its complexity and novelty. The ideation phase consisted of three design processes: testing cost-effective continuous FOG output sensing, developing a municipal FOG layer-thickness sensor, and creating a central interactive dashboard that allows the municipality to quickly interpret sensor data and reduce labor needs. Since the FOG output concept was insufficiently accurate, the final concept focuses on FOG layer-thickness sensing.
The resulting concept, Grease Control, combines a low-cost capacitance sensor with an interactive municipal dashboard and business strategy. The sensor is designed for simple installation and low manufacturing cost, while the dashboard supports quick decision-making through recognizable icons and action-oriented information linked to each sensor address. Although the final designs remain proofs of concept and require validation in real grease trap environments, the project shows how combining sensor data with an interactive municipal system aids municipalities in detecting where and why FOG is discharged. If developed further, the concept is expected by the South-Holland environmental agency and The Hague to reduce municipal FOG removal costs and environmental risks while also financially benefiting grease trap owners.
From Circular Ambition to Investment Decision
Assessing the decision relevance of material-related circular strategies in new-build care real estate
reuse and value retention over a building’s lifecycle. Their integration into investment decisionmaking
remains difficult because present costs are relatively visible, while future lifecycle effects are
uncertain and must be assessed alongside care requirements, functionality, affordability, technical
feasibility and organisational constraints. This study examines what process and assessment conditions
shape the decision relevance of material-related circular strategies in investment decision-making for
new-build care real estate.
The research combined a literature review with an intensive reconstruction of one Dutch new-build
care project and an exploratory what-if analysis within the organisation’s existing financial appraisal.
Project documents and semi-structured interviews were used to trace how material-related circular
strategies developed through the investment process. The what-if analysis examined how selected
lifecycle assumptions and residual value could be represented and assessed under uncertainty. The
findings were subsequently translated into a decision-support framework.
The results show that loss of decision relevance did not occur at one formal decision gate. Instead,
strategies changed position as project choices narrowed. Project routines readily produced specific
evidence for present costs, while future effects were more often represented at building level or
qualitatively and were therefore harder to link to specific material or design choices. The what-if
analysis showed that changing lifecycle assumptions could substantially alter the financial appraisal
without settling the investment decision. A favourable financial result was not sufficient on its own.
Decision-makers also required evidence strong enough to justify changing an appraisal assumption,
while any resulting financial improvement still competed with other project and portfolio priorities.
More detailed evidence could therefore support either changing or retaining an assumption, depending
on what it revealed.
The study concludes that decision relevance is conditional rather than inherent. It depended on whether
a strategy and the reason for considering it remained visible, whether supporting evidence became
available while the choice could still be influenced and whether the expected physical or lifecycle effect
could be clearly linked to the specific material or design choice and considered through existing financial
or governance procedures. Care-related, functional and technical consequences could also influence
the decision without first being converted into monetary value. The resulting framework structures
these relationships into a traceable assessment process. As the study concerns one case and modelled
what-if judgements rather than observed investment decisions under real commitment, it identifies
mechanisms and conditions rather than their prevalence across the sector. ...
reuse and value retention over a building’s lifecycle. Their integration into investment decisionmaking
remains difficult because present costs are relatively visible, while future lifecycle effects are
uncertain and must be assessed alongside care requirements, functionality, affordability, technical
feasibility and organisational constraints. This study examines what process and assessment conditions
shape the decision relevance of material-related circular strategies in investment decision-making for
new-build care real estate.
The research combined a literature review with an intensive reconstruction of one Dutch new-build
care project and an exploratory what-if analysis within the organisation’s existing financial appraisal.
Project documents and semi-structured interviews were used to trace how material-related circular
strategies developed through the investment process. The what-if analysis examined how selected
lifecycle assumptions and residual value could be represented and assessed under uncertainty. The
findings were subsequently translated into a decision-support framework.
The results show that loss of decision relevance did not occur at one formal decision gate. Instead,
strategies changed position as project choices narrowed. Project routines readily produced specific
evidence for present costs, while future effects were more often represented at building level or
qualitatively and were therefore harder to link to specific material or design choices. The what-if
analysis showed that changing lifecycle assumptions could substantially alter the financial appraisal
without settling the investment decision. A favourable financial result was not sufficient on its own.
Decision-makers also required evidence strong enough to justify changing an appraisal assumption,
while any resulting financial improvement still competed with other project and portfolio priorities.
More detailed evidence could therefore support either changing or retaining an assumption, depending
on what it revealed.
The study concludes that decision relevance is conditional rather than inherent. It depended on whether
a strategy and the reason for considering it remained visible, whether supporting evidence became
available while the choice could still be influenced and whether the expected physical or lifecycle effect
could be clearly linked to the specific material or design choice and considered through existing financial
or governance procedures. Care-related, functional and technical consequences could also influence
the decision without first being converted into monetary value. The resulting framework structures
these relationships into a traceable assessment process. As the study concerns one case and modelled
what-if judgements rather than observed investment decisions under real commitment, it identifies
mechanisms and conditions rather than their prevalence across the sector.
As rail networks face increasing pressure to improve punctuality and capacity under mixed-traffic conditions, digital support tools such as Connected Driver Advisory Systems (C-DAS) are increasingly deployed. Yet, empirical evidence of their operational effects in daily practice remains limited. This paper presents a data-driven two-level approach based on macroscopic and microscopic event graph representations, constructed from the same underlying corridor and observed train movements, to evaluate the performance of C-DAS. It fuses timetable event records, track section occupation and release data, and C-DAS usage logs to enable comparison between trains operated with and without C-DAS at timetable point and block section levels. Derived from the event graphs, differences in timetable deviation, running time deviation, and the occurrence of unplanned yellow signal aspects are assessed using non-parametric statistical tests. The approach is demonstrated through its application to RouteLint, a C-DAS deployed for freight operations in the Netherlands, using one year of data from a mixed-traffic mainline corridor comprising 23,573 freight train runs. The results show modest but consistent differences in operational performance between trains operated with and without RouteLint. Statistically significant differences in timetable deviation are identified at multiple key locations, with RouteLint-equipped trains showing approximately 30–70 s lower deviations at major stations and junctions. At the microscopic level, running time deviations exhibit substantial local variability, while lower deviations are observed on selected block sections for RouteLint-equipped trains. In addition, RouteLint-equipped trains show approximately 6% lower overall odds that an observed yellow signal aspect is unplanned, while the association varies across operating contexts.
In many cities, policymakers struggle with public support for transformative changes in public spaces, moving away from private cars to other functionalities such as safe bike paths, greenery, housing and leisure. Binary referenda often suggest there is no support for transformative changes. Other voting instruments are sparsely used but might produce different results. This paper compares the (dis)advantages of binary, multi-option and portfolio voting schemes and provides arguments for selecting the appropriate instrument. Next, we compare a binary referendum and a portfolio voting scheme (based on the Participatory Value Evaluation method), organized between March-June 2024, about a transformative mobility policy package in Haarlem, the Netherlands. We investigate to what extent these instruments allowed voters to express their preferences, produced different measures of public support and equipped policymakers with actionable insights. We find that 82% voted against this proposal in the referendum, whereas the PVE indicates there are several groups of opinions regarding the policy proposal, correlating with socio-demographic variables (e.g. primary commuting modality and financial situation). Based on a discussion of the limitations of both instruments, we conclude binary referenda can be a useful if policymakers want to know if there is (no) majority support for a proposal. But if a majority votes against a complex proposal, binary referenda provide no insights about how to proceed, and its simplicity becomes an obstacle. PVE provides more insights on how to adapt a proposal to citizens preferences, values and concerns although ensuring its design is perceived as legitimacy remains challenging.
Ethical innovation of quantum computing in Europe
A policy intervention
This intervention on European quantum technology policy shares key insights from a workshop that took place at TU Delft in September 2025, organised by the Delft Quantum Governance and Values Lab and funded by the Netherlands’ Centre for Quantum and Society. The workshop brought together scientists, policymakers, industry actors, and Ethical, Legal, and Social Aspects (ELSA) scholars. Extended discussions between these experts identified five targeted interventions, intended especially for policymakers of the EU Member States and the European Commission, but also relevant for quantum researchers, ELSA researchers, and industry actors within and outside the EU. We believe implementation of these interventions will promote the development and uptake of quantum computing in the public interest and foster public trust in these emerging technologies and the institutions that make use of them.