This study investigates sustainable alternatives to diesel generators for data centre backup power, focusing on renewable diesel (HVO), Hydrogen energy storage (HES), batteries (Lithium-ion and Sodium Sulfur) and Compressed Air Energy Storage (CAES). As environmental scrutiny of data centres grows, the need for cleaner energy sources intensifies. Our research assesses various storage technologies' energy performance metrics, environmental impacts, and economic feasibility. HVO is a seamless substitute for conventional diesel, compatible with existing infrastructure and less carbon-intensive. CAES offers lower life cycle emissions and operational costs but is geographically dependent. While currently more costly, batteries could achieve better economics with increased operational hours. However, extending the backup duration increases their capital and operating costs significantly, which is less advantageous than other technologies, where only fuel costs increase with longer backup times. For existing data centres transitioning to sustainable energy, HVO is optimal; for new facilities, CAES is ideal if geography allows, with HES as a robust alternative. This analysis offers a pathway for data centres to adopt sustainable, cost-effective energy storage solutions and reduce carbon footprints through on-site renewables or green energy procurement.

The city of Amsterdam has ambitious goals to achieve a 95% reduction in carbon emissions by 2050 and to phase out natural gas by 2040. Disconnecting the building stock from natural gas requires well-ventilated and well-insulated buildings and a switch to renewable energy sources, making optimal use of heat pumps and sustainable heating solutions available locally. Most buildings in the historical city centre are protected and often insufficiently insulated, leading to increased energy use and a poor thermal environment. Standard retrofitting interventions may be restricted, requiring new approaches to balancing the need for energy efficiency and the preservation of heritage significance. With the case of the Amsterdam City Centre, the goal of this research is to present a parametric modelling approach for energy retrofitting heritage buildings and to identify minimum requirements for preparing the residential stock to lower temperature heat (LTH). Using parametric design and bottom-up energy modelling, the research estimates that a 69.1% of natural gas reduction could be achieved when upgrading the buildings to lower temperature (LT). Results of this paper also demonstrate how the applied approach can be used to guide decisions on the improvement in energy performance of the historic built environment.

The urban energy transition requires innovative heating and cooling systems, as well as enhanced flexibility in electricity usage. This paper explores the theoretical potential for vertical farms to contribute to the energy transition by supplying residual heat to local district heat networks and flexible electricity usage. A stepped approach was used to design energy systems that achieve thermal energy balance through heat and cold exchange between a vertical farm and buildings within a specific Dutch neighbourhood. Furthermore, alternative lighting strategies for vertical farms were explored to reduce grid congestion and to respond to electricity price fluctuations, limiting the mismatch between electricity generation and demand. Compared to the baseline scenario, the energy system with an integrated vertical farm reduces overall energy use by 15 %, even when accounting for the farm's electricity use. By adopting intermittent lighting that is better aligned with electricity price fluctuations, the vertical farm obtained annual cost savings of 14 %. The integration of vertical farms into energy systems can, therefore, contribute to the urban energy transition by producing residual heat to balance thermal energy system and save money for growers by optimising LED operations to align with electricity price fluctuations, whilst producing fresh vegetables for the city.

The joint deployment of energy reduction actions across multiple buildings at once is much needed to reach climate targets, but collective decision-making with shared ownership is a complex process. Each homeowner is accountable for their own energy use, while being constrained by their personal financial capacity and will to act with other co-owners. At the same time, decision-making for energy retrofits involves multiple constraints and criteria, relating to divergent and sometimes conflicting technical, environmental, economic, and social issues, leading to a fragmented response to the retrofitting challenge. This article presents a community-led approach to energy retrofit based on parametric modelling and design space exploration. The approach was tested under the conditions of a homeowner association residing in a heritage building in Amsterdam. Cards displaying each retrofit option and its associated impacts in terms of costs, operational carbon emissions, and energy performance were designed to facilitate negotiation between the participants and their interaction with the computational model. The intention was to empower the group by enabling the exploration of various design alternatives and to nourish conversations about sustainable retrofitting that would normally not take place. Participant feedback shows that the approach effectively improved the quality of the discussion and increased their understanding on the pathways to make their building more sustainable. This article presents the Collect your Retrofits project and describes the potentials and limitations of using parametric modelling to facilitate group decisions made at early stages of retrofit design.

Abstract: The main task of a university is to conduct scientific research, accommodate scientific education, and transfer knowledge. Within this environment, new models, approaches, strategies and technologies can be tested and investigated safely. Simultaneously these processes can be monitored, evaluated and adjusted and enhanced when needed. Due to these characteristics, universities and other institutes of higher education can and should be at the forefront of sustainable development and climate action. Universities should pave the way for other organisations, companies, and cities and show how to reach the climate goals. A Vision, Ambition and Action Plan with 5 specific goals for Delft University of Technology (TU Delft) and was adopted by the university’s executive board. In 2030, the university wants all activities on and from the campus to be carbon neutral, circular and climate adaptive, and to contribute to the quality of life for its users and nature and demonstrate sustainable innovations on campus. This paper will show which steps TU Delft has taken to set these ambitions in place and how they want to become a Climate University and example for others. The main elements addressed are Sustainable Operations and Behavioural Change.

The city of Amsterdam has the ambitious greenhouse emission reduction targets: to achieve a 95% reduction in emissions by 2050 and to phase out natural gas by 2040. Disconnecting the existing building stock from natural gas requires a switch to alternative energy-efficient sources, making optimal use of heat pumps and sustainable heating solutions available locally. The present study aims to identify minimum retrofitting strategies to prepare the historical city centre for lower temperature heat. The vast majority of the buildings in the historic centre of Amsterdam are protected and often poorly insulated, leading to increased energy use and poor thermal environment. Standard retrofitting interventions and the use of new materials may be restricted, requiring new approaches to balancing the need for energy efficiency and the preservation of heritage significance.

Using parametric design tools, the developed multi-criteria model allows to iterate retrofitting scenarios (post-insulation measures, air tightness, windows or equipment upgrades) and identify minimum requirements to make buildings suitable for lower temperature heating. By integrating bottom-up energy modelling and Geographical Information Systems data, the research estimates the effect of the selected retrofit packages on the energy demand of residential stock at the district scale. The study also provides knowledge for the municipality of Amsterdam to guide decisions on the improvement in energy performance and decarbonisation of the historic built environment.

According to the Paris Agreement, cities need to be carbon neutral by 2050. This entails a dramatic transition from a fossil fuel based built environment to one entirely running on renewable energy. In many European cities this means moving away from natural gas as prime source. At present, three options are generally considered as alternatives to a fossil energy system: (1) all-electric, using solar or wind power and solar heat or heat pump systems, (2) district heating, using high-temperature industrial waste heat or geothermal heat, (3) green gas, which can be biogas or synthetic gases as green hydrogen or synthetic methane. In addition, hybrid solutions are also an option. Which of the sustainable alternatives is most suited strongly depends on the urban plan, building typology and technology used so far. Districts with a great extent of repetition can be easier renovated to a net zero-energy plan than an area with a great variety of building types. High-density districts are suited for relatively expensive district heating. Districts that are neither are usually designated for a green gas-based system. The problem however is that few cities can produce sufficient biogas or do not have a renewable power over-production to generate synthetic gases. This in particular applies to historic city centres. The 17th-century inner city of Amsterdam is facing a similar problem. The municipality decided to keep this part of the Dutch capital connected to the gas grid, but under the condition that the demand for gas would be reduced by 70%, as to enable usage of locally produced green gas. However, with a great share of listed buildings – a large part of the inner city of Amsterdam is Unesco World Heritage – such a reduction in heat demand is virtually impossible. Or is it? From various studies it is known that the old city centre has considerable sources of renewable heat, among which residual heat from cooling processes and exhaust air. This heat is now released into the air, disturbing the temperature in the city and getting lost for other purposed. In the research project presented, sources of renewable heat and residual heat were investigated, quantified and proposed as feed-in for a low-temperature heat (and cold) network, including seasonal storage. The full paper will discuss this study relevant to many cities across the continent.

Vertical farms use some resources very efficiently. However, their electricity use is considerable, and a significant amount of waste heat is produced. This paper investigates how the integration of vertical farms in buildings could reduce the use of energy, water, and nutrients collectively across both entities by leveraging potential resource synergies. The paper considered the integration of vertical farms in apartments, offices, restaurants, swimming pools, and supermarkets located in the Netherlands. For each typology, the floor area heated and the amount of building users fed by one m2 of one production layer within the vertical farm was calculated, along with required outputs of water and nutrients from the building to sustain the vertical farm. The energy savings of different integration strategies were calculated for each building typology in comparison to a non-integrated approach. Results showed that the synergetic integration of vertical farms with buildings reduced the year-round energy use of the climate systems of both entities collectively by between 12 and 51%. The integration of vertical farms with buildings decreases the use of energy, water, and nutrients from external sources and offers great potentials to reduce the environmental impacts of both entities, whilst producing food in urban environments.

Universities and other institutes of higher education can be at the forefront of sustainable development and climate action. As organisations that develop knowledge, conduct research, and valorise their experience, universities are capable of testing and investigating new approaches, models, strategies, technology… The process thereof can be monitored, evaluated and corrected or enhanced when needed. Therefore, universities can be safe places for the roll-out of climate action and sustainability measures, paving the way for other organisations and cities to reach their climate goals. TU Delft adopted its Vision, Ambition and Action Plan as the basis of all sustainable transitions on the campus. Aiming at five sustainability goals – becoming carbon neutral, climate adaptive and circular by 2030, contributing to quality of life, and demonstrating sustainable innovations on campus – an all-encompassing plan was drawn up to set in motion serious changes. The four main elements addressed in this paper are: Education for Sustainability, Campus as a Living Lab, Sustainable Operations, and Community Engagement. This paper will discuss the steps taken by TU Delft to become a climate university and exemplar for other organisations and institutions.

The production, processing, and transportation of food, in particular animal-based products, imposes great environmental burden on the planet. The current food supply system often constitutes a considerable part of the total carbon emissions of urban communities in industrialised cities. Urban food production (UFP) is a method that can potentially diminish food emissions. In parallel, a shift towards a predominantly plant-based diet that meets the nutritional protein intake is an effective method to curtail carbon emissions from food. Considering the high land use associated with the production of animal-based products, such a shift will prompt a community food demand that is more inclined to be satisfied with local production. Therefore, during the design process of a future low-carbon city, the combined application of both methods is worth exploring. This work introduces, describes, and demonstrates the diet shift component of the FEWprint platform, a user friendly UFP assessment platform for designers that is constructed around the broader three-pronged strategy of evaluation, shift, and design. For three neighborhoods, in Amsterdam, Belfast, and Detroit, the contextual consumption and country-specific environmental footprint data are applied to simulate a theoretical community-wide diet shift from a conventional to a vegan diet, whilst maintaining protein intake equilibrium. The results show that in total terms, the largest carbon mitigation potential awaits in Detroit (−916 kg CO2eq/cap/year), followed by Belfast (−866 kg) and Amsterdam (−509 kg). In relative terms, the carbon reduction potential is largest in Belfast (−25%), followed by Amsterdam (−15%) and Detroit (−7%). The FEWprint can be used to generate preliminary figures on the carbon implications of dietary adaptations and can be employed to give a first indication of the potential of UFP in urban communities.

Current urbanization rates concentrate the ever growing demand for food, energy and water (FEW) resources particularly in cities, making them one of the main drivers of greenhouse gas emissions. The FEW nexus integrative approach offers a potential framework for sustainable resource management in cities. However, existing nexus evaluation tools are limited in application and often inadequate. This is primarily due to the FEW nexus intricacy, the tools’ operational complexity and/or the need to input comprehensive data that is often unavailable to users. Having outlined these current gaps, this paper introduces the FEWprint, an integrated carbon accounting platform that provides an accessible process for FEW nexus-based evaluations of urban areas. This spreadsheet-based framework is employed to calculate a consumption-based footprint derived from food consumption, thermal/electrical energy use, car fuel demand, water management, and domestic waste processing. A comparative assessment between six different communities reveals significant differences in total annual emissions. The food sector impact shows emissions ranging between 993Kg/cap∗yr and 1366Kg/cap∗yr in Amsterdam and Tokyo respectively, but is also the least deviating from all considered resource sectors. This holistic carbon footprint and considered food inventory will serve as a baseline for future integrated urban farming strategies and urban design proposals to be tested.

Potted plants have been reported to uptake VOCs and help “cleaning” the air. This paper presents the results of a laboratory study in which two species of plants (peace lily and Boston fern) and three kinds of substrates (expanded clay, soil, and activated carbon) were tested and monitored on their capacity to deplete formaldehyde and CO2 in a glass chamber. Formaldehyde and CO2 were selected as indicators to evaluate the biofiltration efficacy of 28 different test conditions; relative humidity (RH) and temperature (T) were monitored during the experiments. To evaluate the efficacy of every test, the clean air delivery rate (CADR) was calculated. Overall, soil had the best performance in removing formaldehyde (~0.07–0.16 m3/h), while plants, in particular, were more effective in reducing CO2 concentrations (peace lily 0.01m3/h) (Boston fern 0.02–0.03 m3/h). On average, plants (~0.03 m3/h) were as effective as dry expanded clay (0.02–0.04 m3/h) in depleting formaldehyde from the chamber. Regarding air-cleaning performance, Boston ferns presented the best performance among the plant species, and the best performing substrate was the soil

Zero-Acreage Farming (ZAF) recently developed as a novel land-use form and is aimed at addressing food security and sustainable urban development. While it is often lauded as a sustainable land-use form with potential to improve resource consumption and urban sustainability, little research into the spatial and technological requirements of this land-use form is available. This study undertakes a comparative analysis of ZAF and ground-based urban agriculture (UA) farms in diverse countries to differentiate their technical and spatial implementation parameters and uncover ZAF-specific characteristics and their implementation feasibility in rapidly developing cities. This qualitative study uses semi-structured interviews, triangulated with observational studies, to document ZAF and UA farms in South Africa, Belgium, the Netherlands and Singapore. The findings reveal UA as highly flexible, modular land-use forms while, contrastingly, the technological focus of ZAF farms often results in monofunctional and inflexible once implemented, isolated, and non-contextual solutions. While ZAF farms are appropriate to improve livelihoods and food security in dense urban contexts, the study highlights trends that must be addressed to promote the implementation of ZAF in poorer rapidly developing cities.

Architectural space layout has proven to be influential on building energy performance. However, the relationship between different space layouts and their consequent energy demands has not yet been systematically studied. This study thoroughly investigates such a relationship. In order to do so, a computational method was developed, which includes a method to generate space layouts featuring energy-related variables and an assessment method for energy demand. Additionally, a design of experiments was performed, and its results were used to analyse the relationship between space layouts and energy demands. In order to identify their relationship, four types of design indicators of space layout were proposed, both for the overall layout and for each function. Finally, several optimisations were performed to minimise heating, cooling and lighting demands. The optimisation results showed that the maximum reduction between different layouts was up to 54% for lighting demand, 51% for heating demand and 38% for cooling demand. The relationship analysis shows that when comparing the four types of design indicators, the façade area-to-floor area ratio showed a stronger correlation with energy demands than the façade area ratio, floor area ratio and height-to-depth ratio. Overall, this study shows that designing a space layout helps to reduce energy demands for heating, cooling and lighting, and also provides a reference for other researchers and designers to optimise space layout with improved energy performance.

Over the past decades, various farming methods have evolved in response to the global challenges of increasing food demands, decreasing availability of arable land, and climate change. One of these new farming methods is vertical farming. To understand the contribution of vertical farms to future sustainable food production, beyond its efficient land-use and high yields, this paper evaluates the current carbon footprint of lettuce produced in an operational vertical farm in comparison to conventional open-field farming and both soil-based and hydroponic greenhouse cultivation in the Netherlands. The assessment includes the greenhouse gas emissions of the life cycle of the farm and the crop, from cradle-to-grave. An alternative scenario is explored to include the lost carbon sequestration potential by land-use change, identical packaging for all farming methods, and renewable energy
usage. The carbon footprint of the vertical farm was 5.6–16.7 times greater than that of the conventional farming methods in the baseline scenario and 2.3 to 3.3 times in the alternative scenario. The electricity demands of the vertical farm represented 85% of the carbon footprint in the baseline scenario and 66% in the alternative scenario, suggesting that a significant reduction in electricity use is required to compete with conventional farming methods from a carbon footprint perspective. If this could be achieved, vertical farming could become a valid component of future sustainable and food secure systems by its efficient use of land, high yields, minimal use of water, nutrients, pesticides and herbicides, and the ability to be located within or adjacent to cities.

Active plant-based systems are emerging technologies that aim to improve indoor air quality (IAQ). A person’s olfactory system is able to recognize the perceived odor intensity of various materials relatively well, and in many cases, the nose seems to be a better perceiver of pollutants than some equipment is. The aim of this study was to assess the odor coming out of two different test chambers in the SenseLab, where the participants were asked to evaluate blindly the level of acceptability, intensity, odor recognition, and preference at individual level with their noses. Two chambers were furnished with the same amount of new flooring material, and one of the chambers, Chamber A, also included an active plant-based system. The results showed that in general, the level of odor intensity was lower in Chamber B than in Chamber A, the level of acceptability was lower in Chamber A than in Chamber B, and the participants identified similar sources in both chambers. Finally, the preference was slightly higher for Chamber B over Chamber A. When people do not see the interior details of a room and have to rely on olfactory perception, they prefer a room without plants.

By the year 2040, Amsterdam aims to be independent from natural gas, and by 2050 the entire city needs to be carbon neutral; to meet these ambitions it is crucial to define a long-term strategy for the historical city centre, the area with the highest heat demand density. The inner city, designated as UNESCO World Heritage site, is now mainly served by natural gas boilers and an extensive energy renovation is difficult due the lack of space and the monumental status of many buildings. The project presented intends to support the municipality in identifying energy measures allowing for maximum impact while preserving the city’s historic and aesthetic values. By identifying key recommendations and collective measures, the work proposes a generic approach on energy retrofit decisions for historical buildings and it explores opportunities for sustainable heating solutions available locally, such as aquathermal energy from canal water, residual heat and other forms of low-temperature heat. The research contributes to develop knowledge for the gradual energy transition of the historical city centre of Amsterdam but ultimately, the planning approach can be applied to similar urban areas.

Deze publicatie is een weerslag van de uitkomsten van het KaDEr-project (Karakteristiek Duurzaam Erfgoed) dat de TU Delft in opdracht van en in samenwerking met de Provincie Gelderland heeft uitgevoerd. De lezer wordt meegenomen in de zoektocht om invulling te geven aan de relatie wetenschap, praktijk en beleid rondom duurzaam erfgoed op verschillende schaalniveaus. Aan de hand van acht bijdragen wordt gereflecteerd op het proces en de uitkomsten. De auteurs gaan in op een thema dat gedurende de afgelopen vier jaar aan de orde is geweest. Ook nemen zij stelling in met betrekking tot het debat dat naar aanleiding van dit thema gevoerd is en in veel gevallen nog verder gevoerd kan worden. Daarnaast hebben we een aantal meer zijdelings betrokkenen gevraagd om stelling te nemen met een uitspraak naar aanleiding van hun ervaringen tijdens het project.

Het KaDEr-project omvatte na een intensieve voorbereiding vier kalenderjaren. We denken dat op het onderdelen nog een vervolg behoeft. KaDEr staat dus voor Karakteristiek Duurzaam Erfgoed en in het project is gewerkt aan energetische duurzaamheid, financieel gezond perspectief, functioneel gebruik en het borgen kennis op lange termijn. Het project zelf werd opgebouwd rond vier Living Labs om theorie en praktijk aan elkaar te koppelen:
 Living Lab XL-Stad: Zutphen, Winterswijk en Elburg. Daarbij droegen we vanuit KaDEr bij aan een onderzoek naar Kerkenvisies en de Energietransitie voor diverse gemeenten;
 Living Lab L-Stad: Landgoederen, waar het Baaksebeek-gebied en Gelders Arcadië centraal stonden en het onderzoek resulteerde in de betreffende Ontwerpatlas;
 Living Lab M-Typologie: Kerken. Nationaal en regionaal een opgave die veel aandacht kreeg de afgelopen vier jaar. Specifiek keken wij vanuit KaDEr naar het functioneren van Energiescans en de Financiële Duurzaamheid aan de hand van de Eusebiuskerk in Arnhem en de Stevenskerk in Nijmegen;
 Living Lab S-Gebouw: Reuversweerd. Een (bouw)locatie die we vier jaar lang intensief hebben gevolgd en waar alle partijen veel van hebben geleerd. We hebben daarnaast onderzoek gedaan naar Afwegingsmodellen voor het verduurzamen van monumenten en de Gevolgen van het na-isoleren van monumenten met binnenisolatie.

Er werden binnen de Living Labs en deelonderzoeken diverse overkoepelende thema’s aan de orde gesteld en beproefd en daar is lering uitgetrokken. Dit heeft zich ook vertaald in het gaandeweg aanpassen van de aanpak en in de voorbereiding van nieuw beleid. Het geeft ook aanleiding om op lange termijn zaken anders te gaan doen. Wat er is geleerd en waar bijgestuurd kan worden is in acht hoofdstukken samengevat. We reflecteren op het proces van het KaDEr-project. We geven adviezen voor het bijsturen van beleid. Een visie op de toekomst, vanuit de provincie zelf, komt vervolgens aan de orde. Tijdens de vier jaren van uitvoering van het project is er op diverse schaalgebieden geacteerd.

Op het grote schaalgebied is met het Living Lab L-Gebied (Landgoederen), een koppeling met het Europese Innocastle project gemaakt. Daar hebben ook ontwerpprojecten met studenten plaatsgevonden en er is een Ontwerpatlas samengesteld.

Het leren van elkaar stond van het begin af aan bij het KaDEr-project centraal Samen met het Gelders Restauratie Centrum en de Monumentenwacht Gelderland zijn er onderwerpen via kennisoverdracht en workshops uitgewerkt. Via de koppeling van onderwijs aan bijvoorbeeld de stad werd in het Living Lab XL-Stad tussen studenten, gemeenteambtenaren en gebouweigenaren samengewerkt om van elkaar te leren.

Bijzonder is het kerkelijk erfgoed en de wijze waarop de Kerkenvisie als instrument een rol zal spelen bij de herontwikkeling van kerken. Dit is in de praktijk samen met drie gemeenten uit de Oost-Achterhoek uitgewerkt. In het KaDEr project komen zo theorie en praktijk mooi samen. Concreet kunnen en zullen beslissingen op het schaalgebied van gebouw en materiaalgebruik belangrijke gevolgen hebben voor opdrachtverlening, uitvoering, instandhouding en subsidieverstrekking aan erfgoed.

Door alle schalen heen richtten we steeds de blik op de toekomst. Daarbij kunnen we aan de energietransitie, die steeds urgenter wordt, niet voorbijgaan. Daar ligt zeker voor historische binnensteden een uitdaging. In twee gemeenten is hiervoor een inspirerende driedaagse ‘roadshow’ gehouden en is een energietransitie roadmap uitgewerkt.

Het KaDEr-project heeft geleid tot een veelheid aan leerzame ervaringen die nu in de nabije de toekomst kunnen inspireren en hun weerslag krijgen in provinciaal beleid dat een duurzame instandhouding van monumentaal erfgoed binnen de provincie Gelderland een stap verder brengt. Duurzame instandhouding biedt een visie op de lange termijn en is de basis voor een maatschappelijk verantwoorde werkwijze.

Het KaDEr-project kon alleen tot stand komen door een goede samenwerking tussen en vele krachtsinspanningen van vele partijen en personen. Namens de TU Delft bedankt de redactie van de publicatie KaDEr-stellingen alle betrokken personen bij de provincie Gelderland, de gemeenteambtenaren in Zutphen, Elburg, Winterswijk, Aalten en Oost-Gelre, de partners van de Gelderse Erfgoed Alliantie, de monumenteneigenaren en hun architecten, adviseurs en projectleiders op locatie en met name die op Reuversweerd. Daarnaast was het succes van KaDEr niet mogelijk geweest zonder de inzet van docenten, onderzoekers vanuit drie afdelingen van de faculteit Bouwkunde van de TU Delft en de vele studenten die vier jaar lang aan het project hebben gewerkt en het tot een inspirerend en leerzaam geheel hebben gemaakt.