Access to modern energy services derived from renewable sources is a prerequisite, not only for economic growth, rural development and sustainable development, but also for energy security and climate change mitigation. The least developed countries (LDCs) primarily use traditional biomass and have little access to commercial energy sources. They are more vulnerable to problems relating to energy security, air pollution, and the need for hard-cash currency to import fossil fuels. This thesis evaluates sugarcane-molasses bioethanol, a renewable energy source with the potential to be used as a transport fuel in Nepal. Sustainability aspects of molasses-based ethanol have been analyzed. Two important indicators for sustainability, viz. net energy and greenhouse gas (GHG) balances have been used to assess the appropriateness of bioethanol in the life cycle assessment (LCA) framework. This thesis has found that the production of bioethanol is energy-efficient in terms of the fossil fuel inputs required to produce it. Life cycle greenhouse gas (GHG) emissions from production and combustion are also lower than those of gasoline. The impacts of important physical and market parameters, such as sugar cane productivity, the use of fertilizers, energy consumption in different processes, and price have been observed in evaluating the sustainability aspects of bioethanol production. The production potential of bioethanol has been assessed. Concerns relating to the fuel vs. food debate, energy security, and air pollution have also been discussed. The thesis concludes that the major sustainability indicators for molasses ethanol in Nepal are in line with the goals of sustainable development. Thus, Nepal could be a good example for other LDCs when favorable governmental policy, institutional set-ups, and developmental cooperation from donor partners are in place to strengthen the development of renewable energy technologies. / QC 20101029

The recognition of nature in the resolution of societal challenges has been growing in relevance. This recognition has been associated with the development of new concepts from science and policy such as natural capital, ecosystem services, green infrastructure, and more recently Nature-Based Solutions (NBS). NBS intends to address societal challenges in an effective and adaptive form providing economic, social, and environmental benefits. The overall aim of this PhD thesis is to develop an environmental and economic assessment of NBS for highly urbanised territories based on rationales and models underpinning ecosystem services, urban/landscape ecology, and life cycle thinking approaches. This combined evaluation approach would help to better understand if NBS are cost-effective or not. The aim is developed according to four specific objectives. The first objective corresponds to the characterisation of NBS in relation to urban contexts and the problematics that they can help to address or mitigate. To achieve this objective a critical review on the study of the relationship between NBS, ecosystem services (ES) and urban challenges (UC) was developed. As a main output, a graph of plausible cause-effect relationships between NBS, ES and UC is obtained. The graph represents a first step to support sustainable urban planning, moving from problems (i.e. urban challenges) to actions (i.e. NBS) to resolutions (i.e. ES). The second objective corresponds to the definition of an adequate set of biophysical and monetary assessment methods and indicators to evaluate the value of NBS in urbanised contexts. To achieve this objective, a review of existing methods on ecosystem services valuation, life cycle cost analysis and life-cycle assessment are developed. The review takes into account specific constraints such as easiness to use and availability of data. At the end, potential methods and indicators were selected, which will be later integrated in the combined assessment framework. The third objective corresponds to the design of a combined assessment framework integrating methods from life cycle assessment, landscape/urban ecology and ecosystem services that quantifies the environmental and economic value of NBS informing about the cost-effectiveness of its entire life cycle. To achieve this objective, a conceptual framework is developed. From it, a system dynamics model of ecosystem (dis)services is developed and coupled with a life cycle assessment method. The combined evaluation is tested with a relevant NBS type (i.e. urban forest) in a case study in the metropolitan area of Madrid. The fourth objective is the development of a decision support (DSS) tool that integrates the assessment framework as part of iterative design processes in urban planning and landscape design. The DSS intends to enhance the interrelation between science, policy and planning/design. To achieve this objective a user-friendly web-based prototype DSS on NBS, called NBenefit$®, is developed. The prototype DSS provides the user a simple form of quantifying the provision of multiple ES and costs over the entire life cycle (implementation, operational life, and end-of-life) of NBS. This thesis contributed to the characterisation of NBS and its environmental and economic assessment to inform urban planning and landscape design processes, allowing decisions that are more informed. / Il riconoscimento della natura nella risoluzione delle sfide sociali è diventato sempre più importante. Questo riconoscimento è stato associato allo sviluppo di nuovi concetti provenienti dalla scienza e dalla politica, come il capitale naturale, i servizi ecosistemici, le infrastrutture verdi e, più recentemente, le soluzioni basate sulla natura (NBS). NBS intende affrontare le sfide della società in una forma efficace e adattabile fornendo benefici economici, sociali e ambientali. Lo scopo di ricerca di questa tesi di dottorato è quello di sviluppare una valutazione ambientale ed economica delle NBS per territori altamente urbanizzati basata su logiche e modelli che hanno alla base i servizi ecosistemici, l'ecologia urbana e paesaggistica e degli approcci di approcio life cycle. Questo quadro di valutazione combinato aiuterebbe a capire meglio se le NBS sono costo effetive e se contribuiscono a uno sviluppo resiliente e sostenibile. Questo scopo di ricerca è sviluppato secondo quattro obiettivi specifici. Il primo obiettivo corrisponde alla caratterizzazione delle NBS in relazione ai contesti urbani e alle problematiche che possono aiutare ad affrontare o mitigare. Per raggiungere questo obiettivo è stata sviluppata una revisione critica dell letteratura sullo studio della relazione tra NBS, servizi ecosistemici (ES) e sfide urbane (UC). Come risultato principale, si ottiene un grafico delle relazioni causa-effetto plausibili tra NBS, ES ed UC. Il grafico rappresenta un primo passo per supportare la pianificazione urbana sostenibile, passando dai problemi (es. UC) alle azioni (es. NBS) alle risoluzioni (es. ES). Il secondo obiettivo corrisponde alla definizione di un set di metodi e indicatori di valutazione biofisica e monetaria adeguate per valutare il valore della NBS in contesti urbanizzati. Per raggiungere questo obiettivo, viene sviluppata una revisione dei metodi esistenti sulla valutazione dei servizi ecosistemici, l'analisi dei costi del ciclo di vita e la valutazione del ciclo di vita. La revisione tiene conto di vincoli specifici come la facilità d'uso e la disponibilità dei dati. Alla fine, sono stati selezionati potenziali metodi e indicatori, che saranno successivamente integrati nel quadro di valutazione combinato. Il terzo obiettivo corrisponde alla progettazione del quadro di valutazione combinato, integrando metodi di valutazione del ciclo di vita, ecologia paesaggistica / urbana e servizi ecosistemici che quantifica il valore ambientale ed economico della NBS informando sull'efficacia in termini di costi del suo intero ciclo di vita. Per raggiungere questo obiettivo, prima viene sviluppato un quadro concettuale. Da esso, viene sviluppato un modello di dinamica di sistemi per calcolare i servizi (e disservici) ecosistemici, il quale è interrelazionato con un metodo di valutazione life cycle. Questa valutazione combinata viene testata con un tipo di NBS pertinente (foresta urbana) in un caso di studio nell'area metropolitana di Madrid. Il quarto obiettivo è lo sviluppo di uno strumento di supporto decisionale (DSS) che integri il quadro di valutazione come parte dei processi di progettazione iterativa nella pianificazione urbana e nella progettazione del paesaggio. Il DSS intende migliorare l'interrelazione tra scienza, politica e pianificazione / progettazione. Per raggiungere questo obiettivo è stato sviluppato Nbenefit$® un prototipo di DSS online per la valutazzione NBS di facile uso. Il prototipo DSS fornisce all'utente una forma semplice per quantificare multipli ES e costi (internalizatti o no) durante l'intero ciclo di vita (implementazione, vita operativa e fine vita) del NBS. In conclusione, questa tesi ha contribuito alla caratterizzazione di NBS e alla sua valutazione ambientale ed economica per informare i processi di pianificazione urbana e progettazione del paesaggio, consentendo decisioni più informate.

The key role of diet in both human health and environmental sustainability is well known. However, there is a lack of studies investigating the environmental impact of children’s dietary behavior. The aim of this observational study was to investigate the dietary environmental impact in a sample of primary school children living in Parma (Italy, n = 172, 8–10 years), in relation to their adherence to the Mediterranean diet (MD). Children completed a 3-day food record in both winter and spring. Dietary records were processed to obtain: (i) adherence to the MD and (ii) mean daily carbon and ecological footprints. Adherence to the MD was similar in winter and spring, with almost half of the participants showing a medium MD score. Carbon and ecological footprints were higher during winter, and the main dietary contributors were red and processed meat for both indexes. A small positive correlation was observed between adherence to the MD and total carbon and ecological footprints. This study provided the first analysis of the relationship between adherence to the MD and environmental impact of primary school children. Further research is needed to better investigate the environmental impact of primary school children’s diet and the possible relationship between the MD and environmental sustainability.

Purpose: Sustainability and sustainable manufacturing has grown in importance in recent years, and more legislation and demands are put on organizations to show how their operations affect the environment. Life cycle assessment is a proactive and efficient sustainability tool to report a company’s effects on the environment. Nevertheless, life cycle assessments of products and organizations are complex and require significant resources. Therefore, the purpose of this study is to investigate what potential barriers can occur within the initial acceptance phase when implementing life cycle assessment in the manufacturing industry. Method: This research project is a single case study of a Swedish manufacturing company. The theory was deduced from literature where eight internal factors influencing the implementation of tools and systems created a foundation for data collection and analysis. Five semi-structured interviews and unstructured observations have been conducted to collect empirical data. Findings: Nine second-order themes of factors influencing the project as barriers have been identified that construct the three aggregate dimensions ̈Lack of management support ̈, ̈Lack of resources ̈, and ̈Lack of interdepartmental coordination ̈. From the empirical findings, it is also suggested that the three aggregate dimensions are interrelated. The interrelationships are later used to find three change suggestions to mitigate the barriers by using the relationships between the dimensions and targeting as many barriers as possible. Namely, ̈educate top management ̈, ̈enhance the education of project participants ̈, and ̈spend more time on project planning ̈. Implications: This study provides a deeper and more detailed understanding of different barriers within the initial acceptance phase of a project. It also gives further insights into various interrelationships between barriers and how one dimension can influence the other in both positive and negative ways. Furthermore, this study's findings can guide managers and practitioners in preparing for a project aiming to implement a tool or a system. Limitations: As in all interpretative research, the interpretations of the empirical data are based on subjective thoughts influenced by the researcher’s positionality, the relationships with the participants, and preconceived perceptions. Furthermore, this research project is a single case study, and the results apply to this case. The findings cannot be statistically generalizable, meaning that the theories and themes created in this report should not be seen as absolute truths but instead as suggestive theories within the field.

Metal additive manufacturing (MAM) is a manufacturing technology experiencing a rapid expansion rate. Metal laser powder bed fusion (ML-PBF) is among the most popular techniques in this field. The environmental implications of it are often discussed in literature and compared to conventional manufacturing. However, the system in its entirety, from a cradle-to-gate perspective, has not seen intense scrutiny so far. A Life Cycle Assessment (LCA) often serves as the evaluation method when investigating environmental impacts; however, this method has been proven to be complex and time-consuming. Efforts are made to reduce this burden by, among others, developing streamlined LCA tools for MAM. This thesis presents three different life cycle assessments, each with different system boundaries, methodologies, and data qualities. In all of them, Global Warming Potential (GWP) and CO2 emissions are focused on. The aim of this thesis is to investigate how large the environmental impact of ML-PBF is when considering the whole system, and to compare this to a streamlined assessment, per kilogram of printed AlSi10Mg based on an average production scenario. The database ecoinvent v.3 and the characterization method ReCiPe 2016 midpoint (H) are used for the analysis with wider system boundaries in combination with specific data. Whereas a third-party streamlined LCA tool is used for the LCA with narrower system boundaries, using the specific energy content of the material. Previous research in the field of ML-PBF often neglects the impact of inert gas and attributes a large portion of the impact to processing electricity. Moreover, post-processing and machine impacts are usually not included in the system boundaries but have been advocated by many to be worth investigating. The results in this thesis show that in contrast to previous research, argon gas accounted for the biggest GWP and where process electricity accounted for less than half of argon. A system boundary expansion was also found to lead to an increase of nearly 230 % of CO2 eq emissions, making it significant to the analysis. Many minuscule factors such as machining, various losses, idle time, machine impact and compressed air contributed to this contrast. Combining this with an improvement and generalizability analysis showed that the global warming potential associated with ML-PBF can be lowered by more than 75 % through either altering the electricity mix or optimizing process parameters, both at the company and upstream. Additionally, it was discovered that the LCA calculation method, and deviations in data quality, contributed to a higher difference in the environmental impact than expanding the system boundaries.

The increasing demand for digitalization has spurred the need for novel and sustainable designs of electronic devices like sensors. Advanced additive print technologies, organic inks, and bio-based substrates in device fabrication exhibit promising potential for reducing energy and raw material consumption, thereby alleviating environmental impacts. One such innovation is the novel method of laser graphitization in designing devices like printed humidity sensors. This study focuses on evaluating the environmental impacts of implementing this novel technique in the field of printed electronics. In particular, the thesis conducts a cradle-to-gate life cycle assessment (LCA) of producing a resistive-type humidity sensor from a forest-based wood ink using laser graphitization. The sensor is based on the design that was demonstrated in the lab facilities at the Research Institutes of Sweden (RISE), Norrköping. The assessment is at a lab-scale production of making 1mm2 area of a laser-induced graphitized (LIG) sensor, excluding usage, disposal, or recycling phases. The results highlight impacts from electricity usage as the primary contributor to the overall environmental impacts, across the production process, followed by the impacts from material usage. The impact share distribution from these two hotspots identifies opportunities in the process that need to be prioritized for immediate actions. Sensitivity analyses varying the sensor layer thickness and the electricity mix of the laboratory facilities reveal insightful impact trends. The results from scenario analyses show the LIG sensor to have much lower environmental impacts than that of a sensor with silver electrodes and carbon-based sensing ink. They also show potential for achieving economies of scale from the mass production of LIG sensors. The data inventory for the processes and components of the sensor stands as a crucial part of this study, relying heavily on literature, assumptions, and proxy data. While these may reveal some uncertainties and limitations, the study nonetheless, serves as an important reference for future research concerning similar databases and a cradle-to-grave LCA of the sensor. / Den ökade efterfrågan för digitalisering har skapat behov av nya och hållbara designs av elektroniska enheter som sensorer. Avancerade lager printteknologier, organiskt bläck och biobaserat substrat i enhetstillverkning visar lovande potential för att reducera energi och rå materielkonsumtion och därmed minskning av miljöpåverkan. En sådan innovation är den nya metoden av lasergrafitisering i designenheter som printad fuktighetssensor. Denna studie har som fokus att utvärdera miljöpåverkan av ny teknik inom området tryckt elektronik. I synnerhet ska avhandlingen göra en livscykelanalys (LCA), från råvaruutvinning till slutprodukt av att producera en resistent fuktsensor från ett skogsbaserat träbläck genom lasergrafitisering. Sensorn är baserad på en design som var demonstrerad i en labbanläggning hos forskningsinstitutet RISE i Norrköping. Forskningen är analysen av laboratorieskalad produktion av 1mm2 lasergrafitiserad sensoryta, exklusive användning, bortskaffande och återvinningsfaser. Resultaten lyfter fram påverkan från elektronisk användning som den primära bidragaren till övergripande miljöpåverkan över hela produktionsprocessen, följd av påverkan från materiell användning. Påverkan från dessa två hotspots uppmärksamgör möjligheter i processen som är av prioritet för omedelbart åtgärdande. Känslighetsanalyser av de varierande sensorskiktens tjockhet och elektronisk mix i laboratoriums faciliteten, påvisar insiktsfulla påverkanstrender. Resultaten från scenarioanalyser visar att LIG sensorer har mycket lägre miljöpåverkan än sensorer med silverelektroner och kolbaserat avläsningsbläck. De visar också potential för att uppnå ekonomisk skalbarhet för massproducering av LIG-sensorer. Datalagring för processerna och komponenterna av sensorn står som kritisk del av studien, med en tung tillit på litteratur, antaganden och proxydata. Då dessa faktorer kan påvisa några osäkerheter och begränsningar så bidrar studien ändå som en viktig referens för framtida forskning berörande liknande databaser och en LCA från råvaruutvinning till sluthanteringsfasen av sensorn.

Oil palm dominates global oil production, trade, and consumption. Nigeria is one of the leading palm oil producers and consumers. A significant challenge of the palm oil industry is to reduce the environmental impacts (e.g. pollution and carbon footprint) and integrate a circular economy in operation. This study aims to comparatively quantify the environmental impacts of technologies used by different mills. We applied a life cycle assessment in the case of Nigeria. The study covers the reception and processing of fresh fruit bunch (FFB) to end-product palm oil. The inputs include generated empty fruit bunch (EFB), mesocarp fibre, palm kernel shell, palm oil mill effluent, diesel, water and all outputs to the environment for a functional unit of 1-tonne FFB. The results showed that large-scale mills perform worse (468 kg CO₂-eq per t FFB) than the semi-mechanised and smallholder mills in effects on climate change but better in the other impact categories, including human toxicity, ecotoxicity, and fine particulate matter formation. In large-scale mills, the climate change impacts decrease by 75% when the raw palm oil mill effluent (POME) is used in composting EFB. Similarly, climate change impacts reduce by 44% when biogas from POME substitutes diesel in the semi-mechanised and smallholder mills. We conclude that regulatory measures are needed to ensure improved management practices in the production processes. Particular attention should be paid to the generation and reuse of biomass and POME. This study provides a handy reference to assist the sustainable energy transition in Nigeria’s and other parts of sub-Saharan Africa’s oil palm industry to mitigate climate change and form a cleaner bioeconomy.

This study examines the ecological impact of exemplary processes for the feedstock recycling of waste fractions. It is shown that the material process efficiency of gasification and pyrolysis has a low impact on the greenhouse gas balance in the short term, but that high product yields are necessary in the long term to avoid an increasing climate impact. In a systemic context, different process routes of syngas and pyrolysis oil utilization are compared, and their efficiency and quantitative potential for greenhouse gas reduction compared to electricity-based alternatives of process direct heating of conventional processes and electrolysis-based process chains are classified. It is shown that direct utilization options with few process steps are ecologically more efficient. Feedstock recycling shows a similar reduction potential to direct heating, while the use of electrolysis-based process chains is inefficient but necessary to achieve systemic climate neutrality.:1. Introduction and outline 1 2. Life cycle assessment methodology 5 2.1. Previous LCA investigation on feedstock recycling 7 2.2. Assessment scope 9 2.3. Attributional vs. consequential LCI modelling 11 2.4. Inventory modelling consistency 12 2.5. Prospective technology assessment 13 2.6. Conclusions for the applied methodology 14 3. Process description and modelling 16 3.1. Feedstock recycling technologies 18 3.1.1. Gasification 18 3.1.2. Syngas conditioning and purification 23 3.1.3. Pyrolysis 29 3.1.4. Pyrolysis oil hydroprocessing 32 3.2. Chemical production technologies 34 3.2.1. Steam cracking 35 3.2.2. Catalytic reforming 37 3.2.3. Olefin and BTX recovery 38 3.2.4. Conventional syngas production 41 3.2.5. Methanol and methanol-based synthesis 43 3.2.6. Ammonia synthesis 48 3.3. Electric power integration options 49 3.4. Conventional waste treatment processes 53 3.4.1. Mechanical biological treatment and material recovery 54 3.4.2. Waste incineration 57 3.5. Utility processes and process chain balancing 59 3.6. Electricity and heat supply modelling 65 4. Individual assessment of feedstock recycling processes 68 4.1. Goal and scope definition 68 4.2. Life cycle inventory 68 4.3. Impact assessment 72 4.4. Interpretation 80 5. System-based assessment of feedstock recycling processes 82 5.1. Goal and scope definition 82 5.2. Life cycle inventory 86 5.2.1. Utility, background system inventory and system integration 88 5.2.2. Assessment scenario definition and parameter variation 90 5.3. Impact assessment 93 5.3.1. Framework Status Quo (FSQ) 93 5.3.2. Framework Energy Integration (FEI) 99 5.4. Interpretation 106 6. Summary and conclusion 109 6.1. Results 110 6.2. Recommendations and outlook 111 References 113 Supplementary Material 136

The United Nations projects that by the year 2050, there will be as many as 9.7 billion people on earth (UN, 2019). Along with the world population growth, the demand for food production will be increased. On the other side, agriculture plays a crucial role in global warming, increasing food production challenges. Thus, more sustainable methods should be chosen to respond to population demand and decrease the impact of agricultural activities on climate change. One of these alternative methods is Urban farming, specifically hydroponic vertical farming, in which the food is produced indoors under exceptional conditions as using artificial lighting and less water. Hydroponic vertical farming has several benefits, higher production per area, a controlled environment, less land usage, less water consumption, etc.  Vertical farms use LEDs as lightning sources to help photosynthesis; LEDs produce a massive amount of excess heat, which will be released to the environment and impact global warming. Therefore, a solution should be found to use the excess heat for other purposes instead of releasing it into the environment. In this study, the environmental performance of SweGreen’s hydroponic vertical farm will be assessed using a Life cycle assessment. The SweGreen hydroponic farm is located in a basement of a host building in Stockholm, Sweden. There is a symbiotic network between the farm and the host building where the farm provides the building with excess heat produced from the LEDs and, in return, gains carbon dioxide from the building. The result of this study shows that symbiotic network can decrease the impact of agriculture and excess produced heat, where the required heat for the building will be replaced from district heating by the produced excess heat. The symbiotic development between the host building and the farm will benefit the farm in various aspects and highlights the importance of urban symbiosis to reduce the impacts. / Enligt prognoser av Förenta Nationerna ska leva 9.7 billion människor på jorden till och med 2050 (FN, 2019). Världens befolkningstillväxt orsakar ökade efterfrågningar på livsmedelsproduktion. Tillsammans med de här ökade efterfrågningarna behov av jordbruk och dess produktioner ska ökas. De ökningarna skaffar seriösa utmaningar och oror Global uppvärmning. Därför behöver världen nya hållbara metoder att kunna hitta bra lösningar som minskas sådana påverkningar på klimatförändringarna. En av de nya hållbara metoderna är Urban Farming och speciellt hydroponiskt vertikalt jordbruk. Med denna metod livsmedel produceras inomhus med hjälpen av konstgjord belysning. Under de kontrollerade situationer ska mötas högre produktion per område och mindre vattenkonsumtion.   Lysdioder (LEDs) bidrar behov av belysning för fotosyntesprocess i Vertikal Farms. Dock släpper LEDs ut en enorm mängd överskottsvärme i miljön som har en direkt påverkan på globala uppvärmningen. En bra lösning för detta problem är att hittas ett sätt att använda överskottsvärmen för andra ändamål. I den här studien ska granskas miljöprestandan för SweGreen’s hydroponic vertikal farm med hjälp av en livscykelanalys. Gården ligger i Stockholm, Sverige. Det finns ett symbiotiskt nätverk mellan gården och vårdbyggnaden där levereras LEDs överskottsvärmen för byggnaden och fås koldioxid från den.   Resultatet av denna studie provar att symbiotiska nätverken kan minska påverkan av producerad överskottsvärmen på klimatförändringarna och Global uppvärmning.Symbiotiska utvecklingen mellan vårdbyggnaden och gården är intressant från olika aspekter och är viktig att minska påverkningarna på miljön.

The Swedish government introduced on Monday 3rd of January 2022, a new bill to promote buildings’ sustainability. Assigned by the government, the bill was developed by the Swedish National Board of Housing, Building and Planning (Boverket). When applying the Life Cycle Assessment (LCA) framework, developers must now declare the greenhouse gas emissions resulting from the production and construction processes of their proposed construction, using the Global Warming Potential (GWP) indicator. Boverket is currently planning for the climate declaration’s evolution regarding limit values, building components, and the life cycle stages considered. Use and end-of life stages are facing major challenges as they are prone to high uncertainty, especially due to projections into the future. Currently, no International, European, nor national guidelines or norms agree on calculation methods for maintenance and replacement processes. However, methodological choices related to system boundaries, as well as maintenance and replacement needs and frequencies, significantly affect these calculation results.  This master thesis, focusing on maintenance and replacement processes LCA calculations, is a follow up of KTH research. Mandated by Boverket, it developed a national database for buildings’ components and reference values for production and construction processes. This study uses the same sample of buildings, representative of recent Swedish buildings stock for several functions, such as schools, apartment buildings, and offices. In line with Boverket’s plan, a method of calculation is developed based on literature for the maintenance and replacement processes of buildings’ roofs and façades. The relevance of considering these processes in buildings’ climate declarations is addressed. In addition, this study investigates methodological and practical challenges in a Swedish context. Specifically, it assesses the effect of calculation method on the consideration of replacement components’ environmental impact and service lives. Practical difficulties regarding implementation of these LCA processes are also discussed.  This study concludes on the relevance of considering replacement and maintenance processes in buildings’ climate declarations to avoid misleading conclusions over sustainable buildings designs. The influence of methodological choices is confirmed, and the need for harmonisation for clear definitions and guidelines for maintenance and replacement processes is emphasised. The study also identifies practical data requirements and reflects on the requirement of LCA internalization in the construction sector, from the early steps of buildings’ conception and the inclusion of all stakeholders, especially from industry. / Måndagen den 3 januari 2022 framförde regeringen ett nytt lagförslag i syfte att främja byggnaders hållbarhet. Propositionen har i uppdrag av regeringen tagits fram av Boverket. När utvecklarna tillämpar ramverket för livscykelanalys (LCA) måste de nu deklarera de utsläpp av växthusgaser som härrör från produktions- och byggprocesserna för den föreslagna konstruktionen, detta med hjälp av indikatorn global uppvärmningspotential (GWP). Boverket planerar i nuläget för klimatdeklarationens utveckling avseende gränsvärden, byggkomponenter samt de livscykelstadierna som beaktas. Användning- och uttändestadier står inför stora utmaningar eftersom de är benägna att ha hög osäkerhet, särskilt på grund av framtida prognoser. För närvarande är inga internationella, europeiska eller nationella riktlinjer eller normer överens om beräkningsmetoder för underhålls- och ersättningsprocesser. Metodval relaterade till systemgränser, liksom underhåll, utbytesbehov och frekvenser, påverkar dock dessa beräkningsresultat avsevärt.  Studien är en uppföljning av KTH:s forskning, på uppdrag av Boverket, om utvecklingen av en nationell databas för byggnaders komponenter samt referensvärden för produktions- och byggprocesser. Samma urval av byggnader används, representativt för den senaste tidens svenska byggnadsbestånd, för flera funktioner, såsom skolor, flerbostadshus och kontor. I linje med Boverkets plan tas en beräkningsmetod fram för underhålls- och utbytesprocesser av byggnaders tak och fasader, detta baserat på litteraturstudier. Den tar upp relevansen av att beakta dessa processer i byggnadernas klimatdeklarationer. Dessutom undersöker denna studi.e. metodologiska och praktiska utmaningar i ett svenskt sammanhang. Närmare bestämt bedöms beräkningsmetodens effekt på hänsynen till ersättningskomponenters miljöpåverkan och livslängd. De praktiska svårigheterna med genomförandet av dessa LCA- processer diskuteras också.  Denna studi.e. drar slutsatsen om relevansen av att överväga ersättnings- och underhållsprocesser i byggnaders klimatdeklaration för att undvika vilseledande slutsatser om byggnaders hållbara utformning. Metodvalens inverkan bekräftas, och behovet av harmonisering av tydliga definitioner samt riktlinjer för underhålls- och ersättningsprocesser betonas. Studien identifierar också praktiska datakrav och reflekterar över kravet på LCA- internalisering inom byggsektorn från de tidiga stegen i byggnaders utformning och inkludering av alla intressenter, särskilt från industrin.