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Otakaari 1 grandhall. Photo: Esa Kapila
 

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Sustainability of Bio-based Plastics and Composites
(2024) Äkräs, Laura
 School of Chemical Technology | Doctoral dissertation (article-based)
Plastics undoubtedly are indispensable and widespread commodities of the modern world, commonly found in a vast range of applications. Nonetheless, the awareness and concerns about the environmental impacts associated with the fossil-based plastics - that is, climate change, depletion of fossil resources, and plastic debris - are continuously on the rise. To efficaciously abate these impacts, different disciplines and approaches are needed to be used in a complementary manner, with contributions derived from the development of novel, bio-based materials as well as analytical and legal tools. To this end, in the present doctoral dissertation, approaches of material synthesis, multi-criteria decision-making (MCDM) analysis, life cycle assessment (LCA), and instruments of private law were combined in an interdisciplinary manner to analyze the selected set of bio-based plastics and composites. Accordingly, the MCDM analysis techniques of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Simple Additive Weighting (SAW) were applied to identify the most suitable and interesting raw materials to produce bio-based plastics, which results were further utilized to synthesize a set of selected biocomposites in the laboratory conditions. A widely used methodology of LCA was, subsequently, employed to explore the environmental impacts derived from the developed biocomposites, with a focus on the impact categories of carbon footprint as well as agricultural-related indicators of acidification, eutrophication, and land use. Finally, the potential of a range of private law instruments - ecolabels, certification marks, and European certification marks (EUCM) - was explored as vessels to convey the sustainability information derived from the results of LCA.  MCDM analysis revealed that the cultivation of castor beans and extraction of subsequent castor oil possessed the highest environmental impacts in comparison with other alternatives, despite the popularity of castor oil as a building block for commercial, bio-based polyamides (PAs). Consequently, varying concentrations of biofillers of starch and biochar were blended with the selected, neat PA- and polylactic acid (PLA) -matrices, which substantially reduced the carbon footprint and agricultural-related impacts of the plain plastics. Lastly, integration of LCA-results with different private law instruments were found not only to strengthen the sustainability information they convey, but also to possess potential to shape the behaviour of the targeted stakeholders. Overall, despite the need to enhance certainty, credibility, and comprehensivity of the applied data and methodologies, the present doctoral dissertation offers valuable information about the sustainability of the selected bio-based plastics and composites. 
Modelling, design, and control of hybrid ground source heat pump system coupled with district heating in an educational building complex
(2025) Xue, Tianchen
 School of Engineering | Doctoral dissertation (article-based)
Ground source heat pumps (GSHPs) are an efficient solution for the decarbonization of building heating and cooling systems. They utilize borehole fields to extract heat from the ground for heating. The borehole fields can also supply free cooling energy for buildings in cold climates. Since buildings are heating-dominated in cold climates, conventional GSHPs face significant underground thermal imbalances. This often requires larger and more costly borehole fields to sustain high operating performance. An effective way to improve operational viability and financial sustainability is to integrate GSHPs with backup heating sources, such as district heating (DH), creating a hybrid GSHP system. This thesis investigated the modeling, design, and control of a hybrid GSHP system coupled with DH in an educational building complex based on simulation studies. The simplified modeling of an asymmetric-layout borehole field was validated using onsite brine temperature measurements. High-performing design methods for the hybrid GSHP system were explored by adjusting key design parameters, such as air handling unit (AHU) cooling water temperature level, indoor air temperature heating and cooling setpoints, GSHP design heating power, borehole number, and borehole depth. Regarding control, a cost-effective control strategy was developed to reduce system energy costs. The effects of power limitations, the input coefficient of performance (COP) value, and the control time horizon within the control algorithm were analyzed. Furthermore, a demand response control strategy was implemented to utilize the thermal storage of building thermal mass, investigating various DR control algorithms and parameters. Results indicate the simplified-geometry borehole field models can predict average inlet and outlet brine temperatures within a deviation of 1 °C from measured data and can also reduce computational time by up to 72% compared to the detailed models. Compared to the reference hybrid GSHP system design, increasing AHU cooling water temperature level and using lower indoor air temperature heating and cooling setpoints can raise the minimum outlet brine temperature from –6 °C to –3 °C over a 25-year lifetime, while also slightly improving the average heat pump COP in the last heating season. To ensure non-freezing boreholes, it is still necessary to increase the overall borehole length or reduce the GSHP design heating power. Compared to a GSHP-prioritized control strategy, the cost-effective control strategy, which incorporates power limitations and optimizes input COP values for control, achieves a 6.4% reduction in annual energy costs with hourly electricity and DH pricing. Implementing the DR control strategy to space heating enhances energy flexibilities for both electricity and DH networks without compromising indoor thermal comfort. Among studied DR control algorithms, the dual-price DR algorithm yields the highest cost savings. When it is combined with the cost-effective control, the hybrid GSHP system can achieve by up to a 10.8% reduction in annual energy costs with hourly electricity and DH pricing.
Enhancing urban vitality : integrating traditional metrics with big data and socio-economic insights
(2024) Osunkoya, Kofoworola Modupe; Partanen, Jenni
 A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
A city is an intricate system where interactions between transport, land use, the environment, and the population occur at various scales. This complexity makes it challenging to predict and govern these interactions. However, big data on human activity patterns allows researchers to discover dynamic, temporary patterns in the activity landscape and understand the choreographies of people’s behavior to enhance urban areas’ vitality through planning. In this article, we hypothesized that a higher diversity of urban spatio-functional and socio-economic features indicates higher urban vitality in Tallinn, Estonia. We explored multi-sourced indexes to interpret this formation of urban vitality using complex agent variables of location, cluster, diversity, and similar actors generating self-organizing patterns of urban life. We used functional and morphological components and socio-economic data identified as traditional, ‘slow’ vitality measures (SM), and mobile phone location data as dynamic metrics (DM), respectively. We analyzed them in a geographic information system (GIS) environment to measure the types of spatial configurations, temporal variation of vital places, and their correlation. The results indicate a positive correlation (r= 0.5116) between the slow metrics and the high mobile phone activity. These correlations demonstrate that cell phone data provides a detailed and accurate view of people’s daily rhythms and choreographies. The diversity indicators offer a new method to interpret urban vitality in cities and make planning decisions that support its emergence.
A tale of four studios: Evolving planning and architecture education towards mixed modality in a post-pandemic world
(2024-07) Hewidy, Hossam; Purkarthofer, Eva; Eräranta, Susa
 A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The COVID-19 pandemic imposed urgent challenges for educational institutions. The sudden shift from on-site teaching to online distance learning offered the possibility to examine new settings of the studio, a core element of planning and architecture education. Although the pandemic is now over, online learning has secured a fixed place in university education, and consequently, educational institutions need to reconsider studio education based on the lessons learned during the pandemic. Through studying four studios taught at Aalto University, Finland, in 2020 and 2021, this article examines student-teacher experiences, and proposes opportunities for evolving studio education. The findings show that distance learning has in general sustained the objectives of studio education. However, challenges remain especially regarding the social aspects of learning. The degree of success of online teaching varied greatly depending on the tasks and the orientation of the studio (design or strategy). Technological aids and devices also had an influence on fulfilling the pedagogical objectives of learning. Professional socialization was highly affected by the online environment both in design and planning studios and the architectural representation witnessed difficulties specifically in design studios. To evolve the studio setting, the article suggests a mixed modality model supporting the social dimension of studio teaching by combining on-site and online learning activities to enrich the learning process. Such a model can harmonize the intended learning objectives and activities with the teaching methods and modality, thus improving the social dimension of studio teaching.
Human, All Too Human: Do We Lose Free Spirit in the Digital Age?
(2025-01-09) Sushchenko, Aleksandra; Yatsenko, Olena
 A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This article engages in a philosophical dialogue with Nietzsche’s views on the discourse of power, examining the rising concerns surrounding the digitization and algorithmization of society in the context of advancements in robotics and AI. It highlights human agency through Nietzsche’s perspective on creative culture as a space for individuals to actively engage in free thought and action, with responsibility as the key foundation of social resilience. By approaching metaphysical systems through the discourse of power, Nietzsche emphasizes that humanity can overcome system-driven delusions through reason, which he understands as the form of critical reflection existing solely in the domain of creative culture. We assert that Nietzsche’s arguments offer alternative perspectives on the ethics of technology, particularly through the dialectics of “weak and strong types of behavior”. It allows us to explore how resistance—existing in creative culture—can serve as a vital counterbalance to the mechanization of social life. Such dialectics provide a strong foundation for supporting algorithmic resistance by inspiring ethical frameworks rooted in individuality and emotional depth, challenging the homogenizing tendencies of digitization and algorithmization. It emphasizes the importance of subjective stories, emotions, and compassion, forming human-centered ethical principles that preserve the richness of individual experiences and protect against system-driven delusions.