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A mixed-method approach to understand energy-related occupant behavior and everyday practices in multi-story residential buildings
Get PDFIn recent decades, attention has increased to investigating energy-related occupant behavior and everyday practices to contribute to bridging buildings’ well-known energy performance gap. Understanding some of the mechanisms behind this gap, such as, the energy-related decisions and/or shared heating practices among occupants, could foster effective strategies for promoting energy efficiency. However, such mechanisms are not yet well identified, especially in residential contexts and low-energy buildings, where the relative impact of occupants’ behavior is predominant. Aiming to contribute to tackling this knowledge gap, this article presents the results of a sequential mixed-method approach, combining quantitative and qualitative methods to study the energy-related practices of six occupants in five households of a multi-story low-energy household block located in Denmark. The households are monitored with sensors measuring heating use, room temperature, and heating setpoint temperature, enabling to capture human-building interactions at a high resolution. The quantitative analyses (data analyses) showed substantial differences in heating behavior and practices and thermal comfort preferences across households and over the seasons (from 90 to 301 heating days a year). Nevertheless, the qualitative analysis (semi-structured interviews) indicates shared practices regarding the use of the feedback display installed in each dwelling. This suggests that despite individual differences in preferences and habits, households living in the same building still share heating practices. The findings underpin the importance of the building managers’ support and trust in improving feedback implementation and ensuring heating practices to support building energy efficiency.</p
A techno-economic assessment framework for district-scale thermal source networks serving existing buildings
Get PDFThermal Source Network (TSN)s are ultra-low-temperature district heating systems that use decentralised heat pumps, offering significant potential for urban heating decarbonization. While previous research has extensively examined the application of TSNs in newly constructed, energy-efficient buildings, studies on their feasibility in older, inefficient building stocks remain limited and less systematically explored. This study introduces a techno-economic framework to evaluate the feasibility of connecting districts with older, low-rated buildings to TSNs. The framework provides a systematic approach to assess economic viability, using Levelised Cost of Heat (LCOH) as a financial metric, and environmental performance. By integrating GIS-based Energy Performance Certificates (EPC) data and building archetype models, it estimates district heat demand, calculates the necessary network and equipment capacities, and evaluates the economic and environmental impacts of TSNs at different building-level temperatures. The study also reviews strategies for reducing Space Heating Water Temperature (SHWT) at the building level, including their costs and potential to achieve lower SHWT targets. The analysis compares TSNs with other heat electrification scenarios, including centralised district heating with Ground-Source Heat Pump (GSHP) and Air-Source Heat Pump (ASHP), and individual ASHPs. The results indicate that TSNs are the most economically attractive solution when substations are owned by the district heating company, mainly due to the lower electricity prices for businesses in the studied case. In contrast, centralised district heating becomes the most viable option when substations are owned by households, which incur higher electricity prices. TSNs also provide significant environmental advantages, with lower operational carbon footprints compared to other alternatives. For TSNs, every 1 ∘C reduction in building SHWT reduces the LCOH with environmental externalities by 1.99 to 2.24 €/MWhheat, depending on the system configuration. This study evaluates ownership and pricing policies, demonstrating how centralised ownership and business electricity tariffs enhance the economic feasibility of TSNs. By addressing an important gap in the literature, this study offers a structured approach for policymakers to enhance the feasibility of TSNs in older areas through targeted retrofitting and heating system optimization, supporting their adoption as a scalable and sustainable solution for urban heating systems, particularly in districts with ageing building stocks.</p
Patient Perspectives on the 'Future Patient' Telerehabilitation Program for Atrial Fibrillation:Qualitative Study
No full textBackground: Atrial fibrillation (AF) is a prevalent chronic condition with increasing incidence worldwide. AF increases the risks of stroke, heart failure, and myocardial infarction and imposes a substantial burden on the health care system. Cardiac rehabilitation programs, while effective, often have low patient adherence. Recent evidence suggests that cardiac telerehabilitation, where patients are given home monitoring devices, could enhance adherence and outcomes. The program “Future Patient—Telerehabilitation of Patients with AF” (FP-AF) was created to assess the effects and potential benefits of cardiac telerehabilitation on patients with AF. Objective: The objective of this study is to explore the experiences of patients participating in the FP-AF program. Methods: This qualitative sub-study is part of the multicenter, randomized controlled FP-AF trial, which included 208 patients. Semi-structured interviews were conducted on 14 patients, randomly selected from participants in the intervention arm of the FP-AF program. The patient interviews, guided by self-determination theory, focused on patients’ experiences with the FP-AF program, including the use of telerehabilitation technologies and a web-based portal called the “HeartPortal.” Interview responses were analyzed using NVivo software (version 14.0; QSR International), with thematic coding based on interview guides and methodological guidance elaborated by Brinkmann & Kvale. The study adhered to ethical guidelines, with informed consent obtained from all participants. Results: Based on the interviews, the following themes were identified: the home monitoring devices are viewed positively by the patients; the HeartPortal is a useful digital toolbox; patients develop new coping strategies for living with AF; the measured values are useful for the patients; the community of practice is beneficial; and the FP-AF program creates a sense of security. Conclusions: Participation in the FP-AF program enhanced patients’ sense of security, empowerment, and knowledge about AF. This improvement was due largely to a combination of patients’ use of the HeartPortal and the educational sessions at health care centers. Telerehabilitation for patients with AF may be a useful way of researching this group of patients with a focus on rehabilitation and may be an effective means of offering rehabilitation to this group in the future.</p
Efficacy of a Self-monitoring Traffic Light for Weight Control in Patients with Heart Failure in a Telerehabilitation Program
No full textHeart Failure (HF), a life-threatening condition, poses a significant global health challenge. Monitoring patients’ symptoms and weight is essential, as key HF symptoms tend to cause weight gain and indicate decompensation. The aim of this study is to evaluate the effect of a traffic light algorithm on home monitoring of weight in HF patients. In the project ‘Future Patient – Telerehabilitation of Patients with HF II’, HF patients monitored their weight, blood pressure, pulse, steps, and sleep at home. Data has been transmitted to the web portal HeartPortal. Each measurement in the weight overview was color-coded using a traffic light algorithm that would indicate whether the patient’s weight changes were within the acceptable range. The patients’ monitoring data, along with their questionnaire responses, were then analyzed and interpreted. The analysis of the data suggests that the traffic light was effective in alerting patients to weight changes according to clinical guidelines. Most of the patients noticed the traffic light and understood the significance of the colors. The study demonstrates that the traffic light is an effective tool for alerting HF patients to weight fluctuations. The traffic light provides early warnings, enabling timely interventions, and encouraging patient engagement in understanding the causes behind weight changes
The Gurit98m:a detailed open-source modern offshore wind turbine blade structural model with optimization applications
No full textOne of the primary challenges in wind turbine blade optimization research is creating a model that is representative of current state-of-the-art blade structures. This task is complex and time-consuming, given the multiple disciplines involved in blade design and the large-scale of such blades, which now exceed 100 milliseconds in length. Moreover, the procedures used to establish the models are typically not scientific, implying a significant risk associated with blade research, as substantial resources spent on developing models are wasted if the actual research ideas are ineffective in practice. To reduce the risk and accelerate research efforts in the scientific community, this work introduces an open-source large offshore wind turbine blade model and demonstrates application in structural optimization research. A detailed thickness optimization of the blade’s constituent material layers is performed, with the objective of minimizing cost while accounting for buckling, tip displacement, and static failure constraints, which are many of the key design criteria according to design certification guidelines. A semi-analytical adjoint design sensitivity analysis approach is used to efficiently compute problem sensitivities, allowing inclusion of the constraints for up to twelve extreme load cases each. Application of the presented optimization strategy reduces cost by 17% and mass by 25%, while maintaining all constraints within allowable limits. The change from initial to optimized laminate thickness distribution is shown, and the optimized function response is demonstrated on the blade, showing the material is at its load-carrying limit throughout the entire blade, highlighting the efficiency of the achieved design.</p
Compressibility characterization of organic and inorganic fouling by the 3ω method
Get PDFMembrane fouling is a major problem that reduces the sustainability and efficiency of separation processes. In this study, an online fouling monitoring technique using the 3ω method was investigated to distinguish between different compositions and compactness of fouling layers based on their distinct thermal properties. Dead-end filtration of kaolin or humic acid suspensions were performed to represent both an inorganic and organic fouling while the 3ω signals were measured during the fouling layer build-up. The formation of an inorganic fouling layer reduced the 3ω signal due to its higher thermal conductivity compared to water. Limited compaction of the kaolin fouling layer was observed by elevating the pressure. In the organic fouling layer on the other hand, the 3ω signal showed higher values than for water, due to the insulating effect of organic materials. It was also possible to detect the compaction of the fouling layer, which was in good agreement with measurements of specific cake resistance and water content. The 3ω method can potentially characterize fouling layers in a non-destructive way at a distance ranging from micrometers to a few millimeters from the surface of the membrane, thus providing operators with insights for tailored fouling mitigation strategies
Community-Based Futuring: Towards Alternative and Meaningful Green Energy-Enabled Rural Futures
Get PDFAutonomous Control of Electric Vehicles using Voltage Droop
No full textThe surge in electric vehicles (EVs) in Denmark challenges the country’s residential low-voltage (LV) distribution system. In particular, it increases the demand for home EV charging significantly and possibly overloads the LV grid. This study analyzes the impact of EV charging integration on Denmark’s residential distribution networks. A residential grid comprising 67 households powered by a 630 kVA transformer is studied using DiGSILENT PowerFactory. With the assumption of simultaneous charging of all EVs, the transformer can be heavily loaded up to 147.2%. Thus, a voltage-droop based autonomous control approach is adopted, where the EV charging power is dynamically adjusted based on the point-of-connection voltage of each charger instead of the fixed rated power. This strategy eliminates overloading of the transformers and cables, ensuring they operate within a pre-set limit of 80%. Voltage drops are mitigated within the acceptable safety range of ±10% from normal voltage. These results highlight the effectiveness of the droop control strategy in managing EV charging power. Finally, it exemplifies the benefits of intelligent EV charging systems in Horizon 2020 EU Projects like SERENE and SUSTENANCE. The findings underscore the necessity to integrate smart control mechanisms, consider reinforcing grids, and promote active consumer participation to meet the rising demand for a low-carbon future.</p
Tilblivelsen af et Sted for Væren
No full textEssayet argumenterer for materialiteters afgørende betydning i tilblivelsen af steder ved at analysere artefakters betydning i skabelsen af Möllegaarden, som et tredje sted for væren, hvor nøje udvalgte artefakter ekkoer tidsrytmer fra 1970’erne. Væren reflekteres her med hjælp fra Rosas (2014) betoning af tidsrytmer og resonans, koblet med Oldenburgs (1997) tredjesstedsbegreb. Muligheden for væren opstår i mødet mellem tredjestedets kuratering, deltagernes habitus med indlejrede tidsrytmer og stedets evne til at decelerere samme ved at invitere lokale +50-årige til en tredjestedssamspilsform (brætspil og kortspil), som initierer andre ‘pulsslag’. Overraskende viser det sig at hygge her får en central plads. Facetterne af stedets tilblivelse kortlægges gennem Nexus Analysens (NA) begreber discourse in place, historical bodies og interaction order (Scollon & Scollon, 2004) for at indfange brydningen mellem sted, personer og samspilsformer, hvor artefakter agerer som medierende midler