bluuebunny/crossref_metadata_2025 huggingface dataset:
How understanding large language models can inform the use of ChatGPT in physics education
Authors: Polverini Giulia , Gregorcic Bor
Published: December 2023

The paper aims to fulfil three main functions: (1) to serve as an introduction for the physics education community to the functioning of large language models (LLMs), (2) to present a series of illustrative examples demonstrating how prompt-engineering techniques can impact LLMs performance on conceptual physics tasks and (3) to discuss potential implications of the understanding of LLMs and prompt engineering for physics teaching and learning. We first summarise existing research on the performance of a popular LLM-based chatbot (ChatGPT) on physics tasks. We then give a basic account of how LLMs work, illustrate essential features of their functioning, and discuss their strengths and limitations. Equipped with this knowledge, we discuss some challenges with generating useful output withChatGPT-4in the context of introductory physics, paying special attention to conceptual questions and problems. We then provide a condensed overview of relevant literature on prompt engineering and demonstrate through illustrative examples how selected prompt-engineering techniques can be employed to improveChatGPT-4’s output on conceptual introductory physics problems. Qualitatively studying these examples provides additional insights into ChatGPT’s functioning and its utility in physics problem-solving. Finally, we consider how insights from the paper can inform the use of LLMs in the teaching and learning of physics.
Liquid treatment with a plasma jet surrounded by a gas shield: effect of the treated substrate and gas shield geometry on the plasma effluent conditions
Authors: Heirman Pepijn , Verloy Ruben , Baroen Jana , Privat-Maldonado Angela , Smits Evelien , Bogaerts Annemie
Published: December 2023

The treatment of a well plate by an atmospheric pressure plasma jet is common for in vitro plasma medicine research. Here, reactive species are largely produced through the mixing of the jet effluent with the surrounding atmosphere. This mixing can be influenced not only by the ambient conditions, but also by the geometry of the treated well. To limit this influence and control the atmosphere, a shielding gas is sometimes applied. However, the interplay between the gas shield and the well geometry has not been investigated. In this work, we developed a 2D-axisymmetric computational fluid dynamics model of the kINPen plasma jet, to study the mixing of the jet effluent with the surrounding atmosphere, with and without gas shield. Our computational and experimental results show that the choice of well type can have a significant influence on the effluent conditions, as well as on the effectiveness of the gas shield. Furthermore, the geometry of the shielding gas device can substantially influence the mixing as well. Our results provide a deeper understanding of how the choice of setup geometry can influence the plasma treatment, even when all other operating parameters are unchanged.
High performance photodetector based on CdS/CdS0.42Se0.58 nanobelts heterojunction
Authors: Ma Ran , Tan Qiuhong , Liu Yingkai , Wang Qianjin
Published: December 2023

The ternary alloy CdS
x
Se1−x
combines the physical properties of CdS and CdSe, and its band gap can be adjusted by changing the element composition. The alloy has charming photoelectric properties as well as potential application value in photoelectric devices. In this work, the CdS/CdS0.42Se0.58 nanobelt (NB) heterojunction device was prepared by chemical vapor deposition combined with a typical dry transfer technique. The heterojunction photodetector shows high light switching ratio of 6.79 × 104, large spectral responsivity of 1260 A W−1, high external quantum efficiency of 2.66 × 105% and large detectivity of 7.19 × 1015cm Hz1/2 W−1 under 590 nm illumination and 3 V bias. Its rise and decay time is about 45/90 μs. The performance of the heterojunction photodetector was comparable or even better than that of other CdS(Se) based photodetector device. The results indicate that the CdS/CdS0.42Se0.58 NB heterojunction possesses a promising potential application in high performance photodetectors.
Silicon nanowire FET biosensor and its application in acute myocardial infarction
Authors: Zhang J , Xiao M , Su RG , Kong T , Zhang D , Zhou CW , Cheng GS
Published: December 2023

Over the last two decades, silicon nanowire field-effect transistors (SiNW-FETs) with prominent merits of high surface-to-volume ratio, excellent biocompatibility and mature fabrication with standard silicon technology, have been widely studied as ultrahigh sensitive biosensors for the detection of target biomolecules, such as proteins, nucleic acids, cells and viruses so on. Herein we present a comprehensive review of the fundamental aspects of SiNW-FET biosensors, involving the working principle and the device fabrication, surface functionalization, and system integration with fluid exchange and electrical detection. Futhermore, we emphatically discuss the electrical detection of cardiac-specific biomarkers related to acute myocardial infarction disease. SiNW-FET biosensors are being increasingly exploited as promising diagnostic devices, which provide high sensitivity, high integration density, high speed sampling, strong specificity, and real-time and label-free detection for simple and cheap clinical testing.
Approaches through effects of Hall current, nanoparticle radius, inter-particle spacing and multiple slips on the suspension of copper-water nanofluid with gyrotactic microorganisms
Authors: Khan Noor Saeed , Sulaiman M
Published: December 2023

In this comprehensive study, the dynamic behavior of a copper-water nanofluid infused with gyrotactic microorganisms, focusing on the effects of Hall current, nanoparticle radius, inter-particle spacing, and multiple slip mechanisms is investigated. Through advanced numerical simulations and rigorous analysis, intricate relationships between the parameters and the suspension’s characteristics are uncovered. Comparison of the present results show a good agreement with the published results. The research findings unveil the potential for fine-tuning transport processes, manipulating thermal properties, and controlling dispersion and aggregation in nanofluids. These insights hold promise for a wide array of applications, from enhancing heat exchangers and cooling systems to pioneering biomedical devices utilizing gyrotactic microorganisms for targeted drug delivery and sensing. This study not only advances the fundamental understanding of nanofluid dynamics but also paves the way for innovative developments across various scientific and engineering domains.
Direct growth of graphene on hyper-doped silicon to enhance carrier transport for infrared photodetection
Authors: Yu Zhiguo , Cong Jingkun , Khan Afzal , Hang Pengjie , Yang Deren , Yu Xuegong
Published: December 2023

The importance of infrared photodetectors cannot be overstated, especially in fields such as security, communication, and military. While silicon-based infrared photodetectors are widely used due to the maturity of the semiconductor industry, their band gap of 1.12 eV limits their infrared light absorption above 1100 nm, making them less effective. To overcome this limitation, we report a novel infrared photodetector prepared by growing graphene on the surface of zinc hyper-doped silicon. This technique utilizes hyper-doping to introduce deep level assisted infrared light absorption benefit from the enhanced carrier collection capacity of graphene. Without introducing new energy consumption, the hyper-doped substrate annealing treatment is completed during the growth of graphene. By the improvement of transport and collection of charge carriers, the graphene growth adjusts the band structure to upgrade electrode contact, resulting in a response of 1.6 mA W−1 under laser irradiation with a wavelength of 1550 nm and a power of 2 mW. In comparison, the response of the photodetector without graphene was only 0.51 mA W−1, indicating a three-fold performance improvement. Additionally, the device has lower dark current and lower noise current, resulting in a noise equivalent power of 7.6 × 10–8 W Hz−0.5. Thus, the combination of transition metal hyper-doping and graphene growth technology has enormous potential for developing the next generation of infrared photodetectors.
Continuous precision separation of gold using a metal–organic framework/polymer composite
Authors: Mitchell Emily , Hernandez Dana , Deatherage Ashlin , Coull Martin , Altoé M Virginia , Klivansky Liana , Witman Matthew , Sun Daniel T
Published: December 2023

Critical metals of environmental and economic relevance can be found within complex mixtures, such as mine tailings, electronic waste and wastewater, at trace amounts. Specifically, gold is a critical metal that carries desired redox active properties in various applications, including modern electronics, medicine and chemical catalysis. Here we report the structuring of sub-micron Fe-BTC/PpPDA crystallites into larger 250 μm or 500 μm granules for continuous packed bed experiments for the precision separation of gold. The Structured Fe-BTC/PpPDA is highly crystalline and porous with a BET surface area of 750 m2 g−1. Further, the hybrid nanocomposite material maintains its selectivity for gold ions over common inorganic interferents. The structuring approach reported prevents excessive pressure drop and ensures stability over time and operation in a packed bed column. Further, we demonstrate that the Structured Fe-BTC/PpPDA can concentrate at least 42 wt% of gold under a dynamic continuous flow operation. These findings highlight the potential of Structured Fe-BTC/PpPDA for practical applications in industry, particularly in the selective capture of gold from complex mixtures.
A comparative analysis of mathematical methods for detecting lactate thresholds using muscle oxygenation data during a graded cycling test
Authors: Sendra-Pérez Carlos , Encarnación-Martínez Alberto , Oficial-Casado Fran , Salvador-Palmer Rosario , Priego-Quesada Jose I
Published: December 2023

Objective. Threshold determination for improving training and sports performance is important for researchers and trainers, who currently use different methods for determining lactate, ventilatory or muscle oxygenation (SmO2) thresholds. Our study aimed to compare the identification of the intensity at the first and second thresholds using lactate and SmO2data by different mathematical methods in different muscles during a graded cycling test.Approach. Twenty-six cyclists (15 males and 11 females; 23 ±6 years, 1.71 ± 0.09 m, 64.3 ± 8.8 Kg and 12 ± 3 training hours per week) performed a graded test on the cycle ergometer. Power output and saturation of muscle oxygen in four muscles (vastus lateralis, biceps femoris, gastrocnemius and tibialis anterior) were measured, along with systemic lactate concentration.Main Results. Our results showed that any method was reliable for determining the first muscle oxygenation threshold (MOT1) when comparing the lactate threshold in any muscle. However, the best method for determining the second muscle oxygenation threshold (MOT2) was the Exp-Dmax (p< 0.01; ICC = 0.79–0.91) in all muscles. In particular, the vastus lateralis muscle showed the highest intraclass correlation coefficient (ICC = 0.91, CI95% [0.81, 0.96]). However, results varied per sex across all muscles analyzed.Significance. Although the first muscle oxygenation threshold could not be determined using mathematical methods in all the muscles analyzed, the Exp-Dmax method presented excellent results in detecting the second systemic threshold in the vastus lateralis.
MLP-RL-CRD: diagnosis of cardiovascular risk in athletes using a reinforcement learning-based multilayer perceptron
Authors: Bostani Arsam , Mirzaeibonehkhater Marzieh , Najafi Hamidreza , Mehrtash Mohammad , Alizadehsani Roohallah , Tan Ru-San , Acharya U Rajendra
Published: December 2023

Objective. Pre-participation medical screening of athletes is necessary to pinpoint individuals susceptible to cardiovascular events. Approach. The article presents a reinforcement learning (RL)-based multilayer perceptron, termed MLP-RL-CRD, designed to detect cardiovascular risk among athletes. The model underwent training using a publicized dataset that included the anthropological measurements (such as height and weight) and biomedical metrics (covering blood pressure and pulse rate) of 26 002 athletes. To address the data imbalance, a novel RL-based technique was adopted. The problem was framed as a series of sequential decisions in which an agent classified a received instance and received a reward at each level. To resolve the insensitivity to the initialization of conventional gradient-based learning methods, a mutual learning-based artificial bee colony (ML-ABC) was proposed. Main Results. The model outcomes were validated against positive (P) and negative (N) ECG findings that had been labeled by experts to signify individuals ‘at risk’ and ‘not at risk,’ respectively. The MLP-RL-CRD approach achieves superior outcomes (F-measure 87.4%; geometric mean 89.6%) compared with other deep models and traditional machine learning techniques. Optimal values for crucial parameters, including the reward function, were identified for the model based on experiments on the study dataset. Ablation studies, which omitted elements of the suggested model, affirmed the autonomous, positive, stepwise influence of these components on performing the model. Significance. This study introduces a novel, effective method for early cardiovascular risk detection in athletes, merging reinforcement learning and multilayer perceptrons, advancing medical screening and predictive healthcare. The results could have far-reaching implications for athlete health management and the broader field of predictive healthcare analytics.
Electrostatic-hydraulic coupled soft actuator for micropump application
Authors: Ahmad Fuaad Mariatul Rawdhah , Hasan Mohammed Nazibul , Muthalif Asan G A , Mohamed Ali Mohamed Sultan
Published: December 2023

The development of a soft actuator with high displacement is crucial for the effective operation of micropumps, ensuring a high fluid pump rate. This study introduces an innovative approach by presenting the design and fabrication of a novel electrostatic-hydraulic coupled soft actuator for a micropump within a microfluidic system. This pioneering soft actuator, leveraging electrostatic-hydraulic coupling, showcases a unique solution to enhance the performance of micropumps. The versatility of such a soft actuator makes it particularly promising for biomedical applications. The actuator comprises dielectric fluid in an elastomeric shell and electrodes to form the out-of-plane fluid-amplified displacement. This displacement amplification was used to generate a pumping actuation in the micropump. The actuator was characterized in terms of dielectric fluid volume, electrode size, temporal response, and amplification displacement. The soft actuator showed a maximum amplified displacement of 0.51 mm at 10 kV of the applied voltage, but a higher voltage caused a dielectric breakdown. Moreover, the actuator demonstrated the ability to operate at frequencies of 0.25 Hz and 0.1 Hz. The results of the study indicate that the fabricated electrostatic-hydraulic coupled soft actuator is a dependable and effective method of actuation for a micropump in a microfluidic system. The experimental characterization of the micropump revealed a maximum flow rate of 2304 μl min−1.
Quench analysis of a no-insulation REBCO magnet based on the ADI method considering the coupling effect of the cryostat
Authors: Zheng Hengkang , Liu Mengyu , Song Yunxing , Li Liang
Published: December 2023

A no-insulation (NI) REBCO superconducting magnet is under development at Wuhan National High Magnetic Field Center, China. The magnet with the liquid helium cryostat system has a compact structure to reduce the space required for operation. During a quench, the fast-changing spatial magnetic field around the NI magnet may induce a strong eddy current in the conductive parts of the cryostat. The eddy current and its associated Lorentz force will generate mechanical stress on the cryostat, especially on the thermal shield (TS). The mechanical strength of the cryostat needs verification in the preliminary design. Furthermore, the degree to which the electromagnetic coupling between the cryostat and NI magnet might impact the quench behaviors of the NI magnet remains uncertain. In this paper, a multi-physics quench model is newly developed for the NI REBCO magnet, and the alternating direction implicit method is employed for the solver of the thermal model to improve computational efficiency. This simulation model can consider the electromagnetic coupling effect between the NI magnet and cryostat by constructing a partial element equivalent circuit. A quench analysis has been performed and we found that: (1) The cryostat can function as a secondary shorted circuit to the NI magnet and slow down the quench speed to a certain extent. (2) During the rather fast inductive quench phase, the cryostat will experience an attraction force towards the quench propagation frontier. (3) A quench propagation from one end of the magnet can cause a significant z-axis unbalanced force on the TS. (4) Cryostat materials with drastically changed electrical conductivity can significantly affect their mechanical responses during a quench. However, the eddy current density and maximum Von Mises stress on the TS are barely affected by the thickness of the TS and the contact resistance of the NI REBCO magnet.
Phonon and maxon instability in Bose–Einstein condensates with parity-time symmetric spin–orbit coupling
Authors: Qin Jieli , Zhou Lu , Dong Guangjiong
Published: December 2023

Parity-time (

P
T

) symmetry has drawn great research interest in non-Hermitian physics. Recently, there is an emerging model of

P
T

-symmetric spin–orbit coupling (SOC) which could be realized with spin-1/2 atomic Bose–Einstein condensates (BECs) when the two spin components are respectively subjected to momentum-dependent gain and loss (Qin et al 2022 New J. Phys.
24 063025). In this model, inter-atom interaction has no influence on the

P
T

-symmetric plane waves. Thus, collective excitation playing the role of fingerprint of inter-atom interaction is investigated in this paper. For the phonon excitation, it is shown that the repulsive interaction between atoms in different spin states, which tends to drive the atoms to populate in only one spin component, can break the

P
T

-symmetry, and leads to a phonon instability. Whereas, for the case of the phonon-maxon-roton collective excitation spectrum, the repulsive interaction between atoms in different spin states can lead to a maxon instability, which does not occur in Hermitian BEC systems (dipolar BECs or BECs with Raman induced SOC). Simulation of the time evolution of the plane wave solution against small noise shows that the maxon instability can result in the formation of a supersolid-like stripe pattern at the initial stage, but the non-Hermitian nature of the system finally destroys the pattern. The phase diagram of stability shows that the Rabi coupling and repulsive interaction between the atoms in the same spin state can stabilize the system.
Monte Carlo approach to the evaluation of the security of device-independent quantum key distribution
Authors: Su Hong-Yi
Published: December 2023

We present a generic study on the information-theoretic security of multi-setting device-independent quantum key distribution (DIQKD) protocols, i.e. ones that involve more than two measurements (or inputs) for each party to perform, and yield dichotomic results (or outputs). The approach we develop, when applied in protocols with either symmetric or asymmetric Bell experiments, yields nontrivial upper bounds on the secure key rates, along with the detection efficiencies required upon the measuring devices. The results imply that increasing the number of measurements may lower the detection efficiency required by the security criterion. The improvement, however, depends on (i) the choice of multi-setting Bell inequalities chosen to be tested in a protocol, and (ii) either a symmetric or asymmetric Bell experiment is considered. Our results serve as an advance toward the quest for evaluating security and reducing efficiency requirement of applying DIQKD in scenarios without heralding.
R-modes as a new probe of dark matter in neutron stars
Authors: Shirke Swarnim , Ghosh Suprovo , Chatterjee Debarati , Sagunski Laura , Schaffner-Bielich Jürgen
Published: December 2023

In this work, we perform the first systematic investigation of effects of the presence of
dark matter on r-mode oscillations in neutron stars (NSs). Using a self-interacting dark matter (DM) model based on the neutron decay anomaly and a hadronic model obtained from the posterior
distribution of a recent Bayesian analysis, we impose constraints on the DM self-interaction
strength using recent multimessenger astrophysical observations. We also put new constraints on
the DM fraction for this model of DM. The constrained DM interaction strength is then used to
estimate DM self-interaction cross section and shear viscosity resulting from DM, which is found
to be several orders of magnitude smaller than shear viscosity due to hadronic matter. Assuming
chemical equilibrium among DM fermions and neutrons, we estimate the bulk viscosity resulting from
the dark decay of neutrons considering different scenarios for the temperature dependence of the
reaction rate and investigate the effect on the r-mode instability window. We conclude that DM
shear and bulk viscosity may significantly modify the r-mode instability window compared with
the minimal hadronic viscosities, depending on the temperature dependence of the process. We also
found that for the window to be compatible with the X-ray and pulsar observational data, the rate
for the dark decay process must be fast.
Time-reversal asymmetries in
*
Authors: Geng 耿 Chao-Qiang 朝强 , Liu 刘 Chia-Wei 佳韦 , Wei 魏 Zheng-Yi 正乙
Published: December 2023

We study the decays of

with

. We examine the full angular distributions with polarized

, where the T-odd observables are identified. We discuss the possible effects of new physics (NP) and find that the T-odd observables are sensitive to them as they vanish in the standard model. Special attention is given to the interference of (pseudo)scalar operators with (axial)vector operators in polarized

, which are studied for the first time. Their effects are proportional to the lepton masses and therefore may evade the constraint from

at the LHCb naturally. As

is uncontaminated by the charmonia resonance, it provides a clean background to probe NP. In addition, we show that the experimental central value of

in

at the LHCb can be explained by the NP case, which couples to the right-handed quarks and leptons. The polarization fraction of

at the LHCb is found to be consistent with zero regardless of the NP scenarios.
On the distinction between SI base units and SI derived units
Authors: Brown Richard J C
Published: December 2023

This letter discusses the criteria that should be considered when deciding whether or not the distinction between base units and derived units in the International System of Units (SI) is useful, a debate that has been reignited following the 2019 revision of the SI. It is proposed that the correct question to ask is whether the concept of independent quantities, and the dimensional analysis it allows, remains useful—since that is the ultimate origin of the distinction between SI base units and SI derived units. Furthermore, the letter explains that this distinction is not related to whether the defining constants used in the revised SI after 2019 are any more fundamental than they were previously, nor whether the links between defining constants and SI base units are any less direct than they were prior to 2019. Finally, an opinion is offered that the concept of quantity dimensions and dimensional analysis remains useful, and certainly does no harm.
Hygrothermal Performance of Prefabricated Insulation Elements for Serial Renovation of Apartment Buildings in a Moderately Continental German Climate
Authors: Pihelo P , Kalamees T
Published: December 2023

The reduction of energy use in the buildings is expected to be reached by fulfilling several requirements of the low- and nearly-zero energy buildings (nZEB) policy. The improvement of the energy performance of the building envelope and the service systems of the existing buildings offers great potential for energy savings as the annual replacement of the existing stock is only 1 to 2%. The efficient way to accomplish the purpose and global goals of the nZEB is to apply the integrated design process, development, and application of prefabricated insulation elements on a large scale. In this project, in the Berlin area of Germany, prefabricated timber frame insulation elements were designed for the external insulation of the envelope of the apartment building in the serial renovation process, with the thermal transmittance of the external envelope U
external-wall = 0.14–0.16 W/(m2·K). In the current study, the potential hygrothermal risks and their effect on highly insulated multi-story apartment building envelope were analyzed. The study contained a set of hygrothermal analyses to ensure the moisture safety of highly insulated facade structures and the selection of materials from the perspective of hygrothermal performance and low risk of degradation. This research found that the risk of mold growth is high if timber elements are installed without protective measures against drying-out built-in moisture, wind-driven rain, and other weather conditions. The initial moisture content of the external concrete slab, to be considered critical, is 90 kg/m3, and the drying out period is longer than the covered with new layers constructions can sustain if a proper vapor control layer is not added between the existing moist wall and installed insulation elements. Furthermore, the wind barrier layer with high thermal resistance and vapor permeability of the installed insulation element helps to minimize the risk of mold growth. A careful analysis and selection of materials allow to design moisture-safe timber frame insulation elements and provide low thermal transmittance of renovated building envelopes. The results showed that before the final design and installation of the insulation elements, a thorough hygrothermal analysis of the original external envelope with actual climatic conditions and moisture loads must be realized.
Quantification of Building Envelope Heat Losses on a District Level for Comparative Renovation Strategies Assessment
Authors: Arumägi Endrik , Hallik Jaanus , Pikas Ergo , Kalamees Targo , Liiv Innar , Kisel Einari
Published: December 2023

A renovation wave calls for an integrated, participatory, and neighbourhood to neighbourhood approach tailored to the local environments. This can be hindered by the lack of geometric and performance input data about the existing building stock. Depending on the Level of Detail (LOD) of buildings in national registries the calculation results for heat loss and energy performance differ. This paper aims to analyse the impact of LOD on heating energy demand (HED) and energy performance value (EPV) using existing data from the building registry and digital twin model. As a rule, compared to the calculations based on project data or to the measured energy consumption, the calculations based on the LOD building geometry overestimate the HED and EPV. When comparing different LOD, using the same building sample, the difference between heating energy demand (HED) and energy performance value (EPV) ranges from 1% to 57% and 1% to 41% (complex geometry) or from 2% to 7% and 2% to 5% (unsophisticated geometry) accordingly. The results exhibit a good correlation of the discrepancy between the difference in the shape of LOD and the building in the reality and show that the more complex the shape of the buildings, the more important it is to use highest LOD possible. Pooling the building envelope heat loss calculation on a district level improves accuracy on average allowing better assessment of comparative renovation strategies.
Practical Solutions for Building Envelope Retrofitting of Historic Buildings in Cold Climates
Authors: Felius L C , Brandser A , Smits F
Published: December 2023

Improving the energy efficiency of buildings is one of the main strategies to reach the European target to reduce greenhouse gas emissions. As most of the future building stock is already built, retrofitting existing buildings will play a significant role in reaching this goal. In Norway, buildings that undergo full retrofitting must fulfil the same energy efficiency requirements as new buildings. This is challenging, especially in the case of historic buildings. Improvements should not damage or change the existing structure. As it is often challenging to retrofit historic buildings, this paper aims to provide practical guidelines for building envelope retrofitting as well as identify key points that need to be taken into consideration in the design phase. First, retrofitting measures recommended in historic case study buildings in Norway are analyzed. Second, an overview of typical challenges for retrofitting historic buildings is given. These are identified from literature review and from experiences during the design phase. Interviews with public building owners, contractors, consultants and architects were conducted to discuss challenges from different perspectives. Finally, findings from the literature, interviews and case studies are discussed to identify similarities.
Historic buildings to Positive Energy Buildings: a trilemma between energy efficiency, lifecycle carbon and architecture conservation.
Authors: Mathew Dennis , O’Hegarty Richard , Kinnane Oliver
Published: December 2023

Heritage buildings define the distinctive character of many urban areas by creating continuity with the past and serving as a visual cultural reference. To ensure their continued use, these buildings must be adapted for better performance that demands energy retrofitting strategies while satisfying indoor environmental quality. Energy retrofit reduces CO2eq emissions in the operation phase but typically entails embodied carbon and is not always applicable to historic buildings that require architectural and cultural conservation. This study phrases it as a trilemma and aims to identify an optimal balance between increased energy efficiency and decreased lifecycle carbon when architecture conservation is acknowledged. The research is applied to a traditional fisherman’s cottage in the village on Howth Head, Ireland with an aim to make it a Positive Energy Building (PEB). First, the construction method and heritage value are investigated followed by an experimental U-value calculation to identify the intervention needs. Then, a range of retrofit strategies to increase the energy efficiency of the building, but sensitive to the architectural conservation agenda, are proposed. Furthermore, using the EnergyPlus simulation engine, the study analyses the implications of different building materials for thermal insulation, building façade and window retrofit, on the building’s operational energy performance. Finally, for each scenario, a lifecycle carbon analysis was applied to identify the optimal strategy when architecture conservation is considered. The best retrofit strategies for reducing operational carbon do not always decrease embodied carbon. Similarly, the optimal materials to be used to achieve the highest level of energy efficiency and reduced life cycle carbon to become a PEB do not adhere to architectural conservation objectives. Further analysis is undertaken to achieve a balanced strategy which can be adopted in similar conservation retrofit projects.
Wind-driven rain load in Finland in present and future projected climates
Authors: Pakkala Toni A. , Lahdensivu Jukka
Published: December 2023

The amount of wind-driven rain (WDR) has been shown to have a major effect on the different deterioration mechanisms of outdoor exposed structures. For example, in recent studies of Finnish existing concrete element buildings the amount of WDR has been shown to have strong correlation with the corrosion rate of reinforcements in carbonated concrete and the freeze-thaw damage of concrete. The latter can be related to all porous stone-based materials (e.g., bricks and mortars). In addition, the amount of WDR has a major effect on mould growth potential in different materials or structures sensitive to it. Thus, the effect of the amount of WDR in present climate has been studied comprehensively. In this study, the amount of WDR is calculated for a new 30-year period (1989-2018) presenting the present climate among with two future periods presenting 2050 and 2080 climates. In future climate projections, three different CMPI5 based scenarios are used: RCP2.6, RCP4.5 and RCP8.5. All calculations take into account the wind directions and they are made for four different locations presenting Finland: coastal area, southern Finland, inland and northern Finland (Lapland). Based on the results, the WDR load in the form of rain or sleet is increasing in all locations and from every direction regardless of the used scenario. The highest relative increase is in inland and Lapland, though, the load is still significantly higher in coastal and southern parts of Finland. With all the scenarios the WDR load is still focusing on southern directions, but it will be more evenly divided for other directions than in present climate. In addition, the WDR load is increasing during autumn and wintertime, i.e., during the periods when in the latitudes the drying conditions are weak because of the lack of solar radiation and the high-level relative humidity.
Comparing Canadian and Norwegian moisture indices for building climate adaptation
Authors: Gaarder J E , Andenæs E , Astrup I , Lacasse M , Time B , Kvande T
Published: December 2023

To evaluate the suitability of materials and solutions in building envelopes, it is necessary to quantify the relevant climate loads. The critical climate load is typically a combination of multiple parameters, such as temperature and precipitation. Climate indices may be used for finding critical climate loads, and their use helps guide design choices when adapting to local climates. The purpose of this study is to evaluate the suitability of the Canadian Moisture Index (MI) for use in Norway. The values of MI are linked to design recommendations in the Canadian building code, thus enabling a tangible link between index values and moisture design practice. MI has been calculated for 12 locations in Norway, and compared to two indices already in national use: the driving rain index (DRI) and wood decay potential index (WDPI). The applicability of a climate index as a design tool depends on (1) describing a relevant climate stress; (2) logical differentiation of values, and; (3) translating index values to design recommendations. These are fulfilled for MI in a Canadian context, thus making it applicable as a design tool. However, significant adaptation may be required for the index to be adopted to a Norwegian context. As MI and DRI have a similar field of application, introducing MI into a Norwegian context may therefore be redundant. A drawback with the Norwegian indices is the relative weak link between index values and design recommendations, thus further development of recommendations based on index values may improve their applicability as design tools.
Freeze-thaw risk in solid masonry: The difference between a climate-based and response-based analysis to study climate change.
Authors: Vandemeulebroucke I , Kotova L , Caluwaerts S , Van Den Bossche N
Published: December 2023

Climate change (CC) has an impact on freeze-thaw degradation in historical buildings. The changing risk is not uniform over Europe according to climate-based analyses (i.e. only using climate data). Though, degradation risks are highly affected by building parameters (e.g. wall composition, material properties…). Response-based analyses (i.e. using hygrothermal simulation results) account for building parameters, and are more detailed. Nonetheless, they are not state-of-the-art for large domains given the high computational cost. Therefore, we compared a climate-based and response-based analysis for 10 locations in Europe and the Mediterranean, focussing on the critical Freeze-Thaw Cycles (FTC) in solid masonry walls. This paper presents the CC impact for 1.780 building parameter variations at each location. The Spearman rank correlation is 0.79 between the absolute values of the climate-based frost-indices (i.e. frost decay exposure index and FTC based on air temperature (FTCair)), and the critical FTC in the brick masonry. The correlation of the change in freeze-thaw risk is weaker (0.33 for FTCair). The error when using a climate-based analysis to represent the CC impact goes up to 100%. Alongside, the climate-based analysis cannot represent the spread of the CC impact between different parameter variations. The climate-based analysis is only suitable as an estimation.
Improving hygrothermal risk assessment tools for brick walls in a changing climate
Authors: Janssens Kaat , Marincioni Valentina , Van Den Bossche Nathan
Published: December 2023

Due to the heritage value of historical buildings, the external facade can often not be modified. Therefore, heritage buildings require interior insulation when undergoing an energy renovation. However, interior retrofitting drastically changes the hygrothermal behaviour of a wall and can potentially cause moisture-related problems. Besides an interior retrofit, a changing climate might also trigger some of these damage mechanisms since parameters such as temperature and precipitation will change over time. It is proven that hygrothermal models can provide relevant insights into the risk of deterioration associated with these damage phenomena. Heat, Air and Moisture (HAM) tools are commercially available but rarely used in the building industry to study deterioration risks. Translating research into practical tools and guidelines is a challenge across the whole field of building renovation. This paper aims to tackle that challenge, by means of creating a hygrothermal risk assessment tool based on 48,384 HAM-simulations for the climate of Brussels, Belgium. Seven different performance criteria are addressed and discussed: freeze-thaw damage, mould growth, wood rot, corrosion, moisture accumulation, salt efflorescence and bio-colonisation. Subsequent to a sensitivity analysis, the study further investigates how these results can be translated into practice, providing building practitioners the most suitable insights and recommendations.
A Method for the Evaluation of Frost Damage at different Moisture Contents and Temperatures based on Laboratory Measurements
Authors: Hirsch Hauke , Petzold Hans , Heyn Rüdiger , Grunewald John
Published: December 2023

The frost damage of façade materials, especially bricks, is still a problem of importance, mainly for historical constructions. Existing tests like the freeze-thaw test (CDF test) use conditions of full water saturation and very low freezing temperatures, which most likely occur rather rarely in practice. Therefore, we conducted experiments on bricks with different moisture levels, using impulse excitation to determine the change in Young’s modulus as damage assessment. The results show a strong decrease in Young’s modulus and a clear dependence of the damage on the moisture content. We applied the results to a novel frost assessment method, which differentiates the damage potential of different parts of the pore system, based on the present temperature and moisture content.
Metrological evaluation of facade coating systems regarding their resistance to microorganism growth
Authors: Bishara Ayman , Bishara Nadja , Kramberger-Kaplan Helge
Published: December 2023

The presence of liquid water on the facade surface significantly contributes to the growth of microorganisms. This issue has become increasingly important with the growing use of thermal insulation in buildings. However, the formation of condensation on these façades is often increased due to low surface temperatures. Therefore, innovative coating systems with special physical parameters have been developed to prevent condensation formation and thus the growth of algae on the facade surface. These coatings should be evaluated with respect to their surface condensation to identify their resistance against condensation. Since no suitable method is available for this purpose, it is necessary to develop a method for controlling the wetness and drying out of façades. This paper presents the development and verification of innovative coating systems, as well as an active facade moisture detection system (ONE). The measuring method is designed to provide long-term non-destructive measurements of surface wetness. The measurement data obtained in this research are used to develop facade materials and coatings that improve their drying properties and the balance between hydrophilic and hydrophobic surfaces. This is aimed at preventing or reducing algae growth on the façade. A case study consisting of four test walls was conducted in Central Germany under real climate conditions to examine the resistance of coating systems with different pigments (conventional and modified pigments) to moisture formation on the surface. The results show that the developed coating system has significant potential to increase surface temperatures, leading to a reduced deviation of the dew point. This can help to prevent the growth of algae on the facade.
Moisture safety strategy for construction of CLT structures in a coastal Nordic climate
Authors: Time Berit , Andenæs Erlend , Karlsen Trygve , Geving Stig , Kvande Tore
Published: December 2023

To reduce the carbon impact of new buildings, wood is seeing increased use as a structural material. Cross-laminated timber (CLT) and glue-laminated wood (glulam) elements allow the construction of multi-storey buildings. However, wood is vulnerable to moisture, especially when naked wood is exposed to weather during the construction process. This paper presents the moisture strategy employed during the construction of a four-storey CLT/glulam building in Trondheim, Norway. The building was constructed without the use of a weather-protective tent, requiring alternative protective measures. The construction of the main structure was scheduled to be as short as possible. Local protective measures were employed to protect the structure from rain and free water was removed after rain events. The project was closely supervised by the client, with particular care for moisture control. Moisture was regularly measured at 50 points throughout the building. No wooden surfaces were encapsulated until a wood moisture content below 15 weight-% was measured. The performance of the moisture strategy was evaluated using measurements of wood moisture, indoor climate, airtightness, and visual inspections. The wood moisture content quickly decreased as the building envelope was assembled, indicating that drying was well facilitated. In the first year after construction, gaps between the flooring and baseboards were observed, suggesting that the wooden elements have experienced some shrinkage. The moisture safety strategy is deemed to have been generally successful. The overall experiences were important in the development of new recommendations in the SINTEF Building Research Design Guides for CLT structures.
Estimating the hydratable surface area of building materials from water vapour sorption
Authors: Frandsen K M , Lennert J V , Jensen R L , Møldrup P
Published: December 2023

The specific surface area of a building material controls its physical, chemical, and biological functions and services, including its moisture regulating potential. The Hydratable Specific Surface Area (H-SSA) of a building material can be estimated from its primary water vapour adsorption and desorption isotherm at a given relative humidity (RH) value or range of RH. The concept is illustrated for 12 mineral and bio-based building materials. The estimated H-SSA for only 1 kg of some building materials can approach the area of a typical agricultural field (500,000 m2, 50 ha.), which helps explain and illustrate the great moisture regulating properties of many bio-based materials. The H-SSA appears useful to help characterize and classify building materials.
Capillary condensation redistribution (CCR) test: measurement results of 5 materials and comparison to modelling
Authors: Klõšeiko P , Valk T , Põldaru M , Kalamees T
Published: December 2023

To improve the accuracy of hygrothermal modelling, a capillary condensation redistribution (CCR) has been proposed to help distribute the share of vapour and liquid conductivity functions based on a wider experimental dataset. This paper aims to provide further data by presenting the CCR test measurement results of 2 calcium silicate (CaSi) boards, 2 aerated autoclaved concrete (AAC) boards and spruce (the latter both perpendicular and parallel to the grain). A variation of the CCR test setup is described. The measurement results agree with those from literature where some of the materials presented here were also tested. Modelling results using previously available material properties are compared to measurement results: none of the AAC and longitudinal spruce material properties can reproduce the moisture content levels achieved in the study, while CCR-optimized CaSi material data is close to the measured results. The best agreement between measurements and modelling of spruce perpendicular to grain are achieved with material properties which discard liquid conductivity and presume increased vapour permeability due to increase of moisture content instead.
Archetype Building Energy Models for Residential Sector: Importance of Uncontrolled Inputs in Predictive Control and Energy Flexibility
Authors: Abtahi S M , Athienitis A K , Delcroix B
Published: December 2023

A 1st-order gray-box archetype is developed using high-quality measurements from an unoccupied experimental house to investigate the sensitivity of economic model-based predictive control performance under Québec’s dynamic electricity tariff for the residential sector, rate Flex-D, to uncertainty in the weather forecast. The archetype incorporates the outside air temperature and the solar gain as uncontrolled heat sources and has three parameters: the overall thermal capacitance, the thermal resistance to the outside air temperature, and the solar aperture. The performance of economic model-based predictive control is compared under the uncertain day-ahead forecast and the historical measurements of the same day. The results show that the most influential uncontrolled input directing the performance of economic model-based predictive control under rate Flex-D is the price signal, which makes the impact of uncertainty in the weather forecast almost negligible.