bluuebunny/crossref_metadata_2025 huggingface dataset:
NIR reflective Paints as an Alternative for Sustainable Façade Renovation
Authors: Souza Andrea R. , Veloso Rita Carvalho , Maia Joana , Flores-Colen Inês , Ramos Nuno M. M.
Published: December 2023

Several studies of infrared reflective materials used on opaque envelopes have shown that their application can reduce the surface temperature and the cooling energy needs of buildings and help mitigate the urban heat island effect. Some of these studies were carried out by incorporating near-infrared (NIR) reflective materials on new buildings or as part of new construction systems, considering that one of the simpler and most used façade renovation methods is repainting. In a repainting process, the reflectance could change since the reflectance depends on the interaction between the reflective layer and the substrate. A study was carried out on the reflectance of paints with NIR reflective properties applied on the finishing coat of external thermal insulation composite systems (ETICS), simulating a façade renovation. A black NIR reflective paint was applied in one layer over the existing finishing coat of two ETICS samples: one with a grey mortar colour and another with a conventional black colour. A second configuration was considered by adding an intermediate layer of regularisation with white colour. Traditional black colour and the mortars were applied on a transparent acrylic base as a reference. The samples were assessed with a modular spectrophotometer to assess the total and NIR reflectance and the colour coordinates on the CIELab space. The results showed that the reflectance and colour of the new layer are independent of the colour or type of the first layer in the case of conventional paint. Conversely, the substrate affects the NIR paint performance, where a lighter substrate can help improve the reflectance but can also lead to a more significant colour change. Likewise, the results of the paint over a new white layer resulted in a lower reflectance compared to the reflectance of a single paint layer.
Assessing the deterioration risk of mural paintings in Cave 98 of Mogao Grottoes based on the hygrothermal behavior
Authors: Hu X Q , Zhang Z M , Zhang R B , Yang Z X , Hokoi S , Li Y H
Published: December 2023

Cave 98 is a typical cave in Mogao Grottos with various and serious degradations. This paper aims to clarify the heat and moisture transfer law of Cave 98 and murals and evaluate whether the current hygrothermal environment is conducive to the long-term preservation of murals. In this paper, a coupled heat and moisture transfer 2D model of Cave 98 was first established, and the accuracy of the model was verified by on-site monitoring data. Then, the spatial distributions of the temperature and moisture in Cave 98 were analyzed, and the quantitative evaluation of the deterioration risk of mural paintings in different locations was further evaluated. The results showed that 14% and 13.8% of the time indoor temperature and relative humidity (RH) exceeded the target range. Salt damage occurred more than 10 days a year, mold contamination occurred just a few days a year, and deterioration occurred at its peak in summer. Dehumidification measures can be taken during periods of high humidity to improve the adaptability of the current preservation environment.
Distribution and location of damages in Swedish buildings
Authors: Mundt-Petersen S O , Wallentén P , Joelsson A , Kläth M
Published: December 2023

Different damages and defects in buildings create huge cost for owners and the society. Besides free water damages, current knowledge about damages in buildings in general focuses on costs and has a qualitative approach rather than based on real quantitative facts. This paper presents the location and distribution of 1105 different damages, failures, and functional defects in Swedish buildings based on real damage investigations. Besides moisture inventories, most of the damage investigations were initiated by perceived SBS (Sick Building Syndrome) or visible free water. Possible negative effects on the indoor environment caused by different types of microbial growth were the most common damage. Damages often become noticed and, at a later state, located in ordinary rooms or classrooms. Most of the damages were located in the exterior wall and generally in wooden materials. The number of reported damages in the form of emissions from flooring due to degradation of glue was low in the studied sample.
Sensitivity Analysis of Traditional Solid Masonry Wall to Frost Damage in North China
Authors: Chen Xiaolin , Van De Bossche Nathan
Published: December 2023

The historic façades are significant to building heritage, but they are also extremely vulnerable to changing environmental conditions. Water is well studied as the primary agent that causes the deterioration of porous materials, but the impact of variations in moisture storage, moisture transport, and thermal properties of the materials in solid masonry wall construction remains uncertain and requires quantitative analysis. Sensitivity analysis of solid wall construction can be beneficial in understanding the correlation between material properties and risk in proposing rational preservation strategies. This paper aims to investigate the predominant parameters for frost damage criteria in traditional Chinese masonry construction in North China. Under typical outdoor climate conditions in North China and a constant indoor climate, a 2D Heat, Air Moisture (HAM) model is applied to 240mm and 370 mm thick walls. The sensitivity analysis is quantified with three frost-related criteria. The hygrothermal simulation validates that the main dominant factor varies with different criteria and that the properties of adjacent materials dominate the frost damage risk at certain locations. The results could contribute to the expansion of the international material database and the conservation of masonry heritage from the risk of the freeze-thaw cycle.
Development of laboratory experiments to determine critical moisture condition of CLT constructions
Authors: Olsson Lars , Lång Lukas , Bok Gunilla , Mjörnell Kristina
Published: December 2023

There is an increased interest in using Cross-laminated timber (CLT) in construction, but many buildings are erected without weather protection, which poses a risk of moisture impact if wood is exposed to precipitation during construction. The construction industry argues that there are no documented critical moisture levels for CLT and no specific test method. In the study, a laboratory test set-up was developed to study mould growth under realistic and controlled climatic conditions after exposure to distilled water and spore suspension. In the experiments, small test specimens of CLT structures were exposed to distilled water for 1 day or 1 week. During the development of the method it was found that exposed for one day and then given the opportunity for open drying did not give rise to mould growth. On the other hand, growth occurred on surfaces that could not dry immediately, for example at connection points. For specimens exposed for one week, mould growth arose regardless of whether the surfaces could dry immediately or not. The conclusions apply primarily to the climates studied. The methodology needs to be further developed, with other scenarios being studied, and calibrated against samples exposed to outdoor air, dust, dirt and rainwater.
Impact of different water penetration criteria and cavity ventilation rates on the risk of mold growth in timber frame walls with brick veneer cladding
Authors: Kahangi Shahreza S , Abdul Hamid A
Published: December 2023

The present paper investigates the impact of different water penetration criteria on the risk for damage in a common type of building envelope in Nordic countries, timber frame walls with brick masonry veneer. The studied walls are evaluated based on one damage criterion, the risk of mold growth. The study investigates several parameters: water penetration criterion, type of moisture source (uniformly distributed or point source) and its position in the wall assembly, air change rate (ACR) (representing different workmanship scenarios), wind-driven rain (WDR) coefficient, and locations (Gothenburg and Rensjön, with different average annual rainfall and temperature). Two criteria on how to implement water penetration are compared: a) a commonly accepted reference model that assumes one percent of all wind-driven rain deposited on the façade to penetrate the clay brick cladding, and b) a new criterion stating that 3.8% of WDR penetrates when the water content of the brick veneer cladding is above 90% of its saturation capacity. The simulation is done for a thirteen-year period with WUFI Pro and WUFI 2D. The results indicate the greater importance of implementing water penetration compared to ventilation in cavities. Further, the findings suggest that the moisture source’s location significantly impacts the mold growth risk. The results also show that the choice of the WDR coefficient affects the risks, which suggests that this factor needs accurate quantification for hygrothermal analyses. The results in this study suggest that an effective measure for the design/maintenance of such walls should incorporate: a) limiting the amount of water penetrating through the cladding, particularly stopping water from reaching the sensitive elements, i.e., timber studs, b) removing extruded mortar stemming from poor workmanship, if any, which may act as a capillary bridge.
Experimental and Numerical Investigation of Mould Growth Risk on Wooden Load-Bearing Structure in Hemp-lime Concrete Facades
Authors: Petersen S , Svendsen S , Hahn-Hundsdahl M
Published: December 2023

The need for reducing the environmental impact of the production of building materials has accelerated the emergence of new types of bio-based façade systems. Some of these systems are claimed to have hygro-thermal properties that eliminate the need for a dedicated air and/or vapour barrier as a part of the façade buildup. This paper presents a risk assessment of moisture-related deterioration of the wooden load-bearing structure in an existing hemp-lime concrete building façade system constructed without a dedicated air or vapour barrier in Aarhus, Denmark. Destructive investigation found no mould on structure. The façade was then modelled in WUFI 2D and calibrated using time series data from field measurements of temperature and relative humidity internally in the construction and in its surroundings. The calibrated WUFI model was used to simulate the annual moisture cycle using different initial conditions and weather data. The simulation output was analysed for the risk of mould growth at the wooden load-bearing structure using the Mould Growth Index. Results indicate that the initial moisture content of materials, the position of the wood structure, and the season of construction completion is important to consider to minimise risk of mould growth in the build-up.
Equilibrium Moisture Content of High Strength Concrete Used in Hollow Core Slabs
Authors: Vänttinen Kari , Tuominen Olli , Tuominen Eero , Valovirta Ilkka , Karjala Pauli , Tuurala Ilkka , Vinha Juha
Published: December 2023

The aim of this study was to measure equilibrium moisture content of hollow core slabs on both hygroscopic and capillary ranges. Because of the fabrication method of hollow core slabs, concrete grades and compacting methods used in the production differ from those used with reinforced concrete structures and elements. Test samples were taken from two slabs delivered by different manufacturers. Both slabs had similar geometry and were made of C50/60 grade concrete. Hygroscopic moisture equilibrium values were determined in climate chambers. Thin test specimens were used to perform tests within a reasonable time. Hygroscopic moisture equilibrium was measured at high relative humidities (RH), from 85 to 97 % RH. These measurements could be connected to the measurements of the retention curve done by a pressure plate. Measurements done in climate chambers and by pressure plate provided coherent results within the accuracies of these two methods. The results of two concrete slabs representing two different manufacturers differed significantly from each other, indicating the deviation of hygrothermal material properties even if the studied slabs were almost identical in many respects. Measured data is especially useful in modelling as well as analysing moisture damages.
Ruggedness test made with mortars by free water intake test
Authors: Tuominen Eero , Vinha Juha
Published: December 2023

Capillary movement in porous building materials is modelled by unsaturated flow. Material property needed for the calculations is liquid water diffusivity which is usually estimated by water absorption coefficient and capillary saturation moisture content. While determining of water absorption coefficient can be done according to EN-ISO 15148:2002 there is still lack of knowledge about sources of uncertainty in the experiment. In this paper author presents results of ruggedness tests done with mortar. The sources of errors investigated here was the shape and water inflow area of the specimen. Some specimens were also deprived of side sealing and sealing of upper surface as it was known to have impact on results. Results shows there is no considerable impact on measured capillary properties if the specimen sides are sealed or not. Nor does affect the immersed surface area of the specimen. The shape of the immersed surface instead has significant impact on values of both water absorption coefficient and capillary saturation of the specimen.
Measurement of water vapor transmission properties using the cup method – error caused by air buoyancy
Authors: Richter Jan , Staněk Kamil , Kopecký Pavel , Tywoniak Jan
Published: December 2023

The determination of water vapor transmission properties is commonly performed using the cup method. The method is based on periodic weighing of the cup assembly over time. If the air density surrounding the balance differs between weighings, measured change of mass is affected by the difference of ambient air buoyant force. For the correction of this effect can be used a mathematical formula presented in the literature and standards. The ASTM E96 states that this correction is important if observing changes of water vapor mass 0–100 mg. This paper therefore analyses possible errors of measured water vapor transmission properties based on a single 100 mg mass change without applying the buoyancy correction. It was found that for most common samples of building materials (sd < 3 m) and regular sizes of cup assemblies the error of a single mass change measurement can be up to ca. ±13 %, while assemblies with higher volume, higher mass, or more vapor tight samples can experience an error up to ±26 %. However, the vapor transmission properties are usually determined based on five consecutive weight changes. In that case the error can be up to five times lower (±2.5–5 %). Regarding the formula of the buoyancy correction the most important parameter was found to be the chosen volume of the cup assembly which, however, depends on particular setup and sample air-permeance. Only two extreme scenarios regarding this topic were analyzed while the full understanding of the accurate correction is still unsolved in its complexity.
Weather protection at the construction site: work environment and conditions for moisture and mould growth on massive timber
Authors: Bolmsvik Å , Eriksson O , Tengberg C Svensson , Johansson P
Published: December 2023

During the last decade, the use of timber (especially massive timber) has increased worldwide, mainly driven by anticipated environmental benefits. However, there is debate on how to handle the susceptibility against microbial growth for wooden constructions, especially during the construction phase. Sometimes full weather protection is used to avoid exposing the wooden material to outdoor conditions, but oftentimes the structures are fully exposed to precipitation. In an earlier study, one construction site using a full weather protection was studied, and the results showed promising results on the improved hygrothermal conditions and reduced risk of mould growth. Moreover, the site contractor also indicated improved work environment and productivity, however, this was not included in that study. This present study aims to investigate the effects of using full weather protection during construction in seven different construction projects to follow-up and broaden the earlier single project study. The studied aspects include the hygrothermal conditions, potential of mould growth, and influence on the work environment.

Temperature and relative humidity were measured and analysed. Samples of cross-laminated timber (CLT) were analysed using a microscope, and the results are compared to theoretical mould growth potential. This is measured both inside the weather protection and outside at the seven construction projects. Furthermore, a work environment questionnaire is distributed to workers at the sites to collect the perceived work environment using a full weather protection.

The results of the study partly confirm the conclusions from the earlier study, i.e., reducing the risk of mould growth and causing a slightly warmer and dryer conditions than outside. In addition, the results indicate an improved work environment. The majority of the interviewees wishes a weather protection in their next project regarding the work environment.
Karsten tube analysis for joint mortar identification in masonry
Authors: Stenholt-Jacobsen Rasmus , Hansen Kurt Kielsgaard , Rörig-Dalgaard Inge
Published: December 2023

The present work examines the Karsten tube penetration test to identify mortar types in existing masonry, for mortars containing air-lime or hydraulic binders. Mortar type identification is e.g. of relevance for the reusability of the fired clay bricks in the masonry, where a hydraulic binder content makes the mortar removal process significantly more difficult. The Karsten tube test makes it possible to make a simple and non-destructive mortar analysis on-site assessing the water absorption of the mortar, via the surface of the mortar joint alone. The present approach considers both the effect of the surrounding bricks and the surface finish of the pointing. Furthermore, the setup masks the brick surface exposed under the Karsten tube to focus the exposure on the mortar. Three different mortar types in existing masonry were tested: air-lime mortar, air-lime/hydraulic lime mortar and air-lime/cement mortar. The results showed linear water absorptions, which were clearly distinguishable for the hydraulic and non-hydraulic binders during the 15-minute tests. The measurement results in the present work document how the Karsten tube penetration test can be used for simple and non-destructive identification of joint mortar types determining whether the masonry was constructed with air-lime mortar or mortar containing hydraulic binders.
Modelling Rain Water Ingress in Hygrothermal Simulations
Authors: Van Den Bossche Nathan , Van Linden Stéphanie
Published: December 2023

The hygrothermal response of building envelope components is often studied by means of numerical Heat-Air-Moisture (HAM) simulation models. There models aim to capture the most important physics that affect the transport and storage of heat and moisture due to climatic excitations. For a lot of climates and components the wind driven rain load is the main driver for moisture uptake in the construction, and as well, the trigger of important degradation phenomena e.g., freeze-thaw damage, mold growth, wood decay, corrosion, salt transport, algae growth. When building components are subjected to wind driven rain loads and driving rain wind pressures, capillary uptake in porous materials is typically considered in models, but rain water often infiltrates directly into different layers of the construction and these infiltrations may have a significant impact on the hygrothermal behavior. This paper offers a straightforward methodology to take the rain water management of building envelope components into account in hygrothermal simulations. For different types of façade systems a categorical approach is presented to simulate rain water ingress into the different layers. Next to that, also the drainage and retention is discussed in detail. Finally, this methodological approach is embedded in the SAMiRA-framework, which comprises 3 performance levels for each input parameter of the simulations: (i) Superior, (ii) Advanced, (iii) Minimum Requirement Approach. Hence, 3 different levels are offered to implement rainwater infiltration in hygrothermal simulations.
Assessing Statistical Indices for Calibrating Building Performance Simulation Models via Continuous Time Series
Authors: Freudenberg P. , Dresel M. D. , Batayneh Z.
Published: December 2023

In engineering planning practice, building simulation is becoming increasingly crucial for evaluating buildings’ energetic and thermal behaviour. The appropriate application in the form of models that represent reality precisely, therefore, faces the challenge of realistic parameter specification for uncertain BES model properties. Many of them can only be restricted to a probable range of values. Additional knowledge can be obtained for the case of available measurement data via inverse modelling. This approach minimises cost function values representing discrepancies between associated time series (measured and simulated data sets). Much research has been published in this field for energy consumption characteristics. These approaches differ in several aspects from measured continuous physical state quantities. This article applies general cost indices to air temperature measurement series. For isolated effects such as time delay and amplitude attenuation, the impact on the characteristic values is examined, and their response is evaluated. This survey leads to the conclusion that there is no single parameter suitable for identifying all effects, and a combination is recommended. A new proposal is made for such a combined statistical index, and exemplary applied for measured temperature curves from a castle near Potsdam.
Predicting the performance of hybrid ventilation in buildings using a multivariate attention-based biLSTM Encoder – Decoder
Authors: Chaudhary Gaurav , Johra Hicham , Georges Laurent , Austbø Bjørn
Published: December 2023

Hybrid ventilation is an energy-efficient solution to provide fresh air for most climates, given that it has a reliable control system. To operate such systems optimally, a high-fidelity control-oriented modesl is required. It should enable near-real time forecast of the indoor air temperature based on operational conditions such as window opening and HVAC operating schedules. However, physics-based control-oriented models (i.e., white-box models) are labour-intensive and computationally expensive. Alternatively, black-box models based on artificial neural networks can be trained to be good estimators for building dynamics. This paper investigates the capabilities of a deep neural network (DNN), which is a multivariate multi-head attention-based long short-term memory (LSTM) encoder-decoder neural network, to predict indoor air temperature when windows are opened or closed. Training and test data are generated from a detailed multi-zone office building model (EnergyPlus). Pseudo-random signals are used for the indoor air temperature setpoints and window opening instances. The results indicate that the DNN is able to accurately predict the indoor air temperature of five zones whenever windows are opened or closed. The prediction error plateaus after the 24th step ahead prediction (6 hr ahead prediction).
Cooling Demand and Indoor Temperatures of a Detached House in Southern Finland: Feasibility of a Monthly calculation Method
Authors: Rantanen Olli , Järvistö Socorro , Valovirta Ilkka , Vinha Juha
Published: December 2023

The aim of this study was to compare dynamic thermal modelling with a monthly calculation method based on a European standard and Finnish regulations. Effect of thermal insulation level of a building envelope, solar shading, solar heat gain coefficient and window area on cooling demand were also studied. Increasing the thermal insulation of building shell increased indoor temperatures and hence cooling demand considerably. Solar shading by blinds between window panes decreased indoor temperatures effectively, indicating the performance of passive cooling in Finnish climate. There were rather large differences between calculated indoor temperatures and cooling demands between the two methods although both methods were able to take into account differences between variations in building shell. According to the study, the monthly calculation method underestimates the cooling need which can be significant considering the energy consumption of buildings. Therefore, it is recommended to investigate both summer temperatures and the cooling energy needs of detached houses by modelling.
How reliable is the co-heating test?
Authors: Ritosa K , Saelens D , Roels S
Published: December 2023

The predicted or designed envelope’s energy performance often differs from the in-reality achieved one and this phenomenon, known as the building fabric performance gap, is usually caused by poor workmanship or material properties differing from ones specified in the design phase. To bridge this gap, and quantify the achieved envelope’s thermal characteristics, different methodologies based on dedicated on-site monitoring campaigns are applied. One of the recognized methods for evaluating the building’s Heat Loss Coefficient (HLC) is the co-heating test, during which a vacated house is submitted to elevated temperatures while the delivered heat and the indoor and outdoor environments are precisely monitored. In recent years, researchers are turning towards non-intrusive methods and to validate them the co-heating test is often recognized as the benchmark. However, the validity of this approach is hard to prove since the reference is undefined, therefore, the aim of this work is to evaluate the reliability of the HLC estimation by the co-heating test. Since in this investigation actual reference values are required, such an assessment was performed by applying the co-heating testing procedure and established statistical models to artificially generated data which resemble ideal monitoring campaigns. In this work, the prescribed co-heating testing procedure and statistical models are applied to a simulated sample size of single-family dwellings characteristic of Flanders. The main aim here is to assess the trends in the results when different estimation approaches are applied to the same ideal monitoring dataset. Moreover, the analysis can be performed on a large sample size and, since indoor conditions are prescribed, outdoor conditions can be manipulated in a way to isolate the effect of different weather parameters on the estimation.
A review of the 1-2 apartment residential building stock in Lithuania based on an analysis of Energy Performance Certificates
Authors: Monstvilas E , Borg Simon Paul , Norvaišienė R , Banionis K , Bliūdžius R
Published: December 2023

One of priorities of the EU’s climate change policy is the energy performance of buildings. This is reflected primarily through the series of Directives the EU has enacted along the years, but is most precisely conveyed in the Energy Performance of Buildings Directive (EPBD). As part of the European Union, Lithuania has enacted its own long-term strategy aimed at transforming the current building stock in one which is more energy efficient. Building energy certification, legalized in accordance with the requirements of the directive is the primary tool used to evaluate the energy-efficiency of a building, which includes determination of the energy consumption of a building and subsequently assigning it with an energy performance class. Energy performance certificates (EPC) are obligatory for new and existing buildings in all European Union (EU) member states and provide not only a description of the energy performance characteristics of individual buildings, but are also useful source of legal information for determination of the achievements of building energy efficiency improvement strategy. Despite the current wide spread presence of EPC analyses in other European countries, similar information on the national EPC register of Lithuania is still hardly present in research studies. To this effect this paper presents a detailed overview of the stock of Lithuanian residential 1-2 apartments buildings using data from the national EPC register. The results obtained present the impact of the implementation of EPBD on Lithuanian residential 1-2 apartments buildings, including changes in thermal insulation of building elements, heating system typology, energy consumption and CO2 emissions.
To Shade or not to Shade (and how)? Annual heating energy balance and internal temperature in low energy houses in Wrocław, Poland.
Authors: Baborska-Narożny Magdalena , Bandurski Karol , Grudzińska Magdalena
Published: December 2023

One of the important areas of occupant–building fabric interaction with IEQ consequences is windows’ shading. The relevance of shading has been explored through modeling studies in the context of energy, daylighting and thermal comfort, typically aiming to inform the design stage. In owner occupied housing the architectural design sets the scene for subsequent residents’ decisions concerning windows treatment. Here, based on varied treatments for 20m2living room window observed during an in-depth building performance evaluation in same homes, dynamic modeling in TRNSYS is used to establish the related heating loads and internal temperatures. The results allow to rank five shading usage scenarios for three physical settings, namely lack of shading, external blind and internal curtain on lower half of the window, in terms of their overheating mitigation potential, based on simplified assumptions for heating, ventilation and shading practices. The modelling points towards severe overheating issue and crucial impact of shading usage patterns on its mitigation. Yearly modelled share of overheating hours (>26 °C) are almost double for unshaded scenario compared to the most effective shading strategy (25% and 13%). The simulation contributes to understanding of the field monitoring results where the unshaded living rooms experience more severe overheating, and the two shading settings in place are associated with comparable internal thermal conditions, respectively 22% vs. 5% and 6% of yearly share of overheating hours. The simplification of human-HVAC-building interaction model likely obfuscates solar heat gain control contribution to heating load.
Benchmarking Heating System Performance in Office Buildings through Grey-box Modeling
Authors: Fjerbæk Esben Visby , Hviid Christian Anker
Published: December 2023

The transition to renewable energy sources requires that larger shares of heating production should come from heat pumps both on individual level and in district heating networks. The efficiency of heat pumps is highly dependent on the temperature lift. Therefore, it is key to assess the possibilities of low-temperature heating in buildings. This paper proposes a data-driven methodology to analyse and benchmark the performance of radiator heating systems, by estimating parameters for the building’s envelope and heating system using Modelica with ModestPy. The methodology requires little a-priori knowledge and common data sources and provide valuable insights on the potentials of lowered operating temperatures. The methodology was tested on a newly renovated office building in Copenhagen and was able to consistently estimate characteristics of the envelope and capacity of the heating system. By using information on the actual capacity of the heating system, the methodology demonstrated the potential for lowering the heating supply temperatures, thereby reducing heat pump electricity consumption with 9 %.
Novel functional materials capable of humidity regulation and thermal storage for building energy conservation
Authors: Hou Pu Ming , Qin Menghao
Published: December 2023

Functional materials with large hygrothermal inertia can passively mitigate indoor temperature and humidity variations, thus improving indoor environmental quality and reducing energy demand for heating, ventilation, and air-conditioning (HVAC) systems. In this study, a novel functional phase-change humidity control material (PCHCM) was developed based on the integration of microencapsulated phase-change material (MicPCM) and novel moisture adsorbent: Metal-Organic Frameworks (MOFs). The novel MOF-based PCHCM is a dual-functional composite material. It can simultaneously uptake/release heat and humidity from indoor air and control the hygrothermal environment passively. The materials characterizations show that the new MOF-based PCHCM has better thermal and moisture buffering ability than most conventional building materials. The effect of the new material on building energy conservation was calculated by a newly developed HAMT-enthalpy model. The simulation results show that MOF-based PCHCM can effectively moderate the fluctuations of temperature and relative humidity and reduce building energy consumption in most climates worldwide. The maximum energy-saving potential could reach up to 35% in hot-dry climates. The paper will guide the application and further development of dual-functional PCHCM composites under different climates.
Effects of coating a drying Calcium Sulphate Floor on the relative humidity of the Structure
Authors: Raunima T , Tuominen E , Vinha J
Published: December 2023

Cast structures must be allowed to dry sufficiently before they can be covered with impermeable coatings. During a commissioned study on the drying rate of calcium sulphate screed cast floor, it was observed that the measured relative humidity of the structure increased significantly after a vinyl flooring was glued to the surface of the structure. The cause for the phenomenon could not be determined based on the carried-out test arrangements. Therefore, a follow-up study with identical test structures was conducted to isolate the cause of the increase in measured relative humidity after coating. Tests confirmed that the effect was caused by the water contained in the adhesive. The adhesive was initially dosed by applying it with a trowel with specified notching as instructed. In the follow-up study, weighing the applied amount of adhesive revealed that the instructed amount was exceeded significantly. Due to the shape of the material’s equilibrium moisture content curve, even a small increase in moisture content significantly increases the structure’s relative humidity. Therefore, dosing instructions of applied adhesive must be followed precisely, as overdosing can potentially lead to moisture damages in related structures.
Super adsorbent bio-polymer additive to improve hygroscopic and acoustic properties of a conventional lime plaster
Authors: Gentile Vincenzo , Libralato Michele , Fantucci Stefano , Shtrepi Louena , Autretto Giorgia
Published: December 2023

The paper introduces a new lime plaster composition, with a Super Bio-Polymeric Adsorbent (SABP), for interior applications to improve hygrothermal and acoustic comfort. Alginate SABP is added to a conventional lime plaster to improve hygroscopic and acoustic performance. The hygrothermal and acoustic properties of the modified plaster are compared with the ones of the original plaster with a preliminary moisture uptake test, the evaluation of the sorption isotherm, the moisture buffering value (MBV), and the acoustic absorption. The results show a significant increase in the equilibrium moisture contents and the MBV (from 0.7 to 6.2 g/(m2⋅%RH)). At the same time, the sound absorption coefficient is slightly improved, increasing 0.1-0.2 at frequencies higher than 500 Hz compared to the reference conventional lime plaster. The paper describes the material characterization: the sorption isotherm and the MBV are obtained using a dynamic vapor sorption (DVS) analyzer. The acoustic absorption is measured using the impedance tube method.
How to design the drying of porous materials?
Authors: Fei Linlin , Derome Dominique , Carmeliet Jan
Published: December 2023

The convective drying of porous materials is studied at the pore scale using a two-component two-phase Lattice Boltzmann model. Capillary pumping from coarse to fine pores is found to enhance the drying in first drying period at high rate. A ‘toy’ model of four connected channels is developed to design the drying of porous materials. This approach has to be seen to supplement the continuum modelling of drying using known moisture transport properties and convective moisture transfer coefficient, allowing to better understand convective drying and design the pore structure to optimize the drying rate.
Protection of pre-treated wood and construction materials using intumescent coatings
Authors: Markert F , González I , De La Parra Rogero C , Hosta E Serra
Published: December 2023

Intumescent paints’ behaviour is investigated for protecting wood pre-treated with phosphate or a silicate-based flame retardant. Additionally, the ageing effects of intumescent paint under several conditions are investigated. The cone calorimeter is applied, measuring the reaction to heat responses and the char development. Pre-treatment showed an improved fire performance of samples with intumescent coatings. The effects depend on the moisture contents and the homogeneity of the pre-treatments. Also, the experiments showed differences in fire resistance depending on the ageing method. UV exposure ageing retained the heat-insulating properties, while samples immersed in acid suffered a drastic reduction of their fire resistance. The latter ageing test increased the char’s pore size resulting in a reduced expansion factor and reduced thermal insulation performance of the intumescent coating.
Experimental characterization of exhaled flow dynamics of human breathing and vocalization
Authors: Pan Shihai , Ren Yijing , Li Na , Ma Weiqiang , Xu Chunwen
Published: December 2023

During the onging pandemic of COVID-19, there are numerous asymptomatic patients who are infectious. The exhaled droplets from their daily respiratory activities like breathing or speaking can be the sources of airborne disease transmission of COVID-19. The understanding of the airflow dynamics of these respiratory activities may be helpful to develop effective measures to prevent and control the spread of the disease. In this study, the exhaled flows from human breathing and vocalization of specific syllables are characterized using particle image velocimetry (PIV) and smoke visualization. The exhaled flow generated by ten phonemes including vowels, fricatives, affricates, plosives and nasals as well as mouth breathing are studied. The dynamic developments of the airflow processes are described by a series of parameters, including peak velocity, peak velocity time, duration time, propagation velocity and distance. Results show that vocalization of affricates and plosives as well as mouth breathing tend to have higher peak velocities and propagation distances. The evolutions of exhaled flows generated from these respiratory processes are found to have different jet structures, which are related to the stroke ratio (L/D). The flow field of a small L/D only has a pair of dominant vortices. Whereas that of a large L/D presents both a pair of dominant vortex ring and a trailing jet. Certain phoneme (e.g., /t/) is found to display a two-stage jet similar to a cough with the starting jet and an interrupted jet. The characterization of human exhaled flow of this study may be helpful to provide basis of CFD simulations and a better understanding of the spread of airborne diseases from human breathing.
Assessment of the Effects of the Cavity in BIPV Applications
Authors: Alzade Abdella , Saelens Dirk
Published: December 2023

As building-integrated photovoltaics (BIPV) become a promising application of decentralized PV systems, it is important to accurately assess their behavior in buildings energy simulations. The module temperature is a major factor in assessing its lifetime and generated power. High module temperatures lead to significant performance deteriorations. The addition of cavity ventilation contributes to decreasing the cavity temperature and is expected to improve the overall performance of BIPV. Thus, the aim of this paper is to explore the impact of the dimensioning of the BIPV cavity and its inlets on the cavity temperature which directly affects the module’s operating temperature. The simulation model developed in previous work was then validated and expanded in order to add an adjustable opening to conduct a sensitivity analysis on the BIPV cavity inlet opening dimension. The projected model consisted of two main parts: a thermal model and an airflow model. These models interact to predict the impact of airflow through the cavity on the cavity’s temperature. The sensitivity analysis included a range of simulations while modifying the dimensions for the ventilation cavity geometry of the BIPV module. The results of the sensitivity analysis revealed that the cavity temperature decreased when the cavity opening was implemented. Different degrees of influence on the cavity temperature were observed by widening or tightening the opening to certain degrees.
Model predictive control for demand response in all-electric school buildings
Authors: Morovat N , Athienitis A K , Candanedo J A
Published: December 2023

This paper presents predictive control strategies for all-electric school buildings in cold regions to activate energy flexibility based on changes in electricity prices. A fully electric school building near Montreal, Canada, is used as a case study. This study investigates three scenarios: 1) Reference case with a proportional–integral controller and flat rate electricity price, 2) Model predictive control with flat rate electricity price, and 3) Model predictive control with dynamic electricity price. These scenarios are modelled using the resistance-capacitance thermal networks model, and energy performance is determined and compared over a typical heating season. The proposed approach takes into account the physical parameters of the building, weather predictions, and thermal comfort constraints to maintain optimal energy consumption. A building energy flexibility index is used to quantify the building energy flexibility with a focus on peak demand reduction when the electricity prices are higher than usual. The results show that the MPC strategy can reduce peak power demand by up to 100% and minimize the cost of electricity during demand response events while maintaining acceptable comfort conditions.
Analysis of the influence of district thermal properties for enhancing energy flexibility through thermal mass activation
Authors: Jafarinejad Tohid , Erfani Arash , Ritosa Katia , Saelens Dirk
Published: December 2023

This study investigates the use of thermal mass within a smart sustainable district (SSD) to facilitate the renewables’ integration. The aim is to pinpoint the most suitable archetypes in a SSD and the most optimal energy flow to each of them; moreover, to establish a relation between the suitability to activate thermal mass and the properties of the archetypes, namely Heat Loss Coefficient (HLC), Structural mass (SM) and time constant (TC). First a dummy residential district is defined, then using construction and envelope properties, archetypes are defined. Based on the archetypes, the district is clustered and then it is modelled using Artificial Neural Networks (ANN). The energy optimization and renewable integration is casted as an Optimal Control Problem (OCP). Solving this OCP ensures thermal comfort within the building clusters and the renewable energy is stored optimally through the thermal mass. Finally, conclusions are drawn on which clusters of buildings offer the most opportunities to store the renewables through their thermal mass within a district and which criteria best reflect on that. The results signify that HLC and TC are more suitable criteria.
Hygrothermal performance of corners and floor junctions of timber-framed exterior walls: a simulation study
Authors: Moisio Topi , Valovirta Ilkka , Laukkarinen Anssi , Vinha Juha
Published: December 2023

Corners and basement junctions of different timber-framed walls were studied by computer simulation using Delphin 5.8.3 software. Wooden cladding and brick veneer were compared with each other, as well as different wind barrier solutions. Both internal and external corners were studied, first assuming them airtight and then modelling an air leak. Simulations were performed both in present and future climate conditions. According to the results, the walls with wooden cladding and brick veneer had a big difference in their hygrothermal behaviour. Mould index rose considerably after construction in sole plate of brick clad wall, even if the plate was originally dry. Wet sole plates dried up very slowly. Almost all corner junctions of walls with wooden cladding performed well when there was no air leak. Corners of brick clad walls were more problematic. With an air leak, all studied walls developed considerably high mould indices, underlining the importance of building airtightness.
Evaluating Floor Losses in the Context of QUB Measurements of a Passivhaus Dwelling
Authors: Collett Mark , Hardy Adam , Meulemans Johann , Glew David
Published: December 2023

Measuring the performance of building fabric is increasingly important as stakeholders wish to compare as-built performance with design expectations. When measuring whole house performance (Heat Transfer Coefficient) heat losses through the floor in slab-on-ground type constructions are intractable and introduce uncertainty into measurements. As such efforts are often made to isolate them from measurements. The QUB method is a practical method of measuring whole house building performance. Previous work has shown floor losses can successfully be isolated from measurement through use of heat flux measurements and additional calculation steps. To further test this isolation procedure, three QUB tests were performed on a slab-on-ground Passivhaus dwelling. Whilst the whole house performance measurements agree with the design performance (all results within 11% of the design) the floor losses measured appear unrealistically high. The conditions of the tests, conducted in late summer and in a highly insulated property, are likely causing the heat flux measurements to capture heat being stored in the floor construction rather than heat being lost from the property. Follow up measurements in more preferable conditions are planned which will assist in determining the cause of these observations.
Watertight insertion of heavy sliding doors in exterior walls
Authors: Andenæs Erlend , Raugstad Torill , Strid Jonas , Gullbrekken Lars , Kvande Tore
Published: December 2023

The joints around heavy terrace doors are considered a weak point in rain-exposed façades, as it is vulnerable to defects in design and construction. The insertion process of heavy sliding doors is a notable challenge. Design recommendations from manufacturers as well as national advisory agencies are currently lacking. This paper presents a full-scale laboratory study on the water tightness of heavy sliding doors with joints waterproofed according to five different solutions. The door assembly is mounted in a pressurized cabinet with water spray nozzles to simulate wind-driven rain. The interior side of the joint around the door is monitored for moisture leaks at steadily increasing pressure levels. It was found that leaks most often occur in the corners of the frame. Sealant mounted before the door itself was hoisted in place tended to be twisted or distorted as the door was adjusted in the frame, spoiling the waterproofing. A common feature of the most watertight solutions was that the sealant was mounted after the door itself was fastened to the frame. The sealant should be continuous, flexible, mounted in a single plane, and preferably be accessible during the assembly process. Waterproofing recommendations for the design and insertion of sliding doors should account for practical challenges brought on by the heavy weight.