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The CSTB Optical Lock-in Spectrometer Analog and Digital Instruments
No full textThis report describes three different types of analog and digital optical lock-in spectrometers developed at the CSTB. These instruments bring the power of lock-in detection to modern compact spectrometers based on CMOS or CCD sensors
Numerical simulation of a moisture leak
No full textInternational audienceThe moisture performance of building is of threefold importance. At first, the building envelope degradation process is engaged by mould growth on structural components, on a second level, the energy performance is mitigated by water vapor accumulation within insulation layers and finally indoor air quality is impacted. The study of water vapor diffusion inside building envelope faces the lack of proper model to consider air leakage impacts on moisture performances. The present work proposes an original approach to consider the ingress of moist air into a wall and calculate the impact in terms of moisture related risks. A numerical model is developed, which aims at representing an air flow path through the building envelope. This model is coupled to a classic coupled heat and mass transfer model, enabling water vapor and thermal exchanges between the wall and the air leakage. Depending on the boundary conditions (temperature, humidity, air pressure difference), the temperature and humidity field inside the wall is calculated at each time step. The developed model is presented in details and results are evaluated using a reference case based on data from the literature. The model is also compared to another well-known model to assess the reliability of the new approach. The results are satisfactory, although some improvements are identifie
Le Laboratoire Capteurs du CSTB pour la Conception et le Test des Détecteurs d'Occupation
No full textThis document illustrates the capability of the CSTB laboratories for testing sensors commonly used in buildings to monitor occupancy, detect motion and presence. Tested sensors includes passive infrared (PIR) pyroelectric , thermopiles, low resolution thermal imaging based on microbolometers, and ultrasonic sensors
Analysis of Intensity Limits for Light Emitting Diodes Used in Toys and Consequences for Children's Visual Health
No full textThe analysis of the current safety standards for electric toys showed that the normative intensity limits for visible light emitted by LEDs integrated in toys are overestimated. These limits were originally set in a scientific article published in 2012 that was adapted into the international safety standard published in 2017, and into the subsequent European and national standards, all published in 2020. The overestimation of the intensity limits results from several errors made in the original article. Accordingly, the current normative intensity limits for visible light used in toys do not protect the children's eyes against adverse effects of exposure to high intensity LEDs which may compromise their visual health. Updating the safety standards for electric toys using a method based on robust scientific data is recommended to protect children's visual health and ensure their long-term well-being. An extended version of this preprint, including optical measurements of LEDs in toys, was published in English by the French Agency for Food, Environmental and Occupational Health and Safety (ANSES) under the following reference: ANSES opinion on "consideration in the regulatory framework of the effects on children's health of LEDs contained in toys" (Request No 2022-SA-0193). Maisons-Alfort, France: ANSES, 32 p, 1st October 2024
Effects of Oxygen Concentration on the Reaction to Fire of Cross-Laminated Timber in a Controlled-Atmosphere Cone Calorimeter
No full textInternational audienceThis paper deals with the fire reaction as well as the gas and aerosol production of Cross-Laminated Timber (CLT) submitted to fire in oxygen-depleted environments. A Controlled-Atmosphere Cone Calorimeter (CACC) coupled to a Fourier Transform Infrared (FTIR) spectroscopy and an Electrical Low Pressure Impactor (ELPI) was used for this purpose. This combination enabled simultaneous assessments of Mass Loss Rate (MLR), evolved gases (qualitatively and quantitatively) and aerosols (size distribution and concentration) in the smoke. Several oxygen levels (21, 18, 15 and 10% O2) were studied at an external heat flux of 50 and 20 kW/m2. The combination of these two parameters allowed the response of CLT to be classified according to different fire scenarios. Indeed, an oxygen decrease shifted the combustion towards incompleteness or even prevented combustion. The production of carbon monoxide and methane was significantly promoted as well as acetaldehyde and ethene in some cases. The aerosol size distribution was slightly affected by oxygen depletion. Furthermore, decreasing the heat flux greatly reduced the decomposition rate but also promoted the production of unburnt gases.Cet article traite de la réaction au feu ainsi que de la production de gaz et d'aérosols du bois lamellé-croisé (CLT) soumis à un incendie dans des environnements pauvres en oxygène. Un calorimètre à cône à atmosphère contrôlée (CACC) couplé à une spectroscopie infrarouge à transformée de Fourier (FTIR) et à un impacteur électrique à basse pression (ELPI) a été utilisé à cette fin. Cette combinaison a permis d'évaluer simultanément le taux de perte de masse (MLR), les gaz dégagés (qualitativement et quantitativement) et les aérosols (distribution de taille et concentration) dans la fumée. Plusieurs taux d'oxygène (21, 18, 15 et 10% O2) ont été étudiés à un flux thermique externe de 50 et 20 kW/m2. La combinaison de ces deux paramètres a permis de classer la réponse du CLT selon différents scénarios d'incendie. En effet, une diminution de l'oxygène a déplacé la combustion vers l'incomplétude ou a même empêché la combustion. La production de monoxyde de carbone et de méthane a été significativement favorisée, ainsi que celle d'acétaldéhyde et d'éthène dans certains cas. La distribution de la taille des aérosols a été légèrement affectée par l'appauvrissement en oxygène. En outre, la diminution du flux de chaleur a fortement réduit le taux de décomposition mais a également favorisé la production de gaz imbrûlés
TyPy -Modéliser la matérialité des bâtiments pour l'aide à la décision en faveur de l'économie circulaire
No full textInternational audienc
Projet LoB+HiE Low Béton / High Earth - Performances acoustiques de parois en terre-chanvre
No full textCe rapport final propose :(1) Une analyse des mesurages en laboratoire des deux parois terre-chanvre investiguées (Section 2)(2) Les résultats de la caractérisation à l’échelle matériaux et à l’échelle paroi (Section 3)(3) Les comparaisons calcul-mesure de l’indice d’affaiblissement acoustique et les données d’entrée ajustées pour l’outil de calcul utilisé (Section 4)(4) Une étude paramétrique pour évaluer l’effet des matériaux (densité et caractéristique élastique notamment), leur type et leur épaisseur, sur la performance acoustique (Section 5)(5) Des lois simplifiées pour évaluer la performance acoustique (Section 6)(6) Des abaques d’aide à la conception des parois terre-chanvre (Section 7)(7) Une conclusion et des perspective
Lighting and Health IEA 4E SSLC Webinar Series: Webinar 1. Temporal Light Modulation
No full textÉcole thématiqueIn October 2024, the IEA 4E SSLC Platform published a report that represents a synthesis of health and lighting studies published over the last decade. The effects of lighting on health are technology agnostic, however advances in physiology and medicine have contributed to new awareness and understanding of the impacts of light on human health. This study examines some features of SSL products that may pose a risk and which could be improved or applied differently to achieve better outcomes in terms of health and well-being. The report covers both acute effects (effects that develop during or immediately following an exposure) of optical radiation on the eye and the skin, discomfort glare, circadian disruptions, neuro-behavioural effects, and temporal light modulation (TLM), as well as long-term effects (effects that build over months or years) including age-related macular degeneration, myopia and cancer risk. In order to communicate the broad set of findings from this report, the SSLC Platform convened a series of webinars. The findings were divided up into three one-hour webinars which were each presented twice, once for Australian/Asian time zones and once for American/European time zones
BIM2TWIN: Optimal Construction Management and Production Control
No full textThe construction sector is often described as a low-productivity sector, weak in terms of innovation and slow to adopt digital solutions. However, the adoption of BIM has streamlined the design process by facilitating communication between the players involved and has proven that the deployment of digital solutions may greatly improve productivity. The act of construction brings together professionals from different companies around the same project for a limited period, and as a result the construction process is affected by numerous problems, such as design and planning issues (both human resources and materials), unsuitable working methods or equipment, as well as safety and security issues for workers on site. The concept of the Digital Twin was first mooted in the 1970s. Initially evoked in relation to factory production processes, the notion has evolved and spread to other areas such as engineering, product design, simulation, predictive maintenance, etc. The popularity of the concept has increased considerably in recent years with technological advances such as the Internet of Things (IoT), artificial intelligence (AI) and advanced 3D modelling. For the construction industry, the adoption of Digital Building Twins (DBT) i the construction site offers the promise to address the inherent complexit of construction activity. A DBT can provide a decision support environment, bringing together an automated system able to capture on-site information and the services able to process, analyse and transform this raw information into knowledge. Accurate and reliable knowledge of the current status facilitates the decision mechanisms in planning production systems that have some resilience to unforeseen events that occur randomly during on-site activities. Applied to the construction sector, a digital twin is a virtual replica of a building or physical infrastructure that already exists or is under construction. This is the context for the BIM2TWIN project, which aimed to research, develop and test a technical solution system that includes a comprehensive set of tools for monitoring the progress of a construction site, focusing on monitoring the construction process, assessing the quality of construction, monitoring the safety and security of workers on site, and optimising the use of equipment. The solution developed in BIM2TWIN also includes a service that takes account of deviations from the planned schedule reported during construction and proposes alternative plans to respond to these deviations as effectively as possible. Thus, this project sought to highlight the potential of the DBT concept for optimising construction processes based on digital monitoring on site and in the supply chain, on artificially intelligent diagnosis of the monitored data, and on simulation and predictive analysis of proposed alternate production plans
MetTLM 20NRM01 TU/e Dataset: Dependence of Temporal Frequency and Chromaticity on the Visibility of the Phantom Array Effect
No full textDatasetThe dataset is supplement to the conference paper "Dependence of Temporal Frequency and Chromaticity on the Visibility of the Phantom Array Effect": 10.25039/x50.2023.OP060 (DOI). The dataset has the following format: 20 (Participants) by 18 (= 3 Chromaticities × 6 Temporal Frequencies) Chromaticities: Red (R); Green (G); Warm White (W) Temporal Frequencies: F1 = 80 Hz; F2 = 300 Hz; F3 = 600 Hz; F4 = 900 Hz; F5 = 1200 Hz; F6 = 1800 Hz. Due to the fractional factorial 3 (colour) × 6 (temporal frequency) mixed design, there are some empty cells. The details are described in Table 2 of the publication. The values in the table represent the visibility thresholds in Modulation Depth (MD). For example, the values of 0.05, 0.1, and 1 mean an MD of 5%, 10% and 100% respectively. The codes to visualize and analyze the dataset are publically available at 10.5281/zenodo.12659308. Keywords: Temporal Light Modulation, Temporal Light Artefact, The Phantom Array Effect, Psychophysics, Visual Perception, Contrast Sensitivity Function