IEA Project on Indoor Air Quality Design and Control in Low Energy Residential Buildings

International audienc

Evaluation of the impact of phase change humidity control material on energy performance of office buildings

Phase change humidity control material (PCHCM) is a new kind of composite made of high performance PCM microcapsules and diatomite. The PCHCM composite can moderate the hygrothermal variations by absorbing or releasing both heat and moisture and significantly reduce the peak/valley values of indoor temperature and relative humidity. In this paper, a novel model is developed to evaluate the energy performance of office buildings with PCHCM. The model is validated by a series of experiments, and then applied to investigate the effect of PCHCM on energy consumption in different typical climates worldwide (i.e. Beijing, Paris, Atlanta, and Guangzhou). Results show that high values of energy efficiencies can be obtained in the climates which characterized by a wide amplitude of temperature and humidity difference all day along (Paris and Atlanta). Noteworthy, the highest potential energy saving rate could be up to 19.57% for the office building in Paris

Development of a Procedure for Estimating the Parameters of Mechanistic Emission Source Models from Chamber Testing Data

In order to evaluate the impacts of volatile organic compounds (VOCs) emissions from building materials on the indoor pollution load and indoor air quality beyond the standard chamber test conditions and test period, mechanistic emission source models have been developed in the past. However, very limited data are available for the required model parameters including the initial concentration (Cm0), in-material diffusion coefficient (Dm), partition coefficient (Kma), and convective mass transfer coefficient (km). In this study, a procedure is developed for estimating the model parameters by using VOC emission data from standard small chamber tests. Multivariate regression analysis on the experimental data are used to determine the parameters. The Least Square and Global search algorithm with multi-starting points are used to achieve a good agreement in the normalized VOC concentrations between the model prediction and experimental data. To verify the procedure and estimate its uncertainty, simulated chamber test data are first generated by superposition of different levels of “experimental uncertainties” on the theoretical curve of the analytical solution to a mechanistic model, and then the procedure is used to estimate the model parameters from these data and determine how well the estimates converged to the original parameter values used for the data generation. Results indicated that the mean value of the estimated model parameters Cm0 was within -0.04%+/-2.47% of the true values if the “experimental uncertainty” were within +/-10% (a typical uncertainty present in small-scale chamber testing). The procedure was further demonstrated by applying it to estimate the model parameters from real chamber test data. Wide applications of the procedure will result in a database of mechanistic source model parameters for assessing the impact of VOC emissions on indoor pollution load, and for evaluating the effectiveness of various IAQ design and control strategies

Interfacial Stresses on Droplet Interface Bilayers Using Two Photon Fluorescence Lifetime Imaging Microscopy

Response of lipid bilayers to external mechanical stimuli is an active area of research with implications for fundamental and synthetic cell biology. However, there is a lack of tools for systematically imposing mechanical strains and non-invasively mapping out interfacial (membrane) stress distributions on lipid bilayers. In this article, we report a miniature platform to manipulate model cell membranes in the form of droplet interface bilayers (DIBs), and non-invasively measure spatio-temporally resolved interfacial stresses using two photon fluorescence lifetime imaging of an interfacially active molecular flipper (Flipper-TR). We established the effectiveness of the developed framework by investigating interfacial stresses accompanying three key processes associated with DIBs: thin film drainage between lipid monolayer coated droplets, bilayer formation, and bilayer separation. Interestingly, the measurements also revealed fundamental aspects of DIBs including the existence of a radially decaying interfacial stress distribution post bilayer formation, and the simultaneous build up and decay of stress respectively at the bilayer corner and center during bilayer separation. Finally, utilizing interfacial rheology measurements and MD simulations, we also reveal that the tested molecular flipper is sensitive to membrane fluidity that changes with interfacial stress - expanding the scientific understanding of how molecular motors sense stress.Comment: 8 pages, 4 figure

TSTBFuse: a two-stage three-branch feature extraction method for infrared and visible image fusion

The purpose of image fusion is to combine information from different source images to produce a comprehensively representative image. Traditional autoencoder architectures often struggle to effectively extract both unique and shared features from these image types. A novel two-stage three-branch feature extraction method (TSTBFuse) was proposed in the study, specialized for the fusion of infrared and visible images. The proposed architecture employed a three-branch encoder that separately captured infrared-specific thermal radiation features, visible-specific texture details, and shared structural information. A two-stage end-to-end training strategy was introduced: the first stage focused on reconstructing the original input images to preserve modality-specific information, while the second stage leveraged the learned representations to generate high-quality fused images. we designed a comprehensive loss function combining mean squared error (MSE), structural similarity index (SSIM), and gradient loss, ensuring both pixel-level accuracy and structural integrity. Extensive experiments on public datasets (TNO, MSRS and RoadScene) demonstrated that TSTBFuse consistently outperformed seven state-of-the-art methods in both subjective and objective evaluations. Furthermore, the method exhibited strong generalization capabilities, successfully extending to challenging tasks such as magnetic resonance imaging-computed tomography (MRI-CT) medical image fusion and red-green-blue (RGB)-infrared image fusion without retraining. The code is publicly available at: https://github.com/QXinYue/TSTBFuse