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Air curtains are used to reduce the heat and mass exchange across open doorways. Their sealing ability is assessed in terms of the effectiveness $\\def \\xmlpi #1{}\\def \\mathsfbi #1{\\boldsymbol {\\mathsf {#1}}}\\let \\le =\\leqslant \\let \\leq =\\leqslant \\let \\ge =\\geqslant \\let \\geq =\\geqslant \\def \\Pr {\\mathit {Pr}}\\def \\Fr {\\mathit {Fr}}\\def \\Rey {\\mathit {Re}}E$ , the fraction of the exchange flow prevented by the air curtain compared to an unobstructed open door. Previous work has studied air-curtain effectiveness when the doorway is the only means of ventilating a space. In this paper, we examine the effects of additional displacement ventilation on the dynamics of the air curtain and the resulting changes in its effectiveness. The main controlling parameter is the deflection modulus $D_{m}$ , which is the ratio between the momentum flux of the air curtain and the transverse forces due to the displacement ventilation. For a relatively warm interior, we find that, for small values of $D_{m}$ , the air curtain is drawn inside the space by the ventilation flow. For large values of $D_{m}$ , the flow through the doorway is controlled by the air curtain. A smooth transition occurs between these two regimes, and we estimate the $D_{m}$ value for the onset of this transition. Our model provides a quantitative prediction of $E(D_{m})$ in the ventilation-driven regime, and gives a qualitative description of the other two regimes. Laboratory experiments were conducted to test the proposed model. The experimental data were compared to theoretical predictions, and good agreement was found.

An approach for evaluating residual strength of reinforced concrete (RC) columns is presented in this paper. The approach is based on the maximum temperature attained in the concrete core and rebars, and associated reduction in strength of steel and concrete. For validating the proposed approach, post-fire residual strength tests were carried out on five high strength concrete columns. The test variables included type of concrete, presence of fibers (polypropylene and/or steel) in concrete and load ratio. The columns were loaded and exposed to a design fire, allowed to cool, and then residual strength tests were carried out. Results from these fire tests indicate that high strength concrete columns retain most of their room-temperature load carrying capacity after exposure to a design fire. A comparison of residual strength predictions with measured values from tests indicates that the proposed approach is capable of predicting the residual strength of fire-exposed RC columns.

This paper presents a review of explosive spalling of concrete at elevated temperatures. The affecting factors, mechanisms and current theoretical and experimental studies are summarized. Using a numerical model proposed by the authors, numerical simulations were performed to investigate the effects of the thermally cracking process considering the effects of heterogeneity of the material properties on the spalling in concrete exposed to a transient thermal load. The investigations showed that the thermal cracking is the key factor causing the corner and surface spalling, and suggested that a coupling of thermal cracking and pore pressure is the main cause of explosive spalling and uncertainty of explosive spalling. The explosive spalling induced by elevated temperatures is a complex nonlinear problem, which can be understood only through establishing a methodology using behavioral aspects for both material science and mechanics.

Purpose Sustainability assessments of buildings using the life cycle approach have become more and more common. This includes the assessment of the environmental performance of buildings. However, the influence of the construction products used for the fabric, the finishing, and the technical building equipment of buildings has hardly been described in literature. For this reason, we evaluated the influence of the technical building equipment and its impact on the environment for different residential buildings. Materials and methods Five residential buildings were evaluated by applying the methodology of life cycle assessment (LCA) (ISO14040) expressed using quantitative assessment categories according to prEN15978. Results and discussion Results show that the optimization of energy performance has already reached a high level in Austria, so that the overall potential for possible improvements is quite low. Especially in low-energy and passive–house-standard residential buildings, the limits for energy optimization in the use phase have mostly been achieved. In contrast to this, the integrated LCA (iLCA) findings attribute a high optimization potential to the construction products used for the technical building equipment as well as to the building fabric and finishing. Additionally, the passive house shows the lowest contribution of the technical building equipment on the overall LCA results. Conclusions The iLCA findings suggest that it is recommended to include the technical building equipment for future assessments of the environmental performance of buildings. It is also suggested to use a broad number of environmental indicators for building LCA.

Self-compacting/consolidating concrete (SCC) is certainly one the most innovative material used today by the construction industry, because of its astonishing workability and low permeability, both properties being ensured by the large amounts of fine aggregates, the special additives and the fillers, that characterize SCC’s mix compared to traditionally-vibrated concrete (VC). Since many of the structures where SCC is used (like tunnel linings, off-shore structures, containment shells, bridge decks, slabs on grade) are often required to face severe environmental conditions, such as fire, information on SCC’s behavior at high temperature is badly required, because SCC’s more dense or compact microstructure, with smaller and less connected pores, may in principle make this material more heat-sensitive than VC, as occurs in high-performance/high-strength concrete. While the thermal effects on VC have been extensively investigated in the last 20 years and several studies have been devoted to SCCs spalling in fire, only in the last few years due attention has been paid to the mechanical properties of SCCs at high temperature (“hot” properties) and/or after cooling (“residual” properties). The few of papers on this subject, however, give limited information on the stress–strain curves in compression and on the tensile behavior, that are the first objective of this project, with reference to three self-compacting “limestone” concretes (target strength f c  = 50, 80 and 95 MPa). The second objective is to synthesize the test results available in the literature and to make systematic comparisons, something that is not as simple as one may expect, because of the different heating rates, specimen types, and procedures in data treatment and presentation. The agreement, however, is more than satisfactory and confirms what has been more or less overtly indicated in previous studies, that the thermal and mechanical behavior of SCC at high temperature is hardly different from that of VC, at least in quasi-static thermal conditions and uniaxial loading.

Using conjoint choice experiments, we surveyed 473 Swiss homeowners about their preferences for energy efficiency home renovations. We find that homeowners are responsive to the upfront costs of the renovation projects, governmentoffered rebates, savings in energy expenses, time horizon over which such savings would be realized, and thermal comfort improvement. The implicit discount rate is low, ranging from 1.5 to 3%, depending on model specification. This is consistent with Hassett and Metcalf (1993) and Metcalf and Rosenthal (1995), and with the fact that our scenarios contain no uncertainty. Respondents who feel completely uncertain about future energy prices are more likely to select the status quo (no renovations) in any given choice task and weight the costs of the investments more heavily than the financial gains (subsidies and savings on the energy bills). Renovations are more likely when respondents believe that climate change considerations are important determinants of home renovations.

Building energy system management is critical for resource-saving approaches amid climate change-driven energy transitions. This paper presents a digital twin toolchain leveraging modern technologies such as Building Information Modeling (BIM), Artificial Intelligence (AI), Virtual Reality (VR), and Augmented Reality (AR). The toolchain automates the derivation of georeferenced digital twins during Technical Building Equipment (TBE) commissioning. Using a Scan vs. BIM process, discrepancies between as-planned and as-built TBE are identified, allowing automatic updates to the BIM model. Validation methods ensure both physical and functional aspects of the TBE are accurate. VR and AR facilitate off- and on-site commissioning, enabling immersive visualization and live sensor data access. An evaluation in small and large-scale demonstrators shows the toolchain's scalability and efficiency, with promising results in performance and accuracy. Future work aims to integrate more operational data, enhancing the digital twin's capabilities for building energy system management.

New lighting technologies create new opportunities that may contribute to people’s experience of light. These opportunities are a result of the increased variety and freedom in terms of colour, form factor and connectivity of the lights. To allow people to fully benefit from the potential of such novel lighting systems, there is a need for a new user interaction paradigm. To develop this paradigm, we have to better understand the aspects that play a part in the interaction with lighting, paying special attention to people’s motivation for interaction. This paper reports on a context-mapping study that was performed to gain insight in these aspects. As result, we present a set of seven themes that regard the interaction with lighting in the current situation and in the future. These themes provide an overview of the relevant aspects in this domain and contain considerations and opportunities for the design of new interfaces for novel lighting systems. We conclude that people have different levels of lighting needs that are highly dependent on context and that also require control at different levels. The context and lighting needs have a large influence on the extent to which people are motivated to adjust their lighting. Moreover, the lighting interface itself has a large effect on this motivation, mainly influenced by the degrees of freedom, the control location and availability, the degree of automation and general interaction qualities.

The influence of age on the fire spalling behaviour of high performance concrete is not known in detail. The present study shows that in three out of four mixes of self compacting concretes tested, the fire spalling tendency decreases at higher age whereas for the fourth mix the spalling did not decrease. The fourth mix, with the highest limestone content, spalled more after 4 years storage than the other mixes despite the fact that the moisture content was in the same region as the other mixes tested. Important findings are also that an addition of polypropylene fibres could expunge the spalling behaviour and that the specimen size and application of compressive load on the test specimens used in this type of studies influence the spalling behaviour strongly.

A novel video smoke detection method using both color and motion features is presented. The result of optical flow is assumed to be an approximation of motion field. Background estimation and color-based decision rule are used to determine candidate smoke regions. The Lucas Kanade optical flow algorithm is proposed to calculate the optical flow of candidate regions. And the motion features are calculated from the optical flow results and use to differentiate smoke from some other moving objects. Finally, a back-propagation neural network is used to classify the smoke features from non-fire smoke features. Experiments show that the algorithm is significant for improving the accuracy of video smoke detection and reducing false alarms.