Thermal radiative protection of fire fighters' protective clothing

A method for measuring the thermal radiative protection of actual fire fighters' garments to an incident radiative heat flux of 8.4 kW/m² is described. Typical results obtained with several conventional and prototype garments are presented. These results indicate the time to pain, and second degree burn as well as the pain alarm time. The thermal inertia of the garments is also measured based upon burn exposure time. Differences in physical properties such as garment thickness, total weight and number of layers are examined in order to establish the existence of any correlations.Issued as NRCC 26171. Reference: M. Day and P. Z. Sturgeon, Thermal Radiative Protection of Fire Fighters' Protective Clothing,Fire Technology, Vol. 23, No. 1, February 1987, p. 49.     

An integrated modeling tool for simultaneous analysis of thermal performance and indoor air quality in buildings

To analyze the thermal performance and indoor air quality (IAQ) in building simultaneously and quickly, we have developed an integrated modeling tool to simulate the dynamic indoor multi-parameters distributions and concentrations. The tool can take the parameters including indoor temperature, indoor humidity, and pollutant concentrations (e.g., volatile organic compounds (VOC) CO₂, particulate matter (PM)), as well as the heating/cooling load of heating, ventilating, and air-conditioning (HVAC) system into account. It couples a new zonal approach based on room air age. This paper presents the basic concept and flow chart in developing the modeling tool, and demonstrates the tool's application in a hypothetical health care building. The tool could be used for design of HVAC system with IAQ control devices and for the simultaneous analysis of thermal performance and IAQ in buildings.     

Contribution to flashover modelling: Development of a validated numerical model for ignition of non-contiguous wood samples

A computational model of flashover is presented that closely follows the experimental setup at CNRS-ENSMA-Poitiers. A propane burner with thermal power of 55 kW is used as a primary source of fire and square beech wood samples (30 mm×30 mm×5 mm) as fire spread targets. The computational model describes the wood pyrolysis with a progress variable. Using the conservation of heat fluxes at the solid–gas interface, the thermal diffusion in the wood samples is coupled with the convective and the radiative heat transfer in the ambient gas phase. The incoming heat flux at the upper surface of the wood samples reaches values between 20 and 30 kW/m². With the ignition and subsequent combustion of the pyrolysis volatiles, the heat flux increases by approx. 12 kW/m². The results show that the ignition of the wood samples is triggered at an approx. surface temperature of 650 K. Due to large local variations in incident heat flux, significant differences in the ignition times of the wood samples are observed. The comparison of the calculated and the experimentally measured temperature shows a good agreement for the first wood sample and the model predicts the ignition time very well. But for the second and the third wood samples the model overpredicts the temperature, which leads to a premature ignition of these wood samples.     

The influence of the envelope on the thermal performance of ventilated and occupied houses

The main objective of this article is to investigate the influence of the thermal properties of the envelope on the thermal performance of occupied and naturally ventilated houses. A naturally ventilated house built in Southern Brazil was modelled and calibrated in the EnergyPlus computer programme. Based on this calibrated model, a reference model for computer simulations was defined, and variations in the materials of the envelope, occupation patterns and ventilation were carried out. Hourly air temperature and relative air humidity were the output data for the thermal zones of each model. By inputting such data in the Analysis Bio computer programme, the percentage of discomfort hours in the models was obtained. Correlations between the percentage of discomfort hours and the equivalent thermal transmittance, thermal capacity and thermal delay values of the components of the envelope were investigated. Such analysis made clear that there is an influence of the envelope on the thermal performance of the occupied and ventilated house, and that the number of discomfort hours is lower in the models with higher thermal capacity and thermal delay envelope values. It was also observed that thermal capacity was the thermal property with the best correlation to discomfort hours.     

Thermal performance evaluation of domed roofs

Domed roofs have been used in Iran and many other countries to cover large buildings such as mosques, shrines, churches, schools. They have been also employed in other buildings like bazaars or market places in Iran due to their favorable thermal performance. The aim of this research is to study about domed roofs thermal performance in order to determine how they can be helpful in reducing the maximum air temperature of inside buildings during the warm seasons considering all parameters like air flow around them, solar radiation, radiation heat transfer with the sky and the ground as well as some openings on the building. The results of the study show that the thermal performance of the investigated domed roof is better than the building with flat roof, particularly when the dome is covered with glazed tiles. In addition to their aesthetic values, domes covered with glazed tiles have thermal benefits of keeping the inside air of these buildings relatively cool during the summer. Moreover, openings cause passive air flow inside building, which is helpful for human comfort.     

Numerical investigation on thermal performance and correlations of double skin façade with buoyancy-driven airflow

This paper briefly reviews the primary parameters for a double skin façade (DSF) design. The research presents an integrated and iterative modeling process for analyzing the thermal performance of DSF cavities with buoyancy-driven airflow by using a building energy simulation program (BESP) along with a computational fluid dynamics (CFD) package. A typical DSF cavity model has been established and simulated. The model and the modeling process have been calibrated and validated against the experimental data. The validated model was used to develop correlations that can be implemented in a BESP, allowing users to take advantage of the accuracy gained from CFD simulations without the required computation time. Correlations were developed for airflow rate through cavity, average and peak cavity air temperature, cavity air pressure, and interior convection coefficient. The correlations are valuable for “back of the envelope” calculation and for examining accuracy of zonal-model-based energy and airflow simulation programs.     

外窗型材热工性能的两个模拟软件差异分析

通过软件对外窗型材的相关性能进行模拟是指导型材设计和进行相关性能评价的有效途径。本文对国际上通用的两种型材热工性能模拟软件之间的差异进行了比较,分析了差异产生的原因,并将两个软件模拟原理与检测原理进行了对比,得到了相应的结论,为相关单位和人员选择使用这两个软件提供一定的依据。     

Simulation of energy use, human thermal comfort and office work performance in buildings with moderately drifting operative temperatures

Annual primary energy use in a central module of an office building consisting of two offices separated with a corridor was estimated by means of dynamic computer simulations. The simulations were conducted for conventional all-air VAV ventilation system and thermo active building system (TABS) supplemented with CAV ventilation. Simulations comprised moderate, hot–dry and hot–humid climate. Heavy and light wall construction and two orientations of the building (east–west and north–south) were considered. Besides the energy use, also capability of examined systems to keep a certain level of thermal comfort was examined. The results showed that with the moderate climate, the TABS decreased the primary energy use by about 16% as compared with the VAV. With hot–humid climate, the portion of the primary energy saved by TABS was ca. 50% even with the supply air dehumidification taken into account. The TABS working in a moderate climate kept the predicted percentage of dissatisfied (PPD) <10% during 60–80% of the working hours per year. Optimization of the TABS's control strategy (circulation pump dead-band, water supply temperature) resulted in significant reduction of the annual working hours with PPD > 10%; 1.4% in comparison to 17.5% h/yr. The highest estimated loss of occupants’ productivity related to their thermal sensation hasn’t exceeded 1% in whole year average.     

The influence of the external walls thermal inertia on the energy performance of well insulated buildings

Energy conscious building design consists in controlling the thermophysical characteristics of the building envelope such as, firstly, thermal transmittance (U-value). However, besides the U-value, the envelope thermal inertia should also be considered. The literature studies report very different estimations regarding the energy saving potential associated with the use of an adequate inertia, ranging from a few percentages to more than 80%. Therefore, this study aims at assessing the parameters enhancing or damping the role of thermal inertia, providing a variety of results. For this purpose several external wall systems with the same U-value but different dynamic properties were investigated to calculate the associated achievable energy savings. A parametric analysis was performed in progressive steps, by running the models of a virtual Test Cell and of a sample building. Both design parameters (heat transfer surface, solar control) and operational ones (ventilation rates, HVAC functional regime) were varied.It was found that the highest energy performance wall system has a proper combination of the dynamic thermal transmittance and thermal admittance values, although not necessarily the best ones. Moreover, it was shown that thermal inertia effects are enhanced if it is coupled with other energy saving measures and an efficient building use.     

An integrated approach for tactical monitoring and data-driven spread forecasting of wildfires

In recent times there have been increasing efforts to integrate technology into wildfire management, especially in the fields of tactical monitoring and simulation. On the one hand, thermal infrared imaging (TIR) systems have been installed aboard surveillance aircraft including unmanned systems (UAS). On the other, there exists a variety of models and simulators able to forecast the fire spread. However, both fields currently present significant limitations. While relevant information is still extracted manually from aerial thermal imagery and is most times merely qualitative, simulators’ accuracy on fire spread prediction has proved insufficient. To solve these issues, this article presents a twofold methodology to couple meaningful automated wildfire monitoring with accurate fire spread forecasting. The main goals are to, firstly, automatically process aerial TIR imagery so that valuable information can be produced in real time during the event and, secondly, use this information to adjust a Rothermel-based simulator in order to improve its accuracy on-line. The fire perimeter location is tracked automatically through an unsupervised edge detector. Afterwards, an assimilation module uses the remotely sensed data to optimise the simulator's fuel and wind parameters, which are assumed to remain constant for a certain period of time. Subsequently, the optimum parameters’ values are used to issue a fire evolution forecast. All outputs are projected onto the corresponding Digital Terrain Model (DTM) and integrated into a Geographic Information System (GIS) for visualization. The global system was validated using two large-scale experiments. If these algorithms can be applied to a sufficiently rich and varied set of experimental data and further developed to cope with more complex scenarios, they could eventually be incorporated into a fire management decision support system.     

气泡混凝土降温性能的试验研究及数值模拟

在解决夏季城市热岛效应和楼顶层高温的方法中,屋顶绿化和含水砂层等都有较好的降温效果,但是分别存在着价格昂贵、维护不便等缺点,因此在工程推广中受到限制.气泡混凝土具有价格便宜且维护简单的优点,并且之前的研究已经体现出了它具有良好蒸发降温性能的潜质.通过对不同吸水性能的气泡混凝土降温性能的试验研究,找出气泡混凝土降温与吸水性能之间的关系,为不同的工程需求提供一定的参考建议;并运用多孔介质热湿迁移模型对其蒸发降温过程进行数值模拟,在用部分试验数据验证数值模型的正确性后,使用此模型对剩余试验数据进行预测,并达到了良好的预测效果.     

An assessment tool for the energy, economic and environmental evaluation of thermal insulation solutions

The paper discusses an assessment tool, used for the energy, economic and environmental evaluation of Thermal Insulation Solutions (TIS). The results of the assessment undertaken with this tool can take the form of a simple rating system in order to enable users to perform comprehensive comparisons amongst various building materials and TIS. A ranking expressed by A, B and C classes is used for energy, environmental and economic parameters. By evaluating the materials, the tool supports the users to make decisions, depending on preferences or priorities such as the energy efficiency achieved, the total cost and the environmental performance. The assessment tool is applied for the double cavity wall and the External Thermal Insulation Composite Systems (ETICS) as they are used throughout Europe, both in new constructions and in the renovation of existing buildings.     

Investigation of green roof thermal performance in temperate climate: A case study of an experimental building in Florianópolis city, Southern Brazil

Green roofs have been investigated as a bioclimatic strategy to improve the energy efficiency of buildings. Quantitative data on this subject are still needed for many specific climatic conditions. This paper deals with the investigation of the green roof thermal performance of an experimental single-family residence in Florianópolis (SC, Brazil), a southern city with a temperate climate. Field measurements during a warm period (01-March-2008-07-March-2008) and during a cold period (25-May-2008-31-May-2008) included internal air temperature of rooms, internal and external surface temperature of three types of roofs (green, ceramic and metallic), heat fluxes through these roofs, green roof's temperature profile, water volumetric content in substrate layer and meteorological data. During the warm period, the green roof reduced heat gain by 92-97% in comparison to ceramic and metallic roofs, respectively, and enhanced the heat loss to 49 and 20%. During the cold period, the green roof reduced heat gain by 70 and 84%, and reduced the heat loss by 44 and 52% in comparison to ceramic and metallic roofs, respectively. From the derived data it has been confirmed that green roof contributes to the thermal benefits and energy efficiency of the building in temperate climate conditions.     

A numerical model to evaluate the thermal behaviour of active transparent façades

Active transparent façades constitute a building envelope component that is becoming more and more common in high-rise office buildings. Many designers have opted for a ventilated façade, claiming that this technology is sustainable, reduces energy consumption and enhances indoor comfort conditions, but these claims have often proved to be wrong. From the thermofluid-dynamic analysis point of view, few design procedures or sufficiently detailed, reliable and easy to use simulation software are available for ventilated façades. A numerical model that has been developed to simulate the thermal behaviour of mechanically ventilated active transparent façades is presented in this paper. The model, developed in the Simulink/Matlab^® environment, simulates the façade in both steady-state and transient conditions and provides the temperature of the different layers of the façade structure and the corresponding heat fluxes as output data. The model has been validated by comparing the simulation results with experimental data obtained in the laboratory. A test has also been performed on a real façade under actual operating conditions. The model performance has resulted to be quite promising. The accuracy of the prediction of the temperature is good, while the simulations of the heat fluxes are slightly less reliable for some operative conditions.     

GisFFE—an integrated software system for the dynamic simulation of fires following an earthquake based on GIS

Fires following earthquake (FFE) are dangerous secondary disasters occurring after large earthquakes, leading to severe property and life losses in certain cities with dense wooden buildings. In order to explore the complicated behavior of fire-spread and to assess the fire-induced losses after a large earthquake scenario, an integrated software system based on GIS (called GisFFE) was developed to perform a dynamic simulation of FFE. The purpose of this paper is to introduce the details of GisFFE, including its architecture, models and simulation flow, and to present a case study. The architecture of GisFFE consists of 4 components: an urban geo-database, a model library, a simulation center and outputs. The urban geo-database provides basic spatial and statistical data used in the GIS platform for FFE simulation; the model library contains three sub-models (ignition, fire-spread and fire-suppression models), which correspond to the three key stages involved in FFE; the simulation center serves as an operation center that integrates data and models; after the simulation is complete, statistical maps and charts are the resulting output.     

Comparison of thermal performance between test cells with different coverage systems for experimental typical day of heat in Brazilian Southeastern

This article shows experimentally the thermal performance of two test cells with different coverage systems, Light Green Roof (LGR) and ceramic roof by analyzing internal surface temperatures (IST) in the ceiling and dry bulb temperatures (DBT). The objective was to evaluate the spatial distribution of temperatures in buildings according to spatial and temporal Dynamic Climatology approaches. An experimental, typical day for heat conditions was determined. The data of the main climatic variables provided by an automatic weather station and temperatures inside the test cells were collected using thermocouples installed such that the entire space is included. The results led to the conclusion that the LGR has a balanced IST and DBT spatial distribution compared with ceramic roofs. Nevertheless, the analysis of the thermal performance is only one of the variables that must be considered when developing a construction proposal that is adapted to the context. The manner in which the thermocouples were placed inside the test cells also showed the importance of specifying the location of the sensors in experimental studies on the behavior and thermal performance of buildings.     

An integrated approach of form finding and construction simulation for glass fiber‐reinforced polymer elastic gridshells

Glass fiber‐reinforced polymer (GFRP) elastic gridshell is composed of long continuous GFRP tubes and achieves its shape through the elastic deformations during the lifting construction process. However, the complicated mechanical behaviors during the practical forming process are rarely examined in the previous researches. In this research, an innovative approach consolidating the form‐finding analysis and the construction simulation is proposed for the GFRP elastic gridshells. The integrated approach, which is developed with the ABAQUS and Python, is based on finite element analysis and iterative optimization; therefore, the mechanical deformations of gridshell can be accurately taken into account. The procedure of the integrated analysis is comprehensively presented by taking a typical double‐hump gridshell as an example. The form‐finding results (i.e., the flat lattices) derived from the iteration are found to be insensitive to the initial input. The structural behavior indexes (e.g., deflections, support reactions, and sectional stresses) during the lifting construction process are also available in the analysis. Based on the indexes, some general structural features of such gridshells are concluded. The achievements provide novel perspectives for the form‐finding analysis of GFRP elastic gridshells where lifting construction is involved, which is beneficial for the design and analysis of such structures.