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In this paper, an innovative method to minimise energy losses through building envelopes is presented, using the Proper Generalised Decomposition (PGD), written in terms of space x , time t , thermal diffusivity α and envelope thickness L . The physical phenomenon is solved at once, contrarily to classical numerical methods that cannot create a parameter dependent model. First, the PGD solution is validated with an analytical solution to prove its accuracy. Then a complex case study of a multi-layer wall submitted to transient boundary conditions is investigated. The parametric solution is computed as a function of the space and time coordinates, as well as the thermal insulation thickness and the load material thermal diffusivity. Physical behaviour and conduction loads are analysed for 76 values of thermal insulation thickness and 100 types of load material properties. Furthermore, the reduced computational cost of the PGD is highlighted. The method computes the solution 100 times faster than standard numerical approaches. In addition, the PGD solution has a low storage cost, providing interesting development of parametric solutions for real-time applications of energy management in buildings. [ABSTRACT FROM AUTHOR]

Abstract: Although the thermal bridge effects on the building energy performance have been presented in the literature, the multidimensional hygrothermal analysis of the building envelope is still a challenge due to many difficulties such as modeling complexity, computer run time, numerical convergence and highly moisture-dependent properties. However, their effects are of paramount importance due to the local increase of heat and mass flux densities so that moisture can be easily accumulated around internal corners, increasing mold growth risk and causing structural damage. Therefore, for analyzing the effects of building lower and upper corners, a multidimensional model has been developed to calculate the coupled heat, air and moisture transfer through building envelopes. The algebraic equations are simultaneously solved for the three driving potentials — temperature, vapor pressure and gas pressure gradients — to improve the numerical stability of the discretized model. In the Results section, the coupling of the upper corner, wall, lower corner (with different types of foundations), ground and floor are analyzed in terms of temperature and relative humidity profiles, vapor flow and heat flux, showing the importance of a detailed hygrothermal analysis for accurately predicting building energy consumption, mold growth and structural damage risks. [Copyright &y& Elsevier]

The article presents two numerical models to predict moisture content and ground temperature in Brazilian field. It mentions that soil moisture and surface heat content provides insight into the process which governs their interactions with the atmosphere including climate dynamics. It reveals that PowerDomus software and a decoupled Philip and de Vries mathematical model are used for accessing the temperature distribution and soil moisture evaluation respectively.

Abstract: Combined multidimensional analysis of heat, air and moisture transport through porous building elements is barely explored in the literature due to many difficulties such as modeling complexity, computer run time, numerical convergence and highly moisture-dependent properties. In this way, a mathematical model considering a combined two-dimensional heat, air and moisture transport through unsaturated building upper corners is presented. In order to improve the discretized model numerical stability, the algebraic equations are simultaneously solved for the three driving potentials: temperature, vapor pressure and moist air pressure gradients. In the results section, the convective effects caused by air stagnation are analyzed in terms of heat flux and mould growth risk for different boundary conditions, showing the importance of a detailed hygrothermal analysis – which is normally disregarded by simulation tools – for accurately predicting building energy consumption, indoor air quality, thermal comfort or mould growth risk. [Copyright &y& Elsevier]

Abstract: The combined heat, air and moisture transfer in building hollow elements is of paramount importance in the construction area for accurate energy consumption prediction, thermal comfort evaluation, moisture growth risk assessment and material deterioration analysis. In this way, a mathematical model considering the combined two-dimensional heat, air and moisture transport through unsaturated building hollow bricks is presented. In the brick porous domain, the differential governing equations are based on driving potentials of temperature, moist air pressure and water vapor pressure gradients, while, in the air domain, a lumped approach is considered for modeling the heat and mass transfer through the brick cavity. The discretized algebraic equations are solved using the MTDMA (MultiTriDiagonal-Matrix Algorithm) for the three driving potentials. Comparisons in terms of heat and vapor fluxes at the internal boundary are presented for hollow, massive and insulating brick blocks. Despite most of building energy simulation codes disregard the moisture effect and the transport multidimensional nature, results show those hypotheses may cause great discrepancy on the prediction of hygrothermal building performance. [Copyright &y& Elsevier]

In the building science area, mathematical models are developed to provide better indoor thermal comfort with lower energy consumption. Although the fact moisture and air transfer can strongly affect the temperature distribution within constructions, whole-building simulation codes do not take into account the convective air transport in porous materials. In this way, this article presents a heat, air, and moisture (HAM) transfer model based on driving potentials of temperature, air pressure, and water vapor pressure gradients for consolidated porous material in both pendular and funicular states. The solution of the set of governing equations has been simultaneously obtained using the MTDMA (MultiTriDiagonal-Matrix Algorithm) for the three potentials. To conclude, results are presented showing the impact of convective terms on the HAM transfer through a two-layer porous building envelope. [ABSTRACT FROM AUTHOR]

Abstract: The present study aims to evaluate the importance of wind turbulence when performing droplet trajectory numerical simulations. Turbulence effect on Wind-Driven Rain is studied by calculating the specific catch ratio of 1 mm droplets for an isolated low-rise building windward surface under a 5 m/s normal wind. An Eulerian Second Moment Closure and a Lagrangian one-way coupling models are used to calculate the airflow field and the droplet trajectories respectively. Results show that turbulence has a negligible effect considering the whole windward wall but can substantially modify the value of the specific catch ratio in the case of Wind-Driven Rain gauges. [Copyright &y& Elsevier]

Abstract: Due to the lack of building simulation programs that can simulate in details the combined heat, vapor and liquid transfer in porous elements and the HVAC systems, a generic and flexible computational algorithm has been elaborated in order to integrate models for both HVAC systems and multizone building hygrothermal model. In the algorithm, models for the primary components (chiller, cooling tower, primary pumps and condensation pumps) and for the secondary components (cooling and dehumidifying coil, humidifier, fan and mixing box) have been presented. Those mathematical models have been integrated into a whole-building simulation model, allowing to perform whole-building hygrothermal simulation combined to HVAC systems and plant simulation. The building hygrothermal model is based on the simultaneous calculation of temperature and moisture content distributions within the porous envelope taking into account both vapor diffusion and capillary migration. First, results are presented for a multizone building to show the usability of the proposed algorithm. Then, the analysis of the influence of the adsorption and desorption phenomena on the calculation of thermal loads and energy consumption is presented, showing that the disregard of moisture may oversize the HVAC system in 13% and underestimate the cooling energy consumption in 4% for the case study defined in this paper. [Copyright &y& Elsevier]

Many of the now well-known building energy simulation programs use the response factor method developed in the early 1970s by Stephenson and Mitalas. These are TRNSYS, EnergyPlus, Blast, and DOE-2, to name but a few. Others, such as PowerDomus, ESP-r, and BSim, perform finite-volume or finite-difference calculations to solve the heat and mass transfer through the building envelope. These two different approaches are known to have strengths and weaknesses. The main objective of the present exercise is to compare the prediction of both methods. A two-step procedure is employed here. The first deals with the pure thermal problem, i.e., without moisture calculation. Three different cases of increasing complexity are studied and compared to analytical solutions. The second step focuses on the moisture problem alone by comparing the responses obtained with a two-layer buffer storage model and a finite-volume discretization for moisture transfer. Results show that time step values are determinant even for pure thermal cases where the classical value of 1 h can lead to notable errors. For problems with moisture sorption in the wall, it has been shown that grid refinement is a very decisive parameter, while the time step has to be set, to unusually small values, to achieve a good response. [ABSTRACT FROM AUTHOR]

Abstract: In order to precisely predict ground heat transfer, room air temperature and humidity, a combined model has been developed and conceived to calculate both the coupled heat and moisture transfer in soil and floor and the psychrometrics condition of indoor air. The present methodology for the soil is based on the theory of Philip and De Vries, using variable thermophysical properties for different materials. The governing equations were discretized using the finite-volume method and a three-dimensional model for describing the physical phenomena of heat and mass transfer in unsaturated moist porous soils and floor. Additionally, a lumped transient approach for a building room and a finite-volume multi-layer model for the building envelope have been developed to integrate with the soil model. Results are presented in terms of temperature, humidity and heat flux at the interface between room air and the floor, showing the importance of the approach presented and the model robustness for long-term simulations with a high time step. [Copyright &y& Elsevier]

Summer mortality of Crassostrea gigas occurs in Brazilian crops, with predominance in the final phase of cultivation, when they reach the commercial size, generating significant losses for local producers. In order to mitigate this problem, a technical solution, whose principle is based on long-term confinement at low temperatures (10 −12°C) for inducing a similar basal metabolism regime, has been developed. According to the current literature, if the spawning process is not triggered, a substantial reduction in the mortality rate can be achieved. This work evaluates not only the effectiveness of this technological solution to reduce summer mortality but also the quality associated to commercial attributes of the oysters as a final product. A ninety-one day experiment has been carried out and has shown that the proposed solution is able to maintain Crassostrea gigas diploid oysters alive and healthy. [ABSTRACT FROM AUTHOR]

Highlights • A detailed mathematical model for the heat, air and mass transfer is achieved. • An efficient numerical model is proposed to save computational efforts. • Demonstration of numerical model efficiency (cpu time, accuracy) for a case study. • Evaluation of the reliability of the model by confronting to experimental results. Abstract This work presents a detailed mathematical model combined with an innovative efficient numerical model to predict heat, air and moisture transfer through porous building materials. The model considers the transient effects of air transport and its impact on the heat and moisture transfer. The achievement of the mathematical model is detailed in the continuity of L uikov 's work. A system composed of two advection–diffusion differential equations plus one exclusively diffusion equation is derived. The main issue to take into account the transient air transfer arises in the very small characteristic time of the transfer, implying very fine discretisation. To circumvent these difficulties, the numerical model is based on the D u F ort –F rankel explicit and unconditionally stable scheme for the exclusively diffusion equation. It is combined with a two–step R unge –K utta scheme in time with the S charfetter –G ummel numerical scheme in space for the coupled advection–diffusion equations. At the end, the numerical model enables to relax the stability condition, and, therefore, to save important computational efforts. A validation case is considered to evaluate the efficiency of the model for a nonlinear problem. Results highlight a very accurate solution computed about 16 times faster than standard approaches. After this numerical validation, the reliability of the mathematical model is evaluated by comparing the numerical predictions to experimental observations. The latter is measured within a multi-layered wall submitted to a sudden increase of vapor pressure on the inner side and driven climate boundary conditions on the outer side. A very satisfactory agreement is noted between the numerical predictions and experimental observations indicating an overall good reliability of the proposed model. [ABSTRACT FROM AUTHOR]

This paper presents an experimental validation procedure of two solar shading calculation techniques - pixel counting (PxC) and polygon clipping (PgC) - and an inter-software comparison to highlight the capabilities and efficiency of each solar shading calculation method. For the first purpose, digital images were taken from the surfaces of small-scale mock-ups specially constructed to generate experimental data for validating simulation results obtained by cases using three different tools: EnergyPlus (PgC based), Shading II SketchUp plug-in (PxC based) and Domus (PxC based). This first task has shown, for prototypes with simple geometries, that all techniques present results in good agreement with the experimental data. However, for a prototype with a hollowed shading device, the PgC-based technique produced results far from the experimental ones since it is not appropriated to simulate multi-hollowed polygons. In order to further explore the capabilities of the two shading calculation techniques, an inter-software comparison has also been carried out for a complex case, considering different building shading solutions, including non-planar trees. The results, in general, have shown that the PxC technique is not limited to geometrical complexities and leads to an accurate and a very fast assessment of sunlit surface fraction. It has also been shown a difference as high as 10 times on the prediction of a daily-integrated solar heat gain by using the two different techniques. [ABSTRACT FROM AUTHOR]

Since the 1970s, due to the worldwide energy crisis, some countries have adopted severe legislation to promote energy efficiency in buildings. The electrical power utilized in buildings is directly related to the equipment required to provide thermal comfort to occupants. In this context, one of the most important factors that determine the choice of these systems is the conduction load through the building envelope. In several countries, hollow concrete blocks have become common over the past few years. Therefore, for the assessment of building energy efficiency, the thermal transmittance evaluation of hollow blocks is required. This study obtains values of thermal transmittance for different cavity configurations of concrete blocks by performing computational fluid dynamics simulations. These transmittances are compared to those calculated using the methodology presented in international standards. In the “Results” section, it is shown that large cavities provide higher transmittance values due to convection and that thermal radiation may play an important role in the overall heat transfer through concrete hollow blocks. Some methods used to reduce the thermal transmittance are presented and discussed. Finally, thermal transmittance of cavities with the same wall height has been compared with the ones of a single block and different strategies are considered for reducing the thermal transmittance of concrete hollow blocks. [ABSTRACT FROM AUTHOR]

In the context of estimating material properties of porous walls based on in-site measurements and identification method, this paper presents the concept of Optimal Experiment Design (OED). It aims at searching the best experimental conditions in terms of quantity and position of sensors and boundary conditions imposed to the material. These optimal conditions ensure to provide the maximum accuracy of the identification method and thus the estimated parameters. The search of the OED is done by using the Fisher information matrix and a priori knowledge of the parameters. The methodology is applied for two case studies. The first one deals with purely conductive heat transfer. The concept of optimal experiment design is detailed and verified with 100 inverse problems for different experiment designs. The second case study combines a strong coupling between heat and moisture transfer through a porous building material. The methodology presented is based on a scientific formalism for efficient planning of experimental work that can be extended to the optimal design of experiments related to other problems in thermal and fluid sciences. [ABSTRACT FROM AUTHOR]

In this paper, the proper generalized decomposition (PGD) is used for model reduction in the solution of an inverse heat conduction problem within the Bayesian framework. Two PGD reduced order models are proposed and the approximation Error model (AEM) is applied to account for the errors between the complete and the reduced models. For the first PGD model, the direct problem solution is computed considering a separate representation of each coordinate of the problem during the process of solving the inverse problem. On the other hand, the second PGD model is based on a generalized solution integrating the unknown parameter as one of the coordinates of the decomposition. For the second PGD model, the reduced solution of the direct problem is computed before the inverse problem within the parameter space provided by the prior information about the parameters, which is required to be proper. These two reduced models are evaluated in terms of accuracy and reduction of the computational time on a transient three-dimensional two region inverse heat transfer problem. In fact, both reduced models result on substantial reduction of the computational time required for the solution of the inverse problem, and provide accurate estimates for the unknown parameter due to the application of the approximation error model approach. [ABSTRACT FROM PUBLISHER]

This study presents an approach to simulating building-integrated photovoltaic glazing systems composed of semitransparent organic photovoltaic (ST-OPV) elements. The approach consists of a mathematical cosimulation model based on the energy balance of complex glazing systems, considering heat transfer as conduction, mixed convection, and radiation effects. The cosimulation method is based on a functional mock-up unit (FMU) developed in Python and the building simulation program Domus. This work aims at presenting a cosimulation technique that can be easily applied to building energy simulation tools for the assessment of photovoltaic energy generation in glazing systems. The cosimulation glazing model was verified according to ANSI/ASHRAE Standard 140-2011, and the zone temperature was kept within with a root medium square error (RMSE) of 1.45 °C. The simulated building with an ST-OPV system showed promising results and could be applied to near-zero energy buildings since each 6-m 2 glazing has a power generation of around 77 W, equivalent to 9% of available solar resource. [ABSTRACT FROM AUTHOR]

Innovative and efficient ways to carry out numerical simulations are worth of investigation to reduce the computational complexity of building models and make it possible to solve complex problems. This paper presents a reduced order model, based on Proper Generalised Decomposition (PGD), to assess 2-dimensional heat and moisture transfer in walls. This model is associated with the multizone model Domus using an indirect coupling method. Both models are co-simulated to perform whole-building hygrothermal simulation, considering 2D transfer in walls. The whole-building model is first validated with data from the IEA Annex 41. Then, a case study is considered taking into account a 2-zones building with an intermediary shared wall modelled in 2 dimensions to illustrate the importance of the technique to analyse the hygrothermal behaviour of the wall. It has been highlighted that the whole model enables to perform more precisely analyses such as mould growth on the internal surface. In addition, important theoretical numerical savings (90%) are observed when compared to the large original model. However, the effective numerical savings are not so important (40%) due to the limitations of the co-simulation method. [ABSTRACT FROM AUTHOR]

Abstract: This paper aims to validate and improve three cross and single-sided natural ventilation models implemented in a whole-building hygrothermal and energy simulation program. The tested models are the British Standard for cross ventilation, the de Gids and Phaff's and Larsen's for single-sided ventilation. Airflow rates obtained by those models have been compared to the measurements performed in two full-scale buildings: one single room house located in a wind tunnel facility and one real three-storey building. Results show a large variation of airflow rates provided by the different models. The Larsen's model can be improved if coupled to the CPCALC algorithm, providing better results for both wind tunnel and on-site experiments. [Copyright &y& Elsevier]

Abstract: The present work is focused on the study of indoor thermal comfort control problem in buildings equipped with HVAC (heating, ventilation and air conditioning) systems. The occupants’ thermal comfort sensation is addressed here by the well-known comfort index known as PMV (predicted mean vote) and by a comfort zone defined in a psychrometric chart. In this context, different strategies for the control algorithms are proposed by using an only-one-actuator system that can be associated to a cooling and/or heating system. The first set of strategies is related to the thermal comfort optimization and the second one includes energy consumption minimization, while maintaining the indoor thermal comfort criterion at an adequate level. The methods are based on the model predictive control scheme and simulation results are presented for two case studies. The results validate the proposed methodology in terms of both thermal comfort and energy savings. [Copyright &y& Elsevier]

Abstract: Regression equations can be used for predicting indoor air temperature, relative humidity and energy consumption in an easier and more rapid way than building energy simulation tools. The independent variables, that is, the input data, are heating, ventilation and air conditioning (HVAC) power, outdoor temperature, relative humidity and total solar radiation. The present methodology for obtaining the regression equations is based on defining a couple of linear Multiple-Input/Single-Output (MISO) models, since two main outputs are involved, that is, indoor temperature and relative humidity. The methodology has been tested for the low- and high-thermal mass cases of the BESTest model (cases 600 and 900) and the output data is generated by using a building hygrothermal simulation tool. Validation procedures have shown very good agreement between the regression equations and the simulation tool for both winter and summer periods. [Copyright &y& Elsevier]

Abstract: Building energy analyses are very sensitive to external convective heat transfer coefficients so that some researchers have conducted sensitivity calculations and proved that depending on the choice of those coefficients, energy demands estimation values can vary from 20% to 40%. In this context, computational fluid dynamics calculations have been performed to predict convective heat transfer coefficients at the external surfaces of a simple shape low-rise building. Effects of wind velocity and orientation have been analyzed considering four surface-to-air temperature differences. Results show that the convective heat transfer coefficient value strongly depends on the wind velocity, that the wind direction has a notable effect for vertical walls and for roofs and that the surface-to-air temperature difference has a negligible effect for wind velocity higher than 2m/s. External convective heat transfer coefficient correlations are provided as a function of the wind free stream velocity and wind-to-surface angle. [Copyright &y& Elsevier]

A two-dimensional model is proposed for energy efficiency assessment through the simulation of heat transfer in building envelopes, considering the influence of the surrounding environment. The model is based on the Du Fort–Frankel approach that provides an explicit scheme with a relaxed stability condition. The model is first validated using an analytical solution and then compared to three other standard schemes. Results show that the proposed model offers a good compromise in terms of high accuracy and reduced computational efforts. Then, a more complex case study is investigated, considering non-uniform shading effects due to the neighboring buildings. In addition, the surface heat transfer coefficient varies with wind velocity and height, which imposes an addition non-uniform boundary condition. After showing the reliability of the model prediction, a comparison over almost 120 cities in France is carried out between the two- and the one-dimensional approaches of the current building simulation programs. Important discrepancies are observed for regions with high magnitudes of solar radiation and wind velocity. Last, a sensitivity analysis is carried out using a derivative-based approach. It enables to assess the variability of the solution according to the modeling of the two-dimensional boundary conditions. Moreover, the proposed model computes efficiently the solution and its sensitivity to the modeling of the urban environment. [ABSTRACT FROM AUTHOR]

Moisture is one of the main issues in building disorders. It can lead to microorganism's growth, material deterioration and impact on energy consumption. A comprehensive overview on the scale of the country considering climatic conditions may be an important starting point for potential moisture risks in building analyses. In this paper, we present a method in which weather-based indicators are developed for a first outline of the potential moisture risk in buildings considering the main climatic sources of moisture. The proposed method is related to weather parameters, comprising two new indicators - in a total of three - that are plotted in the country map using Geographic Information System to spatially represent the risk across the country territory. The method is applied for Brazil, and results indicate high weather-based moisture risks in highly densely populated areas. The case study highlights the importance of the presented methodology as a first analysis of potential moisture risk on a country scale. [ABSTRACT FROM AUTHOR]

A precise hygrothermal model is essential to predict the energy performance of building envelopes providing coupled transport of mass (moisture and air) and heat through porous elements, considering phase change and all heat transfer modes, including the radiative transfer through fibrous materials. Therefore, a new mathematical model, called CAR-HAM (Conductive, Advective, and Radiative Heat, Air and Moisture), is proposed to include the radiative transfer equation to calculate the thermal radiation effects within the porous materials to be taken into account in the energy balance. The moisture and the energy conservation equations are simultaneously solved using a fully implicit scheme and the MTDMA algorithm. The comparison of the proposed model considering some case studies such as attic insulation, bar drying, convection and high humidity (rain load) - showed a good agreement with experimental data available in the literature. [ABSTRACT FROM AUTHOR]

This paper aims at estimating the sorption isotherm coefficients of a wood fiber material using experimental data. First, the mathematical model, based on convective transport of moisture, the Optimal Experiment Design (OED) and the experimental set-up are presented. Then, measurements of relative humidity within the material are carried out, after searching the OED using the computation of the sensitivity functions and a priori values of the unknown parameters. It enables to plan the experimental conditions in terms of sensor positioning and boundary conditions out of 20 possible designs, ensuring the best accuracy for the identification method and, thus, for the estimated parameter. After the measurements, the parameter estimation problem is solved. The determined sorption isotherm coefficients calibrate the numerical model to fit better the experimental data. However, some discrepancies still appear since the hysteresis effects on the sorption capacity are not included in the model. Therefore, the latter is improved proposing an additional differential equation for the sorption capacity to consider the hysteresis effects. The OED approach is developed for the estimation of five of the coefficients involved in the hysteresis model. To conclude, the prediction of the model with hysteresis have better reliability when compared to the experimental observations. [ABSTRACT FROM AUTHOR]

Highlights • Pixel counting technique for interior sunlit area calculation is experimentally validated. • Simulation skillfulness for complex geometries of the pixel counting is investigated. • Pixel counting has good agreement with the experiments. • The impact of internal sun patch position on surface temperature is highlighted. • Importance of computer graphic development to modernize solar energy assessment. Abstract Pixel counting (PxC) emerged as a powerful technique for external solar shading calculations of buildings, providing accurate results with great computational efficiency even for dense geometries. Motivated by this fact and because the technique can be also adapted to cope with interior surfaces without further ado, this paper aims at experimentally evaluating the PxC technique implemented in Domus software for calculating sun patch distribution within building enclosures. For the validation purpose, digital images were taken from the surfaces of an experimental house to compare with the simulation results obtained by using EnergyPlus and two PxC based tools: Domus and Shading II SketchUp plug-in. This first task has shown that the PxC presents results in good agreement with the experimental data, in terms of both location and area of the sun patch. Also, a second case study was constructed to evaluate the capability of PxC for simulating non-convex zones with perforated shading elements. The results, in general, have shown that the PxC can provide accurate results in situations where polygon clipping based algorithms cannot be applied. [ABSTRACT FROM AUTHOR]

This work presents an alternative view on the numerical simulation of diffusion processes applied to the heat and moisture transfer through porous building materials. Traditionally, by using the finite-difference approach, the discretization follows the Method Of Lines (MOL), when the problem is first discretized in space to obtain a large system of coupled Ordinary Differential Equations (ODEs). Thus, this paper proposes to change this viewpoint. First, we discretize in time to obtain a small system of coupled ODEs, which means instead of having a Cauchy (Initial Value) Problem (IVP), we have a Boundary Value Problem (BVP). Fortunately, BVPs can be solved efficiently today using adaptive collocation methods of high order. To demonstrate the benefits of this new approach, three case studies are presented, in which one of them is compared with experimental data. The first one considers nonlinear heat and moisture transfer through one material layer while the second one considers two material layers. Results show how the nonlinearities and the interface between materials are easily treated, by reasonably using a fourth-order adaptive method. Finally, the last case study compares numerical results with experimental measurements, showing a good agreement. [ABSTRACT FROM AUTHOR]

This work is devoted to proposing a hybrid numerical–analytical method to address the problem of heat and moisture transfer in porous soils. Several numerical and analytical models have been used to study heat and moisture transfer. The complexity of the coupled transfer in soils is such that analytical solutions exist only for limited problems, while numerical solutions can deal with more realistic ones but at a higher computational cost. Therefore, we propose to implement analytical solutions where variations of temperature and moisture content are known to be almost nonvarying, while the numerical solution is implemented in the remaining region, near the boundaries. The coupling between solutions is performed assuming the continuity of both fields and fluxes at each interface. This strategy allows assuring the physical phenomenon occurring at the interface. Numerical experiments are performed, showing the accuracy, the efficiency, and the great potential of the method regarding applications in nonlinear soil problems. [ABSTRACT FROM AUTHOR]

This paper presents a practical application of the concept of Optimal Experiment Design (OED) for the determination of properties of porous materials with in situ measurements and an identification method. First, an experimental set-up was presented and used for the measurement of relative humidity within a wood fibre material submitted to single and multiple steps of relative humidity variation. Then, the application of OED enabled to plan the experimental conditions in terms of sensor positioning and boundary conditions out of 20 possible designs. The OED search was performed using the Fisher information matrix and a priori knowledge of the parameters. It ensures to provide the best accuracy of the identification method and thus the estimated parameter. Optimal design results have been found for single steps from the relative humidity ϕ = 10–75%, with one sensor located at the position X between 4 and 6 cm, for the estimation of moisture permeability coefficients, while from ϕ = 75 % to ϕ = 33 % , with one sensor located at X ∘ = 3 cm , for the estimation of the advection coefficient. The OED has also been applied for the identification of couples of parameters. A sample submitted to multiple relative humidity steps ( ϕ = 10–75–33–75%) with a sensor placed at X ∘ = 5 cm was found as the best option for determining both properties with the same experiment. These OED parameters have then been used for the determination of moisture permeability and advection coefficients. The estimated moisture permeability coefficients are twice higher than the a priori values obtained using standard methods. The advection parameter corresponds to the mass average velocity of the order of v = 0.01 mm / s within the material and may play an important role on the simulation of moisture front. [ABSTRACT FROM AUTHOR]

The area of projected shadow on building facades may play a role of paramount importance in the prediction of solar energy conversion and building thermal and energy performance. Algorithms for solar shading calculations may directly affect the accuracy of results obtained by building energy simulation tools. In addition, the consideration of uncertain design parameters imply an estimative of a confidence interval of solar fraction results that determine the reliability as well as the improvement of shading calculation models. In this way, this paper presents a methodology for uncertainty and sensitivity analysis applied to the prediction of sunlit area on building exterior surfaces with shading devices. From a single building model, the solar fraction was investigated for two cities and four typical days. According to the obtained results, more than 20% of all simulation time steps have uncertainties equal or higher than 5% on the solar fraction calculation at 95% confidence level. The maximum values of the uncertainties occur in warmer months, which could significantly impact the building energy balance. Three inputs have higher influence on the uncertainties on solar fraction results: (1) latitude, (2) orientation and (3) width of overhang fins. Perturbation of only 5° on the building orientation may imply important uncertainties on solar fraction, which is normally neglected by designers. The results highlight the importance of assessing the uncertainty of inputs in algorithms such as the one to calculate the surface solar fraction that is an important prerequisite of the final building energy balance. [ABSTRACT FROM AUTHOR]

A proper generalised decomposition for solving inverse heat conduction problems is proposed in this article as an innovative method offering important numerical savings. It is based on the solution of a parametric problem, considering the unknown parameter as a coordinate of the problem. Then, considering this solution, all sets of cost function can be computed as a function of the unknown parameter of the defined domain, identifying the argument that minimises the cost function. In order to illustrate the applicability, the method is used to solve a non-linear inverse heat conduction problem to determine a temperature-dependent thermal conductivity. Then, a comparison is carried out with the local sensitivity and the genetic algorithm methods. It is shown that the proper generalised decomposition method estimates the unknown parameter with the same accuracy as the other two methods. Due to its advantage in terms of reducing the complexity, the method was then used to solve a transient three-dimensional non-linear heat transfer inverse problem. The results have shown that the method is appropriate to determine the unknown parameter with a low computational cost. Furthermore, the main advantage of the technique is its low capacity for storage, which can be used, as an inverse method, for building energy management and extended to evaluate thermal bridges from on-site measurements. [ABSTRACT FROM AUTHOR]

Highlights: [•] Experimental characteristic curves for two room air conditioners are presented. [•] These results can be implemented in building simulation codes. [•] The energy consumption under different conditions can numerically determine. [•] The labeled higher energy efficiency product not always provides the best result. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, several intensive studies have been carried out in order to reduce the energy consumption of buildings. One solution lies on whole building energy simulation that permits to enable the heat (and moisture) transfer through the building envelope and, consequently, is a way to understand how to improve the building performance. This article aims to analyze the modeling level needed to successfully evaluate the heat transfer through glazing parts of windows in such whole-building simulations as it is well-known that windows are the thermally weakest elements of the building envelope. In this way, predictions of glazing surface and zone air temperatures and energy demand obtained using both resistive and finite-volume based models are compared. Results show that for common window glazing structure and outdoor/indoor perturbations, differences between the two models are small. However, in the case of glazing presenting higher solar absorption and thermal inertia, the use of the finite-volume based model is required to accurately predict the glazing internal surface temperature and avoid errors up to 50% for energy consumption in the studied case. Those results put into relief a clear limitation of current whole energy simulation programs to correctly predict the energy consumption of buildings where high thermal inertia double- or triple-glazing windows are installed. [Copyright &y& Elsevier]

Abstract: Studies on the dynamics of temperature and moisture content distributions in porous soils have provided important insight on their effect on the building hygrothermal behavior, where the interaction between both building and soil can contribute to reduce building thermal gains or looses. Hygrothermal aspects can be related to many attributes such as energy consumption, occupants'' thermal comfort and health, and material deterioration. Recently, a great variety of mathematical models to predict thermal and moisture content profiles in porous media have been presented in the literature. Most of those models are based on analysis of multilayer measurements or on Fourier analysis. The development and validation of such mathematical models facilitate the understanding of heat and moisture flows at different soil depths. In this research, a radial basis function neural network (RBF-NN) approach, combined with Gath–Geva clustering method in order to predict the temperature and moisture content profiles in soils, has been presented. A set of data obtained from the computation of the coupled heat and moisture transfer in porous soils for the Curitiba city (Paraná State, Brazil) weather data file has been used by the RBF-NN modeling method. Simulation results indicate the potentialities of the RBF-NNs to learn, for the one step ahead identification, the behavior of temperature and moisture content profiles in the media at various depths. [Copyright &y& Elsevier]

• A multi-criteria method for designing shading devices of buildings is presented. • The method is based on: search of non-dominated solutions and physical programming. • Physical programming allows finding a ranking containing the preferred solutions. • Design objectives are related to Energy Efficiency, Daylighting and Fading Protection. • A Pixel Counting based tool allows evaluating more complex shading devices. Multi-criteria design techniques applied to the analysis of shading devices of buildings have arisen as useful tools for architects. Even though several techniques have been applied to shading devices with simple geometries, they usually require numerous simulations to suitably complete the analysis, making the optimization process time-consuming. Since shading devices should prevent damage to furnishings and materials, performance indicators may not be related exclusively to thermal comfort, energy consumption and daylight performance, but also to other important criteria, such as fading protection. To overcome these limitations, this study aims to present a multi-criteria method for the design of shading devices, including fading protection as an evaluation criterion, regardless of geometry complexity. The method is applied to perforated shading devices of a room office, considering as the design objectives the energy savings, daylight availability on the work plane and solar beam incidence on interior surfaces. As a novelty, a more practical approach is proposed based on two main steps: search process, for obtaining a set of non-dominated solutions, and physical programming method, in which the solutions are ranked according to the preferences of decision makers. Besides, the solar beam incidence on interior surfaces is evaluated by using a pixel counting based method, which was emerged as a powerful algorithm due its capacity to simulate any geometry with accuracy and low computational cost. The results have shown that the proposed method is an effective process in designing of the optimal shading devices to reduce energy consumption, and improve the daylight use and the fading protection, regardless of the geometry complexity. [ABSTRACT FROM AUTHOR]

Clay-based materials are the most traditional components of buildings. To improve their performance in a sustainable way, agents can be mixed to fired clay acting as a pore-forming factor. However, firing temperatures highly influence their microstructure which is closely linked to a material's final performance as a ceramic block. To highlight the influence of the firing temperature on microstructure, and more specifically on the pore size distribution of clay-based materials, three innovative porous materials were manufactured. These materials were produced by mixing clay and pore-forming agents. They were characterized by optical and scanning electronic microscopy, x-ray diffraction, mercury intrusion and nitrogen adsorption. These techniques allow the phase identification of materials, show sample microstructure and quantify the pore size distribution at different scales. Furthermore, geometric parameters of sample microstructure such as grain diameter and roundness are estimated by using computer software. To conclude, results provide an enlightenment about the influence of material microstructure on the pore size distribution at two firing temperatures. These results can be useful to allow the tune of porous characteristics and, therefore, contribute to the production of more sustainable construction materials. [ABSTRACT FROM AUTHOR]