Determinacao do nivel de effciencia da envoltoria de edificacoes comerciais de acordo com o RTQ-C

Este artigo apresenta uma avaliação preliminar sobre a precisão do modelo simplificado para a avaliação da eficiência da envoltória do Regulamento Técnico da Qualidade do Nível de Eficiência Energética de Edifícios Comerciais, de Serviços e Públicos (RTQ-C). A metodologia consiste em avaliar e comparar os níveis de eficiência obtidos para diferentes tipologias através do Método Prescritivo e do Método de Simulação. Foram adotadas 4 tipologias com diferentes caracteristicas, sendo estas analisadas para o clima de Florianópolis – Brasil. O programa computacional Energyplus foi adotado para a utilização do Método de Simulação, uma vez que este enquadra-se em todos os pré-requisitos exigidos pelo RQT-C. Na comparação entre os dois métodos, observou-se que o uso do modelo simplificado resultou em níveis de eficiência de envoltória inferiores para as tipologias adotadas quando comparado ao Método de Simulação. Este comportamento refletiu mais significamante para as tipologias que apresentam o valor de Fator de Forma inferior ao limite mínimo exigido pelo regulamento. Esta análise demonstra limitações do modelo simplificado para a avaliação da envoltória presente no RTQ-C modelo, contribuindo para o aprimoramento dos instrumentos legais relativos a eficiência energética no ambiente construído.ABSTRACTThis paper provides a preliminary evaluation on the accuracy of the simplified model for energy performance assessment provided by the Regulation for Energy Efficiency Labelling of Commercial Buildings in Brazil (RTQ-C). The methodology consisted on evaluating and comparing results obtained for different typologies by applying the Prescriptive Method and Simulation Method, adopting the weather file of Florianópolis – Brazil. The program EnergyPlus was adopted to run the simulations as this program encloses all the requirements established by RTQ-C. Results have shown that the use of the simplified model led to a lower energy efficiency label than the one obtained using the Simulation Method. This behavior was highlighted in typologies with Shape Factor (FF) value outside from the RTQ-C limits conditions. This analysis demonstrates limitations of the RTQ-C simplified model for energy performance assessment, contributing to the improvement of regulation regarding energy efficiency in the built environment

Capability and deficiency of the simplified model for energy calculation of commercial buildings in the Brazilian regulation

This paper provides a preliminary assessment on the accuracy of the Brazilian regulation simplified model for commercial buildings. The first step was to compare its results with BESTEST. The study presents a straightforward approach to apply the BESTEST in other climates than the original one (Denver, Colorado, USA). The second step consisted on applying the simplified model for common buildings, and compare the results with those obtained using a state of the art building energy simulation (BES) program. Significant errors were found when comparing the simplified model with BESTEST and the common buildings analyzed

An arbitrary polynomial chaos-based approach to analyzing the impacts of design parameters on evacuation time under uncertainty

In performance-based fire protection design of buildings, much attention is paid to design parameters by fire engineers or experts. However, due to the time-consuming evacuation models, it is computationally prohibitive to adopt the conventional Monte Carlo simulation (MCS) to examine the effect of design parameters on evacuation time under uncertainty. To determine the suitable values of design parameters under uncertainty with the reduced significantly computational cost, an arbitrary polynomial chaos-based method is presented in this paper. Arbitrary polynomial chaos expansion is used to construct surrogate models of complex evacuation models. Afterwards, simple analytical method can be adopted to calculate the mean and standard deviation of evacuation time as well as Sobol sensitivity indices based on the arbitrary polynomial chaos coefficients. Meanwhile, the distribution of evacuation time can be generated by coupling Latin hypercube sampling (LHS) to the surrogate model. To demonstrate the proposed method, a case in accordance with the Chinese code GB50016-2012 is presented, evaluating the impact of exit width on evacuation time under arbitrary uncertainty caused by occupant density and child-occupant load ratio in a single-storey fire compartment with two exits. And the results of this case show that the proposed method can achieve the distribution of evacuation time close to those from MCS while dramatically reducing the number of evacuation simulations. When exit width per 100 persons is designed in the range of 0.1m and 0.5m, evacuation time uncertainty is severely affected by exit width and is more significant in exit with smaller width. However, exit width has little effect on Sobol sensitivity indices, the reliability level of a certain safety factor, and safety factor at a certain reliability level

Towards external coupling of BES and HAM envelope programs for whole building HAM simulation

This paper presents preliminary results of on-going research on the integration of building energy simulation (BES) and building envelope heat, air and moisture transfer (HAM) programs. The paper contrasts the capabilities of two BES and HAM programs, and presents the theory and preliminary results of one-way coupling between them

Uncertainty in airflow rate calculations due to the use of surface-averaged pressure coefficients

Mean wind pressure coefficients (Cp) are key input parameters for air infiltration and ventilation studies. However, building energy simulation and stand-alone airflow network programs usually only provide and/or use a limited amount of Cp data, which are based on several assumptions. An important assumption consists of using surface-averaged Cp values instead of local Cp values with a high resolution in space. This paper provides information on the uncertainty in the calculated airflow rate due to the use of surface-averaged Cp data. The study is performed using published empirical data on pressure coefficients obtained from extensive wind tunnel experiments. The uncertainty is assessed based on the comparison of the airflow rate () calculated using the surface-averaged Cp values (AV) and the airflow rate calculated using local Cp values (LOC). The results indicate that the uncertainty with a confidence interval of 95% is high: 0.23 AV <LOC <5.07 AV. In cases with the largest surface-averaged ¿Cp, the underestimation or overestimation is smaller but not negligible: 0.52 AV <LOC <1.42 AV. These results provide boundaries for future improvements in Cp data quality, and new developments can be evaluated by comparison with the uncertainty of the current methods

Energy saving potential of long-term climate adaptive greenhouse shells

This paper describes yearly and monthly optimization of greenhouse shells. Simulations adopt a validated building energy simulation program, adapted and re-validated for simulation of commercial greenhouses, including a tomato crop model. The work focuses on multi-objective optimization of thermal and optical greenhouse shell properties using a genetic algorithm. Analysis of optimization results is supported by sensitivity analyses. The paper concludes that monthly adaptation of greenhouse shells provides little improvement in the crop production and energy performance of the greenhouse when compared to the yearly optimized greenhouse. In the case of adaptable shells, however, high-performance low-energy greenhouses can be achieved at a relatively low level of complexity

Review of external convective heat transfer coefficient models in building energy simulation programs : implementation and uncertainty

Convective heat transfer coefficients for external building surfaces (hc,ext) are essential in building energy simulation (BES) to calculate convective heat gains and losses from building facades and roofs to the environment. These coefficients are complex functions of, among other factors, building geometry, building surroundings, building facade roughness, local air flow patterns and temperature differences. Previous research on hc,ext has led to a number of empirical models, many of which are implemented in BES programs. This paper first provides an extensive overview of such models for hc,ext calculation implemented in BES programs together with the corresponding assumptions. Next, the factors taken into account by each model are listed, in order to clarify model capabilities and deficiencies. Finally, the uncertainty related to the use of these models is discussed by means of a case study, where the use of different models shows deviations up to ±30% in the yearly cooling energy demand (in relation to the average result) and ±14% in the hourly peak cooling energy demand of an isolated, well-insulated building, while deviations in yearly heating energy demand are around ±6%. The paper concludes that each model has a specific range of application, which is identified in this review paper. It also concludes that there is considerable uncertainty in the prediction of hc,ext, which can be transferred to the BES results. This large uncertainty highlights the importance of using an appropriate convection model for simulations of a specific building, certainly for calculating cooling demands and related important performance indicators such as indoor temperatures, indoor relatively humidity, thermal comfort, etc