Evidence-based numerical building model enhancement and building energy efficiency evaluation in the case of Morocco

This paper presents a framework for numerical building validation enhancement based on detailed building specifications from in-situ measurements and evidence-based validation assessment undertaken on a detached sustainable lightweight building in a semi-arid climate. The validation process has been undergone in a set of controlled experiments – a free-float period, and steady-state internal temperatures. The validation was conducted for a complete year with a 1-min time step for the hourly indoor temperature and the variable refrigerant flow (VRF) energy consumption. The initial baseline model was improved by three series of validation steps per three different field measurements including thermal transmittance, glazing thermal and optical properties, and airtightness. Then, the accurate and validated model was used for building energy efficiency assessment in 12 regions of Morocco. This study aims to assess the effect of accurate building characteristics values on the numerical model enhancement. The initial CV(RMSE) and NMBE have improved respectively from 14.58 % and −11.23 %–7.85 % and 1.86 % for the indoor temperature. Besides, from 31.17 % to 14.37 %–20.57 % and 9.77 % for energy consumption. The findings demonstrate that the lightweight construction with the use of a variable refrigerant flow system could be energy efficient in the southern regions of Morocco

Monte Carlo Simulation of Radiation in Gases with a Narrow-Band Model and a Net-Exchange Formulation

The Monte Carlo method is used for simulation of radiative heat transfers in non-gray gases. The proposed procedure is based on a Net-Exchange Formulation (NEF). Such a formulation provides an efficient way of systematically fulfilling the reciprocity principle, which avoids some of the major problems usually associated with the Monte Carlo method : numerical efficiency becomes independent of optical thickness, strongly non uniform grid sizes can be used with no increase in computation times and configurations with small temperature differences can be addressed with very good accuracy. The Exchange Monte Carlo Method (EMCM) is detailed for a one-dimensional slab with diffusely or specularly reflecting surfaces. I Introduction While the role of infrared exchanges in gases is well known for very large (atmospheric) or very hot (combustion) systems, its importance in small, nearly isothermal systems at moderate temperature is much less advertised. And yet, several experimental investig..

Heat integration applied on low thermal energy system: Building complex case study

The tertiary-building sector is one of the most important energy consumers in the Morocco, especially thermal energy. Its intensive use of energy is highly related to the building’s inefficient processes. The Moroccan strategy for energy efficiency aims mainly to save 12% of energy consumption by 2020 and 15% by 2030, which reinforce the appearance of many energy saving alternatives ranging from sensitization and construction laws to engineering applications. The present paper addresses the problem of the building complex energy efficiency in order to improve its performance thermally. The proposed approach in this work is based on the pinch technology which is a technique widely used to integrate and optimize the energy of thermal systems and which has demonstrated its successfulness for industrial process. The simulation results reveals that the potential thermal energy saving reaches 21.16%, with heat exchange network design initially proposed to clearly show the potential recovered. Based on the composite curves (CCs), the problem table algorithm (PTA) and the grand composite curve (GCC), the pinch point temperature is turned out to be 15°C with 316,99 kW of hot utility. The obtained results reveal that the proposed pinch technology perform its effectiveness not only in the industrial sector but also in the building-tertiary

Numerical Analysis of the Building Energy Efficiency Using Two Different HVAC Systems: Variable Refrigerant Flow and Variable Air Volume Technologies

Variable refrigerant flow (VRF) and variable air volume (VAV) systems are considered among the best heating, ventilation, and air conditioning systems (HVAC) thanks to their ability to provide cooling and heating in different thermal zones of the same building. As well as their ability to recover the heat rejected from spaces requiring cooling and reuse it to heat another space. Nevertheless, at the same time, these systems are considered one of the most energy-consuming systems in the building. So, it is crucial to well size the system according to the building’s cooling and heating needs and the indoor temperature fluctuations. This study aims to compare these two energy systems by conducting an energy model simulation of a real building under a semi-arid climate for cooling and heating periods. The developed building energy model (BEM) was validated and calibrated using measured and simulated indoor air temperature and energy consumption data. The study aims to evaluate the effect of these HVAC systems on energy consumption and the indoor thermal comfort of the building. The numerical model was based on the Energy Plus simulation engine. The approach used in this paper has allowed us to reach significant quantitative energy saving along with a high level of indoor thermal comfort by using the VRF system compared to the VAV system. The findings prove that the VRF system provides 46.18% of the annual total heating energy savings and 6.14% of the annual cooling and ventilation energy savings compared to the VAV system

Physicochemical and thermomechanical performances study for Timahdite sheep wool fibers application in the building's insulation

Abstract The present research focuses on the development and thermomechanical characterization of unfired solid bricks based on clay (white and red) and Timahdite sheep wool, which are local, durable, abundant, and economical materials. As this clay material is incorporated with sheep wool in the form of yarn multi-layers in opposite directions. It achieves good thermal and mechanical performance and a lightness of these bricks as acquired progress. This new method of reinforcement offers significant thermo-mechanical performance for the composite for thermal insulation in sustainable buildings. Several physicochemical analyses to characterize the raw materials were used. Thermomechanical measurements to characterize the elaborated materials. The wool yarn effect was significant on the mechanical behavior of the developed materials at 90 days, with flexural strength from 18 to 56% for the white clay. And 8–29% for the red one. Decrease in compressive strength from 9 to 36% for the white clay and 5–18% for the red one. These mechanical performances are accompanied by thermal conductivity gain ranging from 4 to 41% for the white and 6–39% for the red for wool fractions: 6–27 g. This green multi-layered bricks from abundant local materials with optimal thermo-mechanical properties, qualified for the intended use for thermal insulation and energy efficiency in the construction and development of local economies

Assessment of the energy efficiency for a building energy model using different glazing windows in a semi-arid climate

To improve the building’s energy efficiency many parameters should be assessed considering the building envelope, energy loads, occupation, and HVAC systems. Fenestration is among the most important variables impacting residential building indoor temperatures. So, it is crucial to use the most optimal energy-efficient window glazing in buildings to reduce energy consumption and at the same time provide visual daylight comfort and thermal comfort. Many studies have focused on the improvement of building energy efficiency focusing on the building envelope or the heating, ventilation, and cooling systems. But just a few studies have focused on studying the effect of glazing on building energy consumption. Thus, this paper aims to study the influence of different glazing types on the building’s heating and cooling energy consumption. A real case study building located under a semi-arid climate was used. The building energy model has been conducted using the OpenStudio simulation engine. Building indoor temperature was calibrated using ASHRAE’s statistical indices. Then a comparative analysis was conducted using seven different types of windows including single, double, and triple glazing filled with air and argon. Tripleglazed and double-glazed windows with argon space offer 37% and 32% of annual energy savings. It should be stressed that the methodology developed in this paper could be useful for further studies to improve building energy efficiency using optimal window glazing

Building energy efficiency improvement using multi-objective optimization for heating and cooling VRF thermostat setpoints

The variable refrigerant flow system is one of the best heating, ventilation, and air conditioning systems (HVAC) thanks to its ability to provide thermal comfort inside buildings. But, at the same time, these systems are considered one of the most energy-consuming systems in the building sector. Thus, it is crucial to well size the system according to the building’s cooling and heating needs and the indoor temperature fluctuations. Although many researchers have studied the optimization of the building energy performance considering heating or cooling needs, using air handling units, radiant floor heating, and direct expansion valves, few studies have considered the use of multi-objective optimization using only the thermostat setpoints of VRF systems for both cooling and heating needs. Thus, the main aim of this study is to conduct a sensitivity analysis and a multi-objective optimization strategy for a residential building containing a variable refrigerant flow system, to evaluate the effect of the building performance on energy consumption and improve the building energy efficiency. The numerical model was based on the EnergyPlus, jEPlus, and jEPlus+EA simulation engines. The approach used in this paper has allowed us to reach significant quantitative energy saving by varying the cooling and heating setpoints and scheduling scenarios. It should be stressed that this approach could be applied to several HVAC systems to reduce energy-building consumption

Mechanical, electrochemical (EIS), and microstructural characterization of reinforced concrete incorporating natural volcanic pozzolan

The primary objective of this study was to assess the benefits of incorporating higher NMP content as a cement substitute in mortar and concrete mixtures. Our aim was to quantify and elucidate the impact of Natural Moroccan Pozzolanic material (NMP) on compressive strength, insulation performance, and corrosion resistance of reinforced concrete when exposed to chloride attack. Higher NMP dosages were considered for both economic and environmental reasons. Notably, this study is the first of its kind to focus on NMP as a cement substitute. In this study, we investigated the performance of reinforced concrete containing varying percentages of NMP as a partial substitution for Portland Cement (PC), ranging from 10% to 50% by weight. We evaluated the corrosion behavior of reinforced concrete in an aggressive medium (3% sodium chloride) after 3 and 90 days using electrochemical impedance spectroscopy (EIS). We also assessed chloride permeability by measuring the degree of chloride penetration. Additionally, we conducted microstructural characterization using Scanning Electron Microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and Raman spectroscopy to analyse the impact of NMP incorporation into concrete. The study's findings revealed that a partial substitution of cement with up to 50% NMP in concrete can be achieved without compromising overall strength. The highest compressive and bending strengths were observed in mixes with a 30% replacement of cement with NMP. The increased silica, alumina, and calcium content of NMP led to the formation of new calcium silicate hydrates (CSH) and calcium alumino silicate hydrates (CASH) gels, including tobermorite and Al-tobermorite, due to a pozzolanic reaction. Furthermore, the use of NMP in concrete construction improved thermal properties, reducing heat transfer and enhancing thermal comfort. Electrochemical impedance spectroscopy (EIS) and Open Circuit Potential (OCP) results indicated that the addition of natural Moroccan pozzolan enhanced the corrosion resistance of reinforced concrete exposed to 3% NaCl medium. Additionally, the incorporation of NMP significantly reduced cement usage, aligning with sustainable development goals by lowering CO2 emissions

Numerical Results for One Dimesionnal Configurations

0K or 500K with emissivities ffl = 1, 0:5 or 0:1. The gas is isothermal at ` = 1000K and is either pure carbon dioxide or pure water vapor at atmospheric pressure. In order to allow comparisons with published results, some simulations where held where only one spectral band is considered : the 3755cm \Gamma1 band for water vapor (extending from 2875cm \Gamma1 to 4250cm \Gamma1 ) and the 3715cm \Gamma1 band for carbon dioxide (extending from 3275cm \Gamma1 to 3875cm \Gamma1 ). Radiative band parameters are those published in Hartman et al. (1984), Soufiani et al. (1985), and Zhang et al. (1988). The discretization is that of Table 1. Surface radiation budgets at the walls and volumetric radi