Energies

Research

18 pages, 8625 KiB

Open AccessArticle

Standardizing Performance Metrics for Building-Level Electrical Distribution Systems

by Moazzam Nazir, Omkar Ghatpande, Willy Bernal Heredia, Cameron Wierzbanowski, Daniel Gerber and Avijit Saha

Energies 2022, 15(1), 136; https://doi.org/10.3390/en15010136 - 25 Dec 2021

Cited by 2 | Viewed by 2641

Abstract

Building-level electrical distribution systems comprise a myriad of current-carrying equipment, conversion devices, and protection devices that deliver power from the utility or local distributed energy resources to end-use building loads. Electric power has traditionally been generated, transmitted, and distributed in alternating current (AC). [...] Read more.

Building-level electrical distribution systems comprise a myriad of current-carrying equipment, conversion devices, and protection devices that deliver power from the utility or local distributed energy resources to end-use building loads. Electric power has traditionally been generated, transmitted, and distributed in alternating current (AC). However, the last decade has seen a significant increase in the integration of native direct current (DC) equipment that has elevated the importance of DC distribution systems. Numerous studies have comparatively examined the performance of various electrical distribution systems in buildings but have failed to achieve uniform conclusions, primarily because of a lack of consistent and analogous performance evaluation methods. This paper aims to fill this gap by providing a standard set of metrics and measurement boundaries to consistently evaluate the performance of AC, DC, or hybrid AC/DC electrical distribution systems. The efficacy of the proposed approach is evaluated on a representative medium-sized commercial office building model with AC distribution and an equivalent hybrid AC/DC and DC distribution model, wherein the AC distribution model is concluded to be the most efficient. The simulation results show variation in computed metrics with different selected boundaries that verify the effectiveness of the proposed approach in ensuring consistent computation of the performance of building-level electrical distribution systems. This paper provides an initial set of guidelines for building energy system stakeholders to adopt appropriate solutions, thus leading to more efficient energy systems. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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44 pages, 18654 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Development of an Integrated Performance Design Platform for Residential Buildings Based on Climate Adaptability

by Zhixing Li, Mimi Tian, Yafei Zhao, Zhao Zhang and Yuxi Ying

Energies 2021, 14(24), 8223; https://doi.org/10.3390/en14248223 - 7 Dec 2021

Cited by 10 | Viewed by 2834

Abstract

Building energy waste has become one of the major challenges confronting the world today, so specifications and targets for building energy efficiency have been put forward in countries around the world in recent years. The schematic design stage matters a lot for building [...] Read more.

Building energy waste has become one of the major challenges confronting the world today, so specifications and targets for building energy efficiency have been put forward in countries around the world in recent years. The schematic design stage matters a lot for building energy efficiency, while most architects nowadays are less likely to make energy efficiency design decisions in this stage due to the lack of necessary means and methods for analysis. An integrated multi-objective multivariate framework for optimization analysis is proposed for the schematic design stage in the paper. Here, the design parameters of the building morphology and the design parameters of the building envelope are integrated for analysis, and an integrated performance prediction model is established for low-rise and medium-rise residential buildings. Then, a comparison of the performance indicators of low-rise and medium-rise residential buildings under five typical urban climatic conditions is carried out, and the change patterns of the lighting environment, thermal environment, building energy demand, and life cycle cost of residential buildings in each city under different morphological parameters and design parameters of the building envelope are summarized. Specific analysis methods and practical tools are provided in the study for architectural design to ensure thermal comfort, lighting comfort, low energy consumption, and low life-cycle cost requirement, and this design method can inspire and guide the climate adaptation analysis and design process of low-rise and medium-rise residential buildings in China, improve architects’ perception of energy-saving design principles of low-rise and medium-rise residential buildings on the ontological level, as well as provide them with a method to follow and a case to follow in the actual design process. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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15 pages, 4052 KiB

Open AccessArticle

A Fundamental Study on the Development of New Energy Performance Index in Office Buildings

by Jin-Hee Kim, Seong-Koo Son, Gyeong-Seok Choi, Young-Tag Kim, Sung-Bum Kim and Won-Ki Choi

Energies 2021, 14(8), 2064; https://doi.org/10.3390/en14082064 - 8 Apr 2021

Cited by 3 | Viewed by 1859

Abstract

Recently, there have been significant concerns regarding excessive energy use in office buildings with a large window-to-wall ratio (WWR) because of the curtain wall structure. However, prior research has confirmed that the impact of the window area on energy consumption varies depending on [...] Read more.

Recently, there have been significant concerns regarding excessive energy use in office buildings with a large window-to-wall ratio (WWR) because of the curtain wall structure. However, prior research has confirmed that the impact of the window area on energy consumption varies depending on building size. A newly proposed window-to-floor ratio (WFR) correlates better with energy consumption in the building. In this paper, we derived the correlation by analyzing a simulation using EnergyPlus, and the results are as follows. In the case of small buildings, the results of this study showed that the WWR and energy requirement increase proportionally, and the smaller the size is, the higher the energy sensitivity will be. However, results also confirmed that this correlation was not established for buildings approximately 3600 m² or larger. Nevertheless, from analyzing the correlation between the WFR and the energy requirements, it could be deduced that energy required increased proportionally when the WFR was 0.1 or higher. On the other hand, the correlation between WWR, U-value, solar heat gain coefficient (SHGC), and material property values of windows had little effect on energy when the WWR was 20%, and the highest effect was seen at a WWR of 100%. Further, with an SHGC below 0.3, the energy requirement decreased with an increasing WWR, regardless of U-value. In addition, we confirmed the need for in-depth research on the impact of the windows’ U-value, SHGC, and WWR, and this will be verified through future studies. In future studies on window performance, U-value, SHGC, visible light transmittance (VLT), wall U-value as sensitivity variables, and correlation between WFR and building size will be examined. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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16 pages, 18721 KiB

Open AccessArticle

Hot Box Investigations of a Ventilated Bioclimatic Wall for NZEB Building Façade

by Dwinanto Sukamto, Monica Siroux and Francois Gloriant

Energies 2021, 14(5), 1327; https://doi.org/10.3390/en14051327 - 1 Mar 2021

Cited by 6 | Viewed by 1985

Abstract

The building sector is the largest consumer of energy, but there are still major scientific challenges in this field. The façade, being the interface between the exterior and interior space, plays a key role in the energy efficiency of a building. In this [...] Read more.

The building sector is the largest consumer of energy, but there are still major scientific challenges in this field. The façade, being the interface between the exterior and interior space, plays a key role in the energy efficiency of a building. In this context, this paper focuses on a ventilated bioclimatic wall for nearly zero-energy buildings (NZEB). The aim of this study is to investigate an experimental setup based on a hot box for the characterization of the thermal performances of the ventilated wall. A specific ventilated prototype and an original thermal metrology are developed. This paper presents the ventilated prototype, the experimental setup, and the experimental results on the thermal performances of the ventilated wall. The influence of the air space thickness and the air flow rate on the thermal performances of the ventilated wall is studied. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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16 pages, 1117 KiB

Open AccessArticle

Using Smart-WiFi Thermostat Data to Improve Prediction of Residential Energy Consumption and Estimation of Savings

by Abdulrahman Alanezi, Kevin P. Hallinan and Rodwan Elhashmi

Energies 2021, 14(1), 187; https://doi.org/10.3390/en14010187 - 1 Jan 2021

Cited by 10 | Viewed by 2621

Abstract

Energy savings based upon use of smart WiFi thermostats ranging from 10 to 15% have been documented, as new features such as geofencing have been added. Here, a new benefit of smart WiFi thermostats is identified and investigated; namely, as a tool to [...] Read more.

Energy savings based upon use of smart WiFi thermostats ranging from 10 to 15% have been documented, as new features such as geofencing have been added. Here, a new benefit of smart WiFi thermostats is identified and investigated; namely, as a tool to improve the estimation accuracy of residential energy consumption and, as a result, estimation of energy savings from energy system upgrades, when only monthly energy consumption is metered. This is made possible from the higher sampling frequency of smart WiFi thermostats. In this study, collected smart WiFi data are combined with outdoor temperature data and known residential geometrical and energy characteristics. Most importantly, unique power spectra are developed for over 100 individual residences from the measured thermostat indoor temperature in each and used as a predictor in the training of a singular machine learning models to predict consumption in any residence. The best model yielded a percentage mean absolute error (MAE) for monthly gas consumption ±8.6%. Applied to two residences to which attic insulation was added, the resolvable energy savings percentage is shown to be approximately 5% for any residence, representing an improvement in the ASHRAE recommended approach for estimating savings from whole-building energy consumption that is deemed incapable at best of resolving savings less than 10% of total consumption. The approach posited thus offers value to utility-wide energy savings measurement and verification. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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18 pages, 4218 KiB

Open AccessArticle

A Parametric Study of a Hybrid Photovoltaic Thermal (PVT) System Coupled with a Domestic Hot Water (DHW) Storage Tank

by Madalina Barbu, George Darie and Monica Siroux

Energies 2020, 13(24), 6481; https://doi.org/10.3390/en13246481 - 8 Dec 2020

Cited by 11 | Viewed by 2667

Abstract

Photovoltaic-thermal panels are hybrid systems that combine the two types of conventional solar energy technologies (photovoltaic and thermal panels) and simultaneously generate both thermal and electrical energy in a micro-cogeneration system. Like any co-generation system, there is an optimal balance that can be [...] Read more.

Photovoltaic-thermal panels are hybrid systems that combine the two types of conventional solar energy technologies (photovoltaic and thermal panels) and simultaneously generate both thermal and electrical energy in a micro-cogeneration system. Like any co-generation system, there is an optimal balance that can be achieved between the thermal and electrical energy produced. For this reason, it is important to establish the relationship and inter-connection between the two. Limited research is available on the cogeneration interaction in a PVT system, so the novelty of this article lies in the consideration of the entire energy system connected to the PVT panel, including the storage tank and the consumer demand curve, and the investigation of the thermal parametric variation. This study analyses the impact of the variation of some thermal parameters of a domestic hot water tank on the electrical efficiency of a photovoltaic-thermal panel. A model of a system of photovoltaic-thermal panels is built in a transient systems simulation program (TRNSYS) and a one-factor-at-a-time analysis is carried out for the cold-water main temperature, tank size, tank outlet flow and consumer demand curve. The results show that the variation of the outlet flow to the consumer has the highest impact on the electrical efficiency, of about 6.8%. The next highest impact factor is the size of the tank with a variation of 4.7%. Matching the profile of the consumer is also an important aspect. It was observed that the peak electrical efficiency occurs during peak consumer demand. Finally, the instantaneous variation of the thermal and electrical power of the system was analysed as a function of the temperature at the inlet of the photovoltaic-thermal panel. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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21 pages, 37568 KiB

Open AccessArticle

Investigation of the Geometric Shape Effect on the Solar Energy Potential of Gymnasium Buildings

by Lei Jiang, Weiqing Liu, Haiping Liao and Jiabao Li

Energies 2020, 13(23), 6369; https://doi.org/10.3390/en13236369 - 2 Dec 2020

Cited by 5 | Viewed by 3517

Abstract

Gymnasium are typically large-span buildings with abundant solar energy resources due to their extensive roof surface. However, relevant research on this topic has not been thoroughly conducted to investigate the effect of the geometric shape of gymnasium buildings on their solar potential. In [...] Read more.

Gymnasium are typically large-span buildings with abundant solar energy resources due to their extensive roof surface. However, relevant research on this topic has not been thoroughly conducted to investigate the effect of the geometric shape of gymnasium buildings on their solar potential. In this paper, an investigation of the geometric shape effect on the solar potential of gymnasium buildings is presented. A three-dimensional radiation transfer model coupled with historical meteorological data was established to estimate the real-time solar potential of the roof of a gymnasium building. The rooftop solar potential of three typical building foundation shapes and different types of roof shapes that have evolved was systematically analyzed. An annual solar potential cloud map of each gymnasium building is generated. The monthly and annual average solar radiation intensities of the different types of roof shapes are investigated. Compared to the optimal tilt angle, the maximum decrease in the average radiation intensity reached −20.42%, while the minimum decline was −8.64% for all types of building shapes. The solar energy potential fluctuated by up to 11% across the various roof shapes, which indicate that shape selection is of vital importance for integrated photovoltaic gymnasium buildings. The results presented in this work are essential for clarifying the effects of the geometric shape of gymnasium buildings on the solar potential of their roofs, which provide an important reference for building design. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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16 pages, 7257 KiB

Open AccessArticle

Building and Urban Cooling Performance Indexes of Wetted and Green Roofs—A Case Study under Current and Future Climates

by Madi Kaboré, Emmanuel Bozonnet and Patrick Salagnac

Energies 2020, 13(23), 6192; https://doi.org/10.3390/en13236192 - 25 Nov 2020

Cited by 8 | Viewed by 2632

Abstract

We developed and studied key performance indexes and representations of energy simulation heat fluxes to evaluate the performance of the evaporative cooling process as a passive cooling technique for a commercial building typology. These performance indexes, related to indoor thermal comfort, energy consumption [...] Read more.

We developed and studied key performance indexes and representations of energy simulation heat fluxes to evaluate the performance of the evaporative cooling process as a passive cooling technique for a commercial building typology. These performance indexes, related to indoor thermal comfort, energy consumption and their interactions with their surrounding environments, contribute to understanding the interactions between the urban climate and building for passive cooling integration. We compare the performance indexes for current and future climates (2080), according to the highest emission scenario A2 of the Special Report on Emission Scenario (SRES). Specific building models were adapted with both green roof and wetted roof techniques. The results show that summer thermal discomfort will increase due to climate change and could become as problematic as winter thermal discomfort in a temperate climate. Thanks to evapotranspiration phenomena, the sensible heat contribution of the building to the urban heat island (UHI) is reduced for both current and future climates with a green roof. The performance of the vegetative roof is related to the water content of the substrate. For wetted roofs, the impacts on heat transferred to the surrounding environment are higher for a Mediterranean climate (Marseille), which is warmer and drier than the Paris climate studied (current and future climates). The impact on indoor thermal comfort depends on building insulation, as demonstrated by parametric studies, with higher effects for wetted roofs. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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29 pages, 50687 KiB

Open AccessArticle

Design Optimization of a Composite Solar Wall Integrating a PCM in a Individual House: Heating Demand and Thermal Comfort Considerations

by Enghok Leang, Pierre Tittelein, Laurent Zalewski and Stéphane Lassue

Energies 2020, 13(21), 5640; https://doi.org/10.3390/en13215640 - 28 Oct 2020

Cited by 9 | Viewed by 2485

Abstract

Thermal energy storage (TES), which features an innovative technology, can enhance energy efficiency in the building sector and reduce CO₂ emissions. Due to their high heat storage capacity, phase change materials (PCMs) have impressed many researchers. This paper investigates the energy performance [...] Read more.

Thermal energy storage (TES), which features an innovative technology, can enhance energy efficiency in the building sector and reduce CO₂ emissions. Due to their high heat storage capacity, phase change materials (PCMs) have impressed many researchers. This paper investigates the energy performance of an individual house integrating a solar Trombe wall containing PCM with respect to heating demand and thermal comfort applications. The thermal energy performance of the design house was simulated using Dymola/Modelica, the thermal building simulation tool, whereby the optimization of objective functions as regards heating demand and thermal comfort was executed using GenOpt, the generic optimization software. Optimization of the solar Trombe wall focuses on the feasibility to find the optimal PCM parameters when running GenOpt, which consist of latent heat, melting temperature, PCM thickness and thermal conductivity, in order to minimize both the annual energy consumption for heating and the number of hours of thermal discomfort. The parametric study was first conducted for each PCM parameter so as to not only observe its effect on the identified energy performance, but also ensure the absence of errors in simulation runs before performing the optimization. The ‘Coordinate Search’ Generalized Pattern Search (GPS) algorithm was applied to minimize the objective function, whereas the ‘Weighted Sum Approach’ was used to solve the multi-objective function problem. Results showed that the higher the latent heat, the lower the heating demand and the greater the thermal comfort. The results of these parametric studies show that for the effect of the parameter on heating, demand is quite limited (1–2 kWh·m

^{- 2}

·year

^{- 1}

) whereas the effect on thermal comfort is more significant. The optimal PCM melting temperature is higher for warmer climates; it is also higher for the studied case applying the optimization method to minimize the objective function by assigning the number of hours of thermal discomfort (from 32.8

^{\circ} C

to 35.9

^{\circ} C

, depending on weather) than it is when applying the optimization method to reduce the objective function by assigning heating demand (from 31.5

^{\circ} C

to 32.9

^{\circ} C

, again depending on weather). Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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29 pages, 7113 KiB

Open AccessArticle

Energy Analysis and Exergy Optimization of Photovoltaic-Thermal Collector

by Sonja Kallio and Monica Siroux

Energies 2020, 13(19), 5106; https://doi.org/10.3390/en13195106 - 1 Oct 2020

Cited by 30 | Viewed by 3286

Abstract

A photovoltaic-thermal (PVT) collector is a solar-based micro-cogeneration system which generates simultaneously heat and power for buildings. The novelty of this paper is to conduct energy and exergy analysis on PVT collector performance under two different European climate conditions. The performance of the [...] Read more.

A photovoltaic-thermal (PVT) collector is a solar-based micro-cogeneration system which generates simultaneously heat and power for buildings. The novelty of this paper is to conduct energy and exergy analysis on PVT collector performance under two different European climate conditions. The performance of the PVT collector is compared to a photovoltaic (PV) panel. Finally, the PVT design is optimized in terms of thermal and electrical exergy efficiencies. The optimized PVT designs are compared to the PV panel performance as well. The main focus is to find out if the PVT is still competitive with the PV panel electrical output, after maximizing its thermal exergy efficiency. The PVT collector is modelled into Matlab/Simulink to evaluate its performance under varying weather conditions. The PV panel is modelled with the CARNOT toolbox library. The optimization is conducted using Matlab gamultiobj-function based on the non-dominated sorting genetic algorithm-II (NSGA-II). The results indicated 7.7% higher annual energy production in Strasbourg. However, the exergy analysis revealed a better quality of thermal energy in Tampere with 72.9% higher thermal exergy production. The electrical output of the PVT is higher than from the PV during the summer months. The thermal exergy- driven PVT design is still competitive compared to the PV panel electrical output. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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