Energy Consumption In Office Buildings Research Articles

Edificios de Oficinas bajo lineamientos de Energía Cero en climas templados

El consumo energético en edificios de oficinas es unos de los más altos comparado con otras tipologías edilicias. Los Edificios Energía Cero tienen el objetivo de disminuir el consumo energético y las emisiones de CO2 generadas por el sector. La calidad ambiental en el interior de los espacios de trabajo contribuye a mejorar el confort de los usuarios, la productividad y evitar las enfermedades relacionadas con el Síndrome del Edificio Enfermo (SBS). Las características climáticas de la ciudad de Mendoza poseen grandes ventajas para enfrentar las problemáticas mencionadas mediante el bioclimatismo. En países desarrollados existen políticas claras para avanzar hacia ciudades post carbono, considerando a los EEC para la renovación del sector edilicio. En el presente trabajo se comunica el estado del arte de la temática y se presentan las consideraciones a tener en cuenta en la investigación, sumado a la necesidad de determinar una metodología soporte para la transformación de los edificios de oficinas del Área Metropolitana de Mendoza.

Generalized additive models: An efficient method for short-term energy prediction in office buildings

In 2018, commercial buildings accounted for nearly 18.2% of the total energy consumption in the USA, making it a significant contributor to the greenhouse gases emissions (see, e.g. [1]). Specifically, office buildings accounted for 14% of the energy usage by the commercial sector. Hence, their energy performance has to be closely monitored and evaluated to address the critical issues of greenhouse gases emissions. Several data-driven statistical and machine learning models have been developed to assess the energy performance of office buildings based on historical data. While these methods often provide reliable prediction accuracy, they typically offer little interpretation of the relationships between variables and their impacts on energy consumption. Moreover, model interpretability is essential to understand, control and manage the variables affecting the energy consumption and therefore, such a feature is crucial and should be emphasized in the modeling procedure in order to obtain reliable and actionable results. For this reason, we use generalized additive models as a flexible, efficient and interpretable alternative to existing approaches in modeling and predicting the energy consumption in office buildings. To demonstrate the advantages of this approach, we consider an application to energy consumption data of HVAC systems in a mixed-use multi-tenant office building in Chicago, Illinois, USA. We present the building characteristics and various influential variables, based on which we construct a generalized additive model. We compare the prediction performance using various commonly used calibration metrics between the proposed model and existing methods, including support vector machine as well as classification and regression tree. We find that the proposed method outperforms the existing approaches, especially in terms of short term prediction.

Impact of meteorological factors on high-rise office building energy consumption in Hong Kong: From a spatiotemporal perspective

This article aims to comprehensively analyse the impact of meteorological factors on the energy consumption of high-rise office buildings in Hong Kong. Fifty-seven runs of EnergyPlus simulations based on 30 years of actual hourly meteorological data between 1989 and 2018 measured from one urban and one rural site as well as the Typical Meteorological Year (TMY) were conducted to examine the joint energy impact of climate change and urban heat island (UHI) effect. Spatiotemporal inaccuracies of TMY-based simulations were discussed in error analysis by comparing with those using actual meteorological data. In longitudinal and cross-sectional analyses, significant energy impact of both climate change and UHI was found and quantitatively reported in terms of total and heating, ventilation and air conditioning (HVAC) energy consumption; long-term dynamics and the winter-dominant intra-annual distribution of the UHI-driven energy discrepancies were revealed; and the inconsistency between UHI-driven energy discrepancies and temperature discrepancies was found and explained. Regression analysis shows that for high-rise office buildings in Hong Kong, energy consumption is more sensitive to temperature and moisture change in hot and humid conditions than in cold and dry conditions; and air pressure may also serve as an indicator for a rough estimation of building energy consumption.

Impact assessment of window to wall ratio on energy consumption of an office building of subtropical monsoon climatic country Bangladesh

Building’s window-to-wall ratio (WWR) plays a significant role for predicting energy consumption in tropical climate because huge amount of solar heat gain occurs through the exterior windows for having high solar radiation intensity and annual average temperature in tropical climatic regions. This study investigates the impact of WWR on energy consumption of air-conditioned office buildings in subtropical monsoon climatic country Bangladesh. This research was conducted through rigorous energy simulation perspective by developing a two storey prototype office building in a validated energy simulation tool eQUEST. Around 216 design alternatives were developed for simulation considering eight major cities of Bangladesh, WWR percentage from 10% to 80%, wall thickness, thermal insulation thickness, shading height and window orientations. A comprehensive data analysis was performed to predict the optimum range of WWR percentage for the air-conditioned office buildings. This research suggests a range of WWR that 30% to 40% is the optimum range for the air-conditioned office buildings in Bangladesh. An existing office building was able to save about 9.40% percent of electricity by incorporating optimum percentage of WWR. The output of this work can be incorporated into Bangladesh National Building Code as energy efficient strategies for designing an air-conditioned office building.

Indoor environmental quality and energy use evaluation of a three-star green office building in China with field study

In order to get more comprehensive operation performance on indoor environment quality (IEQ) and energy consumption, a long-time measurement and a field occupants’ satisfaction survey on IEQ performance of the first three-star-operation-certified green office building in Ningbo city of China have been conducted, and environmental energy efficiency (EEE) also has been analyzed. Moreover, IEQ and energy consumption of the green case office building are compared with other green office example buildings of the same climate zone in other literatures. The results show that the actual indoor thermal environment of the green case office building isn’t quite achieving the design goals with the Chinese standard of thermal comfort level II (GB 50736). Although indoor air quality of CO2 concentration and visual environment are consistent with the design goals, the indoor relative humidity doesn’t reach the design goal in most of the year. The questionnaire survey results illustrate that the green case building has a high occupants’ satisfaction on IEQ. The comparison results show that there is no obvious difference in indoor temperature and visual environment between the green case building and the green office example buildings in other studies. The results of occupant’s satisfaction and CO2 concentration of the green case building are better than in other studies. However, the indoor relative humidity of the green case building in every season is much higher than in other researches. Energy use intensity (EUI) of the green case building is about 56.5 kWh/m2·a, which is much lower than the constraint value of the Chinese standard. The actual performance of the green case building is also evaluated by the indicator of EEE. The results of this article can provide useful reference for green building operational performance promotion and feedback for design phase optimization.

Analysis in Integrated Design Potentials Achieving Nearly Zero Energy in Office Buildings in Bangkok Neighborhood

This study aims to investigate the energy-saving potentials and design approaches to move the small and medium office buildings in Bangkok neighborhood areas to become the Net-Zero Energy Building (NZEB). The envelope designs, such as increasing the material’s thermal resistance, adding shading devices, and using high energy-efficient systems, together with the electricity production from the photovoltaic cell, are applied in the studied buildings. According to the energy simulation results, with the implementation of current design techniques, the annual energy consumption of office buildings cannot reach the NZEB. However, these design approaches can enforce the maximum building’s energy-saving capability at 88 kWh/m2 that is nearly the Economic Building (ECON). The maximum energy reduction occurs when improving the high thermal performance of the building’s envelope and using high energy-efficient systems. To achieve this challenging target. Future studies should account for more energy-efficient systems as well as the building’s operation schedule.

Application of phase change materials, thermal insulation, and external shading for thermal comfort improvement and cooling energy demand reduction in an office building under different coastal tropical climates

Architectural techniques have evolved over the century. Presently, climatic conditions require architecture that is more adaptable to the environment. Coastal regions have been recognised to be the most vulnerable to the effects of climate change. Thus far, limited research has offered some strategies to mitigate the solar effect on thermal comfort and energy demand in coastal tropical regions. To address this problem, this study was conducted with the aim of evaluating, analysing, comparing, and discussing the impacts of passive strategies on thermal comfort and energy consumption (as well as the introduction of photovoltaic panels) in coastal tropical climate regions. All simulations were conducted for a period of one year using the Design Builder software. The results demonstrate that phase change materials (PCMs) have a significant effect on thermal comfort and energy consumption in an office under different coastal tropical climates. The combination of PCMs with thermal insulation has the ability to increase the comfort rate by up to 3% while decreasing the cooling energy consumption by approximately 12% in three studied climate zones. In a naturally ventilated building, the most significant increase in the comfort rate is observed with the introduction of PCMs in combination with thermal insulation, whereas thermal insulation, along with external shading, results in the most significant reduction in the cooling energy consumption of an air-conditioned office building (approximately 19%) in three studied climates. Furthermore, the introduction of photovoltaic panels enables us to generate 43–79% of the total energy consumption of the studied office building.

The Effect of Smart Low Emission Glass Material on Reducing Energy Consumption for Office Building in Hot Arid Climate

There were massive innovations in the field of buildings materials at the beginning of the new millennium especially in the field of smart materials. There were many literatures that searched on the role of the smart materials on reduce energy consumption for buildings. This research problem that there was no obvious studies about the effect of smart low emission glass material on reducing energy consumption for office buildings in Baghdad city as an example for hot aired climate cities. Software simulations were used to comparatively estimate the energy performance model for an office building (Baghdad University office tower) after replace the glass of windows with low emission glass. The results showed that reduce of energy consumption reached to 11% as compared to typical type of glass materials.

Study On The Application Of BP Neural Network In The Prediction Of Office Building Energy Consumption

energy consumption is a big problem that can not be ignored in the development of the world. Energy consumption of building accounts for a large proportion of the total energy consumption. With the development of economy and the improvement of modernization, China’s construction industry is in a stage of rapid development. Therefore, under the strong advocacy of China’s energy conservation and emission reduction policy and sustainable development strategy, the construction industry must also follow this trend. In the future development, it is inevitable to integrate the environmental protection concept including economy, energy conservation and environmental protection. However, the energy-saving technology on buildings in China lags behind compared with developed countries, so based on the pattern of energy consumption on buildings in China, this paper proposes an application scheme of energy consumption prediction of an office building in South China by using BP neural network, in order to produce an available research direction for the prediction of energy consumption of office buildings, and promote it to other types of buildings, and provide relevant data support for building design. It will reduce the investigation cost of building energy consumption and be able to offer some reference for the relevant standards of controlling building energy consumption.

Influence of Heat Reflective Wall on Air Conditioning Energy Consumption of Office Buildings in Chongqing

As the main channel of heat and humidity exchange between the building and the external environment, the improvement of the thermal insulation performance of the external wall is crucial to reduce the building energy consumption. However, the influence of heat reflective exterior walls on the energy consumption of air conditioning is rarely studied. This paper aims to study the effects of heat reflective walls on air conditioning energy consumption (ACEC) through testing and simulation. The measured results show that the heat reflective exterior walls will reduce the summer ACEC of the room and increase the ACEC of the room in winter, but the contribution rate is higher in summer than in winter. At the same time, the ACEC simulation results show that the energy saving per unit area of the heat reflective wall of the office building is 0.0149 kWh/(m2•a) for the west outer wall, 0.0131 kWh/(m2•a) for the east outer wall, 0.0121 kWh/(m2•a) for the south outer wall, and 0.0113 kWh/(m2•a) for the north outer wall. These provide a useful reference for the research and application of heat reflective walls in Chongqing.

Study Influencing Factors for Energy Consumption of Office Buildings in Severe Cold and Cold Region, China

The paper analyzed and studied the factors that affect the energy consumption of office buildings, and some suggests were put forward according to the analysis. Through orthogonal experiment the research selected the exterior wall heat transfer coefficient, exterior window heat transfer coefficient, lighting power density, electricity density, air conditioning system form to analyze and study. Although the ranking factors affecting two models are different, but through the analysis found that the air conditioning system is the greatest impact factor, followed by the lighting equipment, after that is envelope.

Efficiency Energy on Office Building in South Jakarta

South Jakarta is the center of business in Indonesia. As a business center, energy consumption in office buildings in South Jakarta is very high. An office building can consume energy up to 250 kWh/m2/yr. Energy consumption can be analyzed using building performance applications such as Sefaira. Sefaira is used as a method to simulate building energy that allows energy to be efficiently utilized. An energy analysis study was conducted to determine energy efficiency in an office building. The standards and guidelines of energy efficiency are based on ASHRAE 90.1 – 2013 on Sefaira. Efficiency energy is needed to achieve the Sefaira 2030 energy target of 90 kWh/m2/yr. In the previous analysis, the building consumed energy of 186 kWh/m2/yr. Architectural treatment on the building facades is needed, such as providing canopies, double-skin facades, and materials to reduce energy consumption by 96 kWh/m2/yr.

Investigation and modeling of energy consumption of tall office buildings in Iran's `hot-arid' and `cold' climate conditions

Abstract The construction of high-rise buildings has attracted human attention at the beginning of human civilizations’ formation. Presently, making tall buildings is considered as a necessary requirement due to the succeeding reasons: the population increase, the tendency to live in urban centers, the land utilization in the most populated centers of the cities, the need to decrease the cost of horizontal development of cities and technological advances. During the last century, issues related to environmental pollution and high energy use have affected these tall buildings. So, it is crucial to apply appropriate methods and patterns in order to adjust their environmental impacts as much as possible. In addition, the building industry accounts for a significant amount of energy consumption in the world. Therefore, energy-saving and efficiency can be mentioned as a significant issue due to the limitation of fossil resources. The importance of this issue has been increased by eliminating subsidies and realizing the price of fuels in Iran. Efforts in the field of high-rise buildings in Iran are chiefly based on general criteria regarding the location and characteristics of urban imagery and the field of urban design knowledge. The efforts contributed to the energy consumption have not been carried out. The present study provides patterns for the aim of designing high-rise buildings with official use in Tabriz and Yazd. The solutions for the opening design of tall buildings with regular forms to reduce energy consumption are proposed in this study.

Optimal Control Method for HVAC Systems in Offices with a Control Algorithm Based on Thermal Environment

This study examined a method to reduce energy consumption in office buildings. Correspondingly, an optimal control method was proposed for heating, ventilation, and air conditioning (HVAC) systems via two control algorithms that considered the indoor thermal environment. The control algorithms were developed by considering temperature and humidity as the factors of the indoor thermal environment that influence the control of HVAC systems and the predicted mean vote comfort ranges. Furthermore, an experiment was performed using office equipment that incorporated the two control algorithms for HVAC systems, and the correlation between changes in the thermal environment within the office and the occupant’s comfort levels was estimated via an actual survey. The results demonstrated that the proposed control method for HVAC systems, which considered the comfort ranges of temperature and humidity and the thermal adaptation capability, can efficiently maintain the occupant’s comfort with lower energy usage compared with conventional HVAC systems. Thus, the use of the control method contributes to the reduction of total energy consumption in buildings with HVAC systems.

Energy benchmarking for office building towers in mild temperate climate

In most underdeveloped countries the lack of access to constructive and consumption data makes it difficult to create a system for the energy consumption classification of buildings. As benchmarking is an important tool for comparing the energy consumption of a building to reference values this study aimed to develop a methodology for the establishment of a benchmark of the electric energy consumption of office buildings in mild temperate climates in which office buildings can operate a significant part of the year using natural ventilation as the air conditioning mode. The city of Belo Horizonte – Brazil was used as a study case. This study was carried out in three steps: Step 1: as data is not readily available it was necessary to establish of a database and a methodology to treat data; Step 2: elaboration of a methodology to create the benchmarking scale using available data; Step 3: analysis of energy efficiency ratings and the proposal of a rating system based on a logarithmic scale. The results of this study showed that it was possible to create a classification range with a 81% degree of reliability for the selected building typologies. In addition, the creation of different classifications according to the type of air conditioning mode made it possible to evaluate office building towers with similar characteristics. The scales proposed also show that for a mild climate, mixed air conditioning mode is a decisive feature in promoting energy efficiency and sustainability to buildings indicating that this strategy should be seriously considered in enforcement building laws.

Determining the optimal window size of office buildings considering the workers' task performance and the building's energy consumption

In office buildings, the workers' task performance and the buildings' energy consumption may differ greatly by window size. Therefore, the purpose of this study was to determine the optimal window-to-wall ratio (WWR) considering the workers' task performance and the energy consumption in office buildings. To analyze the workers' task performance by WWR, cognitive tests and the NASA-Task Load Index test were conducted in a virtual environment. To calculate the energy consumption of the office building, building energy performance simulation was conducted using a large office building of the Department of Energy. Finally, multi-objective optimization was conducted to determine the optimal WWR by building facade orientation. As a result, it was shown that increasing the WWR in an office building can increase the workers' task performance and decrease the workers’ task load. The 60% WWR showed the highest task performance and the lowest task load. As a result, the optimal WWRs in the office building were 44.47% for the East facade, 50.58% for the South facade, 44.37% for the West facade, and 40.95% for the North facade. It is expected that this study will help in determining the window size that is suitable for the building facade when designing office buildings that can realize both energy efficiency and a healthy work environment.

A review on machine learning algorithms to predict daylighting inside buildings

Steep increases in air temperatures and CO2 emissions have been associated with the global demand for energy. This is coupled with population growth and improved living standards that encourages the reliance on mechanical acclimatization. Lighting energy alone is responsible for a large portion of total energy consumption in office buildings; and the demand for artificial light is expected to grow in the next years. One of sustainable approaches to enhance energy-efficiency is to incorporate daylighting strategies, which entail the controlled use of daylight inside buildings. Daylight simulation is an active area of research that offers accurate estimations, yet requires a complex set of inputs. Even with today’s computers, simulations are computationally expensive and time-consuming, hindering to acquire accelerated preliminary approximations in acceptable timeframes, especially for the iterative design alternatives. Alternatively, predictive models that build on machine learning algorithms have granted much interest from the building design community due to their ability to handle such complex non-linear problems, acting as proxies to heavy simulations. This research presents a review on the growing directions that exploit machine learning to rapidly predict daylighting performance inside buildings, putting a particular focus on scopes of prediction, used algorithms, data sources and sizes, besides evaluation metrics. This work should improve architects’ decision-making and increase the applicability to predict daylighting. Another implication is to point towards knowledge gaps and missing opportunities in the related research domain, revealing future trends that allow for such innovative approaches to be exploited more commonly in Architectural practice.

Design and adaptability of photovoltaic air conditioning system based on office buildings

Photovoltaic (PV) air conditioning (AC) is an effective way to solve the problems of energy consumption of office buildings. In this study, a set of parameters were designed for PV AC, including PV capacity, AC parameter, and inverter parameter. Then, the parameters were applied to a 20-m2 office building, and a PV AC system test platform was built. The test lasted for one year; the corresponding data including typical daily data and annual data were collected and analyzed. The results show that the PV AC system quickly decreases or increases the room temperature by ~9.5% and 17% in 1 h of cooling and heating periods, respectively, thus maintaining the room temperature within the set temperature range of ±0.9 °C. The data also show that by proper design of parameters, a PV AC system can satisfy the electricity demand of AC. In the cooling period, heating period, and annual operation conditions, the PV system provided 114%, 73%, and 188% of the energy for the AC system, respectively. Next, economic calculations show that PV AC is suitable for office buildings. The local payback period is only 7.5 years; both the energy saving and emission reduction are significant.

Environmental impact assessment of office building heating and cooling sources: A life cycle approach

Heating and cooling sources occupy a large proportion of the total energy consumption of office buildings and hence the related environmental impacts cannot be underestimated. In this paper, a localized life cycle impact assessment (LCIA) method was established based on local environmental policies and energy regulations according to the framework of life cycle assessment (LCA). It is used to analyze the heating and cooling sources for office buildings in northern China. The environmental impact inventory was classified, characterized, standardized and weighted based on local energy resources. The exergy exhaustion (EE) factor was adopted to analyze the importance of local primary energy. Cost analysis was conducted to increase the practical value and significance of the research results. Questionnaires were used to determine the weight of environmental impact, EE, and cost analysis (CA) for combination scheme selection. Different heating and cooling sources and 7 combination schemes for office buildings in the cold regions of northern China were comprehensively evaluated. Results showed that gas-fired cogeneration + conventional electric refrigeration air conditioners and ground source heat pump (GSHP) for both heating and cooling were two recommended schemes which had the least comprehensive environmental impact index. These investigations can guide decision-makers and designers to choose environment-friendly and economical heating and cooling sources, and help government departments to formulate appropriate incentive policies to encourage the use of suitable, sustainable, and economical energy sources.

Climate change impacts on extreme energy consumption of office buildings in different climate zones of China

In this paper, 16 cities representing four major architectural climate zones of China were selected, and the heating and cooling loads of office building during the period of 1961–2017 were simulated by using TRNSYS software. Daily extreme heating and cooling loads were determined by percentile methods, and the climate change impact on extreme loads was analyzed. The results showed that the days of extreme heating load of office building significantly decreased in almost all the selected cities, whereas there were no significant changes in the days of extreme cooling load. The daily extreme heating load was dominantly affected by the temperature (R2 = 0.43–0.79), but the daily extreme cooling load was related to multiple climate factors, including temperature, relative humidity, and solar radiation. Single temperature can only explain 3–37% of the changes of daily extreme cooling load, and the combination of multiple climate factors can explain 58–85%. Importantly, the effect of temperature on extreme cooling load showed decrease from the cold to hot climate zones, but the impacts of relative humidity and solar radiation gradually increased. These results suggest that the maximum design capacity of heating systems can properly decrease, and the design capacity of cooling systems may not largely increase with the climate warming. In addition, the combined effect of multiple climate factors rather than the single temperature, as well as the different responses of extreme cooling energy consumption to climate change in different climate zones, should be considered when making measures for improving operating efficiency of air-conditioning system.