Energy Consumption In Office Research Articles

The synergistic effect of multiple design factors on building energy consumption of office blocks: A case study of Wuhan, China

Design factors such as block morphology, building form and building envelope performance are key parameters affecting building energy consumption of urban blocks. However, the synergistic effect of multi-design factors on building energy consumption has not been studied in detail. This paper aims to investigate the synergistic effect of multi-design factors on building energy consumption of office blocks in Wuhan, China. This study employs field survey, satellite map and open street map to extract the typical building forms and construct parametric models of office blocks. Then, 81 representative scenarios considering the synergy of multiple design factors in office blocks are built. Then, based on the Rhino & Grasshopper parametric platform, a building energy assessment tool that considers the synergistic effect of multiple design factors is developed to simulate and record the building energy consumption of each scenarios. Finally, the synergistic effect of multi-design parameters on building energy consumption of office blocks is quantified using correlation and multiple linear regression methods. The findings reveal that the synergistic effect of multi-design factors on building energy consumption is 18.53 %. Building energy consumption for high-rise pavilion typology is saved by 9.64 % than multi-storey courtyard. The key design parameter combinations affecting building energy consumption in office block are building shape factor, solar heat gain coefficient, wall K-value, building width and window-wall ratio of west and east. This study contributes to a deeper understanding of the synergistic effects of multiple design factors on building energy consumption in office blocks and presents a scalable model that can be applied globally to promote sustainable urban development.

Medium office energy consumption optimization using EnergyPlus

This research paper studies the impacts of HVAC system scheduling and building envelope material properties on the building energy efficiency in the downtown New York City, metropolitan area, that is highly associated with Urban Heat Island. By utilizing EnergyPlus for whole energy building simulation, the research compares two HVAC operational cases: a baseline case with constant temperature setpoints, and an occupancy-based temperature setpoint schedule. The study also investigated the influence of thermal conductivity variations in stucco exterior wall materials, with three cases, the default baseline thermal conductivity and a 15% variance, respectively. Results indicate that occupancy-driven scheduling significantly reduces energy consumption by approximately 16% annually compared to baseline. Conversely, the influence of thermal conductivity on energy consumption is minimal, with only a 0.35% deviation noted in response to a 15% variation in thermal conductivity. This suggests that both optimizing HVAC scheduling and the thermal conductivity of building envelope materials can save building energy consumption while optimizing HVAC scheduling has a relatively stronger impact than optimizing the thermal conductivity with a 15% variance in downtown New York City.

Building Energy Savings by Developing Complex Smart Windows and Their Controllers

The interest in zero-energy buildings has increased in Korea recently. Following the significant increases in cooling and lighting energy consumption in offices, various studies have been conducted to implement energy-saving measures. The purpose of this study is to reduce lighting and cooling energy consumption in the summer through the dimming control of a complex smart window system. To achieve this, the optimal dimming control algorithm has been derived and applied in simulations to analyze the energy consumption for lighting and cooling. A smart window incorporates suspended particle display glass that actively responds to changes in indoor and outdoor environments and controls light transmittance. It also includes a light-guiding glass that can actively control solar reflectance. Simulations of office buildings were conducted to develop optimal control algorithms and controllers based on solar radiation. Subsequently, we installed this complex smart window in a test room along with the developed control algorithm and controller, which responded to the amount of insolation and time. To ensure the accuracy of the experiment, we constructed separate test and reference rooms. The experimental results obtained under the same conditions showed a reduction of approximately 36.9% in cooling energy consumption in the test room compared with the reference room and a 54.5% reduction in lighting energy consumption. Furthermore, based on additional simulations and experiments, we confirmed that the application of complex smart window systems in office buildings could reduce considerably the energy consumption for cooling and lighting.

Case Study: Impacts of Air-Conditioner Air Supply Strategy on Thermal Environment and Energy Consumption in Offices Using BES-CFD Co-Simulation.

Due to energy constraints and people's increasing requirements for indoor thermal comfort, improving energy efficiency while ensuring thermal comfort has become the focus of research in the design and operation of HVAC systems. This study took office rooms with few people occupying them in Wuhan as the research object. The EnergyPlus-Fluent co-simulation method was used to study the impact of 12 forms of air distribution on the thermal environment and air-conditioner energy consumption. The results indicate that 3 m/s supply air velocity and 45° supply air angle are more suitable for the case model in this study. The EnergyPlus-Fluent co-simulation method used in this paper provides a reference for the study of indoor environments in offices with few people occupying them.

Importance of air quality indicators for office environments: An overview

Air quality in office buildings has got an impact on working productivity as well as on the working satisfaction in office environments. Moreover, final effect can be linked with thermal comfort conditions since they have significant impact on energy consumption in offices. In this study various factors have been investigated and analysed in order to understand their impact on air quality and occupants’ satisfaction with the environmental conditions. The second perspective of the overview was focused on analysis of the air quality interconnection with thermal comfort conditions, since they are linked. The current issues as well as challenges in the field were also discussed within this investigation. The results of conducted research would be directly useful for more advanced consideration of personal air quality and thermal comfort conditions as vital aspect of smart and high-performance buildings.

Effect of Block Morphology on Building Energy Consumption of Office Blocks: A Case of Wuhan, China

Block morphology refers to critical parameters influencing building energy performance on the block scale. However, analysis of the combined effect of block morphological parameters on building energy consumption with real blocks is lacking. In this paper, the aim is to evaluate the combined effect of office block morphology on building energy consumption in the context of the Hot-summer and Cold-winter zone in China. First, a workflow for the energy assessment of office buildings with the coupled block morphology on the block scale was proposed with evaluation tools. Seventy office blocks in Wuhan were taken as examples and then classified based on building layout typology and building height. Afterwards, the morphological parameters and building energy use intensity (EUI) for different blocks were calculated. Then, the combined effect of block morphology on the buildings’ energy consumption was evaluated and the model on predicting the building energy consumption of office blocks was proposed. Finally, based on the results, low-energy design strategies were projected for office blocks. The results illustrated that the effect of block morphology on building cooling, heating, and lighting is EUI 28.83%, 28.56%, and 23.23%, respectively. Building shape factor (BSF), floor area ratio (FAR), average building height of block (BH), and average building depth of block (BD) are effective block morphological parameters. The key morphological parameters which combined affect the building energy consumption of office blocks are BSF and FAR; BSF has 1.24 times the effect on building energy consumption than FAR. The workflow built in this paper can be applied to other cities around the world for promoting sustainable cities.

A Semi-Automatic Data Management Framework for Studying Thermal Comfort, Cognitive Performance, Physiological Performance, and Environmental Parameters in Semi-Outdoor Spaces

Semi-outdoor space can be used as an alternative to short-term office activities to save office energy consumption and promote a healthy and nature-based working environment. This study evaluated the suitability of semi-outdoor space in four aspects including environmental measurements, physiological measurements, subjective measurements and cognitive performance tests. However, the manual processing and analysis of such multidimensional data can be time-consuming and error-prone. Hence, the objective of this study was to develop a semi-automatic method to manage and analyze the data from different instruments and platforms and two open-source applications (a stroop color and word test and a digit span test) for cognitive performance tests. These codes were critical to the success of the project, providing an effective framework for data extraction, data pre-processing, data analysis and performance tests. Eighty-nine people participated in the experiment of evaluation of thermal comfort, cognitive performance, physiological performance and environmental parameters in semi-outdoor spaces in a tropical setting. Each participant received cognitive tests to assess their selective attention, short-term memory, concentration and creativity quotient. Concurrently, qualitative measurements were conducted to assess thermal sensation, thermal comfort and thermal acceptability. The heart rate, skin temperature, and skin conductance of participants were measured throughout the experiments. Microclimatic variables such as illuminance, noise levels, dry-bulb air temperature, global temperature, relative humidity, air speed, and air direction were monitored simultaneously. To understand the effects of semi-outdoor spaces on participant performance, this study recorded participant performance in different environments through controlled experiments. Data related to participants in different settings include those shared (e.g., environmental measurement), and data unique to each participant (e.g., physiological performance). The results revealed that the subjects’ cognitive and physiological performance did not change significantly after switching to the semi-outdoor space due to the availability of natural and mechanical ventilation, suggesting that short-term office activities in the semi-outdoor space are feasible in the tropics.

Weighting of indoor environment quality parameters for occupant satisfaction and energy efficiency

Sustainable retrofit can increase a building's performance and extend its lifetime. Common sustainable retrofit guides usually ignore the building's indoor environmental quality (IEQ) and occupant satisfaction while only focus on the energy efficiency. During the retrofit, prioritizing improvements to IEQ parameters that are critical for increasing occupant satisfaction but do not considerably increase energy consumption is crucial given the budgetary constraints. This project aims to identify different building experts' perspectives on the impact of IEQ factors and underlying parameters that contribute to occupant satisfaction and energy efficiency in office buildings, and develop an index that ranks the IEQ parameters' overall cost-effectiveness in a sustainable retrofit. The study surveys the views of 30 carefully selected building experts (ten architects, ten building engineers, and ten building assessors) in Australia using multiple criteria decision-making method. Results show that the building engineers and assessors regard thermal comfort as the most critical factor influencing occupant satisfaction, 54.2% and 57.6%, respectively. Alternatively, the architects regard visual comfort as the most important (38.8%). All expert groups have a similar opinion on the relative importance of IEQ factors in office energy consumption. An IEQ Effectiveness index is developed to evaluate the cost-effectiveness of improving a specific IEQ parameter in achieving high occupant satisfaction while not demanding extra energy input. Visual and acoustic IEQ parameters turn out to be ideal IEQ parameters that can be prioritized in a retrofit. Results from this study can provide guidance for the decision-making process of the office building sustainable retrofit.

How can energy saving culture of a company influence energy behaviors and consumptions in its offices? A simulation and optimization model

Office buildings consume a significant amount of energy. Driven by social responsibility and economic cost reduction, many companies are dedicated to greening their offices and reducing their operational energy. Improving the energy saving culture is recognized as an effective measure for companies to reduce office energy consumption. However, few studies have focused on quantifying the relationship between company culture and energy consumption. The influences of culture optimization strategies on energy reduction have not been evaluated quantificationally. This study follows the chain of “culture–intention–behaviors–energy consumption” and builds a system dynamic model to simulate and quantify the influences of a company's energy saving culture on energy consumption. This work was conducted in four steps: factors identification, data collection, an system dynamic model development, and optimization strategies simulation. An application study demonstrated the simulation steps and proved the operability of the model. The results showed that improving the energy saving culture of a company can effectively reduce energy consumption in its offices, the influences of various culture optimization strategies differ, and the initial states of company culture and energy consumption behaviors of employees play distinct roles. This study can assist companies in formulating scientific and effective measures to achieve energy saving goals and promote green offices.

Effect of climate zone change on energy consumption of office and residential buildings in China

Previous studies revealed that building climatic zoning has largely changed in China due to the influence of climate change. However, the possible impacts of changing building climatic zoning on energy consumption for cooling or heating are not clear. In this study, eight representative cities were selected from changed climate zones, and the heating and cooling energy consumption of office and residential buildings of the representative cities under the conditions of the current and new climate zones was simulated to reveal the effect of the climate zone change on building energy consumption. The results showed that there was no heating or cooling energy consumption with the climates changing from hot summer and cold winter (HSCW) and cold (C) to mild (M). Also, no heating energy consumption occurred with the climate zones changing from HSCM to hot summer and warm winter (HSWW), whereas the cooling energy consumption showed a weak decrease. For the climate zones that shifted from severe cold (SC) to C, decreasing heating energy consumption and increasing cooling energy consumption trends were observed, and the total energy use exhibited a decreasing trend. However, in the climate zones changing from C to HSCW, the heating and cooling energy consumption increased, especially for residential buildings (e.g., the heating energy consumption of Zhengzhou and Baoji increased 78.7% and 77.7%, respectively). This study suggests that new climate zones should be fully considered and the new design standard according to the changes of climate zones should be adopted to improve building energy efficiency. The design of residential buildings in the climate zones changing from C to HSCW may not consider the changes of climate zone.

Optimizing energy consumption and occupants comfort in open-plan offices using local control based on occupancy dynamic data

Optimal management of buildings' energy-consuming systems is of great importance for minimizing building energy consumption while satisfying the occupants. Since the operation of building systems are highly dependent on the presence of occupants, considering the dynamic occupancy information has become crucial to reflect the occupancy dynamism within offices and the random patterns in occupant behavior. Thus, occupancy-centered control strategies are required in order to enhance the energy management of buildings. On the other hand, the need for localized and customizable comfort controls is increasing in office buildings to improve the occupants’ satisfaction, and consequently their productivity. To this end, a framework aiming at developing optimal occupancy-centered local control strategies is proposed in this paper. A new simulation-based multi-objective optimization model of the energy consumption in offices is developed to exploit occupancy-related data and evaluate possible local control strategies to select the best ones. A set of real occupancy data collected over a period of one year is fed to the integrated simulation-based optimization model for investigating the energy-saving potentials. Comparing the results shows that a considerable improvement in the indoor comfort condition can be achieved through the application of the proposed framework. We conclude that optimal control strategies not only provide demand-driven control solutions but also optimize building energy performance. The integrated model enables dynamic building energy management according to dynamic occupancy patterns. It avoids over-conditioning that is the result of the application of common practices, which control building systems based on the peak occupancy.

Energy Benchmarking of Existing Office Stock in Spain: Trends and Drivers

Buildings play a central role in the clean energy transition, which is why it is vital to understand how energy is consumed in this sector. Energy performance certificate databases are considered a key source of information on the characteristics of built building stock. Despite a growing portfolio of studies based on information from such databases, little is known about energy consumption in offices. This paper explores the modelled energy performance of existing offices in Spain, using data from 13,701 energy performance certificates collected by the Catalan Institute of Energy (ICAEN) in 2013–2018. Offices were found to consume between 202.66 and 212.10 kWhp/m2·year and were mostly ranked in classes C and D (~64%). Offices with E, F or G labels represent ~28% of the sample while A and B energy ratings are very scarce (~8%). Key drivers of energy consumption variation were found to be the office type, construction period, climate zone, renewable energy use, energy certification procedure and motivation for obtaining an energy performance certificate. Ownership was not found to affect average calculated energy consumption. The results will help policy makers to plan future energy conservation strategies.

Potential of perforated exterior louvers to improve the comfort and energy performance of an office space in different climates

Fully glazed building facades often experience high solar heat gains and daylight transmission, resulting in high cooling energy consumption and visual discomfort. The objective of this study was to investigate the potential of perforated exterior louvers for controlling solar heat gains through a fenestration system, providing visual comfort to the occupant and improving the energy performance of an office space in distinct climates (tropical, semiarid, humid subtropical, continental) based on integrated thermal and lighting simulations. The louvers evaluated have 0%, 5%, 10%, 15%, 20%, 25% and 30% perforations with 120 and 240 mm louver spacing. This study demonstrates the potential of perforated exterior louvers for controlling solar heat gains and daylight transmission to improve the visual comfort of the occupant and the building energy consumption. Since perforations can significantly influence office performance and occupant comfort, it is crucial for an evaluation of this type of louver to be completed in the early design stages with integrated thermal and lighting simulation tools that are able to address the complex thermal and optical properties of the louvers. Louvers with 120 mm spacing and 5%–20% perforations reduce office energy consumption by 15%–63% (depending on the city) compared with an unshaded window while meeting the visual comfort criteria (sDA300/50% between 96% and 100%, ASE4000/400h of 0% and DGPs perception class A). Additionally, the percentage of perforations and spacing of louvers significantly impact the evaluated performance criteria. CFSs fully cover the window but have evenly distributed perforations outperform shading devices with larger spacing between louvers and louvers without perforations.

Analysis of combinations of glazing properties to improve economic efficiency of buildings

The ideal combination of low solar heat gain coefficient (SHGC) and high visible transmittance (VT) to maximize energy efficiency of buildings is difficult to achieve because the two quantities have a trade-off relationship. This study analyzed the combination to reduce the energy consumption of office and residential buildings, then proposed a guideline to improve the economic efficiency based on energy cost compared with initial investment cost. First, the glazings used in South Korea were investigated and the possible combinations of SHGC and VT were classified. Then the energy consumption of each combination was quantified. As SHGC decreased and VT increased, energy consumption decreased in the office building, but not in the residential building. Next, the economic efficiency was analyzed for each combination. The efficiency of the office building can be improved by weighting to favor energy consumption over investment cost. While due to nonlinear relationship of energy consumption between SHGC and VT in the residential building, the increased investment cost and decreased energy cost should be compared. This study can contribute to decision-making in ambiguous conditions, such as when the energy cost decreases but investment cost increases.

Modelling Office Energy Consumption: An Agent Based Approach

In this paper, we develop an agent-based model which integrates four important elements, i.e. organisational energy management policies/regulations, energy management technologies, electric appliances and equipment, and human behaviour, based on a case study, to simulate the energy consumption in office buildings. With the model, we test the effectiveness of different energy management strategies, and solve practical office energy consumption problems. This paper theoretically contributes to an integration of four elements involved in the complex organisational issue of office energy consumption, and practically contributes to an application of agent-based approach for office building energy consumption study.

Impact of natural versus mechanical ventilation on simulated indoor air quality and energy consumption in offices in fourteen U.S. cities

This study simulated the impacts of natural versus mechanical ventilation in offices on indoor concentrations of key pollutants, as well as energy usage. A typical office building was modeled in EnergyPlus in fourteen U.S. cities to assess the energy use and airflows delivered by an ideal variable air volume (VAV) system in a range of climates. Two mechanical ventilation strategies (minimum; minimum + economizer control) were modeled, as well as two analogous natural ventilation strategies, which used a fan-driven recirculation hybrid system to maintain setpoints if necessary. Outputted hourly ventilation, recirculation, and infiltration rates were used in an indoor air model with city-specific outdoor monitoring data to compute indoor concentrations of carbon monoxide, carbon dioxide, formaldehyde, nitrogen dioxide, ozone, and fine particles (PM2.5). Natural ventilation decreased energy use, due to a wider temperature setpoint band for natural ventilation scenarios and somewhat lower fan energy use. Indoor concentrations and indoor/outdoor (I/O) ratios of all pollutants were similar for analogous strategies, except PM2.5, which was reduced by filtration in the supply air. Median PM2.5 I/O ratios were a factor of 1.2, 2.2, and 6.3 larger for natural versus mechanical ventilation strategies with MERV 8, 11, and 16 filters, respectively. The filtration impact was so strong that PM2.5 I/O ratios differed little between mechanical minimum and economizing strategies, especially as filter efficiency increased. These results can be used to understand tradeoffs of energy and indoor air pollution trends of natural versus mechanical ventilation.

Energy positive curtain wall configurations for a cold climate using the Analysis of Variance (ANOVA) approach

Curtain walls are believed to be “energy sinks” because of their relatively low thermal performance; however, the integration of energy generating technologies such as photovoltaic (PV) panels may enable converting these systems to “energy positive” curtain walls. A methodology using the Analysis of Variance (ANOVA) approach is developed and implemented to identify configurations of energy positive curtain walls by accounting for the complex interacting effect of facade design parameters. The “energy positive” curtain wall in this paper is defined as the energy generated by the curtain wall facade on an annual basis exceeds the energy consumption of a perimeter zone office enclosed by this curtain wall facade. Ten design parameters are studied, including glazing U-value, solar heat gain coefficient (SHGC), and visible transmittance (Tv); U-value of the spandrel panel; U-value of the mullion; window wall ratio (WWR); infiltration rate; depth and inclination of overhang; and efficiency of PV modules. The significance of individual design parameters on the energy performance is ranked for four cardinal orientations based on the total sensitivity index. The WWR, U-glazing, and infiltration rate are the three most significant parameters influencing the total annual energy consumption of the office unit simulated, while the WWR, PV efficiency, and U-glazing are the most significant design parameters for achieving energy positive curtain walls. The methodology presented in this paper helps facilitate the design process to resolve the issues with conflicting effects of design parameters.

Should we design buildings that are less sensitive to occupant behaviour? A simulation study of effects of behaviour and design on office energy consumption

In an ideal world, occupants have an understanding of how building systems work and are motivated to use the systems as they were designed to be. There is considerable evidence, however, that occupants do not understand the principles of how buildings function and that they use the systems non-optimally. The purpose of the paper is to quantify the effect of occupant behaviour on energy consumption and show how it is affected by design strategies. Numerical simulations of an office were performed with the dynamic thermal simulation software TRNSYS. Three types of behaviour (‘careless’, ‘normal’, and ‘conscious’) and two types of design (‘ordinary’ and ‘robust’) were considered. The results show that the effect of occupant behaviour on energy consumption is greatly diminished with robust design solutions, solutions that make buildings less sensitive to occupant behaviour. The careless user consumes 75–79 % less energy if the robust design solutions are applied rather than the ordinary design solutions. It is argued that a realistic view of occupant behaviour is advantageous in the creation of energy-efficient buildings (that is, leaving less need to learn how buildings work, to be motivated to save energy, or to perform specific energy-saving actions). However, the possibility of personal control should not be eliminated.

The Impact of Cool Roofs on Energy Consumption of Office Buildings in Chongqing of China

Cool roofs are characterized by high solar reflectance (SR) and high infrared emittance (E). When cool roofs are exposed to solar radiation, it will have a lower surface temperature compared to a similar surface with lower SR and E values, and this would result in decreasing the heat penetration into the building. Cool roofs offer significant cooling energy saving in buildings with air conditioning. In order to quantify the influence of cool roofs on the energy consumption of office buildings in Chongqing, the authors tested the electricity consumptions of air conditioners in two rooms on the top floor of an office building. One of the rooms was with cooling roof installed. The result shows that in summer, the room with cooling roof saved electricity 0.049kWh per square meter per day. However in winter, it increased electricity consumption by 0.012kWh per square meter per day.

Analyzing the impact of urbanization on energy consumption in Jiangsu Province

Jiangsu is one of the most developed regions in China. Its’ urbanization rate increased to 61.9 % in 2011, faster than the whole country level (51.27 %). Exploring the influence of urbanization on energy consumption in Jiangsu may help find the relationship between energy consumption and urbanization. The main results received in this paper are as follows. (1) Urbanization accelerated the produce energy consumption over the study period. The produce energy consumption jumped from 50.7 Mtce in 1995 to 166.6 Mtce in 2011. (2) Due to the rapid urbanization, the gap between residential energy consumption for urban and rural regions gradually has become wide since 2002. However, the gap in residential energy consumption per capita between urban and rural has changed narrow since 1995. (3) The grey relational degree between urbanization and office energy consumption is the biggest. However, the relational grade for construction energy consumption is relatively low. (4) The energy intensity effect plays an important role in decreasing produce energy consumption at the aggregate level, followed by the economic structure effect. The economic activity density effect, urbanization rate effect and population effect are found to be primarily responsible for driving produce energy consumption growth over the study period.