Analysis of variables that influence electric energy consumption in commercial buildings in Brazil

Air conditioning systems in commercial buildings in Brazil are responsible for about 70% share of their energy consumption. According to BEN 2009 (The Brazilian Energy Balance), energy consumption in the residential, commercial and public sectors, where most buildings are found, represents 9.3% of the final energy consumption in Brazil. This paper aims to examine design factors that could contribute to greater reductions of electric energy consumption in commercial buildings, with emphasis on air conditioning. Simulations were carried out using shades and different types of glass, walls, flooring and roofing. The VisualDOE 2.61 was used as a simulation tool for calculating energy consumption of the analyzed building. This paper shows that the energy performance of the building is considerably influenced by the façade protection and shows, through tables, the impact that decisions related to the top-level and façades have on the energy consumption of the building. The authors concluded that the results confirm the importance of taking energy use into account in the very first design stages of the project, since appropriate choices of types of glass, external shading and envelope materials have a significant impact on energy consumption.     

Thermal energy storage in building integrated thermal systems: A review. Part 2. Integration as passive system

Energy consumption trends in residential and commercial buildings show a significant increase in recent decades. One of the key points for reducing energy consumption in buildings is to decrease the energy demand. Buildings envelopes are not just a structure they also provide protection from outdoor weather conditions always taking into account the local climate. Thermal energy storage has been used and applied to the building structure by taking advantage of sensible heat storage of materials with high thermal mass. But in recent years, researchers have focused their studies on the implementation of latent heat storage materials that if well incorporated could have high potential in energy demand reduction without occupying the space required by sensible storage. The aim of this study is to review the thermal energy storage passive systems that have been integrated in building components such as walls, ceilings or floors, and to classify them depending on their component integration.     

The analysis of energy consumption of a commercial building in Tianjin,China

According to statistics and field investigation, the energy consumption situation and reality of commercial building is described in this paper. As the first step of large-scale public building energy efficiency supervision system encouraged by central government of China, the energy consumption of several typical commercial buildings and public buildings was analyzed in detail. The main contents of investigation are as follows: basic information of building, operational record of energy consumption equipment, energy consumption of indoor equipments, energy-efficiency assessment of energy consumption systems and equipments, investigation of behavior energy saving, etc. On this basis further analysis and diagnosis including indoor thermal and humid environment, operation state of air-conditioning water system, operation state of air-conditioning duct system and operation management of air-conditioning system were implemented. The results show that the most energy consumption of buildings in this city is commercial buildings, which can reach to about 240 W/m² per year. Further analysis tells that air conditioning systems play the major role of building energy consumption, and building energy saving has great potential in this city. In this paper, the ways of diagnosis work for building energy consumption are also described and discussed. Reasonable test, diagnosis and analysis are meaningful for building energy efficiency retrofit and management.     

Simulation of energy saving in Iranian buildings using integrative modelling for insulation

According to one survey on energy consumption in Iran, commercial and building sector consume more energy than any other economic sectors. For example, about 38% of total energy that consumed in year 2001 has been used for space heating. Insulation in external walls of buildings has an important role to reduce the environmental effects on indoor space condition. Therefore, always using insulation is an alternative to avoid from the energy loss. In this paper, the effects of the using of a proper insulation on the energy saving in Iranian buildings are studied. For this purpose, an integrative modelling is used for simulation of the energy consumption in buildings. It is shown that energy consumption per square meter of buildings can be reduced up to 35.2% when insulation is used for external walls.     

Impact of voluntary green certification on building energy performance

Credible estimates of energy savings from green buildings are critical for policy makers to examine the cost and benefit of various incentives intended to encourage commercial buildings to go green (e.g. expedited construction permits, government grants, and property tax incentives). Yet, data limitations have hindered reliable estimations. Filling this gap, this study uses a large panel dataset on energy consumption for commercial buildings in Phoenix metropolitan area, Arizona. By tracking building occupants' monthly energy consumption before and after the building's certification as an Energy Star building, we provide new estimates of the environmental gains from private investment in green real estate. Results show that for occupants that occupy space in a certified building in both the pre-certification and post-certification periods, occupants in Energy Star buildings consume 8% less energy. This empirically robust estimate of potential benefit from green-certification provides a quantifiable benchmark against which green-promoting policies can be measured. We also document evidence of heterogeneous treatment effects. Energy savings differ by the building's initial certification points and the building's baseline energy consumption. These results are useful for policy makers to identify targets for green certification.     

Heating energy performance and part load ratio characteristics of boiler staging in an office building

Commercial buildings account for significant portions of the total building energy in South Korea and thus a variety of research on the boiler operation related to heating energy in office buildings has been carried out thus far. However, most of the researches have been conducted on the boiler itself, i.e., the part load ratio characteristics and the corresponding gas energy consumption patterns are not analyzed in the existing studies. In this study, the part load ratio and the operating characteristics of gas boiler have been analyzed within an office building equipped with the conventional variable air volume system. In addition, the gas consumption among different boiler staging schemes has been comparatively analyzed. As a result, significant portions of total operating hours, heating load and energy consumption has been found to be in a part load ratio range of 0 through 40% and thus energy consumption is significantly affected by boiler efficiency at low part load conditions. This suggests that boiler operation at the part load is an important factor in commercial buildings. In addition, utilizing sequential boiler staging scheme can save a gas usage of about 7%. For annual heating energy saving, applying the sequential control boiler with a 3:7 proportion staging is considered to be the optimal control algorithm for maximum efficiency of boilers.     

上海市公共建筑节能与标准化

随着社会的进步,建筑能源消耗也迅速增加.本文分析了上海市与全国建筑能耗的构成,上海建筑能源的需求与发展趋势以及我国与一些工业发达国家在建筑节能工作上的差距.在此基础上详细阐述了上海公共建筑的能耗现状与节能潜力,并就建筑节能工作的重要性、公共建筑的物业管理、新建公共建筑的节能设计标准等问题提出了相应的建议与措施.     

Energy-efficiency supervision systems for energy management in large public buildings: Necessary choice for China

Buildings are important contributors to total energy consumption accounting for around 30% of all energy consumed in China. Of this, around two-fifths are consumed within urban homes, one-fifth within public buildings, and two-fifths within rural area. Government office buildings and large-scale public buildings are the dominant energy consumers in cities but their consumption can be largely cut back through improving efficiency. At present, energy management in the large public sector is a particular priority in China. Firstly, this paper discusses how the large public building is defined, and then energy performance in large public buildings is studied. The paper also describes barriers to improving energy efficiency of large public buildings in China and examines the energy-efficiency policies and programs adopted in United States and European Union. The energy-efficiency supervision (EES) systems developed to improve operation and maintenance practices and promote energy efficiency in large public sector are described. The benefits of the EES systems are finally summarized.     

The effect of energy performance regulations on energy consumption

Governments have developed energy performance regulations in order to lower energy consumption in the housing stock. Most of these regulations are based on the thermal quality of the buildings. In the Netherlands, the energy efficiency for new buildings is expressed as the EPC (energy performance coefficient). Studies have indicated that energy regulations are successful in lowering the energy consumption in residential buildings. However, the actual energy consumption is usually different from the expected energy consumption. This paper explores the effectiveness of energy performance regulations in lowering the energy consumption of dwellings built in the Netherlands after 1996. The effect of the EPC and thermal characteristics on energy consumption was determined by statistical analyses of data on actual energy consumption. The results showed that energy reductions are seen in dwellings built after the introduction of energy performance regulations. However, results suggest that to effectively reduce energy consumption, the tightening of the EPC in not enough. Policies aimed at controlling the construction quality and changing occupant behaviour are also necessary to achieve further energy reductions.     

A study of energy performance and audit of commercial mall in hot-summer/warm-winter climate zone in China

The building energy performance improvement of large-scale public buildings is very important to release China’s energy shortage pressure. The aim of the study is to find out the building energy saving potentials of large-scale public and commercial buildings by energy audit. In this paper, the energy consumption, energy performance, and audit were carried out for a typical commercial mall, the so-called largest mall in Asia, located in a hot-summer and warm-winter climate zone. The total annual energy consumption reaches 210.01 kWh/m², of which lighting energy consumption accounts for 30.03 kWh/m² and the lift and elevator energy consumption accounts for 40.46 kWh/m². It is by far higher than that of the average building energy consumption in the same category. However, the annual heating, ventilation, and air-conditioning (HVAC) energy consumption is only 87.19 kWh/m² even though they run 24/7. It proves that the energy performance of the HVAC system is good. Therefore, the building energy savings potential mainly relies on reducing the excessive usage of lighting, lifts, and elevators.     

Estimation of energy intensity by end-use for commercial buildings

We describe the results of a study to estimate the energy intensities of major end-uses in commercial buildings in the PG&E service area. These energy intensities are central to commercial sector electricity and natural gas consumption forecasting models that utilize an end-use approach. The use of more accurate energy intensities will result in improved estimates of new power generation needs. To our knowledge, this is one of only three studies using the conditional demand approach for the commercial sector. This technique is less costly than end-use metering a large number of commercial buildings to arrive at energy intensity estimates. We obtained these energy intensity estimates for offices, food stores, restaurants, retail buildings, hotels and motels, hospitals, schools, warehouses, and miscellaneous buildings. We applied the conditional demand technique to monthly energy use, building characteristics, and weather data to produce annual estimates of natural gas and electricity use per square foot of floor space. The consumption estimates are for the following seven end-uses: space heating, cooling, lighting, water heating, cooking, refrigeration, and miscellaneous use.We have compared the results of our study to those of two other conditional demand studies and to other studies where data are available. Presently, there are few metered data available for comparison with our estimates. For most business types and end-uses, the energy intensity estimates appear reasonable. For example, for lighting, the mean energy intensity for each business type is within 20% of all the individual values from all comparable studies. Additionally, for each enduse, the highest energy intensity values occur for those business types that would be expected to show greatest utilization.However, for some end-uses in some business types, there are large discrepancies in energy intensity estimates obtained from various studies. For example, for restaurants, the energy intensity estimates for electric water heating and cooking each vary by more than a factor of seven from minimum to maximum. Additional research is needed to determine if such large variations in estimated energy intensities are real or if they are due to such factors as differences in business types (e.g. liquor stores may be included in retail or food stores), different distributions within a business type (e.g. different ratios of refrigerated to non-refrigerated warehouses), and different floor area definitions.     

Evaluation of the impact of the urban heat island on residential and commercial energy consumption in Tokyo

This study evaluated the impact of the urban heat island (UHI) in the Tokyo metropolitan area on energy consumption in the residential and commercial sectors. Although there are many indications that UHIs increase energy consumption by air conditioners, the possible decrease in consumption of heating energy in winter is usually ignored. To quantify the net impact of a UHI, it is crucial to consider both factors. Furthermore, it is important to consider the spatial distribution because a UHI represents the local temperature change in an urban area, and the spatial distribution of energy consumption in an urban area is complicated. We developed a new method to evaluate UHI impact by taking into consideration the spatial and temporal distributions of both energy consumption and air temperature. The results reveal that the UHI increases commercial energy consumption in the Tokyo metropolitan area but decreases residential energy consumption; however, there is a total net decrease in energy consumption. This suggests that UHI mitigation measures should particularly target the city center, where commercial buildings are concentrated, whereas in residential areas, sufficient assessments must be conducted to ensure that mitigation measures are introduced with caution.     

Benchmarking the energy efficiency of commercial buildings

Benchmarking energy-efficiency is an important tool to promote the efficient use of energy in commercial buildings. Benchmarking models are mostly constructed in a simple benchmark table (percentile table) of energy use, which is normalized with floor area and temperature. This paper describes a benchmarking process for energy efficiency by means of multiple regression analysis, where the relationship between energy-use intensities (EUIs) and the explanatory factors (e.g., operating hours) is developed. Using the resulting regression model, these EUIs are then normalized by removing the effect of deviance in the significant explanatory factors. The empirical cumulative distribution of the normalized EUI gives a benchmark table (or percentile table of EUI) for benchmarking an observed EUI. The advantage of this approach is that the benchmark table represents a normalized distribution of EUI, taking into account all the significant explanatory factors that affect energy consumption. An application to supermarkets is presented to illustrate the development and the use of the benchmarking method.     

重庆市酒店类建筑用能现状与节能潜力分析

在对重庆市公共建筑运行能耗及中央空调系统管理现状调查分析的基础上,并与国内外同类建筑相比较,针对酒店类建筑的能耗特点对影响建筑终端用能系统的能源消费量的因素进行探讨,分析了既有酒店类建筑的节能潜力值,提出了对既有高能耗酒店进行节能技术改造和加强节能管理的主要途径。     

Influence of infiltration on energy consumption of a winery building

With the wide use of light steel structure in industrial buildings, some problems such as air leakage, water dripping and condensation and so forth occur during the construction and operation phases. Through the onsite testing of a winery building in Huailai County, Hebei Province in China, the influence of infiltration on energy consumption in industrial buildings was studied. The pressurization test method and moisture condensation method were used to test the infiltration rates. The results show that the winery building is twice as leaky as normal Chinese buildings and five times as leaky as Canadian buildings. The energy use simulation demonstrates that the reduction of the infiltration rate of the exterior rooms to 1/3 and the interior rooms to 1/2 could help decrease a total energy consumption of approximately 20% and reduce a total energy cost of approximately $ 225000. Therefore, it has a great potential to reduce the energy consumption in this type of buildings. Enforcement of the appropriate design, construction and installation would play a significant role in improving the overall performance of the building.     

Analysis of energy saving optimization of campus buildings based on energy simulation

The energy consumption of campus buildings has specific characteristics, because of the concentrated distribution of people’s working time and locations that change in line with distinct seasonal features. The traditional energy system design and operation for campus buildings is only based on the constant room temperature, such as 25°C in summer and 18°C in winter in China, not taking into consideration the real heating or cooling load characteristics of campus buildings with different functions during the whole day and whole year, which usually results in a lot of energy waste. This paper proposes to set different set-point temperatures in different operation stages of public and residential campus buildings to reduce the heating and cooling design load for energy station and total campus energy consumption for annual operation. Taking a campus under construction in Tianjin, China as an example, two kinds of single building models were established as the typical public building and residential building models on the campus. Besides, the models were simulated at both set-point room temperature and constant room temperature respectively. The comparison of the simulation results showed that the single building energy saving method of the peak load clipping could be used for further analysis of the annual energy consumption of campus building groups. The results proved that the strategy of set-point temperature optimization could efficiently reduce the design load and energy consumption of campus building groups.     

Structural,geographic, and social factors in urban building energy use: Analysis of aggregated account-level consumption data in a megacity

Residential and commercial buildings comprise approximately forty percent of total energy consumption and carbon dioxide emissions in the U.S. Yet, while California spends $1.5 billion annually on energy efficiency programs, limited research has explored how building energy consumption varies within cities, including the social and structural factors that influence electricity and natural gas use. We present results from an analysis of aggregated account-level utility billing data for energy consumption across the over two million properties in Los Angeles County. Results show that consumption in L.A. County varies widely with geography, income, building characteristics, and climate. Several higher-income areas have greater total energy use per building even in cooler climates, while many lower-income regions rank higher for energy use per square-foot. Energy consumption also correlates with building age, which varies widely throughout the region. Our results demonstrate the many complex and interrelated factors that influence urban energy use. While billing data is critical for devising energy efficiency programs that actually realize estimated savings and promote more sustainable cities, opening access to such data presents significant challenges for protecting personal privacy. The presented approach is adaptable and scalable to cities seeking to develop data-driven policies to reduce building energy use.     

An energy benchmarking model for ventilation systems of air-conditioned offices in subtropical climates

Since the energy crisis in 1973, engineers have endeavoured to implement energy conservation in buildings. Unfortunately, the effort resulted in energy savings without the fundamental delivery of indoor satisfaction in many cases. In this study, a benchmarking model for the energy consumption of ventilation systems in air-conditioned offices was proposed. This model was developed from the fundamental psychrometric analysis under probable office design conditions in Hong Kong. The results showed that the annual energy-consumption of a ventilation system per unit floor area would be correlated closely with the carbon dioxide (CO₂) concentration in the space, but its correlation with the air temperature set-point would be less significant. In some offices, significant energy-savings potential was demonstrated to provide satisfactory indoor air quality (IAQ) without any comfort penalty to the occupants. This model would be useful for the energy performance evaluation and benchmarking of ventilation systems in air-conditioned offices.     

Unintended anchors: Building rating systems and energy performance goals for U.S. buildings

In the U.S., where buildings account for 40% of energy use, commercial buildings use more energy per unit area than ever before. However, exemplary buildings demonstrate the feasibility of much better energy performance at no additional first cost. This research examines one possible explanation for this inconsistency. The aim is to investigate whether the anchoring bias, which refers to our tendency to gravitate towards a pre-defined standard regardless of its relevance, influences energy performance goals in building design. The scope examines professionals who help set energy performance goals for U.S. buildings. Prior to being asked to set an energy performance goal, these professionals were randomly directed to one of three series of questions. One series set an anchor of 90% energy reduction beyond standard practice, one set a 30% anchor, and one set no anchor. Respondents exposed to the 90% anchor, and respondents exposed to no anchor at all, set higher energy performance goals than respondents exposed to the 30% anchor. These results suggest that building rating systems that only reward incremental energy improvements may inadvertently create anchors, thereby discouraging more advanced energy performance goals and inhibiting energy performance that is technically and economically feasible.     

Thermal energy storage in building integrated thermal systems: A review. Part 1. active storage systems

Energy consumed by heating, ventilation and air conditioning systems (HVAC) in buildings represents an important part of the global energy consumed in Europe. Thermal energy storage is considered as a promising technology to improve the energy efficiency of these systems, and if incorporated in the building envelope the energy demand can be reduced. Many studies are on applications of thermal energy storage in buildings, but few consider their integration in the building. The inclusion of thermal storage in a functional and constructive way could promote these systems in the commercial and residential building sector, as well as providing user-friendly tools to architects and engineers to help implementation at the design stage. The aim of this paper is to review and identify thermal storage building integrated systems and to classify them depending on the location of the thermal storage system.