Total Building Energy Consumption Research Articles

Energy Efficiency Evaluation of Different Glazing and Shading Systems in a School Building

The energy conversations methods and techniques take a significant role in the energy performance of the buildings. Façade and shading systems are in continuous development, and recent studies are showing the importance of implementation of such systems to reduce energy consumption and enhance the effectiveness of the building performance. School buildings are mostly being used during daytime, hence, require active use of sunlight. A measure that is taken on a school building envelope can prevent overheating and overcooling and reduce the heating and cooling energy consumption but at the same time can increase the lighting energy consumption vice versa. Thus, it is necessary to optimise the energy required for climatisation of a building with lighting energy demand. The main aim of the paper is to provide analysis for façade and shading systems applied to a school building and study the effectiveness of it on energy consumption and conservation. The case study for this paper is a typical building project designed to be located in Istanbul, Turkey and has a traditional façade system which is clear double layer windows without any shading devices. The analyses of the energy efficiency of these systems will be presented. The different glazing types and shading systems alternatives will show the most efficient one to be used as some optimised alternatives for the systems. Findings indicate that proper glazing and shading systems can reduce the needed energy for heating and lightening and thus total energy consumption of a school building significantly.

A Study on Energy and Cost Efficiency for Existing Hotel Buildings in Turkey

In Turkey, according to TUİK Sectoral Energy Consumption Statistics (2006), the hotel buildings with the highest share, constitute 35% of the total building energy consumption. Energy needs and consumption behaviours differ according to the typology of the building. Energy Performance of Buildings Directive (EPBD) has been adapted to the conditions of Turkey to increase energy and cost efficiency, to reduce the environmental and economic negative effects. The energy consumption and the global cost were investigated under different conditions in an existing hotel building. The paper is unique in its ability to deliver optimum solution through comparison by evaluating energy and cost efficiency at the same time considering sectoral, climatic, technological and economic national conditions when the literature research detailed in the present works about the problem is evaluated in detail. All findings have been compared simultaneously under different climate regions of seasonal and yearly working conditions of selected test hotel to obtain the energy and cost efficiency. Among the proposed improvement scenarios, the optimum scenario is determined in terms of cost and energy efficiency in S18 which has the highest energy efficiency. In this case, both insulation material type and thickness as well as glass type can be bent and through multiple measures can be achieved by 25.7% improvement for energy efficiency.

Simulation-Based Multi-Objective Optimization of institutional building renovation considering energy consumption, Life-Cycle Cost and Life-Cycle Assessment

Buildings are responsible for a significant amount of energy consumption resulting in a considerable negative environmental impact. Therefore, it is essential to decrease their energy consumption by improving the design of new buildings or renovating existing buildings. Heat losses or gains through building envelopes affect the energy use and the indoor condition. Heating, Ventilation, and Air Conditioning (HVAC) and lighting systems are responsible for 33% and 25% of the total energy consumption in office buildings, respectively. However, renovating building envelopes and energy consuming systems to lessen energy losses is usually expensive and has a long payback period. Despite the significant contribution of research on optimizing energy consumption, there is limited research focusing on the renovation of existing buildings to minimize their Life Cycle Cost (LCC) and environmental impact using Life Cycle Assessment (LCA). This paper aims to find the optimal scenario for the renovation of institutional buildings considering energy consumption and LCA while providing an efficient method to deal with the limited renovation budget. Different scenarios can be compared in a building renovation strategy to improve energy efficiency. Each scenario considers several methods including the improvement of the building envelopes, HVAC and lighting systems. However, some of these scenarios could be inconsistent and should be eliminated. Another consideration in this research is the appropriate coupling of renovation scenarios. For example, the HVAC system must be redesigned when renovating the building envelope to account for the reduced energy demand and to avoid undesirable side effects. A genetic algorithm (GA), coupled with an energy simulation tool, is used for simultaneously minimizing the energy consumption, LCC, and environmental impact of a building. A case study is developed to demonstrate the feasibility of the proposed method.

Lighting Control Including Daylight and Energy Efficiency Improvements Analysis

Energy used for lighting is one of the major components of total energy consumption in buildings. Nowadays, buildings have a great potential to reduce their energy consumption, but to achieve this purpose additional efforts are indispensable. In this study, the need for energy savings evaluation before the implementation of lighting control algorithms for a specified building is highlighted. Therefore, experimental tests have been carried out in a university building with laboratories and other rooms, equipped with KNX building automation system. A dimmable control strategy has been investigated, dependent on daylight illuminance. Moreover, a relationship between external and internal daylight illuminance levels has been evaluated as well. Based on the experimental results, the authors proposed a method for the rough estimation of electrical energy savings. Since, according to the EN 15232 standard, Building Automation and Control Systems (BACS) play an important role in buildings’ energy efficiency improvements, the BACS efficiency factors from this standard have been used to verify the experimental results presented in the paper. The potential to reduce energy consumption from lighting in non-residential buildings by 28% for offices and 24% for educational buildings has been confirmed, but its dependence on specific building parameters has been discussed as well.

Energy efficiency – indoor air quality dilemma in public buildings

The energy efficiency – indoor air quality dilemma is a common predicament in many buildings undergoing energy efficiency improvements. The main goal of this research is to study the impact of this dilemma on national final energy consumption and greenhouse gas emission reduction. A simulation using a system dynamics model was carried out. The stock of public buildings was split into four sub-categories based on when the buildings were constructed. Natural ventilation is used in all buildings before renovation. After implementing energy efficiency measures, two scenarios are simulated: one with and one without mechanical ventilation. Buildings constructed between 1940 and 1992 exhibit the greatest increase in both floor areas with energy efficiency measures and profitability ratio. The simulation results show that if ventilation is operated according to national building standards, total energy consumption in public buildings increases by 1.3 % in 2014 and by 2 % in 2040 compared to the situation where there is no mechanical ventilation. If the implementation of the energy efficiency measures is increasing at higher rate, the difference between both alternatives is increasing more. Energy efficiency measures in public buildings reduce national energy consumption and greenhouse gas emissions. However these measures also reduce indoor air quality thereby causing losses of productivity of the building occupants.

A new type of self-powered external cooling shell of air conditioner

In recent years, with the rising demands one indoor comfort, the use of air conditioners is becoming more and more widespread. The energy consumption of air conditioners is rising, accounting for about 40%-60% of the total building energy consumption[1]. During the use of air conditioner in summer, the disordered discharge of condensate water and the excessive temperature of external machine are two major problems that need to be improved. In view of these above problems, we have designed a new type of self_powered external cooling shell of air conditioner. It includes condensate water collection subsystem, solar panel cover subsystem, energy storage subsystem, intelligent control and ultrasonic atomization subsystem. The purpose of this device is to collect the useless air conditioner condensate water and cool down the air conditioner external machine. This device can not only save water, but also enhance the effect of air conditioner refrigeration, save electric energy and enhance the service life of air conditioner.

End Use Level Water and Energy Interactions: A Large Non-Residential Building Case Study

Within the European Union, buildings account for around 40% of the energy use and 36% of CO2 emissions, thus representing a significant challenge in the context of recent EU directives that require all new buildings to be nearly zero-energy by 2020. Reduced consumption of water, and hot water in particular, provides a significant opportunity to reduce energy consumption. While there have been numerous studies pertaining to the water-energy nexus of residential buildings, the complexity of water networks in larger buildings has meant that this area has been relatively unexplored. The paper presents a comprehensive investigation of the hot water use profile, associated energy use, on-site pumping energy use, carbon emissions, and solar energy harvesting potential in an Irish university building over periods before and after water conservation efforts. Total water-related energy consumption (including the heating and pumping losses) were analysed using the WHAM model and modified pumping energy expressions. The results revealed that water heating including losses contributed to as high as 30% of total building energy consumption, and stringent water conservation measures reduced the average hot water use rate by 8.5 m3/day. It was found that 10% of the total pumping energy was constituted by pump start-ups. Simulation results for solar harvesting potential in the study site found that around 60% of water heating energy demand could be met by solar energy in the new water demand scenario. The study results can act as a benchmark for similar buildings, and the model combination can be emulated in future studies.

Optimalisasi sistem tata udara gedung perkantoran bertingkat dengan metode six sigma (Studi kasus gedung PT.Bank Aceh cabang Lhokseumawe)

The use of energy in the air system of PT. Bank Aceh Lhokseumawe branch annually averages 60 - 75% of total energy consumption in buildings. The purpose of this research is to optimize energy use in air system continuously using Six Sigma approach. The six sigma approach is expected to reduce the cost of using the air system system without neglecting the comfort level according to the national comfort standard (SNI). The problem faced by the air system is the existence of over cooling load (over cooling load), the value reaches the figure beyond the initial 60,000 watts planning capacity. The calculation results obtained actual average cooling load reached 75,580.3 watts. It is known that the cooling overload is caused by several factors, namely: the quantity of occupant / human, the air ventilation factor, the management factor of electric appliances usage, the lighting factor, and the solar radiation / transmission factor. Solutions to improve the air conditioning system by minimizing the factors that cause over cooling load. The results of the improvement get a cooling load of 57,340.9 watts which means savings of 24.2%, or monthly electrical energy savings of 4,428.324 kwh / month or equivalent to 50,739.888 kwh / year. Keywords: cooling load, six sigma, optimization, critical to quality

Analysis of recycled aggregates effect on energy conservation using M5′ model tree algorithm

Sustainability targets can be achieved by pursuing environmental-friendly and energy-efficient design and construction. Being sub-standard in terms of stability, buildings would pose serious threats to the environment and natural sources. Therefore, having sustainable design and construction is of great importance in building industry. To achieve sustainability targets, recently recycled aggregates attracted special attention. While several studies have been conducted on the thermal and hydrometric characteristics of recycled materials, there are few studies available on the evaluation of the applicability of these materials in buildings. Accordingly, in this study, the performance of four different recycled concrete panels, produced using waste and recycled materials, has been investigated in terms of energy consumption in a residential building using Design-Builder software. Moreover, a model tree algorithm (M5′) has been used to evolve formulas for predicting the total energy consumption in the reference building. To do this, up to 1200 simulations using various recycled materials and glass areas have been carried out in Design-Builder software. The performances of the developed formulas have been evaluated on the basis of statistical measures. The results suggest that M5′ could serve as a valuable tool for the estimation of total energy consumption in residential buildings.

Anthropogenic heat flux: advisable spatial resolutions when input data are scarce

Anthropogenic heat flux (QF) may be significant in cities, especially under low solar irradiance and at night. It is of interest to many practitioners including meteorologists, city planners and climatologists. QF estimates at fine temporal and spatial resolution can be derived from models that use varying amounts of empirical data. This study compares simple and detailed models in a European megacity (London) at 500 m spatial resolution. The simple model (LQF) uses spatially resolved population data and national energy statistics. The detailed model (GQF) additionally uses local energy, road network and workday population data. The Fractions Skill Score (FSS) and bias are used to rate the skill with which the simple model reproduces the spatial patterns and magnitudes of QF, and its sub-components, from the detailed model. LQF skill was consistently good across 90% of the city, away from the centre and major roads. The remaining 10% contained elevated emissions and “hot spots” representing 30–40% of the total city-wide energy. This structure was lost because it requires workday population, spatially resolved building energy consumption and/or road network data. Daily total building and traffic energy consumption estimates from national data were within ± 40% of local values. Progressively coarser spatial resolutions to 5 km improved skill for total QF, but important features (hot spots, transport network) were lost at all resolutions when residential population controlled spatial variations. The results demonstrate that simple QF models should be applied with conservative spatial resolution in cities that, like London, exhibit time-varying energy use patterns.

A decision tool to balance indoor air quality and energy consumption: A case study

HVAC systems are responsible for a significant part of the total building energy consumption and in many cases a large portion of that energy is actually used inefficiently. The ability of these systems to adapt to changing numbers of occupants will play a major role in reducing their energy load. Demand Controlled Ventilation systems are helping towards that goal and many of them use CO2 sensors as their core information source, whereby the system tries to maintain CO2 near or under a specified set point. Besides providing a simple feedback mechanism, CO2 can also be utilised in predictive models for indoor air quality and in the estimation of occupancy. The choice of location for the CO2 sensors however can have an impact in the estimations. The objective of this study is two-pronged: Firstly to identify a relationship between occupancy, CO2 setpoint, ventilation rate and cooling load for a university lecture theatre, in a way that it can be used as a decision tool by the facility manager to balance indoor air quality and energy consumption. Secondly, to investigate and quantify how representative the CO2 values detected by different sensors within the lecture theatre are and whether any differences can have a significant effect in estimating the number of occupants within. Results show that both CO2 and occupancy can be estimated with good accuracy with little effect from sensor placement and that it is feasible to easily visualise the balance between CO2 threshold and cooling load for a given level of occupancy.

Data-driven based estimation of HVAC energy consumption using an improved Fourier series decomposition in buildings

Many data-driven algorithms are being explored in the field of building energy performance estimation. Choosing an appropriate method for a specific case is critical to guarantee a successful energy operation management such as measurement and verification. Currently, little research work on assessment of different data-driven algorithms using real time measurement data sets is available. In this paper, five commonly used data-driven algorithms, ARX, SS, N4S, discretized variable BN and continuous variable BN, are used to estimate HVAC related electricity energy consumption in a university dormitory. In practice, total energy consumption data is easily accessible, while separated HVAC energy consumption data is not commonly available due to expensive sub-metering and/or the complexity of mechanical and electrical layouts. A virtual sub-meter based on a decomposition method is proposed to separate HVAC energy consumption from the total building energy consumption, which is derived from an improved Fourier series based decomposition method.

Complex analysis of energy efficiency in operated high-rise residential building: Case study

Energy conservation and human thermal comfort enhancement in buildings is a topical issue of modern architecture and construction. The innovative solution of this problem makes it possible to enhance building ecological and maintenance safety, to reduce hydrocarbon fuel consumption, and to improve life standard of people. The requirements to increase of energy efficiency in buildings should be provided at all the stages of building's life cycle that is at the stage of design, construction and maintenance of buildings. The research purpose is complex analysis of energy efficiency in operated high-rise residential building. Many actions for building energy efficiency are realized according to the project; mainly it is the effective building envelope and engineering systems. Based on results of measurements the energy indicators of the building during annual period have been calculated. The main reason of increase in heat losses consists in the raised infiltration of external air in the building through a building envelope owing to the increased air permeability of windows and balcony doors (construction defects). Thermorenovation of the building based on ventilating and infiltration heat losses reduction through a building envelope allows reducing annual energy consumption. Energy efficiency assessment based on the total annual energy consumption of building, including energy indices for heating and a ventilation, hot water supply and electricity supply, in comparison with heating is more complete. The account of various components in building energy balance completely corresponds to modern direction of researches on energy conservation and thermal comfort enhancement in buildings.

Distributed Energy Optimization for HVAC Systems in University Campus Buildings

Educational buildings consume about 2% of the total energy in a country, which leads to energy cost concerns for building operators. To reduce the building energy cost, an effective way is to intelligently schedule heating, ventilation, and air conditioning (HVAC) systems, which account for above 40% of the total energy consumption in educational buildings. In this paper, we investigate an energy optimization problem for HVAC systems in university campus buildings. To be specific, we first formulate a total cost optimization problem that minimizes the sum of energy cost related to HVAC systems and thermal discomfort cost associated with occupants considering zone occupancy pattern and thermal preference of occupants in each zone. Due to the existence of uncertain parameters as well as spatially and temporally coupled constraints, it is very challenging to solve the formulated problem. To this end, we propose a distributed model predictive control algorithm based on the alternating direction method of multipliers, which has high scalability with an increasing number of zones and can protect user privacy. Extensive simulations based on the real-world traces show that the proposed distributed algorithm could effectively reduce the total cost and offer a flexible tradeoff between energy cost and thermal discomfort.

Energy performance of an electrochromic switchable glazing: Experimental and computational assessments

This paper describes the results of experimental tests and computer simulation modelling aimed at evaluating the performance of an electrochromic (EC) window with respect to solar radiation control and the relative impact on the energy consumption of buildings of the residential type for two typical Italian climates. The research is carried out by a test-cell equipped with a small area EC double glazing unit and by a simulation program of buildings’ energy behaviour in transient regime. The experimental results show that EC devices which modulate solar radiation mainly by absorption, like the one investigated in this paper, generate secondary solar heat gains which entails a 20% decrease of the maximum potential energy flux reduction. Also, this effect could rise the temperature of the internal glass pane of the glazing to levels for which risk of thermal discomfort for the occupants may occur. The computer simulation modelling involves a residential building unoccupied during a large fraction of daytime in weekdays. The savings potential of the investigated EC window are calculated relative to a conventional clear float double glazing unit. Results show that the EC glazing may lead to a considerable decrease of the cooling energy demand (and of the total building energy consumption) in cooling dominated climates. The energy saving benefits become less marked in heating dominated climates and, for low values of the window-to-wall ratio, can be overcame by the increase in lighting and heating energy requirements that results in an increase of the total building energy demand.

Performance Comparison of Solar Assisted and Inverter Air-Conditioning Systems in Malaysia

© 2017, University of Malaya. All rights reserved. Heating, ventilation, and air-conditioning (HVAC) systems account for approximately 55% o f the total energy consumption in buildings. Different types of cooling technologies that integrate solar thermal energy have been explored because of increasing worldwide energy shortage. Latest air-conditioning systems have achieved improved energy efficiency. The application o f solar energy to various types of HVAC systems proved its huge potential for reducing energy usage. However, solar radiation is highly time dependent and fails to meet building demand. In this study, the potential of a 1.5 HP solar assisted air-conditioning system was evaluated by collecting and using real data, including current, voltage, power, and temperature. The application o f the solar-assisted and inverter-type air-conditioning systems was compared for evaluating their performances. The study was conducted in the northern region of Malaysia, specifically Kedah, in a room with the same as that o f a standard office space. Results showed that the average coefficients o f performance of the solar assisted air-conditioning system ranged from 3.00 to 4.45. This range allows for the optimal consumption of electric energy without wastage. Therefore, the solar-assisted air-conditioning system can provide an environmentally friendly alternative to reducing electricity rates.

Reducing cooling load of buildings in the tropical climate through window glazing: A model to model comparison

The comparison studies among various building simulation models are always the research interest for various researchers though most of them are based on a general overview. Here we compared two popular building simulation models TRNSYS & eQUEST for a multizone building to judge the relative accuracy of the models. The base case building having 1465.8m2 area is situated in a tropical climate zone of India. Both the models were validated with actual and simulated annual energy consumption data of the case building and a model to model comparison has also been performed. The RMSE values for both TRNSYS & eQUEST were found varying between 2.1–12.5% and the Relative Error was found varying −19.6% to 18.0% respectively. It was also found that TRNSYS predict more accurately the total energy consumption of building than eQUEST in this case study. However the main aim of this paper is to quantify the energy saving potential of five different type of single and double glazing glasses especially in case of tropical climate condition through two types of simulation models. Five different types of commercially available window glasses were designed using LBNL-Window7 simulation tool and validated with lab tested results. The percentage reduction of electrical energy consumption due to retrofitting of five types window glasses have also been presented separately for both the simulation models. Both the models revealed that SHGC is more dominating factor than U-value to reduce cooling load of building energy.

A Real-Time Energy Consumption Simulation and Comparison of Buildings in Different Construction Years in the Olympic Central Area in Beijing

Energy consumed the in urban sector accounts for a large proportion of total world delivered energy consumption. Residential building energy consumption is an important part of urban energy consumption. However, there are few studies focused on this issue and that have simulated the energy consumption of residential buildings using questionnaire data. In this research, an eQUEST study was conducted for different residential buildings in the Olympic Central Area in Beijing. Real-time meteorological observation data and an actual energy consumption schedule generated by questionnaire data were used to improve the eQUEST model in the absence of actual energy consumption data. The simulated total energy consumption of residential buildings in the case area in 2015 is 21,262.28 tce, and the average annual energy consumption per unit area is 20.09 kgce/(m2·a). Space heating accounted for 45% of the total energy consumption as the highest proportion, and the second highest was household appliances, which accounted for 20%. The results showed that old residential buildings, multi-storey buildings and large-sized apartment buildings consume more energy. The internal units, building height, per capita construction area, the number of occupants and length of power use had significant impact on residential energy consumption. The result of this study will provide practical reference for energy saving reconstruction of residential buildings in Beijing.

How the roofing morphology and housing form affect energy performance of Shanghai’s workers’ village in urban regeneration

Typologies of the building roof influence the form and the view of a city, and have an impact on its energy performance. “From Flat to Slope Roof” is a governmental project in Shanghai to renovate workers’ villages over the past two decades. The project aimed to change monotonous appearance of the urban roofscape by replacing the flat roof with the slop roof, and to bring benefits of passive cooling through the slide roof to reduce energy demand caused by excessive air-conditioning. However, how different roofing typologies affect the building energy performance requires further investigation. Previous test results have shown that near 6% reduction of total annual building energy consumption could be achieved with the substitution of the polymer material on flat roofs, compared with the reduction by 3% on walls, and the reduction by 2% on floors. In this paper, the numerical modeling with EnergyPlus was applied to test the variation of roofing types and how they would affect the total energy consumption from level of a building to the entire whole community. The results show a connection between the thermal insulation of roof morphology and building energy performance, which conclude an energy reduction strategy through urban design in a neighborhood scale.

Quantifying electrical energy savings in offices through installing daylight responsive control systems in hot climates

Lighting is considered as one of the most important issues in reducing energy consumption of a building. It is estimated that electrical lighting consumes 25–40% of the total electrical energy in a typical commercial building in the United States. Over the last three decades, there has been a growing concern about reducing energy consumption associated with artificial lightings. Daylighting could be considered as a cost-effective alternative to artificial lighting which not only reduces the demands for electrical energy, but also provides occupants with a pleasant, attractive, and a healthy indoor environment. Through installing sensors and controllers, daylighting is able to reduce and even eliminates the use of artificial lighting needed to deliver sufficient illuminance levels in an office. Present study is a simulation based research that investigates the impacts of various types of daylighting controllers on enhancing total and lighting electrical energy consumption of office buildings located in hot climates. Effects of Dimming (5%, 10%, and 20% light), On/Off, and Stepped control systems are evaluated in this study. E-Quest is used as the energy simulation tool to calculate and compare electrical and lighting energy consumption. In order to assess the effects of daylight control systems in humid and arid hot climates, Miami, Phoenix, and Houston, located in ASHRAE 90.1 climate zones of 1A, 2B, and 2A respectively, have been chosen as three locations for the prototype building. The prototype building is a four-story open office building measuring 18m wide×36m long×15m high oriented along east-west axis. The window to wall ratio of 20, 40, 60 and 90% in all directions are assessed. Windows consist of horizontal shading in all façades as well as blinds in those of East and West. Results of this study demonstrate that in all studied cities installing daylighting controllers in office buildings significantly reduces electrical energy consumption of the building particularly that of lighting.