Energy Efficiency In Office Buildings Research Articles

Optimum level of insulation for energy efficient envelope of office buildings

Building envelope plays an important role in energy efficiency of the buildings as it is the only permanent source of energy efficiency. A well-designed building envelope reduces the demand of HVAC and lighting load. When insulation is provided in the building envelope, it further enhances the energy efficiency. Therefore, it is important to create thermal resistant building envelope considering both the energy consumption and the associated costs. Thermal insulation has a considerable positive effect on reducing the heating and cooling energy demand. It is seen from the tests conducted by Nasrollahi and Nooraei (2013) for design of energy efficient and cost-effective office buildings that initial increase in insulation reduces the heating/cooling load but beyond a certain limit, there is no substantial effect of reduction in heating/cooling load with increase in insulation indicating that there is an optimum value beyond which insulation has no substantial effect on reduction in heating/cooling load. Therefore, the paper attempts to find out this optimum level of insulation so that the building envelope is cost-effective and energy efficient. Three case studies of energy efficient LEED (Leadership in Energy and Environmental Design)/GRIHA (Green Rating for Integrated Habitat Assessment) certified buildings have been considered to determine the optimum level of insulation. In the analysis, comparison has been made between U-values of various components of the building envelopes of three case studies with the U-values prescribed by Energy Conservation Building Code (ECBC)-2007 for various components of the building envelopes based on daytime or 24-h usage, and location of the buildings in composite/warm and humid climate zones. Thereafter, results obtained from the analysis have been compared with the optimum U-values derived from the tests conducted by Nasrollahi and Nooraei (2013) to arrive at the optimum level of insulation. The optimum level of insulation has been found to be 30% above U-values prescribed by Energy Conservation Building Code.

Income Risk in Energy Efficient Office Buildings.

The study investigates uncertainty of financial performance of energy efficient office buildings to establish how making an asset energy efficient changes its financial characteristics. Two hypotheses explaining why a change may occur are presented and examined (one based on higher demand and one on higher economic efficiency). A large panel dataset, consisting of 30 time periods for 14,395 US commercial office buildings, is examined using different econometric approaches. Overall, the results seem to support theoretical predictions and show a structural change in income risk characteristics of energy efficient assets.

Effect of geometric factors on the energy performance of high-rise office towers in Tianjin, China

To improve energy efficiency of office buildings in Tianjin, we select a prototypical high-rise office tower as an example and focus on the effect of geometric factors on building energy performance. These factors include the orientation, plane shape, floor area, plane shape factor (the ratio of the plane length to the plane width, only as regards to a rectangle-shaped plane), floor height, floor number and window-to-wall ratio. The simulation is performed in DesignBuilder, which integrates artificial lighting with instantaneous daylight during the energy simulation process. The geometric factors of the defined prototype are examined in both single-parameter and multi-parameter evaluations. As to the multi-parameter results, the energy saving rate can vary by up to 18.9%, and reducing the floor height is observed to be the most effective means of reducing annual total end-use energy consumption, followed by increasing the plane shape factor and reducing the floor area. The results can serve as a reference for passive design strategies related to geometric factors in the early design stage.

The Impacts of Energy Efficiency Design Parameters on Office Buildings Energy Consumption in Different Climate Zones in China

Energy consumption of office buildings occupies quite a great proportion of total building energy consumption. The present work investigates the thermal and energy performance of office buildings and identifies major energy saving strategies in different climate zones in China with EnergyPlus. The results are analyzed in heating loads, cooling loads and load components. The primary factors on building energy consumption and major energy saving strategies are obtained with sensitivity analysis. It shows that improvement of the thermal insulation of envelope and infiltration, and passive solar design could have large energy saving potential in Harbin and Beijing. Ventilation and sunshade should be taken into consideration in Wuhan, Guangzhou and Kunming. The results indicate a great significance for energy efficiency of office buildings.

The feasibility of medical office building green upgrades from an owner/lessor perspective

Purpose – The purpose of this paper is to exam the financial impact on the owner/lessor who is considering a partial energy upgrade to an existing medical office building. The owner who leases the building using a triple net lease does the upgrade prior to leasing the building, with the expectation of earning higher rents. How much should the owner who leases the property spend for a given rent per square foot increase? Design/methodology/approach – The empirical study highlights the impact of key financial variables on the dependent variable medical office construction spending put in place in the USA. The independent variables prime interest rate, cost of natural gas per therm and electricity cost per KWH, resale building prices are significant variables when predicting medical office construction spending. A case study using a cost-benefit model is developed. It inputs corporate income tax rates, incorporates a debt service coverage ratio, prime interest rate, analyzes investment tax credit (ITC) and rebate scenarios and varies the level of rental income and energy savings. The case study results provide insight into which factors are enabling higher net construction spending when considering a green energy retrofit project. Both the regression model and the case study model focussed on the owner of a building who rents medical office space to tenants using a triple net lease. The owner/lessor paradigm analyzes revenue enhancements, the tax implications of having these savings and benefits associated with borrowing when financing the green retrofit. The availability of low cost borrowing, increases in the ITC percent and rebates and increases in rent per square foot have an impact on potential energy upgrade spending. Findings – The empirical model finds the independent variables to be significant. Utility cost, resale value of office buildings, the prime interest rate, business bankruptcy court filings and unemployment rate fluctuations adequately explain movements in medical office building spending for the years 2000 through 2015 yielding a R2 of 73.8 percent. The feasibility case study indicates that the energy saving levels and ITCs not income tax rates are the primary drivers for a partial energy retrofit. Research limitations/implications – Market incentives are a function of the cost of energy. If the cost of energy drops, then the profit incentive to conserve energy becomes less important. The role of tax credits, rebates, property tax reductions and government directives, then become primary incentives for installing energy upgrades. The owner of an empty building assumes all of the operating costs normally paid by a tenant under a triple net lease. This possibility was not included in the replacement cost-benefit model used in this paper. Practical implications – The feasibility of doing an energy upgrade to an existing building requires that a cost-benefit analysis be undertaken. The independent variables that are significant when doing a regression model or proxies for these variables are incorporated into a present value model. The results in Table V can be used as an initial template for determining how much to spend per square foot when doing an energy upgrade. The square foot amounts can be applied to different size office buildings. The corporate income tax rate or a personal income tax rate has minimal impact on energy construction upgrade spending. Social implications – More energy efficient office buildings reduce the amount of greenhouse gases released into the atmosphere. Energy efficient buildings also conserve on scarce fuel reserves. ITCs and rebates limit the role of government in directing decisions to do energy upgrades. The market mechanism to some degree can help encourage energy conservation through asset upgrades. Originality/value – The paper incorporates an empirical model which is a form of technical analysis to examine independent variables that explain medical office building spending with a case study structured on expected revenues and costs which takes a fundamental approach to understanding the relationship between the dependent variable and its independent variables. The regression model combines factors that impact the demand for energy efficient medical buildings from an owner/lessor perspective which includes resale values of existing buildings, business bankruptcy filings and unemployment rates. Supply independent variables include the prime interest rate and electricity per KWH and natural gas per therm. The regression model found these variables to be significant. The case study uses the same independent variables or close proxy variables to determine the maximum financially feasible per square foot spending that can be invested in energy upgrades.

Site Planning and Orientation for Energy Efficiency: A Comparative Analysis on Three Office Buildings in Kuala Lumpur to Determine a Location for Building Shading Device

A well-designed energy efficient building provide long term building optimisation while minimising the energy. Site planning and orientation of the building plays an important factor at the early stage of any development. Especially to determine the best location for the building opening and windows and also the suitable materials to enhance comfort to the occupants and reduce the energy consumption. Thus, the aim of this study was to identify the site planning and orientation of the selected office building. The benchmark for the analysis will be based on the architectural and passive design component provided in MS 1525:2007 for the site planning and orientation through comparative analysis. Three energy efficient office building in Kuala Lumpur were selected in this research. This case study is important in helping to understand the relationship between site planning, building orientation, energy efficiency and cost effectiveness.

Parametric study of a cost-optimal, energy efficient office building in Serbia

Recent building regulations in Serbia prescribe the design of highly insulated, airtight buildings with low U-value glazing. Serbia has continental climate with hot summers, so that for office buildings, whose internal gains are higher from the presence of people, computer systems and lighting, this means that far more focus has to be put on cooling demands than on heating demands. This shift toward cooling is studied here through exhaustive simulation of combinations of selected passive solar design parameters for a model of an office building in Belgrade. Design parameters include glazing type, window-to-wall ratio of façades, presence of exterior shading and U-value of opaque envelope components. Optimal variants of the model have been determined with respect to construction cost and heating, cooling and lighting energy use. Results reveal that exterior shading, which has to sustain occasional strong winds in Belgrade, is too expensive to appear in cost-optimal solutions. Hot summers of Belgrade climate imply that cost-optimal solutions have close-to-minimal window-to-wall ratio at the southern façade and significantly larger window-to-wall ratio at the northern façade. Results further show that glazing in cost-optimal solutions has to have small U-value and medium solar heat gain coefficient, although specific choices of optimal glazing type, as well as thermal insulation level, depend on future electricity prices. The case study is repeated for climates of Frankfurt and Stockholm as well, which yield similar results with respect to glazing type and the absence of exterior shading, but with different patterns of window-to-wall ratios at the southern and northern façades.

User satisfaction and well-being in energy efficient office buildings: Evidence from cutting-edge projects in Austria

This paper aims to improve our knowledge of energy use and well-being in energy efficient office buildings. It explores the interrelations between forms and patterns of energy use on the one hand and user satisfaction, comfort, and well-being on the other hand. Findings are derived from qualitative and quantitative data collected in a recently finished research project in Austria. Fieldwork consisted of two qualitative case studies as well as an online-based survey amongst users of energy efficient office buildings. In addition, secondary data from energy-monitoring research was used to underpin the analysis. The results show that extremely low levels of energy use in office buildings can be aligned with high levels of well-being. Based on empirical findings the paper argues that both well-being and energy performance in office buildings are the result of a complex, on-going and intertwined process that involves various material and social elements.

Advanced occupancy sensing for energy efficiency in office buildings

Control systems for heating, ventilation and air conditioning in non-domestic buildings often operate to fixed schedules, assuming maximum occupancy during business hours. Since lower occupancies usually mean less demand for heating, ventilation and air conditioning, energy savings could be made. Air quality sensing, often combined with temperature sensing, has performed sufficiently in the past for this if maintained properly, although sensor and control failures may increase energy use by as much as 50%. As energy costs increase, coupled with increased complexity in building services and reduced commissioning time, all placing ever higher demands on sensing, building controls must meet increasingly stringent environmental requirements, whilst also improving reliability. Sensor fusion offers performance and resilience to meet these demands, while cost and privacy are key factors which are also met. This article describes a neural network approach to sensor fusion for occupancy estimation. Feature selection was carried out using symmetrical uncertainty analysis, while fusion of sensor features used a back-propagation neural network, with occupant count accuracy exceeding 74%.

Best practice space optimisation for office buildings

The energy efficiency of office buildings is a major concern in real estate and facility management (REM/FM); however, often great potential, which can be easily unlocked, lies in the efficient use of available space. Carbon emissions are largely attributed to buildings and the sustainability of buildings (spaces) is a focus of governments and the private sector. Space allocation is tedious work and a great challenge for REM/FM managers, having a considerable economic impact on the entire organisation. Unsatisfying manual allocation results are due to the tremendous complexity involved in space assignment. To date, there are no algorithms that can solve this kind of problem efficiently. Existing IT systems, such as CAFM/IWMS, CAD/BIM or ERP systems, do not provide automated procedures. They can cope with the problem only interactively with a large time and cost effort and are unable to provide close-to-optimal solutions; however, they may provide important initial data and are able to leverage the results. This paper presents a novel approach towards automating this assignment task. The procedure assigns organisational units to available spatial resources taking into account space standards and constraints such as intercommunication, spatial proximity and pre-occupation. Allocation variants are generated and evaluated automatically according to their achievable reduction in cost, time, number of necessary moves and/or communication traffic. The approach allows space utilisation to be improved drastically. A number of best practice examples underpin this hypothesis.

Energy efficient office buildings in Italy

In order to support the decision-making process and to face with the European Directive, it appears overriding focusing on the analysis of administration buildings because many constructions, owned and occupied by public authorities, enclose offices. These constructions are generally complex for typological aspects, their energy-needs are relevant especially for electricity consumptions and require highlevel of indoor comfort. Hence, the present paper presents the logic reference frame of a research that has studied the influence of some design criteria on the energy performance of office buildings located in Italy and proposes an example of low-energy office building.

Effect of facade components on energy efficiency in office buildings

Properties of facade materials should be considered to determine which of them strongly affect building energy performance, regardless of the building shapes, scales, ideal locations, and building types, and thus may be able to promote energy efficiency in buildings. In this study, the effects of four fundamental facade properties related to the energy efficiency of office buildings in Tokyo, Japan, were investigated with the purpose of reducing the heating and cooling energy demands. Some fundamental design factors such as volume and shape were also considered. It was found that the reduction in both the solar heat gain coefficient and window U-value and increase in the solar reflectance of the opaque parts are promising measures for reducing the energy demand. Conversely, the reduction in the U-value of the opaque parts decreased the heating energy demand, and this was accompanied by an increase in the cooling energy demand in some cases because the total energy demands were predominantly for cooling. The above-mentioned promising measures for reducing building energy demands are thus recommended for use, and an appropriate U-value should be applied to the opaque parts based on careful considerations. This study provides some fundamental ideas to adjust the facade properties of buildings.

Smart Transducer Interface—From Networked On-Site Optimization of Energy Balance in Research-Demonstrative Office Building to Smart City Conception

This paper reviews the development and technical infrastructure of an energy-efficient research-demonstrative office building created by the Center for Energy Technology [in polish: Centrum Technologii Energetycznych (CTE)] in Swidnica. This modern structure offers multiple solutions for relevant research topics, such as energy generation, distribution, and preservation. The key contribution of the CTE team was to craft a fusion algorithm that could identify the optimal temporal system conditions, translate them into control system settings, and, through feedback, monitor the energy management processes for the site. Although exemplary results have been observed for the single year depicted in this paper, several years of future installation monitoring are planned. The conclusions obtained from this paper will be formulated as recommendations for researchers, designers, installers, and users of energy-efficient office buildings. The prospective initiatives of the CTE team have also been outlined. The implementation of ISO/IEC/IEEE 21451-x standards has been proposed as an effective tool for scaling this system from the smart-building level up to a smart-city platform.

Comparative evaluation of optimal energy efficiency designs for French and US office buildings

In both the US and French building sectors, significant efforts have been undertaken to reduce the environmental impacts of new constructions notably their fossil energy consumption and related carbon emissions. This paper summarizes the results of a comparative evaluation of optimal design specifications for office buildings for selected locations in both US and France using life cycle cost analysis approach. First, an overview of both the US and French approaches for developing building energy efficiency standards and design of high performance buildings is outlined. Then, a general approach for design optimization of energy efficient office buildings is presented. Finally, selected results of the optimal analysis are discussed. In particular, it is found that optimizing life cycle costs (LCC) resulted on average in 30% in primary energy savings for office buildings located in the US and 40% savings in France. However, it is found that LCC-based optimal building designs do not meet the French energy efficiency RT 2012 standard. When accounting for typical operating conditions, photovoltaic (PV) panels are needed in order to comply with the RT 2012 required thresholds for the total primary energy consumption of the office buildings located in the French cities considered in the analysis.

How energy efficient office buildings challenge and contribute to usability

Purpose – This is an analysis of modern office buildings with high energy efficiency. The purpose of this paper is to focus on how such buildings affects usability for the organizations occupying the buildings. Design/methodology/approach – The analysis combine results from studies of two case projects with a literature review. Case studies include qualitative interviews with key informants, internal post-occupancy evaluations and annual reports from the user organizations. The two buildings are Norwegian pioneers regarding energy efficiency. Findings – The new buildings provide a high degree of usability for the user organizations, including user satisfaction, efficiency and effectiveness. The case projects illustrate the potential in combining improvements for energy efficiency and the usability of buildings. There are synergistic effects in a mutual process of development for the buildings and organizations based upon strategic business goals. Management of the process is crucial in order to succeed. Research limitations/implications – The study applies the approach of usability to an analysis of energy efficient buildings. Two case projects exemplify potentials and challenges. Practical implications – Office buildings can be developed to a high degree of energy efficiency by considering the many aspects of usability for the user organizations. Integrating constructing projects into organizational development processes is crucial for the result. Originality/value – This study contributes to the emerging field, analyzing effects on usability for the organizations occupying energy efficient office buildings. The study also adds to the young field of analyzing the integration of the development of buildings into processes of organizational development by enlightening the potential regarding buildings with high energy ambitions.

User satisfaction adaptive behaviors for assessing energy efficient building indoor cooling and lighting environment

Abstract Many techniques for managing sustainability including sustainable building assessment tools and standards have been developed globally. The sustainable building assessment tools measure the user satisfaction dependent to environmental and economic aspects of energy efficient building practices. However, these tools have not yet measure energy efficiency index by involving user satisfaction from adaptive behaviors dependently, which can determine the actual energy consumption versus the planed energy consumption of the building. Hence, this research aimed at providing a comprehensive list of adaptive behaviors for assessing energy efficient building indoor environment in design phase of building lifecycle. The study focused on identifying and establishing adaptive behaviors that are in response to indoor conditions provided by Cooling and Lighting systems in energy efficient office buildings. This research involves adaptations across Technological and Personal. The research was conducted in two phases. Phase one identified the list of user satisfaction adaptive behaviors through a systematic approach. Next, an expert input study was conducted to validate the findings of the literature review. Expert input data was collected using Delphi structured close group discussion method, and then analyzed through Grounded Group Decision Making (GGDM) method. Eight experts were involved in four sessions of the GGDM application procedure. The research established 18 adaptive behaviors relevant to cooling system in energy efficient indoor environments, and 18 adaptive behaviors relevant to the lighting system. The comprehensive list of user satisfaction adaptive behaviors can be applied in both current and future sustainable building assessment tools׳ energy efficiency indexes. This aids architects, engineers, facility managers, building owners, consultants, authorities, contractors, and academic researchers in accreditation of building users, building design and reduction of building׳s energy consumption.

The coupled effects of personalized occupancy profile based HVAC schedules and room reassignment on building energy use

Abstract Buildings account for nearly 38% of the total energy use in the U.S., and 46% of this use is associated with commercial buildings. More than 40% of the energy in commercial buildings is consumed by HVAC systems, which provide heating, cooling and ventilation to individual zones to maintain comfortable and healthy indoor environments. A more refined control strategy based on actual occupancy might improve HVAC system related energy efficiency. Accurate occupancy profiles are important to determine actual energy demands and corresponding control schedules. This paper focuses on energy efficiency in office buildings with centrally controlled VAV systems by setting zone-level HVAC start/stop schedules using personalized occupancy profiles, which represent occupants’ long-term presence patterns. Evaluation of the method was performed using a simulation model, calibrated by the actual energy use data of an office test bed building. Up to 9% of the energy was saved when personalized occupancy profile based HVAC schedules were used. However, if occupants of a zone have different occupancy patterns, the aggregated patterns may hinder any potential efficiency that might be realized from zone-level HVAC start/stop schedules. This paper also presents an approach for reassigning rooms to unify the start/stop times at the zone level by placing occupants with similar profiles in the same mechanical zones. When room reassignment was implemented and coupled with profile based control schedule, HVAC energy use was reduced by another 8%. The proposed methods could provide reliable personalized HVAC control for small-size office buildings without advanced building automation systems, nevertheless, they could also be extended to buildings with packaged HVAC systems and individual air-conditioning systems.

Study on Energy Efficiency Design of Self-Insulation System with Autoclaved Aerated Concrete Block in Cold Regions

Self-insulation wall made of autoclaved aerated concrete has integrated the functions of structure and insulation in one; it has become the focus of the development of outer wall energy-saving technologies. To study the feasibility of the autoclaved aerated concrete block wall in the cold regions, we take one office building in Jinan City as an engineering example, present the construction practices of the self-insulation wall and the thermal bridge, and carry out the numerical simulation analysis of the energy consumption. The results show that autoclaved aerated concrete self-insulation wall meet the office building energy efficiency design standards for cold areas. Based on the analysis of the wall thermal parameter, the optimum thickness of the block masonry and insulating layer of thermal bridge are proposed for engineering designers reference.

Design Optimization of Energy Efficient Office Buildings in Tunisia

Optimal and cost-effective energy efficiency design and operation options are evaluated for office buildings in Tunisia. In the analysis, several design and operation features are considered including orientation, window location and size, high performance glazing types, wall and roof insulation levels, energy efficient lighting systems, daylighting controls, temperature settings, and energy efficient heating and cooling systems. First, the results of the optimization results from a sequential search technique are compared against those obtained by a more time consuming brute-force optimization approach. Then, the optimal design features for a prototypical office building are determined for selected locations in Tunisia. The optimization results indicate that utilizing daylighting controls, energy efficient lighting fixtures, and low-e double glazing, and roof insulation are required energy efficiency measures to design high energy performance office buildings throughout climatic zones in Tunisia. In particular, it is found that implementing these measures can cost-effectively reduce the annual energy use by 50% compared to the current design practices of office buildings in Tunisia.

Comparison and analysis of energy consumption of energy-efficient office buildings in different climate regions in China: case studies

The purpose of this paper is to analyze the energy consumption (EC) and find out the determining factors of energy-efficient office building cases according to specific case studies in typical cities of different climate zones in China. The investigated building cases were located in four cities (Beijing, Ningbo, Nanjing and Shenzhen) of three architecture thermotechnical design zones (cold zone, hot summer and cold winter zone, hot summer and warm winter zone). The analysis indicates that the energy consumption index (ECI) of these four cases ranges from 41.06 to 74.23 kW·h/(m2·a). Besides, the outdoor climate can change the EC of air conditioning/heating systems, and further determine the monthly volatility of the total EC of the whole building.