Efficient Building Operation Research Articles

A data-driven framework for occupancy optimisation strategies towards energy demand reduction in non-domestic buildings

Proactive strategies for data-driven operational schedules based on monitored occupancy patters can enable energy demand reduction and optimal resource utilisation. A replicable framework that enables strategic closure of specific thermal zones is introduced and design and operational considerations are discussed. The potential of the framework is illustrated through a case study building, where up to 6% annual energy savings were estimated, highlighting the effectiveness of zone closures. Further findings indicated that total energy savings from the simultaneous closure of multiple zones were marginally larger compared to savings from closing off zones individually, depending on zone capacity and use. Therefore, balanced considerations should take place prior to selecting which zones to close off, also taking into account user acceptability, capacity of systems and controls as well as the internal layout of the building. The research enhances the understanding of the relationship between occupancy and energy demand, while offering recommendations for more energy efficient and sustainable building design and operations that require minimal capital cost. Practical Application This paper provides design and operational considerations based on a robust and replicable framework for energy savings by optimising operational building schedules based on monitored occupancy patterns. This allows a proactive implementation of data-driven strategies that maximise resource utilisation, such as closure of specific zones during periods of low occupancy, without requiring any physical intervention. The findings on a case study building demonstrate that annual energy savings can be achieved, underscoring the potential for substantial cost reductions and improved energy efficiency. Applications can also extend to optimising energy demand for energy flexibility.

Digital Trio: Integration of BIM–EIR–IoT for Facilities Management of Mega Construction Projects

Facility Management (FM) has increasingly focused on integrating Building Information Modeling (BIM) with the Internet of Things (IoT), known as digital twins, in large-scale development projects. Effective BIM integration in FM requires improved cooperation among participants across various project stages. This digital revolution aims to enhance planning, construction, and asset management efficiency, benefiting all parties. However, BIM utilization in FM is limited by incomplete owner understanding, insufficient data accessibility, and stakeholders’ unfamiliarity with BIM procedures and standards. Despite recognizing BIM’s significance, the FM industry faces significant implementation challenges. Facility managers often lack a comprehensive understanding of BIM’s benefits in streamlining operations and enhancing cost efficiency, as well as the necessary skills for its use. Addressing these barriers requires developing an Employer’s Information Requirements (EIR) document at a project’s outset, providing a strategic plan and vision for all involved parties. BIM and IoT are pivotal technologies for transitioning to efficient building operations and crucial for reducing time, costs, and operational challenges throughout any project. This research aims to establish a digital trio workflow, integrating BIM, EIR, and IoT to maximize stakeholder benefits. It explores how preparing the EIR through stakeholder communication can improve design processes, sustainability, efficiency, cost, and time, especially for megaprojects.

Imperceptible Attacks on Fault Detection and Diagnosis Systems in Smart Buildings

Automated Fault Detection and Diagnosis (AFDD) systems are critical to safe and efficient operation of smart buildings. A significant amount of building data can be collected and analyzed to detect building compo-nent failures. Attacks against such data that are contami-nated with small additive disturbances (i.e., adversarial per-turbation attacks) could dreadfully impact the performance of such systems while maintaining a high level of imper-ceptibility. The vulnerability studies of such data attacks is lacking. Specifically, most existing detection and clas-sification models have flat structures, regarded as Single-Stage Classifiers (SSCs), are prone to adversarial data perturbation attacks. In this paper, we present a coarse-to-fine Hierarchical Fault Detection and multi-level Diagnosis (HFDD) model, and formulate a mathematical program to derive targeted attacks on the model with respect to a pre-specified target diagnosis level. Two algorithms are developed based on convex relaxations of the formulated program for non-targeted attacks. An Alternating Direction Method of Multipliers (ADMM)-based solver is developed for the convex programs. Extensive experiments are con-ducted using two real-world datasets of measurements from air handling units and chillers, demonstrating the fea-sibility of the proposed attacks with regard to misclassifi-cation rate and imperceptibility of the attack. We also show that the HFDD is more robust to disturbances than SSC-based fault detection and multi-level diagnosis systems.

Cost Optimization and Estimation of Embodied Carbon in Reinforced Concrete Frame Structure

Reinforced concrete (RC) structures are one of the most common building systems around the world. Measures are being taken to reduce the construction industry’s contribution to the greenhouse gas emissions. The contribution of embodied energy of structures is also considered for more efficient operation of buildings. This study investigates the embodied carbon content for the different grades of concrete used for the design and an optimization approach for an economic design. Analysis and design of RC frame structures are done using STAAD-PRO software and cost optimization is carried out using Genetic Algorithm (GA) in MATLAB software. The considered design constraints are geometric, strength and reinforcement areas confirming to Indian Standard codes. The optimized result is used to model the RC structure in Revit Software to determine its embodied carbon content. Candidate structures are then assessed for embodied energy to determine individual relationships. This study shows the possibility to reduce the embodied carbon content of RC frame structure and the proposed optimum design model can be adopted to design commercial buildings as it yields reliable, economical, time-saving and practical designs whilst remaining compliant to given design codes.

Empirical analysis of the prevalence of HVAC faults in commercial buildings

Commercial building HVAC systems experience many sensing, mechanical, and control-related faults that increase energy consumption and impact occupant comfort. Fault detection & diagnostics (FDD) software has been demonstrated to identify and help diagnose these types of faults. Several studies have demonstrated FDD energy savings potential, but there is limited empirical data characterizing the quantity and type of faults reported by FDD tools. This paper presents results of an FDD fault reporting study, employing multi-year monitoring data for over 60,000 pieces of HVAC equipment, covering over 90 fault types, and using new metrics that we developed to characterize fault prevalence. Study results offer an unprecedented accounting of the quantity of faults reported, the most commonly occurring faults, and fault persistence. We find that 21 air handling unit (AHU) faults were reported on 20% or more AHUs in our dataset, and 18 AHU faults persisted for more than 20% of the time period covered by the data. On any given day, 40% of AHUs and 30% of air terminal units saw a reported fault of some kind. Based on in-depth analysis of these results we provide recommendations for building operators, FDD software developers, and researchers to enable more efficient commercial building operation.

Air quality and comfort constrained energy efficient operation of multi-zone buildings

Maintaining indoor air quality (IAQ) through effective ventilation is essential for the well-being and productivity of building occupants. Control strategies aimed at improving the efficiency of heating, ventilation and air conditioning (HVAC) systems must jointly determine ventilation and heating and cooling processes. In this paper, we study the problem of minimizing the energy consumption of the HVAC system in a multi-zone building, while meeting thermal comfort and IAQ requirements. We first perform a steady state analysis of the zonal carbon dioxide (CO2) concentration and the temperature dynamics. The resulting expressions are convex in the zonal mass flow rates and zonal temperatures. Guided by the steady state solutions for meeting the thermal comfort constraints, we develop two control policies for improving the energy efficiency of building HVAC systems while jointly satisfying indoor temperature and IAQ constraints. We compare the performance of our proposed approaches with those of multiple baseline approaches which implement separate regimes for controlling zonal temperature and IAQ for a typical work-day in a multi-zone campus building. We have evaluated the performance of our proposed approaches under varying levels of flexibility in zonal temperatures. We have shown that zonal temperature flexibility can result in energy savings up to 32% (for the same control strategies) as compared to the case where no such flexibility is permitted. Our proposed approaches were seen to offer potential savings of nearly 29% compared to the baseline.

Consensus-based clustering for indoor sensor deployment and indoor condition monitoring

Accurate indoor climate monitoring is important for identifying energy-efficiency strategies in buildings. However, existing indoor monitoring approaches typically use networks of fixed/rigid sensor nodes that are often deployed in an ad-hoc manner, which could be limited in covering the areas/zones of interest or in accounting for the profile variations of the physical parameters over time. To address this gap, this paper proposes a consensus-based clustering method for identifying more robust sensor deployment strategies. The proposed method clusters a co-association matrix of input partitions that capture the periodic variations of the physical parameters from multiple building locations to increase the robustness of the sensing strategy to the daily and hourly changes in the indoor climate conditions. To test the proposed approach, thirty sensing units that sense four physical parameters were deployed in three rooms. Two consensus-clustering-based approaches (hourly- and daily-consensus) and four different frequencies for profile generation were tested, resulting in 48 scenarios for evaluation. The experimental results showed that the proposed approach could be more robust to changes in indoor climate conditions compared to the baseline, achieving a higher strategy performance index by up to 59%, and that the daily-consensus approach is often more robust than the hourly approach. The results also showed that the time frequency affects the strategy robustness and that parameters whose profiles have seasonal components are more likely to outperform. The proposed method could be used to determine reliable indoor sensor locations for capturing the dynamic environmental state of buildings, towards efficient building operation and management.

It's not just technical - Socio-technical challenges to the efficient operation of commercial office buildings

Facility management companies are the primary agents that mediate between building systems and users. As such, the impact of the socio-technical aspects within facility management companies can play a central role in operational energy management. In this study, we conducted and analyzed individual interviews with 11 building management professionals across two facility management companies. Participants included management, energy analysts, and building operator personnel, collectively working on eight commercial office buildings. Our interviews aimed to answer three research questions: (1) How is improving OE viewed, prioritized, and incentivized within the two FM organizations? (2) How are the current building settings and sequences of operations determined and documented by these FM companies? (3) What tools are used by these FM companies to analyze energy when making operational decisions? Using the results from our interviews and existing challenges identified in the literature, we identify nine primary challenges faced by these organizations and provide nine recommendations aimed at the industry. The recommendations cover organizational challenges, contracts with outside stakeholders, implementing sensors and tools, and the development of future tools. The diversity of the recommendations highlights the need for socio-technical analysis of facilities management companies and contributes to a growing body of this type of research.

The use of “digital twins” technology in the operation of buildings and structures

The article discusses the use of Digital twins technology (digital twin) in the operation of construction projects. Its application contributes to the most efficient operation of buildings and structures. The "digital twin" is constantly updated with up-to-date information: maintenance companies are engaged in updating the needs of residents, conducts diagnostics of the condition of the building as a whole. This technology helps to determine the exact timing of equipment replacement. The operated building and its systems are under constant supervision and control of management organizations. The cost of operating the building is reduced, as the building is under constant monitoring and diagnostics.

Digital approach to construction and demolition

High-tech digital solutions play a key role in many areas of modern life. The digitalization of construction is at the stage of development and every year it is being introduced more deeply into the industry: regulatory documentation is being developed, digital platforms for interaction between construction participants are being created, and software requirements are being formed. The construction industry needs professionals who will work in a digital information environment throughout the entire life cycle of a building. The level of modern information modeling makes it possible to create a unified digital environment for the development of design solutions, construction management, efficient operation of buildings and their demolition without causing damage to the natural environment. The article discusses digital technologies that accompany the construction and demolition stages of a building's life cycle. An analysis of the requirements for the content of information models is given, the tasks of organizational and technological design are identified, which can be solved through the introduction of a digital construction model. It is proposed to use an end-to-end information flow to ensure the transfer of reliable information between the stages of the life cycle of an object and the formation of information about secondary building resources that can be used in new construction.

Two-Level Decentralized-Centralized Control of Distributed Energy Resources in Grid-Interactive Efficient Buildings

The flexible, efficient, and reliable operation of grid-interactive efficient buildings (GEBs) is increasingly impacted by the growing penetration of distributed energy resources (DERs). Besides, the optimization and control of DERs, buildings, and distribution networks are further complicated by their interconnections. In this letter, we exploit load-side flexibility and clean energy resources to develop a novel two-level hybrid decentralized-centralized (HDC) algorithm to control DER-connected GEBs. The proposed HDC 1) achieves scalability w.r.t. a large number of grid-connected buildings and devices, 2) incorporates a two-level design where aggregators control buildings centrally and the system operator coordinates the distribution network in a decentralized fashion, and 3) improves the computing efficiency and enhances communicating compatibility with heterogeneous temporal scales. Simulations are conducted based on the prototype of an office building at the Oak Ridge National Laboratory to show the efficiency and efficacy of the proposed approach.

Deep vision-based occupancy counting: Experimental performance evaluation and implementation of ventilation control

Recently, many researchers have become interested in occupant information and occupant-centric control (OCC) strategies, aiming for efficient building operation. Combining a camera with deep learning (hereafter referred to as deep vision-based occupancy counting) is a very effective method for occupancy counting, but there are not many studies evaluating its experimental performance. Furthermore, there are insufficient studies on implementing control using deep vision. The purpose of this study was to experimentally evaluate the performance of deep vision-based occupancy counting and to implement deep vision-based OCC in reality. First, we evaluated the performance of deep vision-based occupancy counting for six offices. Second, we implemented a deep vision-based energy recovery ventilator control strategy in a small office and compared the indoor air quality and energy consumption with those from traditional control strategies. As a result, deep vision-based occupancy counting showed significantly higher performance (root mean square error (RMSE): 0.883, normalized RMSE (NRMSE): 0.141). The larger the floor area, the more frequently the prediction of the number of occupants was lower than the actual number. The control results showed that deep vision-based ventilation control could properly maintain the indoor CO2 concentration with 24–35% lower ventilation rates compared to traditional ventilation control strategies. Furthermore, the proposed strategy was effective in reducing the electrical energy consumption of energy recovery ventilator and heat pump.

ПРИМЕНЕНИЕ ТЕХНОЛОГИИ «ЦИФРОВЫХ ДВОЙНИКОВ» ПРИ ЭКСПЛУАТАЦИИ ЗДАНИЙ И СООРУЖЕНИЙ

The article discusses the use of Digital twins technology in the operation of construction facilities. Its use contributes to the most efficient operation of buildings and structures. The digital twin is regularly updated: the management organization takes into account the new needs of consumers, performs diagnostics of engineering systems. The digital double helps to determine the timing of equipment replacement. The operation of the building is monitored remotely and around the clock. The cost of operation of the facility is reduced: the management organization evaluates its condition and parameters, offers the best tariff and reduces its costs.

A data-driven workflow to improve energy efficient operation of commercial buildings: A review with real-world examples

Data-driven building operation and maintenance research such as metadata inference, fault detection and diagnosis, occupant-centric controls (OCCs), and non-invasive load monitoring have emerged (NILM) as independent domains of study. However, there are strong dependencies between these domains; for example, quality of metadata affects the usability of fault detection and diagnostics techniques. Further, faults in controls hardware and programs limit the performance of OCCs. To this end, a literature review was conducted to identify the dependencies between these domains of research. Additionally, real-world examples using operational data from three institutional buildings in Ottawa, Canada, were provided and discussed to demonstrate these dependencies. Finally, a holistic tool-agnostic workflow was introduced which suggested the implementation of operational energy efficiency measures in the following order to ensure their full potential: (1) improve metadata, (2) address faults, (3) implement OCCs, and (4) monitor enhanced key performance indicators (KPIs). The proposed workflow is intended to be comprehensive, reproducible, nonintrusive, and inexpensive to implement. Practical applications: Optimization of building operations has been emerging among energy management professionals as a relatively low-cost means to achieve energy efficiency and minimize occupants’ discomfort. To this end, this study introduces a tool-agnostic data-driven workflow to building energy management practitioners that can assist them in achieving increased energy efficiency. The proposed workflow recognizes the interdependency of the various domains of research which have historically been treated independently.

AUSTRET: An Automated Step Response Testing Tool for Building Automation and Control Systems

Building energy consumption is still one of the main contributions to global carbon emissions. With the overall digitalization in the building sector, building automation and control systems (BACS) are to play a more important and key role in improving the building sector performance. A well-designed BACS at the building design phase with a high level of control functionalities is not a guarantee for efficient building operation and successful control and management strategies in the operational phase. Thus, a systematic automated initial and retro-commissioning process is key to test the performance of the automation system and the response of the integrated HVAC systems. This is an arduous and time-consuming task susceptible to human errors. As an alternative, the current study proposes a methodological framework to automate step response testing of BACS and to optimize the different steps of this process in a cost-effective way. In addition to newly built buildings, the framework can be applied in existing or retrofitted medium to large-sized buildings that have a building management system capable of receiving actuator commands and responsible to provide updates of several state variables. Based on the proposed framework, a first-of-its kind tool “AUSTRET” for building automated step response testing of BACS is designed and developed. The tool provides the necessary input configuring parameters, building system selection, and output results for each performed test. The framework aims to act upon ventilation, room heating and cooling, and water heating and cooling modules in a building. The implementation and demonstration of the AUSTRET in a medium-sized building case study for two different building systems are presented and evaluated: (1) Ventilation/fan, (2) Room heating. The results show the different dynamic responses on these two systems and how misleading input parameter configuration can invalidate step response tests. The preliminary results highlight the capability of using AUSTRET as a key component in both building initial and retro-commissioning applications.

The meaning of convenience in smart home imaginaries: tech industry insights

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"> Smart home technology (SHT) is being promoted for the enhancement of occupants’ convenience, as well as more efficient and sustainable energy consumption. However, recent research indicates that convenience often takes precedence over energy reduction, threatening to affect inhabitants’ everyday practices in a non-sustainable way. In order to understand the social and environmental consequences of SHT, the meaning of convenience is investigated. How is the concept of convenience developed in concert with technological development? Presenting SHT imaginaries from the industry, the paper builds on qualitative interviews with 11 SHT professionals. By exploring the practices, roles, and relations at play in SHT development, it is demonstrated how the vision to enhance convenience in everyday life is related to a user imaginary characterized by passivity and disengagement from energy savings. Furthermore, convenience is enabled and enforced through the notion of interoperability. Interoperability refers to not only technologies ‘speaking together’ but also a strong interdependency between professional actors. By exploring the practices at play in SHT development, the meaning of convenience is revealed to be an outcome of this interdependency as well as the collectively shaped ideas, and technological standards embedded in the industry. <strong><br /></strong> <strong>Policy relevance</strong> SHT is shaping our domestic futures, influencing material environments as well as social life and energy consumption. Currently, SHT is promoted and supported widely in policy. For instance, the European Commission stresses automation as a means to ensure the more efficient operation of buildings, generating cost and energy savings. However, a focus on convenience risks counteracting sustainability considerations. This study shows how convenience can take precedence across various branches of SHT development, with a consequence of creating passive users who are disengaged from sustainability issues. When policymakers promote the adoption of SHTs and automation of the built environment, a more critical stance is needed toward convenience in order to avoid user passivity and masked energy consumption. Policy instruments, such as the smart readiness indicator (SRI), should not only include calculations of what is technically possible in terms of automation but also examine the outcomes, practices, and behavior that SHT promotes. </div></div></div>

Simple method to improve the TCXDVN 306:2004 indoor climate standard for closed office workplaces in Vietnam

Thermal comfort is an important parameter of indoor climate, which affects office worker health and productivity, and also aids planning for energy efficient building design and operation. To provide satisfactory thermal comfort in office workplaces under hot and humid outdoor conditions, most contemporary office buildings in Vietnam are fitted with ducted air-conditioning systems. The current Vietnamese standard TCXDVN 306:2004 for indoor climate was derived from thermal comfort research conducted between the 1960s and 1980s. This standard is limited by various drawbacks, including no distinction between natural or artificial environments. In response, this 2018 research provides physical measurements and opinion surveys of current indoor climatic conditions in representative office workplaces in three regions of Vietnam: North, Central and South. The measurement results have been transformed into ET, PMV and PPD indicators, which value demonstrate the shortcomings of the TCXDVN 306:2004 standard, while providing a baseline input for updating this standard to meet the thermal comfort needs of air-conditioned office workplaces, based on the concept of probability comfort, which are integral with the ISO and the ASHRAE standard.

Building Performance Evaluation of a New Hospital Building in the UK: Balancing Indoor Environmental Quality and Energy Performance

Hospitals are controlled yet complex ecosystems which provide a therapeutic environment that promotes healing, wellbeing and work efficiency for patients and staff. As these buildings accommodate the sick and vulnerable, occupant wellbeing and good indoor environmental quality (IEQ) that deals with indoor air quality (IAQ), thermal comfort, lighting and acoustics are important objectives. As the specialist nature of hospital function demands highly controlled indoor environments, this makes them energy intensive buildings due to the complex and varying specifications for their functions and operations. This paper reports on a holistic building performance evaluation covering aspects of indoor air quality, thermal comfort, lighting, acoustics, and energy use. It assesses the performance issues and inter-relationships between IEQ and energy in a new building on a hospital campus in the city of Bristol, United Kingdom. The empirical evidence collated from this case study and the feedback received from the hospital staff help identify the endemic issues and constraints related to hospital buildings, such as the need for robust ventilation strategies in hospitals in urban areas that mitigate the effect of indoor and outdoor air pollution and ensuring the use of planned new low-carbon technologies. Whilst the existing guidelines for building design provide useful instructions for the protection of hospital buildings against ingress of particulate matter from outdoors, more advanced filtration strategies may be required to enact chemical reactions required to control the concentration levels of pollutants such as nitrogen dioxide and benzene. Further lessons for improved performance in operation and maintenance of hospitals are highlighted. These include ensuring that the increasingly available metering and monitoring data in new buildings, through building management systems, is used for efficient and optimal building operations for better IEQ and energy management. Overall, the study highlights the need for an integrated and holistic approach to building performance to ensure that healthy environments are provided while energy efficiency targets are met.

Building commissioning costs and savings across three decades and 1500 North American buildings

Building commissioning (Cx) is a process for assuring efficient building operations that can be applied to new construction and existing buildings, resulting in energy and non-energy benefits. Quantifying the benefits of commissioning is challenging, but a 2009 study of 643 commercial buildings provided a solid initial data set to which we added 839 additional buildings for a significantly expanded and updated meta-analysis representing 34.7million square meters (373 million square feet) of floor area. Since 2009 the commissioning industry has continued to grow, driven by building codes, utility programs, and rising awareness of commissioning benefits. In parallel, building controls have become more sophisticated, and analytics software has emerged to assist with commissioning. We find that delivery mechanism and market segment are key determinants of outcomes, although significant and cost-effective savings are found across the spectrum. Median primary energy savings for Cx projects in existing buildings ranged from 5percent for those conducted under utility programs, 9percent for monitoring-based commissioning utility programs (i.e., augmented with submetering and diagnostics), and 14percent for Cx projects outside of utility programs. Across all project types, median savings ranged from 3percent for the lodging market segment to 16percent for public order and safety facilities. Outcomes did not vary significantly by building size or by market segment. Energy savings are rarely estimated for new construction commissioning. We found that the median costs of Cx were lower for the 2018 sample than for the 2009 sample—$2.85 per square meter ($0.26 per square foot) for existing buildings (a 33 percent reduction) and $8.78 per square meter ($0.82 per square foot) for new construction (a reduction of almost 50 percent). The median simple payback time for existing buildings was 1.7 years, with a 25th–75th percentile range of 0.8–3.5 years. This article summarizes these and other key findings, and discusses how the 2018 data reflects shifts in commissioning practice and outcomes.

Impact assessment of air velocity on thermal comfort in composite climate of India

Thermal adaptation plays crucial role in energy efficient operation of buildings without compromising with human thermal comfort. Elevated air velocity is commonly desired to restore comfort requirements at higher temperatures especially in NV and MM buildings located in tropical countries like India. This article is the systematic field study comprising a total of 4872 responses (1874 from NV buildings and 2998 from MM buildings) collected over a period of six years (2011–2017) during summer and moderate seasons under composite climate of Jaipur (India). Subjects’ responses and concurrent field measurements were utilized to investigate the impact of elevated air velocity on indoor thermal comfort. This research is a first attempt of its kind that deals with graphical quantification of air velocity required to offset increased temperature and follows similar approach as presented in ISO 7730. A redefined air velocity offset chart for Indian subjects working in office buildings has been proposed using the evidences (i.e. comfort expectations, preferences and local adaptation) collected from actual field observations. Thus, the offset in comfort operative temperature from base value of 28.04 °C and 26.93 °C for NV and MM buildings were obtained to be 4.78 °C and 4.24 °C, respectively for the elevated air velocity of 1.5 m/s.