Intelligent Building Research-A Review

Automation in Construction 14 (2005) 143 – 159 www.elsevier.com/locate/autcon Review article Intelligent building research: a review J.K.W. Wong a,*, H. Li a, S.W. Wang b b a Department of Building and Real Estate, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong Department of Building Services Engineering, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong Abstract Within the last two decades, substantial amount of literature on intelligent building has been generated. However, there is a lack of systematic review of existing research efforts and achievements. A comprehensive review on existing research provides great benefits to identify where more efforts are needed and therefore the future research directions. For this purpose, this paper reviews the literature related to the subject area of intelligent building. Our review indicates that previous research efforts have dealt mainly with three research aspects including advanced and innovative intelligent technologies research, performance evaluation methodologies and investment evaluation analysis. It is also identified that among the three research aspects, relatively less literature has been found addressing the issues of investment evaluation of intelligent buildings. Based on a comprehensive literature review, the paper also summarizes a few future research directions, which are useful to researchers working in this important area. D 2004 Published by Elsevier B.V. Keywords: Intelligent building; Definition; Performance evaluation; Investment evaluation; Net present value; Life cycle costing analysis; Cost benefit analysis; Analytical hierarchy process; Fuzzy set theory 1. Introduction The word ‘intelligent’ was first used to describe buildings in the United States at the beginning of the 1980s. The concept of ‘intelligent building’ was stimulated by the development of information technology [47,56] and increasingly sophisticated demand for ‘comfort living environment and requirement for increased occupant control of their local environments’ [94]. Research on intelligent building has been conducted ubiquitously and research results have been published in many academic journals. Much research * Corresponding author. Tel.: +852-2766-5111; fax: +8522764-3374. 0926-5805/$ - see front matter D 2004 Published by Elsevier B.V. doi:10.1016/j.autcon.2004.06.001 work has been focusing on the discussion of intelligent building technology development and performance evaluation methodologies. However, little literature has been devoted to addressing investment evaluation techniques of intelligent buildings. Also, there exists insufficient information and support for investment decision-making at the conceptual stage of intelligent building development. The growing investment on intelligent buildings and the greater demand for demonstrating its profitability of intelligent building have led to the investigation for methods and techniques that can be of assistance in evaluating intelligent building investments, preferably at the conceptual stage. The purpose of this paper is to provide a succinct and systematic review of the existing research in 94]. According to the research conducted by Wigginton and Harris [94]. [59]. Most recently. most existing definitions of intelligent buildings are ‘either too vague to be useful guidance for detailed design which either places an unbalanced focus on technologies only or do not fit that culture of Asia’. would become prematurely obsolete or require substantial refurbishment or demolition. They proposed intelligent building is not only able to react and change accordingly to individual. The third section presents future research directions. The need of a precise intelligent building definition is critical as ‘without a correct definition.72. systems. new building will not be optimally designed to meet the next . morale and satisfaction. The Intelligent Building Institute of the United States defines an intelligent building as ‘one which provides a productive and cost-effective environment through optimization of its four basic elements including structures. In contrast.K. The first section provides an overview of research in intelligent building.W. cited in Ref.18] suggested the intelligent building accentuates a ‘multidisciplinary effort to integrate and optimize the building structures. organizational and environmental requirement. In addition. while at the same time enabling efficient management of resources with minimum life-time costs of hardware and facilities’ [94]. Then. but they can furnish the occupants with more intelligence and enable them to work more efficiently’. Cardin (1983. The second section presents methodologies for investment evaluation for investment evaluation of intelligent building projects. This paper begins with the discussion of the definition of intelligent buildings. [29. the paper summarizes current research areas in intelligent building into three sections. cited in Refs. Definitions of intelligent building There have been a myriad of academic and technical literature discussing the definition of intelligent buildings. or in the information technology that they use. investment and operating cost savings. services and management in order to create a productive. a number of authors have extended the definition of intelligent building and have added ‘learning ability’ and ‘performance adjustment from its occupancy and the environment’ in the definition [94. Wong et al. The difference indicates the UK definition is more focused on users’ requirements. [86] pointed out both the intelligent building institutes in the United States and the United Kingdom have inconsistent interpretation of building intelligence. systems. Moreover.98]. but is also capable of learning and adjusting performance from its occupancy and the environment. / Automation in Construction 14 (2005) 143–159 intelligent building in order to identify and suggest future research directions. cost effective and environmentally approved environment for the building occupants’. services and management and the interrelationships between them’ [94]. the UK-based European Intelligent Building Group defines an intelligent building as ‘one that creates an environment which maximizes the effectiveness of the building’s occupants. Preiser and Schramm [74] and Wigginton and Harris [94] suggested that intelligent buildings must respond to user requirements. and in turn it influences human’s productivity. The building environment affects the wellbeing and comfort of human in the workplace. there has been growing awareness that the services systems and work process management of a building have close relationships with the well-being of human. Authors such as Robathan [76]. there exist over 30 separate definitions of intelligence in relation to building. [86] argued that ‘intelligent buildings are not intelligent by themselves. flexibility’. On the other hand.144 J. For example. Some authors [9. The Intelligent Building Institution in Washington (1988. it appears that different intelligent building professional bodies also have different understanding of intelligent building. 2. According to Clements-Croome [29]. DEGW in mid-1980s found that buildings which were unable to cope with changes in the organizations that occupy them.56]) defined intelligent building as ‘one which integrates various systems to effectively manage resources in a coordinated mode to maximize: technical performance. [94]) defined intelligent building as ‘one which has fully automated building service control systems’. Loveday et al. while the US definition is more concentrated on technologies. So et al. The purely technological definition of intelligent building has been criticized by many researchers. So et al. Early definitions of intelligent building focused almost entirely centered on technology aspect and did not suggest user interaction at all [47. acoustical. n M3: cost effectiveness—operation and maintenance with emphasis on effectiveness.64.93].43.31. security system [87. which control.87]. So and Wong [85] suggested that the new definition has two folds.82. network protocol [8.90]. The revised ‘QEM’ (M1 – M10) includes: n M1: environmental friendliness—health and energy conservation.87. Technologically.37. and to provide a fair platform for users and the general public to evaluate the performance of an intelligent building. and building integrity’.90. air-quality and visual comfort. n M6: safety and security measures—fire. Building systems and structure integration.80. disaster and structural damages. including advanced/innovative technologies. as pointed out by Bradshaw and Miller [20]. Previous research efforts in this stream have been focused on the advanced development of system integration [41. search efforts have dealt mainly with three research streams.24] and Arkin and Paciuk [9]. intelligent building technologies are characterized by a hierarchical presentation of system’s integration [9. many intelligent buildings comprise three levels of system integration which include: n The top level which is dealt with the provision of various features of normal and emergency building operation as well as the communication management. supervise and coordinate the intelligent building subsystems.87]. Research in advanced and innovative technologies A plethora of research efforts have been placed on intelligent building technologies.87]. security and safety. etc. this new definition gives designers a clear direction and sufficient details to enable a high quality intelligent building design consistent with intelligent building definition.K.1. n M5: working efficiency.89. According to Carlini [23. Fig.41. thermal.87].61. The first level comprises nine ‘Quality Environment Modules (QEM)’ (M1 – M9) and the second level includes three areas of key elements which are functional requirements.24.87. First. BAS would perform the function of energy management 3. n M7: culture. [86] suggested a two-level strategy to formulate an appropriate intelligent building definition. Chow [27] proposed the inclusion of additional modules (M10) as supplement to the existing nine modules in order to deal with the health issues for buildings.90] and communication system [38.94]. fire protection system [48. n M9: construction process and structure. communication management system (CMS) and office automation (OA) system.28. n M4: human comfort.84. So et al. In response to this. n The middle level which is performed by the building automation system (BAS).83] and building subsystem services. So et al. These three research streams are further described in subsequent sections. energy management system (EMS).70.23. which enable the consideration of technologies. 1 shows the framework for intelligent building research and the connections between the various research streams included.22.87. Previous intelligent building research An overview of literature related to intelligent building research works indicates that previous re- .47.82. 3. functional spaces and technologies. lift system [48. Each of 10 key modules mentioned above will be assigned a number of key elements in an appropriate order of priority. n M2: space utilization and flexibility.J. Also. which include HVAC system [15. / Automation in Construction 14 (2005) 143–159 145 century’ [86]. n M8: image of high technology.21. intelligent building performs and arranges differently from a conventional one. are to provide the ‘qualities that create a productive and efficient environment such as functionality.68. and the needs of users. and n M10: health and sanitation. Wong et al.89. earthquake. [86] redefined intelligent building as one which ‘designed and constructed based on an appropriate selection of ‘Quality Environmental Modules’ to meet the user’s requirements by mapping with appropriate building facilities to achieve long term building values’. performance evaluation methodologies and investment evaluation analysis.W. lighting system [48. / Automation in Construction 14 (2005) 143–159 Fig. fire protection system. 1. security system and communication system. vertical transportation system.K.W. . and n The bottom level which contains subsystems including heating.60]. system and groups all relevant subsystems in some occasions [43. ventilation and air-condition- ing (HVAC) systems. lighting system. Taxonomy of research in intelligent building. Wong et al.146 J. Preiser and Schramm later (in 1997) improved their evaluation models and proposed an ‘integrative building performance evaluation framework’ to evaluate and review the stance in all six major phrases of building delivery and life cycle including planning.84. Typical intelligent building technologies are summarized in Table 1.70. The POE process model is generally executed in three stages.93]: n Fire alarm system would be integrated with other building systems. Early performance evaluation models were developed by Manning in 1965 and Markus et al. Wong et al. and n Facility management is integrated with BAS. such as building services systems/components. devices and programs together in a common architecture so as to share and exchange data’. artificial-intelligence-based technologies designed to detect problems. System integration is the process of ‘connecting systems. Many researchers also paid efforts in developing intelligent control method to be used in modern building management system for improving and optimizing the energy and environmental performance of buildings [91]. Arkin and Paciuk [9] suggested the key to the effective operation of intelligent building was not related to the sophistication of the building services systems. Serafeimidis [81] considered the evaluation process as a feedback mechanism aimed to facilitate learning. . Ivanovich [53] reviewed current research in intelligent building technologies. . the application of wireless technologies with buildings or networking building systems is also a popular research area [37] which has currently attracted attentions of many researchers and industry practitioners. Examples of major intelligent building systems interaction include [48.J. and can relate the determination of the worth of an object’. The IEA BSC research program Annex 25 [51] and Annex 34 [33]. sensors [92] and control devices that are hard detected by human-beings. HVAC systems can be used to prevent the smoke from spreading by opening exhaust dampers and closing outdoor air intake dampers of the fire floor if there is a fire on one floor of building.47. while [100] considered the process of evaluation as ‘a series of activities incorporating understanding. 3. . the mode of operation and in some instances the accessible floor levels. construction. programming. occupancy and recycling. [74]). Research in performance evaluation methodologies Apart from intelligent technologies research and development. Different authorities have tried to develop evaluation models to assess the performance of intelligent building [9. lighting and security through BAS. between the system and the building structure. fuzzy logic.74.87].87. In addition. design. conducted extensive research on the methodology. / Automation in Construction 14 (2005) 143–159 147 Moreover. involving over 10 universities and research institutions from different.85.2. such as HVAC.98]. there have been substantial amount of research devoting to evaluating intelligent building. as well as other software-intensive. Building performance evaluation is a crucial procedure which offers feedback function on the performance of building materials and components for future improvement and reference ([73]: cited in Ref. n Vertical transportation system is interacted with fire alarm or the security systems in order to define the number of elevators required. in 1972 [74].K. It is either a conscious or tacit process which aims to establish the value of or the contribution made by a particular situation. strategy and application of fault detection and diagnosis in HVAC systems. measurement and assessment. Many similar studies have also been conducted attempting to measure the level of intelligence that a building exhibited and to set up criteria for selection of the best intelligent building [47]. intelligent building allows interaction and integration among building subsystem services [48. n Fire alarm program would be interfaced with security to release specific locked doors under alarm conditions. Preiser [75] developed the ‘post-occupancy evaluation process model (POE)’ in order to determine the intelligence level of intelligent buildings.90. Contemporary research efforts have been attempting to develop software with the use of automated diagnostic tools introducing neural networks. rather it was the integration among the various systems. n Security system is interfaced with the lighting and HVAC subsystems to define activation of necessary lighting paths and the specific room occupy mode.W.73. amplifiers. BACnet. [21. e-Card access. motion detectors.48.148 J. n Computer vision system (allows n Air handling unit (AHU) counting of number of residents controller. light sensor. and other device such as touch switch. n CCTV surveillance. n Specific programs for lift n Lift sensors and passenger operation and monitoring detectors.87. and with the BAS wherever the user is other devices such as pressure. Unoccupied Night Purge Program. intruder alarm system and special presence detection sensors n Traditional telephone systems. Recent development HVAC system Lighting system Vertical transportation system n Software program such as Duty Cycle Program. the distribution of the residents) centralized chiller plant. transmission cables. repeat amplifiers. distributed controller. and dish antennas for satellite communication n Advanced drives and artificial intelligence based supervisory control n Computer vision technologies have been used in intelligent building in counting the number of passengers and to aid lift control n Sophisticated fire alarm systems which include stand-alone intelligent fire alarms and intelligent initiating circuit sensors n Internet-based security system n Use of Web-enabled devices which allows remote building control and monitoring . etc.37. n Use of Web-enabled devices for the building automation system which allows remote building control and monitoring by interaction of the central BAS workstation with the remote dial-up system via modem. Unoccupied Period Program. local area network (LAN) and Internet system. etc.38. and n Other specific programs for HVAC operation n Occupied – unoccupied lighting n Charge-coupled device (CCD) control program (time-based cameras. flow sensors. mixers. etc. detection and safety system Communication system n Private automatic branch exchanges (PABX). n Internet-based lighting system Fire protection system n Specific programs for fire protection and detection Security system n Specific programs for security protection. temperature.W. and other software program enabling remote building control and monitoring n Intelligent fire controller (IFC). Zero-energy Band Program and Heating/cooling Plant Efficiency Program. etc. fully addressable automatic fire alarm and detector (sensor) system n Intelligent Access Controller (IAC). operator workstations. attenuators and final TV outlets. integrated service digital network (ISDN). neural network-based controller. Chillers Optimum Start-stop Program. network expansion units. etc. and other devices such as CCD camera. Load Reset Program.K. Enthalpy Program. and other controller (ILC)/lighting specific programs for lighting control management system controller.e. / Automation in Construction 14 (2005) 143–159 Table 1 Intelligent building technologies and systems (adapted from Refs. aerials. intelligent lighting lighting control program).89]) Intelligent building Software/program systems BAS n Standard Protocol (i. application specific controllers and sensor system. LonWorks. motion detectors.) n Direct Digital Control (DDC) Hardware/device n Network control units. within an air-conditioned space fully air-conditioned variable and informs the control system of air-volume system (VAV) controller. Wong et al.80. heating/ cooling elements located across the n Internet-based HVAC system allows authorized users keep close contact occupancy zones of the floor. splitters. The mere provision of a particular facility. discourage total ignorance of minor subjects. n Practically extension of the utility theory. in a building is not a conclusion of its intelligence. and n Have learning ability and able to be upgraded and modified from time to time. there have been many studies trying to develop rating systems for the intelligent building. researchers have currently attempted to construct a set of objective evaluation model in order to reflect the performance and justified price of intelligent building. According to So and Wong [85]. This assessment methodology can be used for evaluation and comparison of single aspect of building’s intelligence and to create a unified index for evaluation of system’s integration in intelligent buildings. The individual assessment index for this methodology was originated from the nine ‘Quality Environment Modules’ (M1 – M9). One of the essential performance rating systems was the ‘building rating method’ developed by DEGW in 1995 based on the ‘building IQ rating method’ and the ‘building quality assessment’ (developed by Intelligent Buildings Europe Work). n Important elements do not receive sufficient emphasis and less important elements are ignored. So and Wong [85] suggested the criteria for an efficient performance evaluation model which states as follows: n Encourage well-balanced performances. third. This model has been adapted by other researchers in the intelligent building performance evaluation such as Yang and Peng. The method employs five categories of factors which are combined to produce overall assessments of the suitability of intelligence provided by the subject building. Preiser and Schramm [74] applied the POE process model to evaluate intelligent building in the cross-cultural context and suggested that the POE model could ‘enhance building performance evaluation in intelligent buildings especially in a long-term. each index possesses a score which is a real number (within the range of 1– 100) calculated by a conver- sion formula. Without a rating system. to form the overall intelligent building index. Therefore. to carry out comparative analysis of data collected and development of recommendations and guidelines for the utilization of the data-gathering instruments worldwide. at the same time. 2001 [98]. . n Slightly different assessment in terms of the weight or priorities of elements for each individual intelligent building project. and n Binary approach of each rule or question is not a good practice. to develop compatible data collection instructions in the conceptual phase. Further research is needed to develop performance evaluation models that can meet the above criteria. it is difficult to classify and justify the level of intelligence of intelligent buildings. n Current assessment method do not contain a learning curve and unable to evolve from time to time. For example. the Asian Institute of Intelligent Buildings [85] constructed a quantitative assessment method. / Automation in Construction 14 (2005) 143–159 149 First. measuring all levels of building performances. some of the performance evaluation models have been criticized for fraught with problems of fairness and partially subjective assessment. or system. On the other hand. A building can be ranked from A to E to indicate the overall intelligent performance. continuing basis’ because the evaluation system allows the ‘tracking of performance of new high-tech systems and their effects on building occupants as well as the effectiveness of these systems in general’. namely the intelligent building index (IBI). n Consistent with human preferences while random judgments must be minimized.K. to apply and pilot testing of evaluation instruments in field studies on intelligent office building. the shortcomings identified are in the following areas: n Inconsistence between final assessment index and human thinking. and between systems and the building’s structure. More recently. However.W.J. weighting as attributes and combining them systematically. second. Arkin and Paciuk [9] developed a ‘‘Magnitude of Systems’ Integration’’ Index (MSIR) to examine the level of systems’ integration of intelligent buildings according to the extent of integration among their systems. In response to insufficiencies of existing performance evaluation models. A summary of the hierarchical development of intelligent building assessment methods is illustrated in Table 2. emphasize important elements but. Wong et al. NS X Ri MSI ¼ i¼t 1988 1991 1992 Camegie Mellon University Kuala Lumpur City Hall Intelligent Building Research Group 1992 1992 – 1994 Intelligent Building in Europe Project Holland. (B) building shell issues (14 items). n Second phase: conducting POE involves methods and instruments—initiating data collection. five-star and four-star). Wong et al. performance criteria and planning the data collection process. monitoring data collection and analyzing data. A simple cumulative index is obtained by summing all the ratings (Ri) attributed to the integration features of various systems in the building. Building IQ rating method: considering needs (10 for individual user. building quality assessment. and (E) building services and technology (12 items) where the result is an overall score by combination of all items Magnitude of systems’ integration: to determine the level of systems’ integration in intelligent buildings. (D) organizational and work process issues (11 items). and serviceability tools and methods Building rating method: involving five sections (A – E) including namely (A) building site/location (7 items). / Automation in Construction 14 (2005) 143–159 Table 2 Intelligent building performance assessment methods (adapted from Refs.W. (1)). systems and services (six-star. and then dividing the sum by the number of available systems. (C) building skin issues (3 items). 15 for organizational.85]) Year 1983 1985 Research agency DEGW DEGW Details of assessment methods Orbit 1: multi-client study (building use studies) Orbit 2: degree of matching between the building. New Zealand and Canada 1995 DEGW 1997 Arkin and Paciuk NS ð1Þ 1998 Harrison et al. the organizations occupying it and IT (using nine key organizations issues and eight key IT issues) Measures of quality. ‘‘MSI’’ was used to evaluate as objective index that quantifies and summarizes the various aspects of integration (Eq. 2002 Preiser and Schramm Building rating method (results matrix): based on the building rating method constructed by DEGW (1995) and demonstrated its use in evaluations through the two plots of the categories (A – B/C. services and applications (not published) Development of three evaluation methodologies to evaluate the quality of buildings and the suitability for different tenant types: real estate norm. [19.27. D – E). recommending actions and reviewing outcomes Intelligent building index (IBI): quantitative assessment methods for IB which was originated from the nine ‘Quality Environment Modules’ (M1 – M9) 2002 So and Wong (AIIB) . satisfaction and efficiency (using six performance criteria and five system integration criteria) Guidelines specifying features of office buildings based on location. 6 for local environmental and 5 for global environmental). design. n Third phase: applying POE involves reporting findings.150 J. Project was not completed Intelligent building rating: key questions based on building shell characteristics.K. The categories are each dimensioned as percent and the four quadrants of each plot are considered to indicate the building’s performance Post-occupancy evaluation process model (POE): three phases of process model include: n First phase: planning POE involves liaison with client. However. This mentality may be explained by following reasons [57. Flax [39] emphasized the importance of technologies. and improving operational effectiveness. efficiency and marketability’. operating and maintenance cost as well as the equipping of the building with automation and communication. Wong et al. n Investors are lack of information and support for investment decision-making at the conception stage of intelligent building development.3. 4.94] suggested that the growing interest in investment has been credited to potential benefits that an intelligent building delivered to the investors. Others apply evaluation techniques to review the project feasibility and adherence to their goals [4]. There is a growing demand for tools to support intelligent building investment decision-making. Hetherington [48] suggested the assessment should be made on ‘a project by project basis taking into account the overall project size.95]. Choi [101] pointed out that the financial viability of intelligent building is the major concern of the developers. Without such identification works. Many of the investment evaluation techniques aims to compare project benefits against costs in an attempt to ‘determine acceptability. / Automation in Construction 14 (2005) 143–159 151 3. there is still a lack of generally accepted tool for supporting intelligent building investment decision making. Also. convenient and comfortable environment for occupants. however. The apparent insufficiency of traditional investment evaluation techniques has been identified by many authors [49. n Investors are failed to observe the connections between initial capital cost. it is difficult to assess and judge the financial viability of the project. (2001) [95] attempted to analyze and examine the . Some property investors review historic performance and request assessment of future performance of property portfolios in formulating the investment strategy decision [3]. It is for this reason that the development of new investment evaluation model has become the focus of intelligent building research. the project costs and benefits need to be identified and classified.K. These techniques have also failed to provide a comprehensive picture of developers’ returns on investment.W. the number of intended work stations and the nature of each intelligent building system to be implemented’. providing a flexible. investors use various types of methods to assess the financial feasibility of a proposed project. Investment to intelligent building has increased dramatically in the Asia Pacific region in recent years [62]. before the evaluation of investment project. [95] argued that many investors would consider cost and benefit when they decide whether it is worthwhile to invest in a new technology. spares costs. and telecommunication in the total building and fit-out capital costs of intelligent building. Wong et al. which is referred as the investment feasibility evaluation of intelligent building projects. and to set a ranking order among competing projects’ [5]. Wong et al. Many prevailing investment evaluation techniques were extended conceptually and functionally from the traditional investment decision making techniques [47. many investors have the mentality of ‘high-risk and low-return’ towards investment in intelligent building. These benefits include ‘reducing operating and occupancy costs.98]: n Investors are unaware of the total cost in relation to the built asset that their business required. data systems. Many authors have attempted to identify and classify the cost components of intelligent building. commissioning costs.88. In the evaluation of project costs of intelligent building.99] as these techniques have ‘failed to reflect the dynamic and constantly hanging reality of businesses’.J. installation costs. Therefore. Research in investment evaluation analysis Another stream of research has been focusing on evaluating economic and financial aspects of intelligent building. Myers [70] identified six types of costs including in an intelligent building project: equipment costs. For example. Despite all these. special software costs and staff/training costs. offering advanced technological facilities together with reduced maintenance costs. Mawson [63] remarked the necessity of justifying the intelligent building investment on the basis of cost and benefit related to the users or investors’ business priorities in order to illustrate the profitability of intelligent building investment. Investment considerations and evaluation techniques for intelligent building Traditionally. A number of authors [26. Table 3 Empirical studies for IB investment evaluation summary Year 2001 Authors/researchers Wong et al.98]) developed techniques and models to assist the process of intelligent building investment evaluation. many authors have tried to evaluate the benefits generated by the intelligent building (e. Only a few authors or research groups (e.54. and the expenditures on building services were higher than conventional building project by 5%.10.152 J. [14. Remer and Nieto [78. the intelligent building involved more application of advanced technological materials and components in building services systems than the conventional building. However. A summary of the empirical studies and research efforts reviewed are illustrated in Table 3. research related to investment evaluation of intelligent building projects are very limited.48. Among these techniques.95.70. Apart from project costs. Simply because. life cycle costing analysis (LCCA) and cost benefit analysis (CBA). The NPV is a traditional technique designed to ‘net the present value of the investment from the present value of the benefit of the project’ [4]. Refs. and reduce energy consumption of the facility which can be quantified in dollar terms. Suttell [88] suggested intelligent building can improve the productivity of building operations. Wong et al.32. environmental controls) and reduce relocation cost of individuals and services. evaluation tool was not specified in the Report However.39.22. or large group revisions. internal rate of return (IRR) and payback period (PB) are often used to appraise capital investment in building projects [20. Our overview of empirical studies for the intelligent building investment evaluation revealed that the three most commonly mentioned approaches are the NPV method. power. a plethora of evaluation techniques have been developed to assist investors to examine and evaluate the economic desirability of projects. In the area of investment evaluation.. net present value (NPV).g. Net present value method One of the most commonly used investment evaluation techniques in the construction industry today is the NPV method.58. partial integration.47. Flax [39] pointed out intelligent building can minimize the cost on all ongoing expenses (i.67]. Approach/methodologies Net present value approach systematic assessment of financial viability of IB by comparing two alternatives: conventional and IB building Cost benefit analysis approach ‘‘BIDS’’. The findings suggested the total project costs of intelligent building were generically higher than that of conventional building by 8%.88]. The basic rule of net present value method is to accept the project with a positive net present value and reject if the value is negative. airconditioning. [54]) NPV method . and full integration) Evaluation tools NPV method 2001 (proceeding) ABSIC Group 2001 (proceeding) Yang and Peng Software-based evaluation model. These techniques are based on ‘time-cost-of-money’ principles and are used in slightly varied procedures to estimate the expected investment monetary returns [67].. 4.g.54.K.79] identified 25 different techniques for project investment evaluation. It examines cash flows of a project over a given time period and resolves them to one equivalent present date cash flow by using various economic evaluation factors [78].W.31. a multi-media decision support tool based on the CBA framework Life cycle costing approach accessing the design alternatives which considering all the significant costs of ownership Life cycle costing approach comparing the life cycle cost of intelligent buildings with different levels of integration approach (non-integrated building.e. according to Kingston [55]. NPV is also a basic tool of CBA approach NPV/discounting method 2003 Lohner (cited in Ref. / Automation in Construction 14 (2005) 143–159 project costs of both intelligent building and conventional building.. [8.1. programs.2. Second. while Gluch and Baumann [44] used the LCCA to determine the environmental decision-making in building investment.17.13. Life cycle costing analysis The LCCA is another approach employed for the evaluation of intelligent building investment. First. Yang and Peng [98] used the LCCA to assess various design alternatives.50]. optimization and quantification of the construction cost during disposal and design stages.30. regulations. Refs. Keel. respectively.77.11. LCCA approach is widely applied in various aspects of construction and building projects (e. " # " # T T X NCFi X Ii NPV ¼ À f f j¼1 ð1 þ kÞ f ¼1 ð1 þ kÞ Wong et al.3. attention should be paid to the following aspects. Many capital investment projects [69] such as budget planning. [95] applied the NPV technique to analyze the financial viability of two project alternatives: conventional or intelligent building. Wong et al. First. different operating and maintenance and repair costs. 4. some studies suggest that information such as development and operating costs. CBA has been traditionally applied to fields including policies. it can be used as an asset management system throughout product’s life cycle [36]. project costs and benefits at each stage of the life cycle are discounted into the present values. Cost benefit analysis The purpose of CBA is to give management ‘a reasonable picture of the costs. Generally. The optimal determination of building life cycles was integrated into the analysis in order to provide a comprehensive financial viability results for intelligent building. and possibly different lives [42].W.J. [95] noted that the reliability of the NPV technique can be affected by the unavailability of relevant cost and benefit data. and tangible benefits by time period must be obtained before performing the CBA [30]. The study concluded that the intelligent building was more favorable option which had a higher property value at the end of life cycle period. The solution which outperforms in functions and quality is then recommended.96.. The cash flow for each option is converted to a common time basis for rational comparison using the NPV technique.97]). The NPV method was used to calculate the life cycle cost of each model of integration. Similar to LCCA. Kingston [55] and Islas et al. projects.69]. demonstrations and other government interventions [16. Despite its simplicity.35. and safety and environmental programs planning [52] have adopted the CBA approach to compare the costs and benefits. the CBA technique relies on the NVP method as the basis for analysis [16. partial integration and full integration). In the use of the CBA technique.44. Aye et al. / Automation in Construction 14 (2005) 143–159 153 When two or more projects are evaluated. The NPV can be computed using the following formula [4]. Their approach starts with the selection of design alternatives. LCCA serves two major functions. Abraham and Dickinson [2] and Bogenstatter [17] ¨ applied the LCCA to the prediction. 4.K. [13] employed the LCCA to evaluate project investment options and make selection between competing alternatives. analysis results can be highly affected by the discount factors employed in the CBA. An unworthy project may be recommended if the chosen rate is . Wong et al. where NCFi represents the net cash flow from the project at period i. it applies in evaluation of alternatives in various aspects [34]. [52] suggested that wrong selection of discount rate would produce a great variation in benefit/cost ratio. the one with higher present value is generally selected. For example. Third. dams and airports construction. It is used to examine the building performance with different initial investment costs. [2.55.40. Second. as an investment evaluation technique of intelligent building. LCCA has been employed in a number of empirical studies. and it then determines the capital cost and costin-use for each alternative. In addition. 2003 [54] applied the LCCA to compare and evaluate the total investment life cycle costs of intelligent building at different levels of integration (non-integrated building. k represents the capital cost and T is the project life span. benefits and risks associated with a given project so that it can be compared to other investment opportunities’ [30]. Results suggested that the fully integrated intelligent building had the lowest life cycle cost compared with non-integrated and partially integrated intelligent buildings.g. For example. and scenarios. Akin to the NPV method. Akalu [4] also noted that the NPV method would lead to different decision results in mutually exclusive projects. Specifically. and n Errors in estimating relationship.66]. Al-Harbi [7]. ABSIC Group [14] employed CBA to evaluate the investment in advanced and innovative building system.69]. Analytical hierarchy process These identified limitations suggest the need to develop new methods to evaluate intelligent building investment projects.154 J. as uncertainty is revolved. First. The analytical approach was built on a three dimensional matrix: design options. CBA fails to include a method for coping with uncertainty during the evaluation of investment opportunities [69]. The AHP is a decision analyzing and structuring method developed by Saaty in 1970s [6. Second. In general.4.K. the LCCA fails to handle irreversible decisions and the results are biased towards the decision maker’s personal values [44].65. The CBA approach has also revealed several limitations in its capacity to evaluate building investment projects [30. named as the ‘Building Investment Decision Support (BIDS)’ system.49.99]. AHP comprises a comprehensive framework which is designed to ‘cope with the intuitive. One drawback is that the result is subject to the availability and reliability of input data due to the complexity of building process and numerous components in a building [12.7.W. the analytical hierarchy process (AHP). the standard CBA approach considers only tangible benefits and is unable to measure intangible benefits in financial terms. n Changes in operational assumptions arising from modifications in user activities. future events turn out differently from what management expected at the beginning’.45.44]. Ho and Liu [49] critiqued that the NPV method fails to ‘respond and capture management’s flexibility to adapt or revise later decision when. (1978) [102] summarized some major uncertainties of the LCCA: n Differences between actual and expected performances of a system could affect future operation and maintenance costs. cost benefit factors. Many of these criticisms indicated that traditional NPV based evaluation techniques are not capable of evaluating investment relating to advanced technologies or systems. Recently. multi-criterion and multi-actor decisions with and without certainty for any number of alternatives’ [65]. n Changes on the price level of a major resource such as energy or manpower.5. which assumes a uni-directional hierarchical relationship among decision levels. the rational and the irrational when the users make multi-objective. Limitations of existing techniques for evaluating investment projects on intelligent building have been recognized [4. The ‘equal class of risk’ assumption in the NPV calculation for both cash inflows and outflows of projects is not practical in the real world. / Automation in Construction 14 (2005) 143–159 too low as the distant benefits are underweighted relative to near-term costs. Moreover. Wong et al. Furthermore. it is difficult to interpret the nature of the methodologies based on the fact that it is a program-based analytical model. 4. an evaluation approach which combines the basics of qualitative and quantitative research.67. Al Khalil [6] and Nassar et al. based on the CBA framework was developed and incorporated within a multi-media decision support tool. is suggested to remedy the existing problems [25].46. [71] extended the AHP to evaluating and analyzing building and construction projects. Macedo et al. n Future technological advances that could provide lower cost alternatives. Many researchers pointed out that traditional evaluation methods are unable to accommodate the task of evaluating intelligent building projects. as there is always an element of uncertainty associated with the estimates and assumptions. there are drawbacks in the LCCA. AHP has been applied in investment evaluation. Al-Harbi [7] applied . Abdel-Kader and Dugdale [1] pointed out the use of ‘arbitrarily’ high hurdle discount rates in the NPV calculation for new technology investment would affect the accuracy of evaluation. A software program. although the ABSIC’s model was very practical and suggestive. AHP can be used to model a decision making framework. The accuracy of the result is highly dependent on the assumptions and estimates made whilst collecting data. There are only several applications of CBA in evaluating intelligent building investment. They argued that AHP is basically concerned with the analytical factors evaluation. / Automation in Construction 14 (2005) 143–159 155 AHP to the building contractor prequalification decision-making so that the client can determine the contractor’s competence or ability to participate in bidding. gross income. expenses. of all costs rather than n Provides more benefits. Nassar et al.e.J. quantitatively effectively evaluated tangible benefits measurable and qualitative factors n Hierarchical n Provide a reasonable n Consider the impact representation of a system picture of the costs. the measuring values must be exact and numerical) where exact assessment data such as investment cost. [71] applied AHP as a decision-making technique to select the appropriate building materials and components based on a set of user-specified criteria and their relative importance weights. the usefulness of AHP in investment evaluation has also been questioned by Chan et al. [25]. Al Khalil [6] employed AHP in the evaluation and selection of an appropriate project delivery method. Abdel- Table 4 Comparison of investment evaluation approaches Investment evaluation approaches Current approaches Life cycle costing (LCC) CBA AHP Recommended approach Fuzzy multi-criteria decision-making method (combining AHP and fuzzy set theory) An integration of risks financial and non-financial factors in investment evaluation. and risks only initial capital costs information on the structure associated with a given n Facilitate choice and function of a system in system development between competing the lower level alternatives project so that can n Provides an overview of compare it to other the actors and their purposes investment opportunities in the upper levels n Not consider any n Considers only Disadvantages/ n Fails to handle tangible benefits assessment regarding limitations uncertainty and ‘linguistic terms’ irreversible decisions n Does not reflect the n No consideration of n Poor availability and uncertainty qualitative and subjective reliability of data nature of many factors n Relies on estimated n Exact assessment data is variables difficult to obtain in real world n Biased results n Conceptual confusion Purpose/reasons Select the best design alternatives based on the life cycle costs Select the best design alternatives based on comparison of cost. Wong et al.. multi-criterion and multi-actor decisions with and without certainty for any number of alternatives Basic tool NPV NPV Comparison matrices Authors [93]. depreciation.K. Furthermore. Lohner. Based on AHP with fuzzy set theory Comprehensive framework designed to cope with the intuitive. 2003 [14] Not applied in IB yet Advantages n Enable investment n Able to consider life n Considers tangible and options to be more cycle cost and intangible. are difficult to obtain in real world.W. tangible benefit and associated risk of design alternatives AHP and fuzzy set theory Not applied in IB yet n Able to deal quantitatively with imprecision or uncertainty n To tackle the ambiguities involved in the process and to assure a more convincing and effective decision-making n Lacks empirical evidence for their applicability and wide acceptance in construction industries . salvage value. However. AHP (as well as the traditional evaluation methods) is based on the concept of accurate measurement and crisp evaluation (i. the rational and the irrational when we make multi-objective. R.91.87] Security system [48.90] Communication system [38. A summary of methods/techniques used for investment evaluation is presented in Table 4 below. it is expected that ambiguities involved in the evaluation process can be minimized.19. British Accounting Review 33 (2001) 455 – 489. Akalu. Katipamula. S. Arkin.I. Kreider (Ed.47.89.156 Table 5 Literature review summary Research area Definition J.S. Re-examining project appraisal and control: developing a focus on wealth creation.80.R.). Dugdale. indexes for IB 75. performance evaluation methodologies.64. Lohner evaluation techniques (2003.28. McGreal.98].74. By using the FMCDCM. 5. [5] M.95.M. Berry.72. Automation in Construction 6 (1997) 471 – 479. Akalu. D.59. a systematic approach by combing fuzzy set theory with AHP.93] Advanced and System integration.90. in: J. International Journal of Project Management 19 (2001) 19 – 27. Curtiss. International Journal of Project Management 20 (2002) 469 – 474. M. cited in and methodologies for IB Ref. Paciuk. The process of investment appraisal: the experience of 10 large British and Dutch companies.77.87. Al-Harbi.18.G. [8] M.N. The paper also revealed that relatively less attention has been paid to addressing investment evaluation of intelligent building. Abraham. W.J. innovative building automation technologies system and communication network HVAC system Performance evaluation Investment evaluation [15.33. Intelligent building system for airport. FMCDCM has been applied in problems related to technology selection and advanced manufacturing investment evaluation.87] Evaluation and Intelligent Buildings construction of Europe Work (cited performance models and in Refs.98]). In view of the inadequacies of the traditional evaluation techniques and AHP. 82. investment evaluation analysis (Table 5 listed main credible publications in these research aspects). (1997 (November)) 31 – 35.S. [2] D. P.41.85. Simultaneously.89. Dickinson. The paper further proposes a ‘fuzzy multi-criteria decision-making method’ (FMCDCM). [7] K.32.51.92. for the purpose of technology selection. This method overcomes deficiencies of traditional evaluation models. ASHRAE Journal. Selecting the appropriate project delivery method using AHP.27. International Journal of Project Management 19 (2001) 375 – 383. Adair. Armstrong. Controls. to overcome the inefficiencies of traditional evaluation techniques.87.87. J.W. Application of AHP in project management. Abdel-Kader and Dugdale [1] suggested the same methodology to model and evaluate investment in advanced manufacturing technology.94] Lighting system [48. Investment decision making: a behavioural perspective. pp. References [1] M.47. 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