Selecting Key Performance Indicators for Sustainable Intelligent buildings H. H. Shah
Y. Ma
S. R. Gulliver
Technologies for Sustainable Built Environments (TSBE) Centre University of Reading, UK
Informatics Research Centre (IRC) University of Reading Reading, UK
Informatics Research Centre (IRC) University of Reading Reading, UK
[email protected]
[email protected]
[email protected]
ABSTRACT Environmental concerns and the continual drive for energy efficiency in buildings, has led industry to look more closely at sustainable development and the sustainability of existing buildings. The majority of building environmental performance assessment methods developed today, involve a building meeting, or satisfying, pre-defined standards and requirements. Improvements to a building’s environmental performance are usually ascertained by first benchmarking the current set up. In order to do this it is necessary to identify and understand specific building key performance indicators (KPIs). Selecting the most suitable KPIs, particularly when building systems are intelligently managed, can be both challenging and critical to the assessment of a building’s environmental performance.
design, and functional use. Considerations concerning the design of a building usually only apply to new builds. As a result the UK government has set targets of zero carbon for all new residential and commercial buildings by, 2016 and 2019, respectively. However, 70% of the buildings that will be around in the year 2050 have already been built [5]. Accordingly focusing simply on improving the performance of new builds will, on its own, have limited impact. Assessment of existing buildings, which often contain wasteful technologies, and the effective improvement of energy performance in these buildings, is critical to achieving sustainability. Figure 1 identifies the general paradox that implementing sustainable new buildings are easier for developers, however more costly and more disruptive to organisations.
This paper assesses some of the current practices and advances in building environmental performance assessment. It also considers how benchmarking and semiotics approaches may be integrated with current environmental assessment methods to more accurately measure the impact of users and building use.
Keywords Key Performance Indicators, Sustainability, assessment, Building, Semiotics
Environmental
Figure 1: Considerations to building energy performance
1. INTRODUCTION Nearly half of the energy currently consumed in the UK, is used in buildings [5]. Therefore, improvements in a building’s energy performance can significantly reduce energy consumption and hence contribute to a more sustainable energy economy. Sustainable development is most commonly applied to new buildings, and attempts to introduce more effective, materials, technologies and practices. Sustainability of existing buildings, however, is more difficult since it is necessary to live with known building deficiencies and accept the fact that not everything can be economically modernised.
Research conducted by Foresight (2009) shows that building usage has a considerable impact on the overall energy usage. Mackay (2008) argues that minor changes in the way we live and work, such as simply switching off something that does not need to be on or replacing high energy equipment with more efficient alternatives, can bring about significant energy savings. The impact of minor changes in large building systems usually means that considerable energy performance improvements can be gained. A building system usually consists of sensors, actuators, communication networks and a central server. Common building systems in ‘intelligent buildings’, along with their function, is shown in Table 1.
The energy performance of a building depends on its architectural Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Conference’10, Month 1–2, 2010, City, State, Country. Copyright 2010 ACM 1-58113-000-0/00/0010…$10.00.
Due to the often high level of complexity in intelligent buildings, and the large potential number of measurable factors, appropriate changes to building energy use can only be realised if the critical factors in building systems are first identified. In the following section we introduce the area of Key Performance Indicators (KPIs), which aims to highlight critical factors impacting specific building performance.
Table 1: Common building systems in ‘intelligent buildings’ and the role they play. BUILDING SYSTEM
FUNCTION
Building Management Systems (BMS)
-Overall building management
Heating, Ventilation and air conditioning (HVAC)
-Controls indoor air quality and comfort
Addressable Fire Detection and alarm (AFA)
-Fire prevention and incident handling
Telecommunications and Data systems (ITS)
-Handle all digital communications
Security Monitoring and Access (SEC)
-CCTV surveillance and access control
Digital Addressable Lighting Control (DALI)
-Efficient Control of lighting
Smart Lift Systems (LS)
-Efficient management of lifts
Comp. Maintenance Management System (CMMS)
-Managing inventory and service works
2. KEY PERFORMANCE INDICATORS Key Performance Indicators (KPIs) are quantifiable measurements, selected beforehand, that are defined as key to benchmarking success. It is critical to limit the number of KPIs to include only factors that are essential to the building’s goals. Continuous monitoring of the KPIs can help identify the progress being made towards a predefined goal set. Various building performance assessment methods have been developed to assess building environmental performance. These methods usually provide a framework or a set of good practices that should then be followed within the operation of the building. Building performances are then measured and compared against the defined best practices, with distinction being made for new and existing builds. As it is too time consuming to assess everything that is measureable within a building, building performance assessment methods need to first identify the KPIs that are specific to the specific building. These are the variables that have the most significant impact on the performance of that particular building, since KPIs can vary significantly depending on a building’s location, climate, legislation, usage, etc. As the choice of KPIs impacts assessment results, selecting the most appropriate KPIs is a big challenge. The following section expands upon current methods used for assessing building KPIs.
3. BUILDING PERFORMANCE ASSESSMENT METHODS Building performance assessment methods and tools have been developed worldwide (see table 2). These methods assess how well a building is performing, or is likely to perform. If properly applied, it can provide a useful set of tools to identify KPI and monitor improvements in the building’s environmental
performance [2]. Building performance assessment methods have helped define many emerging sustainability concerns and have provided a way of communicating this with the building stakeholders. Table 2: Environmental Performance Assessment Methods METHOD
DETAILS
BREEAM (Building Research Establishing Environmental Assessment Method), Building Research Establishment Ltd., UK.
Assesses the environmental performance of both new and existing buildings.
HK-BEAM (Hong Kong Building Environmental Assessment Method), by Hong Kong Environment Building Association, Hong Kong, China.
Based on BREEAM, considered the local situation and government policies to give the guidelines and certifications on building environmental performance.
LEED (Leadership in Energy and Environmental Design), by Green Building Council, U.S.
Voluntary, updated every 5 years. US National standard for developing sustainable high-performance buildings.
CASBEE (Comprehensive Assessment System for Building Environmental Efficiency) by Sustainable Building Consortium, Japan.
Introduced to meet both the political requirements and market demands for achieving a sustainable society through building life span.
IBI 3.0 (Intelligent Building Index: Manual Version 3.0), by The Asian Institute of Intelligent Buildings, Hong Kong, China,
Based on political requirements, construction industry needs and building users’ demands of buildings
GB Tool (Green Building Tool) by International Team (Canada, USA, etc.)
Software developed as part of the international green building challenge process, updated accordingly, and still under development
BREEAM (Building Research Establishing Environmental Assessment Method) is currently the most widely used environmental assessment method for buildings within the UK [1]. BREEAM sets a weighting for each criterion to reflect its importance and significance (see figure 2). Sometimes, buildings can achieve unusually high scores, despite scoring poorly in a few key areas. In this case sustainability can be viewed as an average performance rather than a series of satisfied criteria, which risks ignoring the impact of specific factors. BREEAM, along with all other assessment tools, have the weakness that they are only applied on a voluntary basis. Despite common acceptance, BREEAM also fails to support full life-cycle analysis for buildings.
performance, and, in the construction industry, is a systematic way of evaluating the inputs and outputs in manufacturing operations or construction activity, and therefore acts as a tool for continuous improvements. Benchmarking also supplies tools for assessing the impact of change within existing building by means of performance indicators, however this benchmarking demands a clear set of building requirements; which is perceived as being hard to achieve when considering social, cultural and organisational aspects of use.
Figure 2: Process of BREEAM [1] Current building performance assessment methods can be generally split into two categories: 1. 2.
Based on criteria and weighting system – e.g. BREEAM (UK). Use a checklist of each building performance aspect e.g. LEED (US).
Many of the current building performance assessment methods make use of multiple steps to build a benchmarking framework (see figure 2). Initially performance indicators are discovered using surveys, questionnaires, interviews etc. Then KPIs are selected by senior managers and/or a panel of experts, thus compiling a list of KPIs according to their knowledge and experiences. Finally, the relative importance of each KPI is defined by making use of an Analytic Hierarchy Process (AHP) or Analytic Network Process (ANP). One problem with this process is that even though the decision-makers are all experts, the results can sometimes be very subjective [13]. To avoid this, a concerted effort must be made during the process of selecting KPIs to be objective and clear, whilst also including all building stakeholders. The specification and validation of key performance indicators is essential to the fair assessment of how a building impacts its environment. Current subjective judgement makes it hard to understand the impact of qualitative factors, such as social, cultural and organisational aspects of building use, which, although having a decisive role in the ultimate sustainability of the building, can be hard to quantify or formalise. In sections 4 and 5 we introduce discussion concerning benchmarking and semiotics, which we propose should be integrated in support of current assessment methods to facilitate a more accurate assessment of KPIs relating to building users and building use.
4. BENCHMARKING IN BUILDINGS Benchmarking enables building managers and stakeholders to quantify and compare building environmental performance. Benchmarking has been identified as an important measurement tool for identifying improvements [4]. Eaton (2002), using such phrases as ‘fulfilling needs’, ‘suitable for use’ and ‘fitness for purpose’, states that: in construction, it is a common practice to define quality in relation to performance as ‘the degree to which performance matches requirements’. Fisher (1996) stated that benchmarking therefore plays a key role in underpinning
Cordero (1990) proposed a model of performance measurements in terms of outputs and resources to be measured at different organisational levels, but it failed to reflect the interests of stakeholders, their needs and expectations. The occupants of the building are the people that best understand most aspects of the building use and performance, however very few organisations ask their staff whether the building meets their requirements. Environmental assessment, instead of relying on management and ‘expert’ feedback concerning intended building use, should consider the real-world relationship between the building and its occupants. Sadly, however, analysis of social, cultural and organisational dimensions are often ignored as semantic, pragmatic and social analysis is perceived as being both complex and unable of delivering a formalised set of requirements for use with benchmarking. In section 5 we introduce organisational semiotics, which offers potential methods for problem articulation, and semantic and norm analysis of building KPIs.
5. ORGANISATIONAL SEMIOTICS Organisational Semiotics (OS) is the study of organisations using the concepts and methods taken from semiotics [10]. Using OS, environmental assessment should be able to consider the relationship between the building occupants, the building processes (i.e. use), and the building technology (i.e. both the physical building structure and use of material, but also the legacy integrated technologies). It can be argued that OS can: facilitate clarity when identifying user building requirements; allow environmental consideration of user pragmatic intention within the building; and identify limitations or omissions of current KPI or information capture. In this work, we suggest the application of the Problem Articulation Method (PAM), the Semantic Analysis Method (SAM) and the Norm Analysis Method (NAM), to the problem of building KPIs. PAM, SAM and NAM are methods, defined by Stamper et al (2000) as part of MEASUR (Methods for Eliciting, Analysing and Specifying User’s Requirement), which would support the capture of social, cultural and organisational KPIs relating to building use. In the following sections we will introduce each of these methods in turn, and conclude by asking whether the MEASUR methodologies could be integrated with current environment assessment methods to consider requirements of building users, building intention and use, as well as the KPIs of emerging building intelligence systems.
5.1 Problem Articulation Method (PAM) PAM consists of methods that are normally applied when the problem definition is still unclear. PAM is composed of: Stakeholder Analysis, Valuation Framing and Collateral Analysis (see figure 3); and in essence gets key stakeholders to define issues using Stamper’s Semiotics ladder [8] - see figure 4.
Stakeholder analysis allows definition of those with direct or indirect influence over the building energy use. The clarification of stakeholders in context of building operation, contribution, source, market and community, allows the systematic checking of building use and user identification of stakeholder interests in valuation framing. Valuation framing allows interaction of stakeholder interests to be identified, and for risk areas to be defined where no stakeholder currently claims ownership. The semiotic framework places energy use in context of the semiotic ladder (see figure 4), which shows the stakeholder that energy use is significantly impacted by both structural and human indicators. Collateral analysis allows analysis of the interaction between factors that impact building energy use. This supports clarity concerning the interaction of building use, as well as its impact on environmental factors, which is commonly ignored in other assessment methods.
5.2 Semantic Analysis Method (SAM) SAM takes the defined problem, possibly defined as an output of PAM, and formalises the requirements. With the help of a facilitator, building environment requirements can be defined within a related ontology model, to describe energy use from specific dimensions. This formalised set of requirements can act as the basis for semantic KPI benchmarking.
5.3 Norm Analysis Method (NAM) A norm is the modelling of a behaviour pattern that is regarded as typical. NAM allows the capture of general behaviour patterns, by analysing behaviour regularities. Creation of norms allows us to assess the impact on energy use of social, cultural and organisational factors; factors that are often unrelated to the physical building structure. The other main advantage of using norms is it supports the allocation of responsibilities; an essential step in ensuring long term sustainability.
6. CONCLUSIONS
Figure 3. Adaption of the PAM methodology to support determination of building KPI.
Human Information
SOCIAL WORLD beliefs, expectations, functions, commitments, contracts, law, culture, … PRAGMATICS intentions, communications, conversations, negotiations, ...
SEMANTICS meanings, propositions, validity, truth, signification, denotation, ... IT
SYNTACTICS formal structure, language, logic, data, records, deduction, software, files, … EMPIRICS patterns, variety, noise, entropy, channel capacity, redundancy, efficiency, codes, …
PHYSICAL WORLD signals, traces, physical distinctions, hardware, component density, speed, economics, … Figure 4. The semiotic framework [11].
New and existing buildings are increasingly faced with the challenge of being as sustainable as possible. The process for selecting the Key Performance Indicators (KPIs), for use with performance assessment in buildings, is both technical and complex. The building environmental performance assessment method is used to quantify how ‘environmentally friendly’ or ‘sustainable’ a building is determined as being. The identification of KPIs supports the use of benchmarking and adapts it to the sustainability challenges of the construction industry. Building stakeholders have to be actively involved to assess their own performance, productivity rates, cost estimations, etc. Moreover, building users have to also be more open to benchmarking practices that have been successful in other industries, and adapt them to the construction industry. Benchmarking should be considered as a part of an ongoing process aiming at continually improving building environmental performance. The semiotics approach for modelling semantics in building environmental performance assessment would certainly help in the selection of more user-centric KPIs. This approach can help to form the framework of an improved methodology for assessing the sustainability of a building. The outcomes of a semiotics approach should be of importance to all the building stakeholders. This semiotics approach can also be used as a tool by architects to communicate sustainability issues during the early stages of design. Building users can have access to reliable information about the sustainability performance of a building before purchase, or even before construction. The semiotics methodology has the potential to be used for sustainability certification for buildings. Building environmental performance assessment methods should be designed for easy implementation and therefore not necessitate a great deal of technical expertise from the building users. The selection of KPIs still remains the most challenging aspect of environmental performance assessment and inevitably affects the integrity of the end results. A semiotics approach, although needing further research, in practice forms a basic framework upon which other standards can be built. A worldwide accepted assessment methodology is still a long way off, however convergence of established methods provides the greatest chance of wide spread acceptance.
As building systems become more integrated and building management systems become more intelligent, appropriate capture of building KPIs is essential to ensure sustainability, via effective building assessment and profiling, user feedback. Although additional research and validation is required, we believe the consideration of social, cultural and organisational KPIs are critical to achieving sustainability in both new builds and existing modifications.
7. ACKNOWLEDGEMENTS The authors wish to thank fellow researchers at the IRC and John Sharvell of CDC (UK) for their clarification on the subject of Semiotics and building systems, respectively.
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[5] Energy Policy (2010), Published by Elsevier Ltd. www.elsevier.com/locate/enpol accessed on 20th June 2010. [6] Fisher, J. G. (1996), How to Improve Performance through Benchmarking? London: Kogan Page Limited. [7] Foresight’s Sustainable Energy Management and the Built Environment (SEMBE) Project. Presentation 24th April 2009. www.foresight.gov.uk accessed 5th June 2010 [8] Liu, K. (2000), Semiotics in Information Systems Engineering. Cambridge: Cambridge University Press. [9] MacKay D. J. C. (2008), Sustainable Energy - Without the Hot Air. Chapter 22: Efficient electricity use. UIT Ltd. [10] OSW: The circulation document. Organisational Semiotic Workshop. Enschede (1995), apud Liu, K.: Semiotics in Information Systems Engineering. Cambridge University Press. [11] Stamper, R.K. (1996), Signs, Information, Norms and Systems, in Holmqvist, P., Andersen, [12] Stamper, R., Liu, K., Hafkamp, M. and Ades, Y. (2000), Understanding the roles of signs and norms in organizations – a semiotic approach to information systems design. Behaviour & Information Technology, 19(1), pp. 15-27. [13] Wong J., Li, H and Lai, J. (2008), Evaluating the system intelligence of the intelligent building systems: Part 1: Development of key intelligent indicators and conceptual analytical framework. Automation in Construction, Vol. 17, Issue 3, March 2008, Pages 284-302
