Durability and the factor method of ISO 15686-1

Interest in the service life of buildings and components and the future need for maintenance is growing, and the methodology for service life planning is starting to appear in standards. The standard ISO 15686 prescribes a factor methodology for deciding about the expected service life of a component with a prescribed probability of earlier failure. The methodology is based on extensive knowledge about materials and building technology, and examples of the use of this methodology on building components are of value for the discussion on service life planning. Results from a condition survey of timber windows are used to define the service life and effect of the factor method in the Standard. Wood is a very variable material, and for wooden windows maintenance plays a key role in the durability of the component. In this instance, condition assessment is, therefore, not sufficient to estimate the service life. Information about former maintenance and refurbishment is also needed. The results from a condition assessment and the house owner's answers to a questionnaire are combined to evaluate the estimated service life of the windows. The factors for the standardized method for estimating service life with a given confidence limit are shown to have a wide range in values that give considerable uncertainty to the practical use of the standardized methodology. For example, it is shown that the estimated service life with an 80% confidence limit is much lower than the average service life. Thus, the question is posed whether there is any meaning in estimating the lower limit of service life.     

Service life planning and performance requirements

Service life planning comprises a model for the determination of a reasonable expected service life for buildings and components, and it establishes a routine for the assessment of design alternatives. A design option is considered reasonable when it meets or exceeds performance requirements over time that have been drawn up specifically for the specific project. Due to this assessment reference, there is a very evident link to the concept of performance-based building. Any stakeholder involved in the value chain or in the design process of the building, as well as regulators and building users, can express performance requirements. Identified requirements, both in relevance and in quality, will vary with the stakeholder and his/her perspective of interest. As building sector manufacturers develop most products with reference to standards rather than with reference to specific requirements, there is no direct link from user requirements to the product design. Instead, the building designer has the responsibility to ensure performance requirements are met by the performance of products integrated into the design. As these design decisions also have to be made at the material and component level, a performance-based building would benefit from an established rationale that enables the communication of performance requirements across the relevant system levels in the relevant design processes. A path for the connection of the established concepts of service life planning and performance-based building is presented. The aim is to identify key elements that need to be developed for the successful linkage of performance-based building with service life planning.     

Flat roofing systems: towards integrated techno-economic analysis

A methodology presented for an integrated analysis of roofing systems is used to assess different flat roofing systems in Israel. This approach can help designers with integrating technology issues, performance management and life cycle costs for component systems. The performance and durability survey observed an overall premature failure rate of 30%. The principal cause of failure was poor maintenance and inappropriate use. Life cycle costing analysis indicated that polyvinyl chloride membranes offered the highest life cycle costing effectiveness within Israel, primarily because of low maintenance expenditures. Despite its low initial capital investment, the single-layered modified bitumen roofing system exhibited high life cycle costs due to its short service life and consequent replacements costs.     

Performance-based building and innovation: balancing client and industry needs

One reason for the interest in performance-based building is that it is commonly advocated as a powerful way of enhancing innovation performance by articulating building performance outcomes, and by offering relevant procurement actors the discretion to innovate to meet these performance requirements more effectively and/or efficiently. The paper argues that the current approach to performance-based building assumes that relevant actors have the capacity, ability and motivation to innovate from a business perspective. It is proposed that the prevailing conceptualization of PBB is too restrictive and should be broadened explicitly to accommodate the required business logic that must be in place before actors will innovate. The relevant performance-based building and innovation literature is synthesized to support the assertion. The paper concludes with an innovation-focused definition of performance-based building.     

Cardboard as a construction material: a case study

A small cardboard building with a 25-year intended lifetime was developed as a live innovation project to explore and resolve the practical problems surrounding the design, fabrication and construction, costs, and use of an alternative building material. The primary aim to reduce environmental impacts was based on developing the potential of a recycled material as the main structural and cladding component that could be further recycled at the end of its working life. This case study of a small school building presents both the research and development undertaken by the project team and the practical implications of realizing this as a building for a client.     

High-performance weather-protective flashings

Typical problem areas associated with weather-protective flashing are identified, based on a comprehensive investigation of building damage cases in Norway. A total of 175 assignment reports associated with damaged flashing for the period between 1963 and 2001 are analysed. The investigation clearly shows that certain faults and deficiencies are recurring items. Windowsill/weatherboard flashings comprise as much as 41% of the building damage cases associated with weather-protective flashing. Damage in connection with parapet flashing comprises 27% of all cases included in this investigation. With few exceptions, instances of damage are located in Norway's coastal areas. Existing flashing solutions in the Norwegian Building Research Institute's Building Research Design Sheets have been further developed, based on the results from the analysis. Improved high-performance flashing solutions are presented for a number of typical problem areas. An illustrated summary of problems frequently encountered with different flashing variants is also presented. Finally, recommended best-practice flashing solutions for a number of typical problem areas are provided. The results will be implemented in the Building Research Design Sheets, and will also be used as a basis for the carrying out of new field studies and laboratory investigations.     

Concise exterior lighting simulation methodology

A methodology is proposed which integrates advanced photogrammetric and computer-aided design (CAD) software with lighting simulation tools. The methodology consists of preparing a CAD model from digital photographs and then using lighting simulation packages to carry out the lighting analysis and produce a photo-realistic image. The latter can serve as a decision tool to the lighting designer. The methodology was specifically adapted for illumination studies of buildings of historical and/or architectural importance. The methodology was validated quantitatively by comparing simulation results with on-site field luminance measurements. The rendered photo-realistic images produced also compared favourably with photographs indicating the reliability and effectiveness of the overall simulation procedure.     

Service life prediction of exterior cladding components under standard conditions

An empirical method was developed for the prediction of the service life of building components, based on an evaluation of their actual performance and on the identification of failure mechanisms affecting their durability. The service life of exterior components subjected to normal service conditions is predicted. Four types of exterior claddings are exemplified: cementitious mortar, synthetic rendering, ceramic mosaic, and wet‐fixing stone cladding. The proposed prediction models yield high degrees of fit to the data (R ² in the range of 0.86 to 0.93 at a 0.0001 level of significance). Life cycle costs (LCC) analysis – following service‐life prediction results – leads to the conclusion that maintenance and replacements costs account for 10–80% of initial capital costs. Synthetic rendering exhibited the highest LCC effectiveness, reflecting durability and low capital costs. The method can be used for planning preventive maintenance, evaluating economic implications of failures, and planning service life.     

Deterioration patterns of building cladding components for maintenance management

Increasing demands are made on maintenance programmes to provide tools that will support maintenance planning. Among of the most important parameters affecting the efficiency of maintenance management are the precision and the reliability of the predicted service life (PSL) of building components. The main objective of this study was to develop a methodology for the establishment of databases listing deterioration patterns of building components based upon their actual condition. The methodology consists of four steps: (1) identification of failure patterns, (2) determination of the component performance (CP), (3) determination of the life expectancy of deterioration path (LEDP) and (4) evaluation of the predicted service life (PSL). The proposed methodology can be used for planning of maintenance activities, for evaluation of economic implications caused by intensive decay and for maintenance management.     

Quantification methods of technical building performance

A building performance assessment toolkit was developed for use by large corporate owners and building portfolio managers in the US. A variety of technical performance aspects are addressed such as energy, lighting, thermal comfort, maintenance and indoor air quality. Every assessment is based on a normative and objective Performance Indicator (PI). For easy data capture and calculation of PIs, the toolkit was implemented in a web hosted form, enabling facility managers and staff to collect the data during a walk-through enabled by PDA-based data entry. The current set of performance indicators is discussed and the results of the first benchmarks, most notably the energy benchmarks, are reported.     

Multiobjective optimisation algorithm for sewer network rehabilitation

Understanding of deterioration mechanisms in sewers helps asset managers in developing prediction models for estimating whether or not sewer collapse is likely. Effective utilisation of deterioration prediction models along with the development and use of life cycle maintenance cost analysis contribute to reducing operation and maintenance costs in sewer systems. This article presents a model for life-cycle maintenance planning of deteriorating sewer network as a multi-objective optimisation problem that treats the sewer network condition and service life as well as life-cycle maintenance cost (LCMC) as separate objective functions. The developed model utilises Markov chain model for the prediction of the deterioration of the network. A multi-objective genetic algorithm is used to automatically locate an appropriate maintenance scenario that exhibits an optimised tradeoff among conflicting objectives. Monte Carlo simulation is used to account for LCMC uncertainties. The optimisation algorithm provides an improved opportunity for asset managers to actively select near-optimum maintenance scenario that balances life-cycle maintenance cost, condition and service life of deteriorating sewer network. A case study is used to demonstrate the practical features of developed methodology.     

Environmental impact of dwellings in use: Maintenance of façade components

The use of dwellings contributes significantly to human-induced environmental burden in a number of ways, including energy consumption and the maintenance and replacement of building components. The present study deals with the maintenance and replacement of external doors and windows in a Dutch reference dwelling and describes how life cycle assessment (LCA) methodology can be applied to quantitatively assess the environmental impact of various maintenance scenarios for the façade components. First, the most effective way to reduce the negative environmental impact in this context is to replace existing single and double glazing with high efficiency double glazing, thereby reducing energy consumption for space heating. Second, the use of timber frames causes less environmental impact than PVC frames with a steel core. Third, extending the service life of building components decreases the input of material resources, production processes and the waste processing of building components during the service life of a dwelling, which is beneficial to the environment. Maintenance activities should only be performed when needed, keeping the building components in good condition while minimising the transportation movements of maintenance workers. Finally, protecting timber components with an alternative paint that contains less solvent does not lower the assessed environmental impact, but low-solvent paint may be preferred because of health aspects both for maintenance workers and occupants of the dwelling.     

Maintenance strategies optimisation of metro tunnels in soft soil

This paper proposes a quantitative approach for selecting effective maintenance strategies for metro tunnels in order to reduce maintenance cost and ensure tunnel safety in the presence of structural degradation during the service life. A non-stationary gamma process is used to simulate the tunnel gradual degradation and to investigate the effects of different maintenance measures on the life cycle maintenance cost of metro tunnels in soft soil. Two commonly applied reinforcement methods, Aramid Fibre Reinforced Polymer and bonded steel plate reinforcement, are investigated in this study. The feasibility of the proposed methodology is demonstrated with maintenance strategies based on periodic and aperiodic inspection policies. Numerical results show that the optimisation of maintenance strategy can reduce the life cycle maintenance cost of metro tunnels in soft soil while ensuring sufficient level of structural safety, and the maintenance strategy with aperiodic inspection policy produces lower maintenance cost.     

基于BIM的可视化建筑运维系统构建研究

随着BIM技术的推广普及,三维信息模型在建筑全生命周期中的应用渐成关注的热点。深入剖析BIM可视化建筑运维系统的应用前景,并系统地探讨其运行模式基本架构与主要功能。借助项目案例,以实现构件体块与参数信息之间的"剥离"和"链合"为核心技术,完整地展现从BIM竣工模型到可视化运维系统的实现技术路线,为智能化建筑运维管理系统的构建与应用提供可靠的依据。     

Performance-based building regulation: current situation and future needs

Although performance-based building regulations are in use or under development in numerous countries worldwide, there remain significant challenges in adequately identifying and defining performance, in understanding and addressing diverse societal expectations, and in establishing robust performance-based regulatory systems. These challenges become intensified as the building construction market becomes increasingly global, with the resulting expectation that building regulatory instruments remain valid across borders and do not create barriers to trade, while at the same time address local and national needs without compromising local cultural and societal norms. Many of these issues are just now beginning to be explored, and there is significant opportunity and need for future research and development in these areas.     

Optimized maintenance and renovation scheduling in multifamily buildings – a systematic approach based on condition state and life cycle cost of building components

Proactive maintenance strategies in principle are devised to control degradation and sustain optimal performance of building components. While realizing the technical necessities, they also serve as an instrument towards multiple and often conflicting objectives during financial constraints. An optimal proactive maintenance strategy therefore should comprise a multiannual maintenance action plan optimized on different criteria corresponding to owners’ objectives under existing constraints. This study offers a systematic approach based on a condition-deterioration model to address the complexity involved in decision making regarding optimized maintenance and renovation planning. Life-cycle cost analysis in form of Equivalent Annual Cost (EAC) is used for the economic assessment of maintenance/renovation scenarios. In this paper, the model is used to compare the economy of different maintenance/renovation plans in a chosen scenario in order to determine the optimal maintenance interval for a single and a combination of building components. Two façade elements, windows and façade rendering, are used to illustrate the application of the proposed method. This method is intended to help decision makers at both design and post-construction phases in the choice of both building components and maintenance/renovation strategies.     

Flat roofing systems: towards integrated techno-economic analysis

A methodology presented for an integrated analysis of roofing systems is used to assess different flat roofing systems in Israel. This approach can help designers with integrating technology issues, performance management and life cycle costs for component systems. The performance and durability survey observed an overall premature failure rate of 30%. The principal cause of failure was poor maintenance and inappropriate use. Life cycle costing analysis indicated that polyvinyl chloride membranes offered the highest life cycle costing effectiveness within Israel, primarily because of low maintenance expenditures. Despite its low initial capital investment, the single-layered modified bitumen roofing system exhibited high life cycle costs due to its short service life and consequent replacements costs.     

BuildingsLife: a building management system

The financial resources available for infrastructure maintenance and rehabilitation are always limited, which creates a need for efficient resources' management and for the ability to predict maintenance actions throughout the infrastructure's service life. In the context of bridges, management systems have been developed and are already implemented around the world. A much larger variety of maintenance problems and a reduced number of buildings per owner mean that building management systems (BdMSs) are still quite rare. Actually, efficient methods for the service life prediction of building materials still need to be developed. This paper discusses the service life prediction methods used in building components based on deterministic, stochastic or engineering methods. The architecture of a recently developed BdMS – BuildingsLife – is presented, where the service life analysis of components is based on an initial statistical analysis of anomalies obtained from the inspection of in-use buildings. This method analyses the corresponding degradation through the use of deterministic and stochastic models.     

The use of nested sampling for prediction of infrastructure degradation under uncertainty

Because of the competing demands for scarce resources (funds, manpower, etc) national road owners are required to monitor the condition and performance of infrastructure elements through an effective inspection and assessment regime as part of an overall asset management strategy, the primary aim being to keep the asset in service at minimum cost. A considerable amount of information is then already available through existing databases and other information sources. Various analyses have been carried out to identify the different forms of deterioration affecting infrastructures, to investigate the parameters controlling their susceptibility to, and rate of, deterioration. This paper proposes such an approach by building a transition matrix directly from the condition scores. The Markov assumption is used stating that the condition of a facility at one inspection only depends on the condition at the previous inspection. With this assumption, the present score is the only one which is taken into account to determine the future of the facility. The objective is then to combine nested sampling with a Markov-based estimation of the condition rating of infrastructure elements to put some confidence bounds on Markov transition matrices, and ultimately on corresponding maintenance costs.     

浅析建筑物的交付使用与维护管理

对影响建筑物寿命的主要原因作了分析，结合多年的观察、考证，阐述了在使用、维护管理建筑物的过程中，存在的一些应注意和需要改进的问题，提出了搞好建筑物维护管理的具体措施。