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

Reliability analysis of a timber truss system subjected to decay

Assessing the safety of existing timber structures is of paramount importance for taking reliable decisions on repair actions and their extent. The results obtained through semi-probabilistic methods are unrealistic, as the partial safety factors present in codes are calibrated considering the uncertainty exhibited by new structures. In order to overcome these limitations, and also to include the e ects of decay in the safety analysis, probabilistic methods, based on Monte-Carlo simulation are applied here to assess the safety of existing timber structures. In particular, the impact of decay on structural safety is analyzed and discussed using a simple structural model, similar to that used for current semi-probabilistic analysis.Fundação para a Ciência e a Tecnologia (FCT

Strength of End-Notched Wood Beams: A Critical Fillet Hoop Stress Approach

An equation for predicting the strength of wood beams with end notches on the tension side (Tension-side End Notches or TEN) was derived using a critical fillet hoop stress (CFHS) theory. The equation combines the results of finite element and statistical analyses of 690 different TEN beam configurations and experimental tests of 362 full-size beams. It accounts for the effects of loading type, end support and beam and notch geometry variables such as beam height, fractional notch depth, radius, and notch location. The effect of span-to-depth ratio is implicit to the model. Notched beam strength is represented by a material parameter, k, which can be obtained from notched beam tests. The equation is applicable to both filleted and sharp-cornered notches. An effective radius, Re, which models the effect of a sharp-cornered notch, was determined and confirmed for two wood materials. A method of determining Rc for other materials was established. The results of this study can be used to set new design criteria for the strength of notched wood beams

Response Analysis of Wood Structures Under Natural Hazard Dynamic Loads

The basic requirements needed for response analysis of wood structures against natural hazards are reviewed. A method for stochastic dynamic analysis of wood structures, which allows investigations into their performance and safety under natural hazards such as earthquakes and severe winds, is presented. To illustrate the method, earthquake ground motions are modeled as a stochastic process with Gaussian white noise properties. A single-degree-of-freedom wood structural system is modeled by a hysteretic constitutive law that produces a smoothly varying hysteresis. It models previously observed behavior of wood joints and structural systems, namely, (1) nonlinear, inelastic behavior, (2) stiffness degradation, (3) strength degradation, and (4) pinching. The constitutive law takes into account the experimentally observed dependence of wood joints' response to the input and response at an earlier time (known as memory). Hysteresis shapes produced by the proposed model compare favorably with common wood joints. The hysteresis model can produce a wide variety of hysteresis shapes, degradations, and pinching behavior to model a whole gamut of possible combinations of materials and joint configurations in wood construction. The nonstationary response statistics of a single-degree-of-freedom wood building subjected to white noise excitations are obtained by Monte Carlo simulation and stochastic equivalent linearization. The latter is shown to give a reasonably accurate prediction of the system's response statistics, which may be used in calculating design response values. The method of analysis is general and may be used to study the response of various kinds of structural systems, including multi-degree-of-freedom systems, as long as appropriate structural models are available and appropriate hysteresis model parameters for these systems are known

Effects of Drying Temperature and Tempering Duration on Hybrid Rice Seed Germination, Thin-Layer Drying Characteristics, and Power Requirement

This study presents the results of thin-layer drying tests for hybrid rice seeds. The independent factors were drying air temperature (45, 55, and 65 °C) and tempering duration (1, 2, and 4 h), while the dependent parameters were seed germination and drying characteristics, including drying rate, total and effective drying operation times, and power requirement. Considering one hybrid and 3 mo storage period after drying, the results showed that samples continuously dried at 45 and 55°C resulted in 91 and 86% germination percentages, respectively, which were above the acceptable Philippine national standard of at least 85%. However, when tempered for 2 or 4 h, even samples dried at 65°C resulted in more than 90% germination percentage. Tempered samples had an effective operation time of only 1 - 3 h, which was 50% less than those continuously dried (1.5 - 6 h of effective operation time). In effect, the total power used was halved by applying tempering. These results showed considerable advantages of tempering in terms of seed quality improvement and potential energy savings

Existing benchmark systems for assessing global warming potential of buildings – Analysis of IEA EBC Annex 72 cases

Life cycle assessment (LCA) is increasingly being used as a tool by the building industry and actors to assess the global warming potential (GWP) of building activities. In several countries, life cycle based requirements on GWP are currently being incorporated into building regulations. After the establishment of general calculation rules for building LCA, a crucial next step is to evaluate the performance of the specific building design. For this, reference values or benchmarks are needed, but there are several approaches to defining these. This study presents an overview of existing benchmark systems documented in seventeen cases from the IEA EBC Annex 72 project on LCA of buildings. The study characterizes their different types of methodological background and displays the reported values. Full life cycle target values for residential and non-residential buildings are found around 10-20 kg CO$_2$e/m$^2$/y, whereas reference values are found between 20-80 kg CO$_2$e/m$^2$/y. Possible embodied target- and reference values are found between 1-12 kg CO$_2$e/m$^2$/y for both residential and non-residential buildings. Benchmark stakeholders can use the insights from this study to understand the justifications of the background methodological choices and to gain an overview of the level of GWP performance across benchmark systems

Existing benchmark systems for assessing global warming potential of buildings – Analysis of IEA EBC Annex 72 cases

Life cycle assessment (LCA) is increasingly being used as a tool by the building industry and actors to assess the global warming potential (GWP) of building activities. In several countries, life cycle based requirements on GWP are currently being incorporated into building regulations. After the establishment of general calculation rules for building LCA, a crucial next step is to evaluate the performance of the specific building design. For this, reference values or benchmarks are needed, but there are several approaches to defining these. This study presents an overview of existing benchmark systems documented in seventeen cases from the IEA EBC Annex 72 project on LCA of buildings. The study characterizes their different types of methodological background and displays the reported values. Full life cycle target values for residential and non-residential buildings are found around 10-20 kg CO2e/m2/y, whereas reference values are found between 20-80 kg CO2e/m2/y. Possible embodied target- and reference values are found between 1-12 kg CO2e/m2/y for both residential and non-residential buildings. Benchmark stakeholders can use the insights from this study to understand the justifications of the background methodological choices and to gain an overview of the level of GWP performance across benchmark systems.publishedVersio

Comparison of 16 national methods in the life cycle assessment of carbon storage in wood products in a reference building

Wood and bio-based construction products are perceived as a way to use renewable resources, to save energy and to mitigate greenhouse gas (GHG)-emissions during production and to store carbon during the entire service life of the building. This article compares the carbon footprint per kilogram of wood products (softwood beams, plywood, oriented strand board panel, and fibre board) from the perspective of the life cycle assessment methodology for greenhouse gas (GHG) emissions of practitioners from 16 countries participating in the IEA Annex 72. These materials are used in PAL6 softwood structure multi-residential building. This article aims at comparing the carbon footprint accounting methods from 16 countries for PAL6 multi-residential building. Each national team applied the reference study period (RSP), life cycle modules covered, modelling rules, the geographical scope of inventory data as well as the LCA database according to its specific national method. The results show that there are three types of methodology to assess a building with biogenic content (0/0, -1/+1, -1/+1*). The results were more variable plywood, oriented strand board, and fibreboard than the softwood beams due to the variability in the wood transformation processes among the countries. A net negative carbon balance was obtained for the softwood beam for the countries using -1/+1* with a clear assumption of the fraction of the carbon permanently stored at the end-of-life (EoL). The carbon storage is only possible if it is secured at the EoL. Participating countries apply different definitions of permanence and EoL scenarios. Guideline on assessing, monitoring, and legally reporting carbon storage at the EoL are needed, based on concertation between standard, life cycle assessment, wood industry, and climate expertspublishedVersio