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Jan-olof Dalenbäck - One of the best experts on this subject based on the ideXlab platform.
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optimized maintenance and renovation scheduling in multifamily Buildings a systematic approach based on condition state and life cycle cost of Building Components
Construction Management and Economics, 2019Co-Authors: Abolfazl Sousanabadi Farahani, Holger Wallbaum, Jan-olof DalenbäckAbstract: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 con- straints. 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-deteri- oration model to address the complexity involved in decision making regarding optimized main- tenance 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 com- bination of Building Components. Two fac ade elements, windows and fac ade rendering, are used to illustrate the application of the proposed method. This method is intended to help deci- sion makers at both design and post-construction phases in the choice of both Building compo- nents and maintenance/renovation strategies.
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Optimizing the Life Cycle Costs of Building Components with Regard to Energy Renovation
Springer Proceedings in Energy, 2018Co-Authors: Abolfazl Sousanabadi Farahani, Jan-olof DalenbäckAbstract:ConsideringthehighshareofresidentialBuildingsinthetotalenergyuse in Sweden, having the ambitious national energy and climate goals in mind, the real estate sector and its issues have been under a lot of attention during the past few decades. The Swedish real estate sector has often been identified with its ambitious public housing program during the record years (1960–1974). This was at the time the largest housing program per capita in the world where more than a million apartments were built in a nation with a population of 8 million. These apartments once being the pride of a nation, are facing a lot of problems today, ranging from vacancy and unacceptable physical condition to very poor energy performance. These Buildings at the verge of their service/economic life are in need of extensive maintenance and renovation measures. Considering the technological development today, the problem with maintenance and renovation remains to be the financial constraints. These are what makes planning for maintenance and renovation com- plicated and cost inefficient. Although there are tools that can help property man- agers with maintenance and renovation planning, they all fail to address the complexity of the decision-making process in a multi-objective criteria under financial and time constraints. In this study, the focus is on the life cycle economy of the Building Components subject to energy performance improvements during renovation. A systematic approach has been proposed that can be used to budget and plan renovation with regard to energy efficiency under budget constraints. This approach utilizes a modified condition/deterioration model of the method Schroeder to simulate the maintenance effect on the condition state of Building Components in order to obtain the cost-optimal maintenance regime under given restrictions. This methodology can be used to compare the cost effectiveness of different energy-renovation scenarios and determine the optimal renovation plan for a single or a combination of Buildings with regard to owners’ objectives and existing constraints. The results from this study illustrates how prioritizing action plans can affect the life cycle costs of Building Components.
Paul Strachan - One of the best experts on this subject based on the ideXlab platform.
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Simulation support for performance assessment of Building Components
Building and Environment, 2008Co-Authors: Paul StrachanAbstract:The determination of performance metrics for novel Building Components requires that the tests are conducted in the outdoor environment. It is usually difficult to do this when the Components are located in a full-scale Building because of the difficulty in controlling the experiments. Test cells allow the Components to be tested in realistic, but controlled, conditions. High-quality outdoor experiments and identification analysis methods can be used to determine key parameters that quantify performance. This is important for achieving standardised metrics that characterise the Building component of interest, whether it is a passive solar component such as a ventilated window, or an active component such as a hybrid photovoltaic module. However, such testing and analysis does not determine how the Building component will perform when placed in a real Building in a particular location and climate. For this, it is necessary to model the whole Building with and without the Building component of interest. A procedure has been developed, and applied within several major European projects, that consists of calibrating a simulation model with high-quality data from the outdoor tests and then applying scaling and replication to one or more Buildings and locations to determine performance in practice of Building Components. This paper sets out the methodology that has been developed and applied in these European projects. A case study is included demonstrating its application to the performance evaluation of hybrid photovoltaic modules.
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Case studies of outdoor testing and analysis of Building Components
Building and Environment, 2008Co-Authors: Paul Strachan, L. VandaeleAbstract:The construction and development of the PASSYS/PASLINK outdoor test cells were funded by the European Commission, with the objective of providing high-quality test environments for quantifying the performance of passive solar Building Components. Over the years since the original test cells were commissioned, the initial concept for outdoor testing has been extended to include other test cell types. Significant improvements have been made to the experimental procedures and analysis techniques, and a broad range of Components has been tested. This paper describes representative experiments that have been conducted using these highly controlled outdoor test environments, indicates some of the related analysis, and shows the type of information that can be obtained from such tests. It demonstrates the way in which component performance can be ascertained in the realistic external environment. The case studies chosen range from Building component tests within EC research projects to commercial tests, and from conventional Building Components to novel integrated facade systems. They also include a large range of passive and active Components. Each case study summarises the test component, the purpose of the test, details of the test configuration (period of test, instrumentation, etc.), results and analysis, and associated modelling and monitoring where appropriate. The paper concludes with an appraisal of the advantages and limitations of the test cells for the various component types.
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outdoor testing analysis and modelling of Building Components
Building and Environment, 2008Co-Authors: Paul Strachan, P H BakerAbstract:In 1993 [1], a set of papers was presented on the theme of thermal experiments in outdoor test cells. In the intervening 13 years, there have been several advances in the test procedures, the analysis of the measured data to extract standard performance characteristics, and the link with modelling and simulation. The papers included in this special issue focus on developments made in a series of research projects funded by the Commission of the European Community, all of which have included a significant element of outdoor testing of Building Components. The arguments for using outdoor test cells are still relevant. High quality laboratory facilities exist for testing Components (e.g. hot-box facilities for measuring thermal transmittance, spectrophotometric testing for optical properties of glazings, solar simulators and climatic chambers for testing the output from photovoltaic modules) that are accurate and repeatable. However, they tend to be steady-state tests and do not take into account the dynamically varying boundary conditions that the Components are subjected to when used in the Building envelope. The obvious solution is to test the Components when mounted on a Building in typical operational mode. However, in practice this has been shown to be highly complex - even in unoccupied Buildings, it is difficult to measure all the required inputs (e.g. constructional details, air movement, heating and cooling system operation, and external climate) to the level required to get reliable estimates of component performance. Although some attempts have been made to measure in dedicated full-scale Buildings (e.g. [2], [3] Swinton MC, Moussa H Marchand RG. Commissioning twin houses for assessing the performance of energy conserving technologies. Performance of exterior envelopes of whole Buildings VIII integration of Building envelopes, (NRCC-44995), Clearwater, FL, December 2001. p. 1-10.[3] and [4]), the results can still have significant uncertainties and/or the facilities are very expensive to construct and monitor.
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Simulation in support of outdoor testing of Building Components
2003Co-Authors: Paul StrachanAbstract:The determination of performance metrics for novel Building Components requires that the tests are conducted in the outdoor environment. It is usually difficult to do this when the Components are located in a full-scale Building because of the difficulty in controlling the experiments. Test cells allow the Components to be tested in realistic, but controlled, conditions. High-quality outdoor experiments and identification analysis methods can be used to determine key parameters that quantify performance. This is important for achieving standardised metrics that characterise the Building component of interest, whether it is a passive solar component such as a ventilated window, or an active component such as a hybrid photovoltaic module. However, such testing and analysis does not determine how the Building component will perform when placed in a real Building in a particular location and climate. For this, it is necessary to model the whole Building with and without the Building component of interest. A procedure has been developed, and applied within several major European projects, that consists of calibrating a simulation model with high-quality data from the outdoor tests and then applying scaling and replication to one or more Buildings and locations to determine performance in practice of Building Components. This paper sets out the methodology that has been developed and applied in these European projects. A case study is included demonstrating its application to the performance evaluation of hybrid photovoltaic modules.
Paul Baker - One of the best experts on this subject based on the ideXlab platform.
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PASLINK and dynamic outdoor testing of Building Components
Building and Environment, 2008Co-Authors: Paul Baker, H.a.l. Van DijkAbstract:The PASLINK test facilities and analysis procedures aim to obtain the thermal and solar characteristics of Building Components under real dynamic outdoor conditions. Both the analysis and the test methodology have evolved since the start of the PASSYS Project in 1985. A programme of upgrading the original PASSYS test cells has improved measurement accuracy. The emphasis has moved from steady state to dynamic methods with shorter test durations yielding improved information and more accurate results. Dynamic test procedures aim to de-couple the different thermal processes within the test cell in order to obtain separation between the thermal transmission and the solar aperture of a component. In parallel with improvements in test methodology, software tools have been developed to enable the identification of the component characteristics and provide statistical information on their accuracies from the dynamic test data. The PASLINK Network has implemented quality procedures and promoted the development of participants' expertise in the design, preparation and execution of tests and the analysis of test data. © 2006 Elsevier Ltd. All rights reserved.
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iq test improving quality in testing and evaluation of solar and thermal characteristics of Building Components
Energy and Buildings, 2004Co-Authors: Paul BakerAbstract:IQ-test is a Thematic Network supported by the European Community under the EESD Programme. The objective of IQ-test is to further the development of common quality procedures at the PASLINK test cell facilities in 12 European countries, for the assessment of the thermal characteristics of Building Components. This should consolidate the network, integrate the newer test sites and strengthen its common approach of support for new product developments in the field of innovative Building Components. Round robin tests are underway to assess both the inter-site quality of testing and analytical procedures of the participants. Two Components were designed: (1) an opaque, well insulated, homogeneous panel and (2) a window, which is used to replace the central section of the first component. Common test and quality procedures have been implemented at each test site. The data sets generated by each team have been made available for cross-analysis by another team. The results available so far on the first component indicate good agreement between sites. This paper summarises the progress to date. Results are also presented from a training exercise which asked participants to identify the performance characteristics of an unknown component without providing any physical description of the component.
Staf Roels - One of the best experts on this subject based on the ideXlab platform.
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Predicting the hygrothermal behaviour of Building Components using neural networks
MATEC Web of Conferences, 2019Co-Authors: Astrid Tijskens, Staf Roels, Hans JanssenAbstract:Increasing the energy efficiency of the existing Building stock can be accomplished by adding thermal insulation to the Building envelope. In case of historic Buildings with massive walls, internal insulation is often the only feasible post-insulation technique. Drawback of internal insulation is the modified hygrothermal response of the wall, which can result in moisture damage. Hence, it is crucial to assess the risk of damage accurately beforehand. Given the many uncertainties involved, a probabilistic assessment is advisable. This, however, would require thousands of simulations, which easily becomes computationally inhibitive. To overcome this time-efficiency issue, this paper proposes the use of neural networks to replace the original hygrothermal model. The neural network is trained on a small data set obtained from the hygrothermal model and can subsequently be used to predict the hygrothermal behaviour of Building Components with different boundary conditions and geometry. The transient nature of the hygrothermal behaviour requires a neural network type which can handle long-range time-dependencies. In the past, recurrent neural networks were often used for this type of data. Recently however, results indicate that convolutional neural networks can outperform recurrent neural networks on such tasks. This paper compares the prediction accuracy and training time of both neural network types for the prediction of the hygrothermal behaviour of Building Components.
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Neural networks for metamodelling the hygrothermal behaviour of Building Components
Building and Environment, 2019Co-Authors: Astrid Tijskens, Staf Roels, Hans JanssenAbstract:Abstract When simulating the hygrothermal behaviour of a Building component, there are many inherently uncertain parameters. A probabilistic evaluation takes these uncertainties into account, allowing a more dependable assessment of the hygrothermal behaviour. However, this often necessitates many Monte Carlo simulations, which easily become computationally inhibitive. To overcome this time-expense problem, the hygrothermal model can be replaced by a metamodel, a much simpler mathematical model which aims at mimicking the original model with a strongly reduced calculation time. In this paper, a metamodel is developed to directly predict hygrothermal time series (e.g. temperature, relative humidity, moisture content), rather than single-valued derived performance indicators (e.g. maximum mould index), as these hygrothermal time series yield more information, and also allow the user to post-process the output as desired. So far, no metamodelling strategies able to tackle time series are available in the field of Building physics. Because the hygrothermal response of a Building component is highly non-linear and transient, this paper focuses on neural networks for time series, as they have proven successful in many other fields. The performance and training time of three popular types of networks (multilayer perceptron, recurrent neural network, convolutional neural network) is evaluated based on an application example of a massive masonry wall. The results indicate that only the recurrent and convolutional networks are able to capture the complex patterns of the hygrothermal response. Additionally, the convolutional network performed significantly better and was 10 times faster to train for the current application example, compared to the recurrent network.
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The as-built thermal quality of Building Components: characterising non-stationary phenomena through inverse modelling
Energy Procedia, 2017Co-Authors: An-heleen Deconinck, Staf RoelsAbstract:Abstract The thermal resistance of Building Components is typically seen as a stationary parameter, although in reality, the quantity is often time varying. Several phenomena can lie at the origin of this: some of them are bound to the heat conduction mechanisms in Building materials and cannot be prevented from occurring, while others are induced by external factors that can and should be avoided. Poor workmanship issues, for instance, can induce phenomena such as buoyancy driven air flows or wind washing. These phenomena interact with the regular heat transfer mechanisms in Building Components and can affect their thermal performance. In this paper, it is examined whether the technique of stochastic grey-box modelling holds the ability to characterise a variable thermal resistance indicator quantifying the thermal impact of such phenomena. This is investigated for the specific scenario of an insulated cavity wall that suffers from rotational air looping around its hard insulation boards.
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Is stochastic grey-box modelling suited for physical properties estimation of Building Components from on-site measurements?:
Journal of Building Physics, 2017Co-Authors: An-heleen Deconinck, Staf RoelsAbstract:In current energy requirements, the thermal performance of Buildings is assessed with simplified energy models. A performance label is calculated based on thermal properties of the constituent Components of the Building envelope. These properties, however, do not include factors such as workmanship issues, or moisture or airflow influences which might affect the thermal performance as designed. To have a better view on the actual thermal quality of Building Components, a reliable thermal characterisation method of Building Components on-site is required. The typically used semi-stationary measurement methods have an application that is seasonally bounded or can require long measurement periods. Because of these drawbacks, dynamic parameter estimation methods have gained interest. In this article, the physical interpretability of a typical stochastic grey-box model used to thermally characterise Building Components is assessed. The identifiability of this model structure is examined by observing the profil...
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comparison of characterisation methods determining the thermal resistance of Building Components from onsite measurements
Energy and Buildings, 2016Co-Authors: An-heleen Deconinck, Staf RoelsAbstract:Abstract Reliable in situ thermal characterisation allows to study the actual thermal performance of Building Components rather than the theoretical performance calculated from thermal properties of the constituent material layers. The most generally accepted method for in situ thermal characterisation is the average method as described in ISO 9869. However, due to steady-state assumptions, the method's applicability can require long measurement periods and is often seasonally bounded. A correction for storage effects might shorten the required measurement time spans for the average method, but will not eliminate the seasonally bounded limitations. More advanced dynamic data analysis methods, such as regression modelling, ARX-modelling or stochastic grey-box modelling, can be used to overcome these difficulties. In this paper, a comparison between several semi-stationary and dynamic data analysis methods typically used for the thermal characterisation of Building Components from on-site measurements is made. Thereby, special attention is given to the reliability of the methods thermal resistance estimates when confronted with data sets of limited measurement time spans and different seasonal boundary conditions. First, the methods’ performances are assessed for simulated measurements of a south-facing insulated cavity wall in a moderate European climate. Subsequently, the performances are examined for actual measurement data of a similar test wall.
Jan Carmeliet - One of the best experts on this subject based on the ideXlab platform.
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conservative modelling of the moisture and heat transfer in Building Components under atmospheric excitation
International Journal of Heat and Mass Transfer, 2007Co-Authors: Hans Janssen, Bje Bert Blocken, Jan CarmelietAbstract:While the transfer equations for moisture and heat in Building Components are currently undergoing standardisation, atmospheric boundary conditions, conservative modelling and numerical efficiency are not addressed. In a first part, this paper adds a comprehensive description of those boundary conditions, emphasising wind-driven rain and vapour exchange, the main moisture supply and removal mechanism, respectively. In the second part the numerical implementation is tackled, with specific attention to the monotony of the spatial discretisation, and to the mass and energy conservation of the temporal discretisation. Both issues are illustrated with exemplary hygrothermal simulations. Numerical efficiency is treated in two follow-up papers.
