Commissioning of moisture safety of nZEB renovation with prefabricated timber frame insulation wall elements
TL;DR: The efficient way to accomplish the idea of nearly-zero energy buildings (nZEB) is to apply the int... as discussed by the authors, which is the most efficient way of achieving nZEB.
Abstract: An improvement in energy performance for existing buildings is needed to fulfil EU energy policy. The efficient way to accomplish the idea of nearly-zero energy buildings (nZEB) is to apply the int...
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TL;DR: In this article, the authors identify eight recurrent product and process-related themes and fifteen specific sub-themes of resource efficiency in industrialized housing construction across building lifecycle phases and identify future research directions for resource-efficient industrial housing construction including concepts of circular economy, value chain coordination, and socioeconomic impacts.
51 citations
TL;DR: In this article, the hygrothermal behavior of three external thermal insulation systems: one ETICS including EPS insulation and two ventilated cladding systems including either mineral or biobased insulation.
12 citations
TL;DR: In this paper, a methodology and the results of analysis of choices of realizable sets of timber frame prefabricated insulation elements for major renovation of apartment buildings were presented, and thereupon their performance, installation eligibility, and concurrent cost levels were compared.
Abstract: A need for the refurbishment and renewal of the existing building stock has been in focus for many decades, principally because of excessive global energy consumption and pollution. This paper presents a methodology and the results of analysis of choices of realizable sets of timber frame prefabricated insulation elements for major renovation of apartment buildings. Numerous combinations of elements with different characteristics were analyzed by applying measurements, interviews, and building performance simulation software, and thereupon their performance, installation eligibility, and concurrent cost levels were compared. Mineral wool board with a special wind barrier facing was found to be the best material as a wind barrier from the perspective of hygrothermal performance. An air and vapor barrier should have sufficient vapor permeability to allow dry-out of constructional moisture. It is possible to renovate apartment buildings to meet the nZEB energy performance requirements and their moisture safety can be guaranteed without paying high relative difference cost. Calculations showed that the global cost was lower for solutions with some mold growth risk. Great care is needed when decreasing costs without simultaneous hygrothermal analyses. The facade cladding was found to have the highest influence on the initial cost of the prefabricated insulation element.
10 citations
TL;DR: A methodology for the evaluation of renovation measures, aiming to provide decision support related to the selection of what to renovate and to what extent is proposed, by means of a simplified cost-effective parameter (CEP), linking cost, lifetime, and energy savings.
Abstract: Reaching environmental targets set by the European Union (EU) requires a constant renovation of the existing building stock to nearly Zero Energy Buildings (NZEB) in a cost-optimal manner. Studies show that the renovation rate of the existing building stock is more than two times less than what is necessary to reach the targets. Furthermore, the majority of performed renovations across the EU reach just a small amount of energy savings, whereas NZEB renovations are rarely achieved. This paper proposes a methodology for the evaluation of renovation measures, aiming to provide decision support related to the selection of what to renovate and to what extent. The proposed method is rooted in the well-established cost-optimal methodology, yet it suggests a pre-step to package evaluation. This is done by means of a simplified cost-effective parameter (CEP), linking cost, lifetime, and energy savings. The methodology is demonstrated using a case study building in Denmark. The results show that the CEP provides good grounds for the compilation of single actions to packages. Further developments could focus on the sensitivity of the model inputs and integration of additional evaluation parameters to cost, such as environmental, architectural, comfort, risk, etc.
7 citations
TL;DR: The procedure of examination and assessment of the condition of external curtain walls used in typical prefabricated residential construction systems at the end of the 20th century in Poland and a concept of effective reinforcement of threatened connections was developed.
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References
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TL;DR: In this article, a mathematical model for the simulation of mould fungi growth on wooden material is presented, based on previous regression models for mould growth on sapwood of pine and spruce.
Abstract: A mathematical model for the simulation of mould fungi growth on wooden material is presented, based on previous regression models for mould growth on sapwood of pine and spruce. Quantification of mould growth in the model is based on the mould index used in the experiments for visual inspection. The model consists of differential equations describing the growth rate of the mould index in different fluctuating conditions including the effect of exposure time, temperature, relative humidity and dry periods. Temperature and humidity conditions favourable for mould growth are presented as a mathematical model. The mould index has an upper limit which depends on temperature and relative humidity. This limiting value can also be interpreted as the critical relative humidity needed for mould growth depending also on the mould growth itself. The model enables to calculate the development of mould growth on the surface of small wooden samples exposed to arbitrary fluctuating temperature and humidity conditions including dry periods. The numerical values of the parameters included in the model are fitted for pine and spruce sapwood, but the functional form of the model can be reasoned to be valid also for other wood-based materials.
338 citations
"Commissioning of moisture safety of..." refers methods in this paper
...To study the possible growth rate of mould in structures, the Finnish mould growth model (Hukka and Viitanen 1999, Ojanen et al. 2010) was applied....
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TL;DR: In Sweden, the Million Homes Programme (MHP) as discussed by the authors was proposed to solve the housing shortage in the first decades of the post-war era by building a million new dwellings.
Abstract: The first decades of the post‐war era saw a large and quickly growing need for new housing. In Sweden, rapid urbanization, growing prosperity and demands for higher housing standards led to years‐long housing queues. The housing shortage became a political liability for the ruling Social Democratic party. To end the housing shortage once and for all, the Swedish parliament decided that a million new dwellings should be built in the period 1965 to 1974 and this was achieved. When the Million Homes Programme, as it came to be called, had reached barely half‐way, the housing shortage was replaced by a housing surplus, partly caused by the rapid expansion of the housing stock and by the fact that economic growth gave way to stagnation. At the same time, criticism began to be heard about what some people perceived as uniform and poor architecture and, since then, the Million Homes Programme has never ceased to engage people and provoke debate. Most of the buildings and areas of this era have survived quite wel...
180 citations
"Commissioning of moisture safety of..." refers background in this paper
...Use of prefabricated concrete large-panel (PCLP) construction technology for apartment buildings has been applied in many European countries since the 1960s (Hall and Vidén 2005, Lahdensivu 2012, Barański and Berkowski 2015)....
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TL;DR: In this article, a total of 349 residential building audits were performed in seven European countries to collect data on the degradation of building elements (architectural and installations) at different states of deterioration.
104 citations
"Commissioning of moisture safety of..." refers background in this paper
...As more than 70% of residential buildings in Europe are over 30 years old and about 35% are more than 50 years old (Balaras et al. 2005), a complete technical improvement of their condition has been receiving more attention....
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01 Jan 2010
TL;DR: Ojanen et al. as mentioned in this paper presented the latest findings of mold growth and the modeling of these factors on different materials, such as pine and spruce sapwood, by using the dynamic temperature and relative humidity histories of the subjected material surfaces.
Abstract: Numerical simulation of mold growth can be used as one of the hygrothermal performance criteria of building structures. Mold growth is one of the first signs of too-high moisture content of materials, and it may affect the indoor air quality and also the appearance of the visible surfaces. Mold growth potential can be predicted by solving a numerical value, mold index, by using the dynamic temperature and relative humidity histories of the subjected material surfaces. The model was originally based on mold growth of wooden materials, but it has now been completed with several other building materials. The model can be used parallel with heat, air, and moisture simulation models or as a post-processing tool. This paper presents the latest findings of mold growth and the modeling of these factors on different materials. The mold growth model has been improved by taking into account the effect of seasonal, long dry or cold periods that do not allow growth. This includes mechanisms for the decrease of mold level (decline of mold index) during unfavorable growth periods and the intensity of the growth after these periods. The laboratory and field results show that the sensitivity of the mold index level may vary in a large range depending on materials. Also, the performance on the interface of two materials has been studied. Instead of modeling the performance separately for each material or product, the materials are presented as different mold sensitivity classes varying from resistant to very sensitive. The sensitive class corresponds to the performance of pine sapwood, which was one basic material in the original model format. Other materials are presented by using the detected correlations between these materials. The mold growth sensitivity classes, decline of the growth level, comparison to detected mold level in materials, and numerical application in practical hygrothermal performance analysis are presented and discussed. MOTIVATION AND OBJECTIVES FOR FURTHER DEVELOPMENT OF THE MOLD GROWTH MODEL Numerical simulation of heat, air, and moisture performance of building structures generates the prediction of hygrothermal conditions in different parts of the analyzed structure. Also, monitoring of laboratory experiments and site investigations produces large amounts of data from critical parts of structures. This data should be post processed in order to evaluate the risks connected to overall performance, service life, interaction with indoor climate conditions, and structural safety. Mold growth is one of the first signs of biological deterioration caused by excess moisture; therefore, mold growth can be used as one of the best hygrothermal performance criteria of building structures. Mold does not deteriorate the material, but it is a sign of too-high moisture content and it represents a risk for other moisture-caused problems, such as decay. Mold affects the appearance of the surface and can severely affect the indoor air quality when the growth is in contact with indoor air or with the leakage air flowing into the room space. The mathematical model of mold growth was developed by Hukka and Viitanen (1999) based on regression analysis of the measured data (Viitanen 1996; Viitanen and Ritschkoff 1991) for calculating the development of mold growth, which is expressed as the mold index. An index value from 0 to 6 is defined to describe the evaluation of mold growth on a surface © 2010 ASHRAE. Tuomo Ojanen is a senior research scientist and team leader at VTT Expert Services Ltd, Finland. Hannu Viitanen is a senior research scientist and team leader at VTT Bioprocessing, Finland. Ruut Peuhkuri worked as a research scientist at VTT during the research and is currently a senior consultant with Passivhus.dk ApS, Næstved, Finland. Kimmo Lähdesmäki and Kati Salminen are research scientists and Juha Vinha is a docent in the Department of Civil Engineering at Tampere University of Technology, Tampere, Finland. a) on a microsopic level (1– 2) and b) when the growth can be detected visually (3–6). This mold index is based on the detectable growth of different mixed mold species. The first version of this model was based on a great number of measurements on pine and spruce sapwood material. This model has been used to analyze (in parallel or in post processing) the result derived from numerical simulation models for the dynamic temperature and relative humidity histories of the critical material surfaces. The mold growth risk analysis based on sensitive wooden materials has been applied also for different material layers that have soiled, dusty surfaces and those surfaces having contact with wood-based materials. Since the first version of the model, the research has included several experimental studies on conditions for mold growth, primarily on wood but also on other building materials. In order to predict the risks of mold growth in varying types of structures made of several building products and materials, it is obvious that an improved model to cover several typical building materials has to be developed. RESEARCH CARRIED OUT TO IMPROVE THE MODEL A three-year research project was carried out at Technical Research Center of Finland (VTT) and Tampere University of Technology. This project included large sets of steady-state and dynamic laboratory experiments for common building materials (Salminen et al. 2009), monitoring of mold growth in material surfaces and structures under real climate conditions, and long-period climate chamber experiments. The results of these findings were used to improve the existing numerical model for mold growth. This paper presents the development of the mold growth model in this project (Peuhkuri et al. 2009; Ojanen et al. 2009), which items were taken into account and how these parameters were studied, and the results interpreted numerically for different materials and conditions. The experiments and their findings are presented and discussed only from the modeling aspect. These results are presented in a concise way, and the main findings are shown as the improvements of the numerical model. The emphasis is on the comparison between experiments and the outcome of the new modeling principles. MATERIALS USED IN THE RESEARCH Some typical building materials were chosen for the experiments: spruce board (with glued edges), concrete (K30, maximum grain size 8 mm), aerated concrete, cellular concrete, polyurethane thermal insulation (PUR, with paper surface and with polished surface), glass wool, polyester wool, and expanded polystyrene (EPS). Pine sapwood was used as a reference material. This set of products cannot entirely represent all the products in the building material group, but it gives improved approximation on the mold growth sensitivity of each. The following results are based on the controlled laboratory and well-monitored site experiments of the chosen materials and structures where these products were used. UPDATING THE EXISTING NUMERICAL MOLD GROWTH MODEL The mold growth model based on experiments with wood was updated to be valid also for the mold growth prediction of other building materials. The idea in this research was to keep the original model structure and to adapt the mold growth parameter values of different materials to the existing model. Some improvements were applied for the model structure to better adjust different growth phenomena. The following sections represent the modeling principles for different mold growth parameters. MOLD GROWTH LEVEL—MOLD INDEX Determination of the mold growth levels is the fundamental element of the whole simulation of this biological phenomenon. This determination sets an interpretation of the visual growth levels as numerical values. This is needed both in the evaluation of the experimental results and in the assessment of the simulation results. Figure 1 represents how mold growth was studied under constant conditions for this research. Closed containers had saturated salt solution vessels to maintain known constant humidity levels. There were nine test samples of each material used in the tests. Some focusing was done to better take into account the different mold growth types with different materials and surfaces. The main difference compared to the version for wood-based materials was in the area that is not visible to the naked eye. It was found out that with some materials the mold growth coverage could be quite high already in microscopic areas (see Figure 2). Therefore, the mold index Figure 1 Laboratory test setup with small samples; there were nine samples of each material.
98 citations
"Commissioning of moisture safety of..." refers methods in this paper
...To study the possible growth rate of mould in structures, the Finnish mould growth model (Hukka and Viitanen 1999, Ojanen et al. 2010) was applied....
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11 Apr 2007
TL;DR: In this article, the authors examined the effects of the diffusion of water vapour in wall assemblies in Finnish climatic conditions by examining the effect of different properties of the assembly layers on the moisture performance of the wall, followed by the setting of minimum values for the water vapor resistance ratio between the interior and exterior linings of different wall types based on selected criteria and study conditions.
Abstract: This study looked into the moisture performance of timber-framed external wall assemblies in Finnish climatic conditions by examining the effects of the diffusion of water vapour in wall assemblies. The study has been preceded by decades of discussion about the need of a vapour barrier in the interior wall lining of external wall assemblies. Much research has been conducted related to this subject worldwide in the last 70 years, and studies have shown that in Nordic climatic conditions the interior wall lining always requires sufficient water vapour resistance against the diffusion of the water vapour emitting from indoor air. On the other hand, it has also been found that external wall assemblies can be implemented without incorporating a tight vapour barrier into the interior wall lining. Furthermore, in more southern climatic conditions the interior wall lining may have to be permeable to water vapour when the direction of the diffusion flow is from the outside in. Yet, despite numerous studies, agreement has not been reached on the minimum water vapour resistance that should be required of the interior wall lining of a timber-framed wall assembly under different conditions. Consequently, different guidelines and regulations for water vapour resistance values of interior wall linings exist also in countries located in highly similar climatic conditions. Comprehensive assessment of the moisture performance of wall assemblies requires establishing the performance criteria and limit values that an assembly must meet, the outdoor and indoor conditions to be used in designing moisture performance, and the assembly solution and used materials as well as their building physical properties. The acceptability of the moisture performance of an external wall assembly depends essentially on all these factors during the service life of a building. The aim of this study has been firstly to create a method which allows examining the moisture performance of timber-framed external wall assemblies in different situations. The first phase involved setting the performance criteria, limit values and reference boundary conditions for analysing wall assemblies under Finnish climatic conditions. Then, the effect of the different properties of the assembly layers on the moisture performance of the wall was examined followed by the setting of minimum values for the water vapour resistance ratio between the interior and exterior linings of different wall types based on selected criteria and study conditions. An attempt has been made to ensure the reliability of the developed analysis method by conducting different laboratory and field tests and calculational analyses in connection with the study. External wall assemblies were examined in the laboratory with building physical research equipment developed during this study, the key building physical properties of the materials used in assembly tests were determined for calculational analyses, external wall assemblies were also analysed in field conditions in a one-family house and in test houses at the test field of Tampere University of Technology, indoor air excess moisture was analysed in field tests of timber-framed one-family and row houses, and the performance of the used heat, air and moisture transfer simulation model (HAM model) was verified by tests conducted in various situations. Moisture condensation and mould growth within were chosen as the performance criteria of the external wall assembly. Limit values were selected according to the following principle:
61 citations
"Commissioning of moisture safety of..." refers result in this paper
...We agree with other authors (Vinha 2007, Geving 2017, Colinart et al. 2019) that it is highly important to consider the weather conditions, and moisture safety rules on site must be strictly followed to reach such results....
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