April 2013
Publication year: 2013
Source:Building and Environment, Volume 62
Publication year: 2013
Source:Building and Environment, Volume 62
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Editorial Board
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Evaluation of inhibitory effect of TiO2 nanocoatings against microalgal growth on clay brick façades under weak UV exposure conditions
Available online 18 March 2013
Publication year: 2013
Source:Building and Environment
Microalgal growth largely affects the aesthetical properties of building façades worldwide. It causes biodeterioration of building materials and, in a later stage, it can compromise integrity of the elements and their durability. Recently, the use of nanotechnology to prevent the growth of microalgae is rising. One of the most widespread and promising material is titanium dioxide (TiO2 ). Photocatalytic properties of TiO2 inhibit biofouling of microalgae when this coating is stimulated by UV radiation coming from the sun or from artificial light. In this study, the biocide effect of TiO2 coatings applied on clay brick specimens under weak UV radiation was assessed. Results revealed that TiO2 nanocoating was not able to fully prevent microalgal biofouling, but under optimal UV exposure conditions for the growth of microalgae it efficaciously prevented the adhesion of these microorganisms on the treated substrates through the formation of a superficial water film. This property resulted in a good self-cleaning efficiency of TiO2 .
Publication year: 2013
Source:Building and Environment
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A uniform methodology to establish test parameters for watertightness testing part II: Pareto front analysis on co-occurring rain and wind
May 2013
Publication year: 2013
Source:Building and Environment, Volume 63
A critical review on boundary conditions for watertightness testing was presented in a related paper forming Part I of “A uniform methodology to establish test parameters for watertightness testing”. Existing methodologies to establish test conditions only partially consider co-occurrence of rain and wind, which yields large uncertainties when determining return periods for extreme wind-driven rain events. This paper presents a new approach based on a Pareto fronts method for which wind driven rain intensities and wind pressures are derived. Straight lines can be fitted to consecutive fronts, and a generalized Pareto distribution describes the corresponding probabilities of occurrence of wind-driven rain events. Assumptions in the use of the methods are given and constraints to its use provided by means of case-studies. Advantages over existing methods for estimating watertightness test parameters are highlighted. Test conditions can be calculated for various configurations and different averaging periods depending on the failure behavior of specific building envelop components. Subsequently it is shown that the conversion of case-based test conditions to generic test protocols and performance levels requires careful consideration. Finally, the paper provides practical guidelines on defining realistic watertightness performance levels for building envelop components.
► Co-occurrence of rain and wind is evaluated by means of Pareto front analysis. ► A Pareto distribution allows to determine the probability of extreme WDR events. ► Based on case-studies, large discrepancies with existing methods were found. ► Guidelines on the conversion towards generic performance levels are reported.
Publication year: 2013
Source:Building and Environment, Volume 63
Highlights
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A uniform methodology to establish test parameters for watertightness testing Part I: A critical review
May 2013
Publication year: 2013
Source:Building and Environment, Volume 63
Many of the standards and codes related to watertightness of building components in use today have a long history and in most cases their roots were conceived decades ago. Irrespective of the broad spectrum of research on wind loads, rainfall and wind driven rain (WDR) intensity, little information is available concerning the scientific basis for watertightness test methods or performance criteria. This paper provides an overview of existing methodologies to establish test conditions and a critical review of calculation methods for wind and WDR loads on buildings, from the viewpoint of establishing test parameters for watertightness testing. The operative standard in the field of structural engineering is extended with a gust model to calculate wind loads for varying configurations, return periods and gust lengths, and model implications are discussed. A state-of-the-art on intensity–duration–frequency curves of horizontal rainfall intensity is given, and a new approach to accommodate conflicting models is presented. Furthermore, based on recent advances in WDR research, an adapted semi-empirical model is suggested to calculate extreme WDR intensities on building façades. For two locations boundary conditions for watertightness testing were calculated based on datasets extending over 10 years of 10-min averaged values. Finally, constraints and challenges in extreme value analysis in respect to cut-off values, fitting algorithms, goodness-of-fit (GOF) criteria and co-occurrence of rain and wind are discussed.
► Review of existing methods to establish test conditions for watertightness testing. ► New model for rainfall Intensity–Duration–Frequency curves is presented. ► The sensitivity of extreme value analysis on wind and rain data is discussed. ► Comparison of different approaches and test protocols show large discrepancies.
Publication year: 2013
Source:Building and Environment, Volume 63
Highlights
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Impact of perceived indoor environment quality on overall satisfaction in Swedish dwellings
May 2013
Publication year: 2013
Source:Building and Environment, Volume 63
The aim of this paper is to contribute to the discussion on how satisfaction with different aspects of indoor environment contributes to occupants' overall satisfaction. The analysis is based on survey responses collected during a unique project commissioned by The Swedish National Board of Housing, Building and Planning. The results are representative of adults living in multi-family buildings in Sweden. The analysis shows that generally satisfaction with air quality has the highest impact on occupants' overall satisfaction. The occurrence of problems with indoor environment quality, particularly draught, dust and too low indoor temperature may affect occupants' overall satisfaction. However, it is demonstrated that the importance impact of perceived indoor environment quality on overall satisfaction is affected by individual and building characteristics.
► Discussion on how satisfaction with IEQ weights into occupants overall satisfaction. ► Presents insights into how occupants perceive indoor environment in Sweden. ► Presents insights into the set of problems appearing in dwellings in Sweden. ► Demonstrate impact of individual and building characteristics on overall satisfaction. ► Study shows how individuals’ and building characteristics affect IEQ perception
Publication year: 2013
Source:Building and Environment, Volume 63
Highlights
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Moisture dynamics in an historical masonry structure: The Cathedral of Lecce (South Italy)
May 2013
Publication year: 2013
Source:Building and Environment, Volume 63
Dampness is the main cause of masonry deterioration in many historical buildings but moisture behaviour is often difficult to understand. This is partly due to the complexity of moisture models which are rarely applied in monitoring plans. This paper reports the modelling of the moisture dynamics of the Cathedral of Lecce and its below ground Crypt (South Italy). The aim of this study is to give insights into moisture dynamics in buildings in order to overcome knowledge gaps in the field, such as those related to the estimation of the drying capacity of a microenvironment. The sharp front (SF) theory was used to analyse the main processes involved in rising damp. Moisture transfer dynamics were investigated to and from the walls and columns constituting the Crypt's masonry by first considering a steady state of balance between the water absorbed by capillary forces and that lost by evaporation. A varying state of non-equilibrium was then treated deriving simplified formulae to calculate indoor and outdoor evaporation rates. The model was validated with experimental surveys and site evaporation measurements. The paper shows that many physical quantities (e.g. height of the rise, capillary rise, water stored, drying flow rate, time-scale for drying) can be calculated and modelled over time using formulae that involve commonly available microclimatic and meteorological data (e.g. temperature, relative humidity and air speed). The information obtained can help to understand the periodic moisture behaviour leading to an explanation related to deterioration process dynamics. The results are useful for masonry maintenance.
► Capillary rising and evaporation dynamics were studied in an historical building. ► Simplified formulae were developed to derive evaporation rates indoors and outdoors. ► Common microclimatic and meteorological data were used in the calculations. ► Many physical quantities useful for masonry maintenance were modelled over time. ► The periodic moisture behaviour gave an explanation for the deterioration evidence.
Publication year: 2013
Source:Building and Environment, Volume 63
Highlights
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Editorial Board
May 2013
Publication year: 2013
Source:Building and Environment, Volume 63
Publication year: 2013
Source:Building and Environment, Volume 63
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Experimental Investigation On The Energy Performance Of Living Walls In Temperate Climate
Available online 21 March 2013
Publication year: 2013
Source:Building and Environment
Living Walls, a type of vertical greenery systems, are relatively light structures for architectural green cladding. They embed a thick curtain of plants nurtured by an automated watering system. Three Living Wall field tests are presented for investigating potential effects of the energy behavior on building envelopes. In particular, Living Walls were monitored in a Mediterranean temperate climate context at the latitudes of Northern and Central Italy. As a result, the dependence on the solar radiation forcing came out clearly. During sunny days, difference in temperature (monitored on the external surface) between the bare wall and the covered wall ranges from a minimum of 12°C (case C) to a maximum of 20°C (case A). The analysis was extended also to heat flux. The incoming (positive) heat flux through the bare wall was found to be higher compared to the Living Wall. Considering an overall thermal balance during the monitoring period, the outgoing heat flux through the Living Wall was higher . These results indicate that the use of green architectural cladding can significantly contribute to cooling energy reduction and offer a valuable solution for retrofitting existing buildings.
Publication year: 2013
Source:Building and Environment
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Combined use of wind-driven rain and wind pressure to define water penetration risk into building façades: the Spanish case
Available online 21 March 2013
Publication year: 2013
Source:Building and Environment
This article defines a new index to characterise the risk of atmospheric water penetration into building enclosures. This risk index integrates the two most relevant exposure parameters for this phenomenon into a single value, combining the water supply presented by driving rain and simultaneous wind pressure on the surface of the enclosure. Compared with the usual wind-driven rain exposure maps, the inclusion of driving rain wind pressure in this index permits a more complete assessment of the risk of penetration. Therefore, this index represents a powerful tool for defining more appropriate façade solutions for exposures that result in atmospheric water penetration. This risk index was calculated for 80 Spanish sites scattered around the Iberian Peninsula and the Canary and Balearic Islands using daily precipitation averages and wind speed averages for each location collected over 30 years. As a result, a risk index map has been produced for Spain. The risk characterisation obtained in this study enables an objective improvement of current Spanish building regulations governing the design of façades against the penetration of atmospheric water.
Publication year: 2013
Source:Building and Environment
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Inverse Prediction and Optimization of Flow Control Conditions for Confined Spaces using a CFD-Based Genetic Algorithm
Available online 22 March 2013
Publication year: 2013
Source:Building and Environment
Optimizing an indoor flow pattern according to specific design goals requires systematic evaluation and prediction of the influences of critical flow control conditions such as flow inlet temperature and velocity. In order to identify the best flow control conditions, conventional approach simulates a large number of flow scenarios with different boundary conditions. This paper proposes a method that combines the genetic algorithm (GA) with computational fluid dynamics (CFD) technique, which can efficiently predict and optimize the flow inlet conditions with various objective functions. A coupled simulation platform based on GenOpt (GA program) and Fluent (CFD program) was developed, in which the GA was improved to reduce the required CFD simulations. A mixing convection case in a confined space was used to evaluate the performance of the developed program. The study shows that the method can predict accurately the inlet boundary conditions, with given controlling variable values in the space, with fewer CFD cases. The results reveal that the accuracy of inverse prediction is influenced by the error of CFD simulation that need be controlled within 15%. The study further used the Predicted Mean Vote (PMV) as the cost function to optimize the inlet boundary conditions (e.g., supply velocity, temperature, and angle) of the mixing convection case as well as two more realistic aircraft cabin cases. It presents interesting optimal correlations among those controlling parameters.
Publication year: 2013
Source:Building and Environment
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Catalytic Oxidization of Indoor Formaldehyde at Room Temperature - Effect of Operation Conditions
Available online 22 March 2013
Publication year: 2013
Source:Building and Environment
Catalytic oxidization has been studied for elimination of formaldehyde, which is a common and toxic indoor pollutant. However, most of previous studies were conducted at temperature and concentration level much higher than typical room condition. The current paper is to determine the effectiveness of catalytic oxidization of formaldehyde at room condition. The performance of one noble metal catalyst (Pd/γ-Al2 O3 ) and two transition metal oxide catalysts (Fe2 O3 -MnO2 and CuO-MnO2 ) were studied at room temperature (23∼25 °C). The effect of concentration (0.5-5 ppm), relative humidity (20∼80%) and air velocity (0.2-1.0 m/s) were studied with single-pass breakthrough method. The major conclusions are: (1) Under room temperature and much lower concentration levels than in previous studies, the noble metal catalyst also demonstrated significantly better removal performance than metal oxide, maintaining a constant efficiency with time; (2) For different concentration levels, the efficiency of Pd/γ-Al2 O3 did not change significantly at concentrations below 5 ppm, while the efficiency increased as concentration decreased for Fe2 O3 - MnO2 ; (3) the effect of relative humidity on the catalysts performance was not consistent for different type of catalysts; (4) Regarding the mass transfer mechanism, the importance of external mass transfer process was revealed by tests at different velocity for surface coated catalyst and dimensionless analysis, while both internal diffusion and external mass transfer are influential for homogeneously formed catalyst pellet. (5) The effect of multi-pollutants existence was also investigated, and it was found that the presence of other VOCs slightly decrease the performance of Pd/γ-Al2 O3 , but not Fe2 O3 - MnO2 .
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Publication year: 2013
Source:Building and Environment
Graphical abstract
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Outdoor mean radiant temperature estimation in the tropical urban environment
Available online 27 March 2013
Publication year: 2013
Source:Building and Environment
A large scale estimation of mean radiant temperature (t mrt ) is conducted at two sites using customised globe thermometers. The measurement points cover a variety of urban typologies such as high-rise offices, parks, large water bodies and housing apartments. Data is derived using a t mrt formula calibrated to the local climate. Measurements for clear, sunny days are used for the analysis of the average diurnal t mrt profile. The diurnal t mrt profile shows that the t mrt differential between points is most evident during daytime, and is affected most significantly by shade cast by trees and buildings. Results also show that common urban constituents such as greenery and large water bodies, while proven to effectively reduce the ambient temperature of its surroundings throughout the day, do not affect t mrt significantly after nightfall. Further analysis reveals a correlation between sky view factor and t mrt in the day. Measurement points in different parks exhibit contrasting trends in t mrt reduction. Results of the study also provide a realistic threshold for the lowering of outdoor t mrt . Trees, shrubs and green walls may be introduced into the outdoor environment with the intention of reducing t mrt to a desirable level for a specific time range.
Publication year: 2013
Source:Building and Environment
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A State-space Model for Dynamic Response of Indoor Air Temperature and Humidity
Available online 27 March 2013
Publication year: 2013
Source:Building and Environment
The real-time control of indoor thermal conditions needs dynamic models of air temperature and humidity in rooms. The single-zone dynamic model may be inappropriate to depict the spatial variations of the air parameters, and the computational fluid dynamics model (CFD) is too computationally costly for real-time applications. In comparison, the multi-zone model, which models a space by several zones, may be a better choice. This paper presents a three-zone dynamic model to investigate the dynamic behaviors of indoor air temperature and humidity. By the means of linear approximation, the ordinary differential equations describing the dynamic thermal behaviors of indoor air are transformed into a state space form. The state equation is solved analytically, and the calculated results are then compared to a series of dynamic response experiments. It shows that the dynamic model developed in this paper predicts well the dynamic thermal responses of air in different indoor zones. The average errors of the calculated results compared with the experimental data are all less than 12% for the transient response with a time period of 2400 seconds. This paper also demonstrated the developed room model to simulate the transient responses of the indoor air temperatures and humidity ratios under different perturbations including a step change of supply air temperature, supply air flow rate, indoor occupant number and ambient temperature. The proposed modeling procedure may be especially useful for the development of the dynamic toolbox for the control design of HVAC components.
Publication year: 2013
Source:Building and Environment
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National Survey of Summertime Temperatures and Overheating Risk in English Homes
Available online 27 March 2013
Publication year: 2013
Source:Building and Environment
This paper presents one of the first national scale studies of summertime temperatures in English dwellings. Living room and bedroom temperatures were recorded in 207 homes across the England during the cool summer of 2007. Data was also collected by face-to-face household interviews. Fourteen homes (7%) were observed to be heated for part or all of the analysis period (July to August). Based on the BSEN15251 adaptive thermal comfort model, the 193 free-running dwellings would, in general, to be considered as uncomfortably cool. Over 72% of living rooms and bedrooms had more than 5% of hours below the BSEN15251 Cat II lower threshold, with over 50% having more than 5% of hours below the Cat III threshold. Detached homes and those built before 1919 were significantly cooler (p<0.05) than those of other type and age. Static criteria revealed that, despite the cool summer, 21% of the bedrooms had more than 5% of night time hours over 26°C; which is a recommended upper limit for bedrooms. The bedrooms of modern homes, i.e. those built after 1990 or with cavity walls, were significantly warmer (p<0.05). The bedrooms in homes built prior to 1919 were significantly cooler (p<0.05). The living rooms of flats were significantly warmer than the living rooms in the other dwelling types (p<0.05).The incidence of warm bedrooms in modern homes, even during a cool summer, is of concern, especially as there is a strong trend towards even better insulation standards in new homes and the energy-efficient retrofitting of existing homes.
Publication year: 2013
Source:Building and Environment
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Does the Rapid Development of China’s Urban Residential Buildings Matter for the Environment?
Available online 27 March 2013
Publication year: 2013
Source:Building and Environment
The exponential development of the urban real estate sector has become one of the main forces behind the development of China’s urban economy. The massive development of urban buildings, however, aggregates domestic environmental pressures. This study develops a four-quadrant matrix to elaborate the direct and indirect impacts on the construction and operation of urban residential buildings and applies a hybrid life cycle assessment (LCA) method to quantify the overall impacts. The results show that the total energy consumption, water consumption, chemical oxygen demand (COD), ammonia nitrogen (NH3 -N), sulfur dioxide (SO2 ), and nitrogen oxides (NOX ) emissions of the overall life span of the urban residential buildings accounted for 5.4%, 5.6%, 3.0%, 3.5%, 3.9%, and 4.0%, respectively, of the national total in 2010. The indirect productive impacts accounted for 76.2% of the energy consumption, 86.4% of the water consumption, and 81.6% of the air pollution emission in 2010. With respect to the potential mitigation alternatives in the next five years, a scenario analysis suggests that a moderate slow-down of the construction of new buildings should be the highest priority, and promoting the application of greener housing materials and more advanced construction techniques should also be desired.
Publication year: 2013
Source:Building and Environment
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Potential of structural thermal mass for demand-side management in dwellings
Available online 27 March 2013
Publication year: 2013
Source:Building and Environment
In order to avoid grid instability and decreasing production efficiencies of large power plants due to a widespread integration of renewable electricity production, demand-side management (DSM) is proposed as a solution to overcome the possible mismatch between demand and supply. This research evaluates the potential to improve the balance between the electricity use for heating and local electricity production of a nearly zero energy building (nZEB), by active use of structural thermal storage capacity of the building. To quantify the DSM potential of structural thermal storage, the cover factors and peak electricity demand of a single family dwelling equipped with a photovoltaic (PV) system are chosen. Detailed representations of the PV system and the dwelling itself, heated by an air-water heat pump, are implemented in the modeling environment of Modelica and simulated for the heating-dominated climate of Belgium. The influence of the insulation level and the embedded thermal mass of the construction on the DSM potential is evaluated. The impact of the heat emission system is estimated by comparing a floor heating system with a radiator emission system. Results show that although the influence on the cover factors is limited, the use of the structural storage capacity for demand-side management shows strong potential to shift the peak electricity use for heating to off-peak hours. Furthermore, it is shown that not only the availability of the thermal mass, but also the interaction between the heating system and the thermal mass is of significant importance.
Publication year: 2013
Source:Building and Environment
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Occupants interaction with electric lighting and shading systems in real single-OCCUPIED offices: Results from a monitoring campaign
Available online 29 March 2013
Publication year: 2013
Source:Building and Environment
This study presents the results of a monitoring campaign aiming to further our understanding of occupants’ behavior regarding the manual control of electric lighting in combination with shading control. It was performed on eight single-occupied offices in the city of Porto, Portugal during periods ranging from 28 to 60 days per office, and involving minimal if any disturbance to the occupants regular activities. A wide range of environmental variables including workplane illuminance, window and background luminance, transmitted solar radiation and occupation state was measured with high frequency (20 min time steps or shorter), and a specific emphasis was placed on evaluating luminance distributions within the field of view. The study aimed to address a set of key research questions regarding typical illuminance ranges and occupancy patterns found in offices and their relationship to electric lighting or shading control actions. The main findings that emerged from this analysis were that electric lighting and shading control were influenced more by occupational dynamics (arrival and departure) than by the environmental conditions experienced over the day (daylight workplane illuminance or transmitted solar radiation) although with a large degree of variability between occupants and/or offices. It also revealed that while most of the behavioral models analyzed for comparison purposes were in qualitative agreement with field observations (e.g. more lighting switch-on actions at arrival for lower daylight illuminance), only one model (Pigg’s model) predicted the frequency of lighting switch-off events observed during the monitoring campaign with reasonable accuracy.
Publication year: 2013
Source:Building and Environment
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Forecasting Simulations of Indoor Environment Using Data Assimilation via an Ensemble Kalman Filter
Available online 29 March 2013
Publication year: 2013
Source:Building and Environment
Data assimilation is widely used in weather forecasting and other complex forecasting problems such as hydrology, meteorology, and fire dynamics. Among various data assimilation methods, the Ensemble Kalman Filter (EnKF) is one of the best solutions to large-scale nonlinear problems while the computational cost is relatively less intense than other forecasting methods. In this paper, a new application of EnKF to forecast indoor contaminant concentrations is presented. The first part of the paper introduces the fundamental theories of data assimilation. The second part is a case study of forecasting the concentrations of a tracer gas in a multi-zone manufactured house by using a mass balance model with an EnKF. The benefits of EnKF and several important parameters for EnKF were discussed including numbers of ensemble members and observations, time step of observations, and forecasting lead time. The EnKF method presented is one of the first studies applied to the indoor environment field. It was shown that by using EnKF, the predictability of the simple indoor air model for the multi-zone space was improved significantly
Publication year: 2013
Source:Building and Environment
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Impact of a water-damaged indoor environment on kindergarten student absences due to upper respiratory infection
June 2013
Publication year: 2013
Source:Building and Environment, Volume 64
Children are relatively sensitive to health pollutants, including those in indoor environments. This study was conducted to explore the impact of a water-damaged indoor environment on children's weekly absences resulting from upper respiratory infection in a kindergarten. Twenty-six and 27 children were recruited from water-damaged and non-water-damaged classrooms in the same building, and 936 and 1017 person-weeks were followed up during the study period of 42 weeks. Weekly absence rates were computed from daily absence records. The weekly absence rate was significantly higher for children in the water-damaged classroom (2.99%) than for those in the non-water-damaged classroom (1.28%). After adjusting for gender and grade, the odds ratio for absence was 2.45 (95% CI: 1.15–5.24) for the children in the water-damaged classroom. Additionally, fungal concentration was significantly higher in the water-damaged classroom (993 CFU/m3) than in the non-water damaged classroom (404 CFU/m3). It is tentatively concluded that, in the subtropics, fungal concentration is a better indicator than humidity for early-stage water damage. Periodic fungal measurement is recommended to alter the water-damaged effect.
► The absence rate comparison between water-damaged and non-water-damaged classroom is presented. ► An odds ratio 2.45 indicated more absences occurred in the water-damaged class. ► Higher fungal concentration was detected in the water-damaged classroom.
Publication year: 2013
Source:Building and Environment, Volume 64
Highlights
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Mould resistance design (MRD) model for evaluation of risk for microbial growth under varying climate conditions
Available online 2 April 2013
Publication year: 2013
Source:Building and Environment
The risk for microbial growth depends on the microclimatic conditions at material surfaces. In the building envelope the microclimate will vary significantly with time. Whether microbial growth will occur or not, depends on humidity, temperature, duration of exposure and type of material (substrate). A limit state for onset of mould growth is here defined as a prescribed level observed by microscopy (40x) in laboratory tests. In this paper, a mould resistance design (MRD) model is proposed by which onset of growth can be predicted for an arbitrary climate history of combined relative humidity φ and temperature T . The model is calibrated and verified against a comprehensive set of new experimental data describing mould development on wood specimens (spruce and pine) as a function of exposure of relative humidity and temperature and material and surface characteristics. The exposure in the tests comprised both steady and time-variable conditions. Application of the MRD-model is demonstrated by assessment of mould risk based on results from simulations of an external wall design with hygro-thermal computer software (WUFI). The results show that a generally applicable, quantitative model together with building physics software can be used as a powerful tool for moisture safety design in practice. The model is designed to facilitate continuous improvement by further laboratory testing of various materials under specified climate conditions. The MRD-model is controlled by a basic parameter in the form of a critical dose D crit , which depends on the substrate or material surface on which growth may take place.
Publication year: 2013
Source:Building and Environment
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