April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
The development of a reliable and validated model can facilitate the widespread application of ultra-violet photocatalytic oxidation (UV-PCO) for indoor air treatment and purification in building mechanical ventilation systems. This paper reports the development of a time-dependent model for predicting the performance of an in-duct PCO air cleaner under the conditions relevant to the actual applications. The model was developed by integrating light scattering model, reaction kinetic model, mass balance as well as optional ozonation model. The comprehensive model incorporates the influences of properties of light sources and catalyst, reactor geometry, mass transfer parameters, kinetic parameters, operational conditions, as well as ozonation effect. These parameters can be estimated easily from experiments and/or empirical equations. The UV-PCO model and UV-PCO model combined with ozonation model were validated with experimental results for fiberglass fibers coated with TiO2 (TiO2/FGFs) air filters under different conditions. There was good agreement between the prediction made by the model and the experiment results. It was also demonstrated that the developed model can be applied to predict the UV-PCO performance for carbon cloth fibers loaded with TiO2 (TiO2/CCFs) air filters.
Highlights
► A reliable two-phase based time-dependent UV-PCO model was developed. ► The comprehensive model incorporated the influences of various parameters. ► Ozonation model was proposed to describe the VOCs removal in the reaction with ozone. ► There was good agreement between the model predictions and the experiment results. ► The model can be applied to predict UV-PCO performance for different air filters.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
Building performance simulation is most often used to improve the design and at times the operation of buildings. Within a building model, the thermal characteristics of the envelope and the HVAC (heating, ventilation, and air conditioning) equipment are described by parameters that often cannot be estimated with high accuracy (e.g., occupant behavior, building envelope and HVAC equipment performance). Another common part of the design process of a building is a cost-benefit analysis to compare design options and different scenarios. The results are also heavily dependent on assumptions about uncertain economic parameters (e.g., future inflation rates and energy costs). In this paper a Monte Carlo based methodology for uncertainty quantification that combines the building simulation and the cost-benefit calculation is developed and demonstrated. Furthermore, Monte Carlo filtering is applied to determine the model inputs (e.g., design specifications and boundary conditions) that lead to the desired model output (e.g., a positive net present value of the investment). The aim is to propose a methodology that helps to enhance the design process or building operation and supports related decision-making.
Highlights
► We combine building performance simulation (BPS) with cost-benefit analysis (CBA). ► Monte Carlo (MC) based uncertainty quantification for the combined BPS/CBA. ► Analysis (MC filtering) which input parameter values lead to the desired results. ► We analyzed a solar thermal collector system for hot water and heating supply. ► Economic inputs have much higher influence on the result than the technical inputs.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
An extensive field study has been carried out in non-air-conditioned residences in Kota Kinabalu city, in Malaysia for the prediction and evaluation of the effect of the indoor thermal environment on occupants' thermal comfort. A total of 890 responses over one year were gathered. The hot-humid indoor climates of the surveyed buildings have been described and analyzed in terms of air temperature, globe temperature, relative humidity, wind velocity. The clothing insulation ensemble and metabolic rate of the occupants were also characterized. In the aim to assess the comfort temperature in residential buildings in the hot-humid tropics, each analyzed variable was thoroughly compared with the results of two field studies located in the hot-humid tropics, one conducted in Jakarta by Feriadi and Wong [1] and the second in Singapore by de Dear et al. [2]. Multiple and stepwise regressions were applied for the selection of the independent variable for neutral temperature prediction. Air temperature was chosen as an index for the indoor thermal comfort. The comfort temperature was determined using various approaches. The predicted temperature was found to be nearly 30 °C regardless of the adopted approach. The indoor comfort temperature was close to the recorded mean indoor air temperature of all responses having a difference of about 0.7 °C. The mean and the recorded indoor range temperatures seem to have effect in the prediction of comfort temperature.
Highlights
► Field study has been carried out in non-air-conditioned residences. ► This study was conducted in the equatorial hot-humid climate of Malaysia. ► The comfort temperature of 30 °C was determined using four approaches. ► Factors affecting comfort temperature prediction were analyzed and discussed.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
The influence of constant mechanical wind (CMW) and simulated natural wind (SNW) on human comfort and performance was investigated in a climate chamber. Eighteen subjects (twelve males and six females) were recruited. Four conditions with airflow were designed, including 28 °C with CMW and SNW, 30 °C with CMW and SNW. Two steady-state environments of 26 °C and 28 °C without airflow were also arranged for comparison. Performance was evaluated using three simulated office tasks – memory typing, addition and pattern matching. Subjects were required to finish questionnaires to evaluate their thermal sensation, thermal comfort, satisfaction of environment, workload and working motivation. The results suggested that both airflows would increase comfort in warm environments and the improvement effect was better at 30 °C than at 28 °C. SNW performed better for comfort and working motivation at 30 °C while CMW was better at 28 °C. The performance showed no difference under different environments except for few conditions in the addition task. The influence of CMW and SNW showed no significant influence on human performance.
Highlights
► Constant mechanical wind (CMW) and simulated natural wind (SNW) were investigated. ► CMW was better for comfort at 28 °C while SNW was better at 30 °C. ► Airflow could improve working motivation in warm environment. ► Airflow would not reduce human performance in warm environment.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
The scenario modeling method empowers building managers by enabling comprehensive performance analysis in commercial buildings, but is currently limited to data from the building management domain. This paper proposes that Linked Data and Complex Event Processing can form the basis of an interoperability approach that would help to overcome technical and conceptual barriers to cross-domain scenario modeling. In doing so, this paper illustrates the cross-domain potential of scenario modeling to leverage data from different information silos within organizations and demonstrates how to optimize the role of a building manager in the context of his or her organization. Widespread implementations of cross-domain scenario models require a solution that efficiently manages cross-domain data acquisition and post processing underpinned by the principles of linked data combined with complex event processing. An example implementation highlights the benefits of this new approach. Cross-domain scenario models enhance the role of the building manager within an organization and increase the importance of information communicated by building managers to other organizational stakeholders. In addition, new information presented to stakeholders such as facilities managers and financial controllers can help to identify areas of inefficiency while still maintaining building function and optimized energy consumption. Two key challenges to implementing cross-domain scenario modeling are: the data integration of the different domains' sources, and the need to process scenarios in real-time. This paper presents an implementation approach based on linked data to overcome interoperability issues, and Complex Event Processing to handle real-time scenarios.
Highlights
► Communicates holistic building performance information for building mangers. ► Optimizes the time spent by building managers on performance analysis. ► Links heterogeneous datum sources using linked data. ► Uses data from different organizational silos for the purposes of building performance analysis. ► Efficiently processes data from multiple domains through complex event processing.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
This research studies buoyancy-driven flow patterns in two series-connected chambers, which have the same height and a common divider. Theoretical analysis categories the ventilation modes of two series-connected chambers as the pull and push types of displacement ventilation, according to an extra resistance force of ventilation due to the unforced chamber. For the pull-type displacement ventilation, there is only a buoyant layer in the forced chamber and the extra resistance force is due to the additional upstream opening(s). This paper focuses on the steady-state push-type naturally displacement ventilation, when the forced chamber is located upstream in two series-connected chambers. For the push-type displacement ventilation, a two-layer stratification develops in both chambers, and the extra resistance force is not only due to the additional opening(s), but also the stratification in the downstream unforced chamber. This paper presents a derived theoretical model and analogous salt-bath experimental results, and shows reasonable agreement between them. Our results show that a different opening level on the unforced side wall changes the properties of both buoyant layers in two chambers. Among the openings on the unforced side wall, only those covered by the buoyant layer of the unforced chamber play the role of the exit, and the theoretical model only takes account of their parts for the push-type displacement ventilation. The effects on the opening area ratio of the unforced chamber and the same reduced area at a different opening location are also investigated in this study.
Highlights
► A theoretical model and analogous experiments are presented. ► A different opening level on the unforced side wall changes the flow performance. ► Among the unforced side wall openings at different levels, only certain of them act as exits. ► Experimental results show reasonable agreement with theoretical predictions.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
This paper assesses the practicability of meeting the German federal government's energy-political targets for the residential sector by analysing the potential future development of this sector in an aggregated bottom-up model. The domestic building stock is considered in terms of the likely developments in the housing market, as well as the energetic characteristics of current and future buildings. The employed method is based on deterministic projections of demand floor space and demolition/refurbishment rates. The key novelty lies in the focus on developments in this sector in Germany; existing studies have not had this focus and have therefore employed a more rudimentary methodology, for example with static refurbishment rates, shorter time horizons or no spatial differentiation. The total resulting final heating demand of domestic buildings of about 500 TWh lies above that of other studies in 2050, which is mainly due to the conservative assumptions regarding renovation activity and new build made in the present case. Hence in the reference scenario the target for 2020 is not met, suggesting that further political intervention is required. In another scenario, it is shown that a drastic increase of the renovation rate is required in order to meet the 2020 target, especially amongst existing single family buildings. The supply side is only indirectly considered due to the aggregated nature of the model, which could be improved for further work, but the presented method nevertheless represents a good compromise between using solely freely available data and obtaining superior degree of precision to previous studies.
Highlights
► A bottom-up model of the German residential sector is developed. ► The novelties are: higher granularity, longer timeframe, use of public data. ► Scenarios show a drastic action needed to meet the 2020 target. ► Policy measures should focus on owner-occupiers in single family houses. ► More detailed (public) data on heat supply systems should be sought.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
The time series of indoor and outdoor CO concentrations in natural ventilating rooms were monitored continuously and simultaneously in summer, and the relationships between indoor and outdoor CO concentrations at two sampling locations in the central area of Shanghai were examined and discussed. Linear regression analysis was employed to correlate indoor concentration levels with outdoor concentrations, and the diurnal cycles of the indoor and outdoor CO concentrations show positive correlations at both sampling sites. The monitoring data also indicate that the indoor to outdoor ratios of CO concentrations in the test natural ventilating rooms are less than but close to 1. In addition, a predicting model based on a mass balance assumption of indoor pollutants was applied for estimating the indoor CO concentrations by using the outdoor test data as inputs, resulting in good agreement with the test curves for the two sampling sites.
Graphical abstract
Highlights
► Indoor/outdoor CO levels of natural ventilation (NV) rooms in summer were tested. ► Diurnal cycles of the indoor/outdoor CO concentrations show a positive correlation. ► I/O ratios of the CO concentrations of NV rooms are less than but close to 1. ► Indoor CO concentrations can be obtained by using the regressed outdoor CO curves.
Available online 18 February 2013 Publication year: 2013 Source:Building and Environment
The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the microclimate region and low intake fractions of 1.90×10−4 and 5.9×10−4 were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6×10−4 for fine particle sizes (1 μm) and 2.95×10−4 for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the microclimate.
Highlights
► A ceiling-mounted coaxial PV nozzle was modeled. ► Particle transport and distribution was investigated using two sources locations. ► The predicted flow characteristics were validated experimentally. ► The nozzle was able to deliver improved air quality to the occupants breathing zone. ► The canopy provided a protective zone by reducing particles migration
Available online 18 February 2013 Publication year: 2013 Source:Building and Environment
As an advanced and efficient ventilation method, personalized ventilation (PV) has attracted more and more attentions. This paper investigates the pollutant transmission characteristics and personal exposure under the combination of two types of PV terminals and three kinds of typical background ventilation systems in an office with four work stations. Three kinds of cases are simulated and analyzed, including the most unfavorable condition, the most favorable condition and the ordinary condition. The results show that the interactions between PV and displacement ventilation (DV) or PV and under-floor air distribution (UFAD) are obviously stronger than that between PV and mixed ventilation (MV). Under a constant total ventilation rate, PV with a high flow rate may disrupt the characteristics of the background ventilation system and increase the personal exposure if comparing with the background ventilation alone. The advantage of PV depends on the proper combination of PV and its background ventilation system.
Highlights
► We simulate the transmission of pollutants in an office. ► We study the combinations of personalized ventilation (PV) and background ventilation systems. ► Personalized airflow may disturb the background airflow and increase personal exposure. ► The combination of PV and its background ventilation system should be properly designed.
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
If an appliance perceives the location or health status of a resident in a smart home, it can actively provide more intelligent service. Thus, residents manually control the air conditioning in a passive service environment, whereas a location-based human-adaptive air conditioner autonomously regulates the temperature in a smart home according to residents' patterns of living or health status. This research is focused on developing a human-adaptive air conditioner that functions by measuring human factors with a non-terminal-based indoor positioning system, to provide high-quality intelligent service in single-person households. In this paper, four algorithms were introduced to provide high-quality intelligent service with a location-based human-adaptive air conditioner: (1) calculation of a resident's location and speed, (2) estimation of physical activity and metabolic rate, (3) calculation of the PMV index according to metabolic rate, and (4) an intelligent control algorithm. Finally, the feasibility of the design is evaluated experimentally on a test bed, using a pyroelectric infrared sensor-based location-aware system (PILAS) as the positioning system.
Highlights
► A human-adaptive air conditioner that functions by measuring human factors. ► To get high-quality intelligent service, intelligent control algorithm is proposed. ► Resident's location and speed is calculated using a non-terminal-based IPS. ► Physical activity and metabolic rate is estimated. ► PMV index according to metabolic rate is calculated.
Available online 19 February 2013 Publication year: 2013 Source:Building and Environment
Adsorption based air cleaning technologies have long been employed in various industrial applications but it has remained marginal in office and residential buildings. The present study presents a first step in the development of physically-based models that could help civil engineers to improve the design and maintenance of such systems by considering the complexity of the indoor air cleaning problem, especially variable concentrations, temperature and airflow rate. The breakthrough curves of six challenge gases in a packed bed of non treated granular activated carbon were measured for gases as singles, and then as a mixture, in dry air and under isothermal conditions. On the whole, the results indicate good agreement between measured and predicted concentrations at the filter outlet. Considering the large number of contaminants that can be found in indoor settings, this suggests that the questions of efficiency and lifetime of the filter are probably much more difficult to answer than one can think. Finally, the paper discusses some possible improvements of the models as a way to increase accuracy, but also to allow for the simulation of even more realistic configurations of filter operation.
Highlights
► Fundamentals of adsorption dynamics in activated carbon filters, for indoor air quality applications. ► Heat and mass transfer model validated with experimental data, in dry conditions. ► The model is able to simulate in realistic configurations of operation, with variable inlet parameters.
Available online 19 February 2013 Publication year: 2013 Source:Building and Environment
Intelligent buildings are beginning to utilize sensor networks for monitoring and protecting indoor air quality against contamination events. This paper presents a methodology for determining where to install such sensors. In particular, a multi-objective optimization problem is formulated for minimizing the sensor cost, the average and the worst-case impact damage corresponding to a set of contamination event scenarios. Each contamination scenario is comprised of parameters characterized by some given probability distribution. Based on these distributions, a set of representative contamination scenarios is constructed through grid and random sampling, and the overall impact of each scenario is computed, thus providing a solution to the sensor placement problem. The proposed methodology is illustrated by two case studies, a simple building with five rooms and a realistic building with 14 rooms.
Highlights
► Installation of air quality sensors in indoor building environments. ► Multi-objective optimization program that minimizes sensor cost and impact risk. ► Contamination scenarios construction based on probability distributions. ► Sensor placement optimization with respect to the contamination scenarios. ► Evaluation of methodology using building case studies.
Available online 19 February 2013 Publication year: 2013 Source:Building and Environment
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.
Highlights
► Capillary rising and evaporation dynamics were studied in a 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.
Available online 19 February 2013 Publication year: 2013 Source:Building and Environment
Building energy simulations are mostly implemented using network or multi-zone models that do not consider indoor air temperature and velocity distribution. However, the recent introduction of personal ventilation, floor-heating systems, and displacement ventilation positively utilizes a nonuniform indoor environment to meet the demand for both energy efficiency and thermal comfort. Therefore, it is expected that building energy simulation results will be significantly impacted by the choice of an appropriate reference air temperature for the calculation of heat transfer through constructed materials. This means that the air temperature distribution needs to be taken into account for nonuniform environments when carrying out energy simulations. An alternative approach to this problem is to combine a computational fluid dynamics (CFD) simulation directly with a network model; however, this approach is unfortunately too computationally time-consuming. In this study, we propose an acceptably fast simulation method that couples the contribution ratio of indoor climate (CRI), which is extracted from CFD results and indicates the individual impact of all heat factors, with the network model to implement an energy simulation that incorporates a temperature distribution. With the introduction of CRI, it is possible to achieve a precision as high as that of CFD and a calculation speed as fast as that of the network model. A case study simulating the thermal load of a single office room was carried out with the CRI-coupled method. The energy demand result calculated by CRI-coupled method was 15–20% lower than that of a non-coupled network simulation.
Highlights
► We develop a method to integrate spatial distributions into energy simulation (BES). ► We utilize the contribution ratio of indoor climate (CRI) extracted from CFD results. ► By the proposed method, the BES can be achieved at a much-reduced calculation load. ► A lower difference was obtained when comparing to a non-coupled network simulation.
Available online 20 February 2013 Publication year: 2013 Source:Building and Environment
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.
Highlights
► 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
Available online 26 February 2013 Publication year: 2013 Source:Building and Environment
Activated carbon (AC) has been widely used in indoor air quality (IAQ) control for removal of hazardous volatile organic compounds (VOCs). A detrimental effect of this adsorption technology is that bacteria multiplied on AC may deteriorate IAQ. In this paper, antibacterial AC nanocomposites with well-dispersed silver nanoparticles (Ag/ACs) were prepared by the attachment of Ag+ on the functionalized AC surface via ion-dipole interactions and the subsequent in-situ reduction of Ag+. The surfaces and microporous structures of the obtained Ag/ACs were analyzed by means of scan electron microscope (SEM) and pore size surface area analysis. Antibacterial tests were performed using Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) as model bacteria. Antibacterial activity against airborne bacteria and toluene adsorption capacity of AC nanocomposites were further evaluated. It was found that the introduction of Ag nanoparticles significantly improves antibacterial effect of AC but slightly reduces toluene adsorption ability. Ag/ACs can efficiently kill bacteria within 100 minutes without decreasing adsorption ability toward toluene.
Graphical abstract
Highlights
► Synthesis and characterization of Ag-coated activated carbon nanocomposites. ► Ag/ACs can efficiently kill bacteria within 100 minutes. ► Ag/ACs remain high adsorption capacity toward VOCs
Available online 26 February 2013 Publication year: 2013 Source:Building and Environment
Assessing the atmospheric environmental impacts of district heating (DH) systems is of increasing importance as the environmental concerns and the eco-sustainability concept is more and more widespread in the energy sector around the world. However, this issue has been overlooked to some extent for past decades in China, which led to inappropriate assessments only by measuring pollutant emissions per unit floor area or unit heat supply. In this paper, we present an atmospheric environmental assessment model incorporating the state of the art AERMOD modeling and the concept of normalized population distribution weights (NPDWs) to compute the mean spatial distribution (MSD) of pollutants for qualitatively evaluating the atmospheric environmental impacts of DH. We demonstrate the model in assessing different heating scenarios, characterized by basic heat load ratio in a real-life combined district heating system of Daqing city with a population of 2.7 million. The results show that the presented model and MSD concentrations furnish a better base to assess the atmospheric environmental impact. We also show how the combined district heating system can undertake a part of CO2 emission reduction burden in the DH sector at a city-scale.
Highlights
► Atmospheric environmental impact of a combined heating system is studied. ► An assessment model based on AERMOD is proposed. ► Population distribution is taken into account in the model. ► Mean spatial distribution of pollutants are proposed to measure the impact. ► Combined heating systems using gas-fired boilers are environmentally efficient.
Available online 28 February 2013 Publication year: 2013 Source:Building and Environment
Volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) constitute important classes of indoor air contaminants and characterizing their emissions from building materials and consumer products is of great interest for the purpose of risk assessment and developing environmentally benign products. Compared with emission chamber studies, emission models provide a more cost efficient and powerful way to examine the emission behaviors of VOCs and SVOCs. The objective of this paper is to review existing mechanistic models for predicting VOC and SVOC emissions from various sources, investigate their differences and similarities, and discuss the mass-transfer mechanisms on which the models are constructed. Because the usefulness of the emission models largely depends on the availability and reliability of model parameters, techniques for estimating key model parameters are also reviewed. The models covered in this review fall into three categories: models for VOC emissions from solid materials; models for VOC emissions from liquid materials; and models for SVOC emissions. VOC and SVOC emissions can be modeled within a very consistent mass-transfer framework with the three model categories being intimately related. While substantial advances have been made in developing predictive models and understanding emission mechanisms, large knowledge gaps still exist and further research is needed.
Highlights
► Mechanistic models for predicting VOC and SVOC emissions are reviewed. ► Covers VOC emissions from wet and dry materials and SVOC emissions from dry materials. ► Techniques for estimating key model parameters are also reviewed. ► 003FVOC and SVOC emissions can be modeled within a consistent mass-transfer framework
April 2013 Publication year: 2013 Source:Building and Environment, Volume 62
Materials that are stored or used in damp conditions may be subject to mould growth. However, all materials are not equally susceptible; for each specific material, there is a critical moisture level for mould growth. If this is exceeded, there is a risk that mould fungi will develop on the material. This level can be determined in accelerated laboratory tests, at constant temperatures and relative humidity (RH) favourable to mould growth. Within a building however, these parameters are expected to vary from one part of the construction to another, and are seldom constant; there is fluctuation in temperature and RH due to seasonal or shorter-term variations. In this study, test pieces of the same materials tested in a laboratory environment were placed in three outdoor ventilated crawl spaces and three outdoor ventilated attics, where the temperature and RH varied, and mould growth on the test pieces was studied over 2.5 years. Material-specific mould growth curves were produced based on critical moisture levels, as determined in laboratory experiments under constant temperature and RH. When the actual conditions of RH and temperature exceeded these curves, there was mould growth on the test pieces if the time was sufficiently long. The conclusion from the study is that although conditions in laboratory studies are simplified and accelerated, the results serve well to indicate mould growth within a building construction.
Highlights
► Mould growth on building materials exposed in attics and crawl spaces was studied. ► The relative humidity and temperature conditions were monitored at each test-site. ► Growth limit curves were created based on laboratory data of critical moisture levels. ► The results were compared to results from laboratory studies. ► Laboratory tests can be used to predict mould growth in within a building.
