Hyeun Jun Moon

Investigation of Physical Characteristics of Houses and Occupants’ Behavioural Factors for Mould Infestation in Residential Buildings

Mould growth can deteriorate indoor air quality in buildings. To alleviate problems in the built environment, accurate understanding of the risk factors associated for mould infestation is required. This study aimed at identifying the key risk factors that could affect mould growth on interior surfaces in residential buildings in Korea. Both the physical characteristics of buildings and the behaviour of occupants were recognised as key concerns. A questionnaire survey had been conducted randomly on a national basis for this research. The questionnaire included building-related factors, and occupants’ activities and behaviour. A total of 314 completed questionnaires were collected and processed for statistical analysis. The association of mould growth with locations and types (apartments, multiplex houses, and detached houses) of the residential buildings were tested. The relationships between mould growth and activity factors, for example, bathing, washing clothes, and opening windows were also considered. Apartments were shown to be more vulnerable to mould growth in comparison to other types of residential buildings. The results were compared with findings from other regions in the world to further understand the effects of these key factors.Mould growth can deteriorate indoor air quality in buildings. To alleviate problems in the built environment, accurate understanding of the risk factors associated for mould infestation is required. This study aimed at identifying the key risk factors that could affect mould growth on interior surfaces in residential buildings in Korea. Both the physical characteristics of buildings and the behaviour of occupants were recognised as key concerns. A questionnaire survey had been conducted randomly on a national basis for this research. The questionnaire included building-related factors, and occupants’ activities and behaviour. A total of 314 completed questionnaires were collected and processed for statistical analysis. The association of mould growth with locations and types (apartments, multiplex houses, and detached houses) of the residential buildings were tested. The relationships between mould growth and activity factors, for example, bathing, washing clothes, and opening windows were also considered...

Improvement of indoor living environment by occupants' preferences for heat recovery ventilators in high-rise residential buildings

This study examined the influence of heat recovery ventilators (HRVs) on energy savings and indoor air quality (IAQ) in high-rise residential buildings. Field measurements were performed in four residential units, which were validated by computer simulations and estimated the total annual energy consumption. The operation schedules for HRVs were determined by a survey of residents. Field measurement results indicate that HRVs could effectively improve IAQ and afford effective energy savings. The indoor concentrations of formaldehyde were reduced by 54.6% after HRVs were operated for 24 h. The initial concentration was reduced by 82% after 168 h. Toluene was the dominant volatile organic compounds (VOCs) in the indoor air. Its initial concentration was reduced by 50% and other VOCs were also reduced by 40.1% to 53.1% after HRVs were operated. Annual energy savings of up to 20.26% were predicted when HRVs were operated for 24 h continuously, exchanging sensible and latent heat. HRVs could save energy more effectively in winter than in summer due to the greater temperature difference between outdoor and indoor air. Based on the preferred operation schedules of homes surveyed, an annual energy savings could be as high as 8.52%.

Uncertainty Analysis in Mould Spore Transportation and its Application in an Existing Building

Indoor mould spore concentrations can be predicted by using a mathematical model that accounts for the mechanisms of spore transportation in a building with a mechanical ventilation system. The developed model considers the parameters related to a ventilation system and cleaning activity, and calculates indoor spore concentration, indoor/outdoor ratio, and the amount of deposited spores on interior surfaces in each building case. To get a more realistic outcome, an uncertainty analysis is conducted in the model by considering uncertainties associated with the parameters. The analysis results provide the distribution of spore concentrations as a function of time and give possible ranges of outcome with probability. Thus, a more realistic evaluation is available with the mathematical model. In addition, the identification of dominant parameters that have a major influence on spore transportation is performed using an appropriate parameter screening technique. Based on the identified dominant parameters, rec...Indoor mould spore concentrations can be predicted by using a mathematical model that accounts for the mechanisms of spore transportation in a building with a mechanical ventilation system. The developed model considers the parameters related to a ventilation system and cleaning activity, and calculates indoor spore concentration, indoor/outdoor ratio, and the amount of deposited spores on interior surfaces in each building case. To get a more realistic outcome, an uncertainty analysis is conducted in the model by considering uncertainties associated with the parameters. The analysis results provide the distribution of spore concentrations as a function of time and give possible ranges of outcome with probability. Thus, a more realistic evaluation is available with the mathematical model. In addition, the identification of dominant parameters that have a major influence on spore transportation is performed using an appropriate parameter screening technique. Based on the identified dominant parameters, recommendations can be made to maintain lower indoor spore concentrations in a specific building case. Application of the spore transportation model under uncertainty in an existing building is described in the paper.

Evaluation of the energy performance and thermal comfort of an air conditioner with temperature and humidity controls in a cooling season

Interest in energy and environmental problems is increasing worldwide, and efforts are being made to reduce the environmental burden of the worlds energy needs. Simultaneously, the demand for precise comfort control in buildings has increased as people have acquired a better quality of life. In most cases in residential or small commercial buildings, the desired indoor environment is achieved by set temperature controls for cooling, especially with Variable Refrigerant Flow (VRF) or Variable Refrigerant Volume (VRV) systems. However, this set-temperature control method may not guarantee thermal comfort for occupants in energy efficient operation. In this study, a new comfort control algorithm is suggested to ensure better thermal comfort of residents, taking into consideration indoor humidity and initial status of indoor air to run the air conditioner. Furthermore, the performance of the algorithm in terms of energy consumption and the thermal comfort ratio is examined and compared with that of the set-temperature control method.

An integrated comfort control with cooling, ventilation, and humidification systems for thermal comfort and low energy consumption

Over the past few decades, interest in issues related to the global environment and energy resources have increased in many industries, including the building sector which accounts for nearly 40% of the global energy consumption. Simultaneously, the demand for precise comfort control in buildings has increased because people have acquired a better quality of life and expect more from modern technology. In most cases, air-conditioning and ventilation systems have been installed in residential and commercial buildings. However, these systems can increase energy consumption requirements because of their lack of appropriate control. Such increases can be reduced by integrating the control of available sources of cooling, humidification, ventilation, lighting, and so on. An integrated comfort control strategy that integrates an air-conditioning, a humidifier, and a ventilation system by considering the outdoor environment is proposed for ensuring indoor thermal comfort and energy savings in buildings. The control strategy was evaluated in a virtual test bed with a variable refrigerant flow system, a humidifier, and ventilation fans. The performance of the proposed integrated comfort control was compared to that of conventional individual controls using EnergyPlus in terms of thermal comfort and energy consumption. The results showed that the integrated comfort control improved thermal comfort and lowered energy consumption. The methodology of deriving the integrated comfort control was expected to be useful for designing better control logics for thermal comfort and energy conservation.

Investigation of IAQ in Mechanically Ventilated Kindergartens and Elementary Schools in Korea

This study investigates the indoor pollutant levels in school buildings according to the operation of mechanical ventilation system. Three classrooms at two different elementary schools and four classrooms at two childrens day care center in Korea were chosen for investigation of indoor air quality with mechanical ventilation systems. Measurements were conducted for particulate matter, formaldehyde, total volatile organic compounds, carbon monoxide, carbon dioxide, nitrogen dioxide, ozone, radon, and total bacteria counts. Differences in indoor pollutants concentrations with and without operation of ventilation systems in each classroom were analyzed. The results show that operation of ventilation systems could decrease the levels of indoor pollutants in the classrooms, especially showing the reduction of HCHO concentrations by 14.9-62.3%. representative samples in Singapore. This study reported that indoor CO 2 concentration levels were lower in Singapore child care centers when compared to child care centers from other cold climate countries due to the higher ventilation rate of child care centers in Singapore. St-Jean et al. (11) have assessed indoor air quality in 21 day care centers in Montreal, Canada and determined association between building characteristics and IAQ. They reported that over 85% of the day care centers had a mean CO 2 concentration higher than 1000 ppm. The mean formaldehyde concentration was 22.9 µg/m 3 . They also reported that the presence of a mechanical ventilation system and a large surface of play are per child were significantly associated with lower CO 2 levels. Chitra and Nagendra (4) have investigated indoor air quality parameters in a naturally ventilated school building located near an urban roadway in India. This study reported that the mean value of indoor PM 10 , PM 2.5 , PM 1 and CO concentrations were found to be 149 ± 69, 61 ± 29, 43 ± 24, 0.10 ± 0.18 and 95 ± 61, 32 ± 16, 18 ± 9 µg/m 3 , 0.11 ± 0.14 ppm, respectively for winter and summer seasons. Norback et al. (12) have studied the relationship between VOCs, respirable dust, and personal factors to prevalence and incidence of sick building syndrome in six primary schools. They reported that the average CO 2 concentrations in all sites were greater than 800 ppm and indicated inadequate ventilation. Lee and Chang (13) investigated IAQ of five classrooms in Hong Kong. This study showed that the average respirable suspended particulate matter (RSPM) concentrations were higher than the Hong Kong air quality objective (annual average, 55 µg/m 3

Mould germination and the growth rate on wallpapers with different physical properties and the surface structures

Mould infestation problems in building are a complex phenomenon involving various causes such as environmental conditions, substrates, exposure time, and so on. The physical properties of building materials, e.g. surface structure, can be a key factor for mould germination and growth. The aim of this study is to determine the influence of the hygroscopic properties and surface structures of the wallpapers on the mould growth. An experimental study was conducted to characterize the hygroscopic properties and surface structures of the wallpapers. Four types of wallpapers with low chemical emissions were selected in order to exclude influence on chemicals on mould germination. Cross sections of the selected wallpapers were observed in order to characterize the surface structure of wallpapers using the scanning electron microscope. Three different fungi species were inoculated on the wallpapers, and mould growth on the selected wallpapers were observed for about two weeks. The results showed that the wallpapers with irregular patterns or a flat surface structure could delay mould growth. Wallpapers with higher moisture sorption capability would limit the development of mould growth under the experimental condition. Our study has shown a clear correlation between the mould growth rate and hygroscopic properties of the wallpapers.

Confirmation of the performance of exfoliated graphite nanoplatelets for pollutant reduction rate on wood panel

Exfoliated graphite nanoplatelets have been used as an additive for the improvement of a variety of properties. Nowadays, it is used as an adsorbent for pollutants, especially volatile organic compounds and formaldehyde. Additionally, exfoliated graphite nanoplatelets have been used as an additive in wood composites, because wood composites have a higher thermal conductivity than timber or typical wood-based panels. Therefore, exfoliated graphite nanoplatelets have been applied to high-density fiberboard which is a core material of wood flooring for the emission rate reduction of volatile organic compounds and formaldehyde and for increasing the thermal conductivity of wood flooring in radiant floor heating systems. Volatile organic compound emissions have been reduced significantly in wood composite boards according to the addition of exfoliated graphite nanoplatelets. The properties of formaldehyde emission and thermal conductivity decreased when 2% exfoliated graphite nanoplatelets are added to high-density fiberboard. However, these properties increased with the increase in the addition of exfoliated graphite nanoplatelets from 2% to 4%.

Effects of indoor temperature and background noise on floor impact noise perception

This study investigates effects of room air temperature and background noise on the perception of floor impact noises in a room. Floor impact noises were recorded in apartment buildings and were presented in an indoor climate chamber with background noise for subjective evaluation. Thirty-two participants were subjected to all combinations of three thermal conditions (20%C, 25%C, 30%C and relative humidity 50%), four background noise types (Babble, Fan, Traffic and Water), three background noise levels (35 dBA, 40 dBA and 45 dBA) and four floor impact noises (Man Jumping, Children Running, Man Running and Chair Scraping). After a 1-h thermal adaptation period for each thermal condition, the participants were asked to evaluate their thermal and acoustic perceptions. Statistically significant effects were found for the room air temperature and background noise level on the perception of the floor impact noises. Noisiness, loudness and complaints of floor impact noise increased with increasing room temperature and background noise level. Annoyance of floor impact noise showed a peak in acceptable thermal environment for general comfort. Room air temperature was a dominant non-auditory factor contributing to floor impact noise annoyance, while the floor impact noise level influenced the floor impact noise loudness and the floor impact noisiness was almost equally affected by the room temperature, background noise level and floor impact noise level. Further investigation is needed to fully understand the combined perception of floor impact noise under various indoor environmental conditions.

Effects of indoor water sounds on intrusive noise perception and speech recognition in rooms

While water sounds have been used for soundscape improvement, little is known about their applicability in indoor environments. In order to investigate the effects of indoor water sounds on noise perception, a simple indoor water fountain system was used to produce water sounds over three different types of indoor intrusive noise (traffic noise, higher frequency dominated noise of a chair scraping the floor above, lower frequency dominated impact noise of a man running on the floor above) and speech in a test laboratory. Intrusive noise perception (annoyance and pleasantness) and speech recognition (KS-MWL-A) were assessed with three water sound levels (40, 50, 60 dBA) at two exposure times (immediate and 50 min) of water sounds by 54 participants. Short-term exposure to indoor water sounds improved the pleasantness of intrusive noise without increasing annoyance except lower frequency dominated impact noise. The increase in exposure time to indoor water sounds did not affect intrusive noise perception and speech recognition. The water to noise ratio significantly affected annoyance and pleasantness of traffic noise only; however, the level of water sounds did not significantly affect intrusive noise perception. Indoor water sounds can be used to improve intrusive noise perception except lower frequency dominated floor impact noise with no adverse effects on speech recognition dependent upon the speech to water sound ratio. Practical application: This simple indoor water fountain can be directly applied to small offices or rooms to improve intrusive noise perception. When the simple fountain produces water sounds in a room, pleasantness of traffic noise throughout window openings or higher frequency dominated noise such as chair scraping noise can be improved without increment of annoyance and decrement of speech recognition. Short-term exposure to indoor water sounds is effective to increase pleasantness of the intrusive noises.