Janghoo Seo

Influence of Environmental Factors on Performance of Sorptive Building Materials

Recently, sorptive building materials have been used to improve indoor air quality in Japan. By making use of sorptive building materials, the concentration of volatile organic compounds (VOCs) within rooms can be reduced without the need to install any special equipment. In this paper, the effect of sorptive building materials with respect to reducing toluene concentrations in the air of small test chambers has been assessed using sorption flux. We have also examined how environmental parameters influence concentration reduction performance. The effectiveness of activated carbon at reducing toluene concentrations when used as a sorptive building material depend considerably on the air exchange rate of the chamber, the load factor of the sorptive materials and the mass transfer coefficient. In order to evaluate and compare the sorptive performance of various building materials, it is necessary to conduct tests under identical parameter conditions. The experimental results and computational fluid dynamics analysis show that sorptive building materials are a fairly effective agent for reducing indoor VOC concentrations, and that this effect can be expected to be replicated during practical use.

Measurement of 2-ethyl-1-hexanol emitted from flooring materials and adhesives

It has been reported that 2-ethyl-1-hexanol (2E1H) was emitted through hydrolysis between di-2-ethylhexyl phthalate used as plasticizer in flooring material and moisture generated from a strongly alkaline material such as concrete slab. The purpose of this study was to clarify the relationship between diffusion of 2E1H in flooring material and 2E1H emission rate from floor surface. In this study, we measured 2E1H emitted from floor paper, poly(vinyl chloride) (PVC) tile, cushion floor and carpet for 200, days and effective diffusion coefficients for 2E1H in various flooring materials were measured. Effective diffusion coefficients of 2E1H for cushion floor and PVC tile were 115 × 10−9 and 7.8 × 10−9 m2/s, respectively. Emission rate of 2E1H emitted from flooring material significantly depends on the kind and shape of flooring materials and was influenced by the effective diffusion coefficient for 2E1H of flooring material. Emission rates of 2E1H from floor surface varied with the amount of 2E1H and resin present in the adhesive. When carpet was attached to the flooring material with high water content using adhesive, emission of 2E1H significantly increased. The results show that primary and secondary emissions of 2E1H from the adhesive influence the emission rate of 2E1H for flooring material.

Evaluation of the Convective Heat Transfer Coefficient of the Human Body Using the Wind Tunnel and Thermal Manikin

Abstract This study was conducted to determine the convective heat transfer rates (αc) of each part of the human body and of the whole body when a human is in a standing or sedentary posture in an outdoor environment. A wind tunnel was used to reproduce the side wind in an outdoor environment, and a naked thermal manikin was used to control the detailed thermal characteristics of the human body. Accurate radiation analysis was employed to evaluate the radiation effect of the thermal manikin. The αcs of the whole body and of each part of the body increased along with the wind velocity in the standing and sedentary postures. In the standing position, the αcs of the head, feet, and hands, the terminuses of the human body, were about 20-30% higher than the average αc of the whole body. In the sedentary position, the αcs of the head, hands, and arms, the terminuses of the human body, were about 20% higher than the average αc of the whole body. The αcs in this study were lower than those obtained from the climate chamber. Meanwhile, they were similar to or slightly higher than those from the results in wind tunnels.

Measurements of formaldehyde and TVOC emission from paints and coating materials using small chamber method for building composites

An optimal test method for paint is proposed; additionally, the Field and Laboratory Emission Cell (FLEC) method used in Europe is applied as a substitute for the 20 L small chamber method. The emission factors of total volatile organic compounds (TVOC) and formaldehyde from oil-based paint, emulsion paint, and water-dispersion paint with a coating weight of 300 g/m2, cured for 24/48 hours, were measured using the 20 L small chamber method. The emission rate of TVOC and formaldehyde from all paints began to stabilize after approximately 7 days after 24/48 hours of curing even though Korean standards stipulate that paint should be measured and analyzed after the third day of application. The emission factor of TVOC and formaldehyde from oil-based, emulsion, and water-dispersion paints were also measured using the FLEC method. There was good correlation between the 20 L small chamber method and the FLEC method for oil-based, emulsion, and water-dispersion paint emissions. With the FLEC method, using paints prepared under identical conditions, the emission rate was stable 24 hours after installation of samples because the air flow rate of FLEC is much higher than that of a 20 L small chamber, and the relative cell volume of FLEC is much smaller than that of a 20 L small chamber.

Optimum Installation of Sorptive Building Materials Using Contribution Ratio of Pollution Source for Improvement of Indoor Air Quality

Reinforcing the insulation and airtightness of buildings and the use of building materials containing new chemical substances have caused indoor air quality problems. Use of sorptive building materials along with removal of pollutants, constant ventilation, bake-out, etc. are gaining attention in Korea and Japan as methods for improving such indoor air quality problems. On the other hand, sorptive building materials are considered a passive method of reducing the concentration of pollutants, and their application should be reviewed in the early stages. Thus, in this research, activated carbon was prepared as a sorptive building material. Then, computational fluid dynamics (CFD) was conducted, and a method for optimal installation of sorptive building materials was derived according to the indoor environment using the contribution ratio of pollution source (CRP) index. The results show that a method for optimal installation of sorptive building materials can be derived by predicting the contribution ratio of pollutant sources according to the CRP index.

Influence of water content in sub-flooring materials using adhesive on chemical compounds emission

Indoor air pollution is caused predominantly by emission of primary pollutants from building materials or finishing materials. Recently, there has been increasing interest in the new secondary pollutants caused by chemical reaction of the primary pollutants. In this study, the pollutants emitted from poly(vinyl chloride) (PVC) flooring material were measured, and 2-ethyl-1-hexanol (2E1H) and volatile organic compounds (VOCs) emitted from composite building materials made of PVC flooring material used as a self-leveling flooring were measured to identify the mechanism of emission of 2E1H. The moisture sorption isotherm was measured with a Magnetic Suspension Balance to examine the moisture content of the self-leveling flooring material and its effect on emission of 2E1H. 2E1H was emitted from the PVC flooring material through hydrolysis or oxidation of di-2-ethylhexyl phthalate (DEHP). The composite building material including the self-leveling flooring material emitted more 2E1H through hydrolysis over time. It was determined that liquid prevails in the self-leveling flooring material when the water content is higher than 4% and vapor prevails when the water content is lower than 4%. The prevailing liquid in the flooring material contributes to the increased emission of 2E1H and the prevailing vapor in the material did not cause increase in emission of 2E1H. It is considered that control of water in the self-leveling flooring material or concrete slab is very important in order to inhibit emission of 2E1H through hydrolysis of DEHP on the floor.

Development and Performance Evaluation of Light Shelves Using Width-Adjustable Reflectors

In recent years, there has been an increase in the consumption of energy for lighting purposes, which has led to an increase in the number of studies being conducted on this subject. Most studies have focused on light shelves, which are daylighting systems used for reducing the lighting energy required for the interiors of buildings. However, the existing light shelves cannot actively deal with external environmental factors, which often lead to an infringement of the right to light during the night when the performance of the light shelf deteriorates. Therefore, in this study, we propose a light shelf with a width-adjustable reflector and verify its validity using a testbed. The reflector of the proposed light shelf system is modularized so that the length can be adjusted in stages. The optimum width of the light shelf is calculated in terms of the energy reduction and uniformity ratio improvement, and the obtained optimum width is varied depending on the season. We find that the width-adjustable reflector can save 20% and 21.6% more lighting energy than light shelves with fixed reflector widths of 0.3 m and 0.6 m, respectively.

Evaluation of a light shelf based on energy consumption for lighting and air conditioning

The shading effects of light shelves in indoor thermal environments have not been investigated to date. Thus, this study aims to identify the effectiveness and appropriate parameters required for a light shelf by evaluating its performance in the presence of lighting and air conditioning. A full-scale testbed was established in this study for evaluating the performance of the light shelf. Moreover, the performance evaluation was conducted by calculating the energy consumed for lighting and air conditioning to maintain proper temperature and illuminance. This study found the following: (1) During summer, the use of a light shelf would reduce the energy consumption for lighting and air conditioning by 0%–10.5% and 6.9%–9.3%, respectively. (2) During winter, the use of a light shelf would increase the energy consumption for lighting and air conditioning by 0%–25.3% and 0.2%–3.2%, respectively, which is undesirable. (3) Increasing the angle of the light shelf would increase the amount of light penetrating to indoors, thus would reduce the energy required for lighting. Based on these findings, we recommend the installation of a detachable light shelf that is 0.6-m wide with a 30° angle for buildings in Korea; and during winter, the light shelf should be removed to save energy.

Control of emission rates of chemical compounds emitted by controlling their mass transfer coefficients on the surface of the tested building material

The air change rate in the chamber, the loading factor of the materials, and the mass transfer coefficient are very important factors in the measurement of chemical compounds, because they have a decisive effect on emission rates of chemical compounds emitted from materials. Small 20-liter chambers, such as the advanced pollution and air quality chamber, are generally used in Korea and Japan for measuring the amount of released chemicals. In this study, chemical compounds released from building materials and adhesives were measured using a chamber proposed by the authors to control the mass transfer coefficient on the surface of the tested building material and we examined the distribution of chemical compounds concentrations in the chamber by means of computational fluid dynamics to confirm test reliability. The chamber was controlled and maintained at 28 °C, a relative humidity of 50%, a mass transfer coefficient of 14 m/h with an air change rate of 0.50 h−1, and formaldehyde and total volatile organic compounds were emitted from the flooring material and adhesive. As the mass transfer coefficient on the surface of the tested building material increased, the emission rates of chemical compounds measured using the proposed chamber increased. The mass transfer coefficient on the surface of the tested building material significantly influenced the emission rates of the chemical compounds released from the building material and adhesive.

Long/Short-Term Performance Test for Evaluating the Reduction of Indoor Formaldehyde Using Sorptive Building Materials

In this paper, a test method for evaluating the ability of sorptive building materials to reduce the concentration of formaldehyde is examined. The authors developed a new method that uses a small chamber to test the suppressive effect of sorptive building material on formaldehyde-emitting materials. Two small chambers were prepared, with the formaldehyde-emitting building material placed in one chamber and a composite building material comprised of sorptive building material attached to the formaldehyde-emitting building material in the other. The formaldehyde emission factors of the two chambers were compared, and the equivalent ventilation rate Qads was calculated. The test method would enable the indoor concentration reducing performance and the suppressive performance of the sorptive building materials to be evaluated at the same time. The suppressive effects of several kinds of sorptive building materials were examined, and accordingly the validity of the test method was verified. The continuous reduction performance of indoor formaldehyde for sorptive building materials using sorption breakthrough capacity method was also evaluated.