This study proposes the air-surface temperature ratio (ASTR) method as an in situ measurement method to rapidly and accurately measure wall U-values in existing houses. Herein, the wall U-values were measured in situ applying the heat flow meter (HFM) method of ISO 9869-1 and the ASTR method. The results obtained using the HFM and ASTR methods were compared, and the relative error rate and accuracy of the measurements were analyzed. The aging rates of the wall U-values were compared and analyzed by comparing them with the wall U-values before and after the installation of retrofit insulation. Subsequently, the ASTR method was used to analyze the U-value measurement error rates according to the number of measurement days (one day to seven days). In addition, this method calculated the appropriate measurement period required to satisfy the measurement conditions. As a result, the mean relative measurement errors rates of the HFM and ASTR methods were ±3.21%. The short-term (one day) and long-term (seven days or longer) measurement results indicated the average error rates as approximately ±2.63%. These results were included in the tolerance range. Therefore, it was determined that the ASTR method can rapidly and accurately measure wall U-values.

No abstract

Daylight responsive dimming control systems are analysed in a small office with a double-skin envelope to recommend better control alternatives for achieving target illuminance and better energy savings. Computer simulations are performed for photosensors positioned at three different locations in three different shielding conditions. These are applied in both northwards and southwards facing rooms. Daylight conditions included three sky types at different times of the day and year. Shading device conditions are: a horizontal blind on the external envelope, a combination of a horizontal blind on an external envelope and a retractable shading device on an internal envelope. A partially-shielded condition generally achieved good dimming performance under clear and intermediate cloudy skies. Regardless of position, the unshielded photosensors generally fails to achieve target illuminance, providing excessive dimming levels for all tested daylight conditions. Reasonable lighting energy savings are achieved. The savings were not critically influenced by the photosensor positions, but rather are impacted significantly by the sky conditions. Linear prediction models are studied to determine the relationship between photosensor signals and workplane illuminance according to photosensor conditions. The models are acceptable with low significance levels. The linear correlation is best for the partially-shielded condition, but the correlation is weaker for the fully-shielded photosensor.

Abstract:In high-rise buildings, the stack effect causes various problems, especially problems related to excessive pressure differences across main entrance doors and elevator doors, particularly in heating seasons. To reduce the stack effect, this study aims to find effective operation schemes for the HVAC systems in a 60-story commercial building, located in Seoul, Korea. Field measurements were conducted to identify the problems related to the stack effect in the building. Computer simulations were conducted to examine the effectiveness of various HVAC operation schemes in reducing the stack effect. Then, an optimum and effective operation scheme was adopted from the computer simulation results and applied in the field. The adopted scheme was used to pressurize the upper zone of the building. Through field application and an adjustment process, a proper amount of air volume was found to effectively pressurize the upper zone of this building, solving the problems related to the stack effect. The required air volume for pressurization was maintained in the building by reducing the volume of the exhaust air (EA) while maintaining a constant volume of outdoor air (OA).

In this study, the indoor concentrations of pollutants from different materials that are used in kitchens and living rooms are measured during the construction process. The measurements are carried out in three households: the first is built using only conventional materials, the second household uses some environmentally sound materials and the last uses nothing but environmentally sound materials. The construction stage that had the greatest effect on indoor pollutant concentration is evaluated after installing all of the materials and measuring the indoor concentrations throughout the construction process. The pollutant concentration is measured 10 times at different stages of construction and in the days following the completion of construction. Results show that the living room and kitchen furniture made of particle board and MDF emits the largest amounts of pollutants. In addition, of all the pollutants measured, including benzene, toluene, ethylbenzene, styrene, 1,4-dichloro-benzene and formaldehyde, only toluene did not satisfy the Indoor Air Quality Management Act of Korea. The toluene concentration increase rapidly after the introduction of kitchen and living room indoor furniture. This is due to the material of which the furniture is composed and these results are validated using a small chamber method.

Under-floor air distribution (UFAD) systems are occupied-area-based air conditioning systems that generally offer advantages over ceiling-based air distribution (CBAD) systems in terms of energy efficiency and thermal comfort; accordingly, UFAD systems have become more popular lately. The purpose of this study is to provide reasonable UFAD application conditions by comparing and analyzing the influences of cooling loads when UFAD and CBAD are applied to thermally control indoor environments. A chamber experiment was conducted to allow comparisons of the indoor thermal environment under CBAD and UFAD, with the experimental variables of the thermal load of the occupied area and the supply airflow rate. In conclusion, the lower the supply airflow and the higher the lighting power density, the more the thermal comfort of the indoor environment could be improved by using UFAD instead of CBAD. In the lighting power density range of 0-30 W/m 2 , correlations were calculated whereby the lighting power density levels could be predicted that would ensure thermal comfort at a desired level.

The goal of this study was to provide building designers with daylight performance data on four-sided atria with various well and canopy configurations under an overcast sky. A total of seven different atrium well configurations and a total of 36 atrium canopy configurations were parametrically evaluated with physical scale models in terms of their impacts on the illuminance levels on the atrium floor. Effective transmittance data of the 36 canopy systems were determined from the measured daylight factors so that the effective transmittance data could be used when determining daylight factors inside atria with various alternative canopy systems.

Controlling indoor relative humidity is of great importance in the evaluation of thermal comfort and perceived air quality. This study aimed to develop a new mineral fiber board as an interior surface material with high capacity of moisture adsorption and desorption. A series of experiments were carried out in this study using an accurately controlled chamber, mock-up rooms, and real-scale test houses. The chamber test was conducted to measure the moisture adsorption and desorption content of the materials. In the mock-up rooms, the effects of the new mineral fiber board on indoor humidity were investigated under three different conditions. The three different conditions include: 1) a mock-up room with an electric humidifier, 2) a mock-up room with an open water basin, and 3) a mock-up room without artificial humidifying measures. In the real-scale test houses, the efficiency of the new mineral fiber board was also investigated under two different conditions of low-humidity and very high-humidity. Through the chamber test, it was found that the moisture adsorption content of the new mineral fiber board was three times more than that of the ordinary mineral fiber board. The moisture desorption content of the new board was also two and half times more than that of the ordinary mineral fiber board. In the mock-up test, the newly developed mineral fiber board could also control indoor humidity levels effectively by desorbing moisture under low humidity conditions. However, through the real-scale test, it was found that the new mineral fiber board could not absorb or desorb indoor moisture effectively if extremely dry or humid conditions last for a long time. Overall, the new mineral fiber board was proven to be effective in controlling indoor moisture except under extremely dry or humid conditions.