커튼월의 경면반사 영향과 불능현휘 평가 방법

Abstract

An evaluation method on the disability glare and the effect of specular reflection from curtain wall by Yong-Gee, Kim

Department of Architectural Engineering Graduate School, Pukyong National University, Busan, Korea

Abstract

Many design professionals applies the curtain wall (CW) because they consider the building envelop for the dead load reducing and the aesthetic exterior of high rise building. For the reduction of cooling and heating load, they apply the reflective glazing such as the Low-emissivity glazing in CW. However, it creates the specular reflection (SR) at the day time throughout the year. And SR with CW will impact the light pollution such as the disability glare, excessive solar radiation in the neighborhood.

Disability glare with SR impact to the health of eye, the perspective of view of peoples who the occupant, the pedestrian, and the driver of vehicle in the neighborhood. The mechanism of SR is that the light from a single incoming direction is reflected into a single outgoing direction, and sun moves on the path of sun during daytime as well as during four seasons. Therefore, the variation of disability glare depends on the path of sun as well as the shapes of building.

Design professional should be watchful of the SR effects in the neighborhood due to CW during design phase of the building. However, the estimation methods of SR angle, length and area are very complicated work and the studies on these methods are insufficient.

In the experiment with small model curtain wall, the curtain wall occurred specular reflection such as over 25,000cd/㎡ during day time, the temperature of surface where suffers from solar radiation and specular reflection was approximately 10℃ higher than the surface of only solar radiation.

This study aims to establish the estimation formula of SR with the high rise building and contribute in the estimation methods of SR angle, length and area. This study will utilize earth-sun geometry, apparent solar time, local time, vertical and horizontal shadow angle theories, and sets a square building with the height of 100m and the width of 30 m as the ordinary CW. The areas of SR with variation of CW directions during four days such as the spring equinox, the summer solstice, the autumnal equinox, the winter solstice have been calculated with the method established from the study. The method simulates the SR ratio on CW areas of four facades during the year. The study showed that the area of SR in the south, the south east, and the south west were the highest such as 3,600∼4,100% of CW.

And second purpose of this study is present that the evaluation method on the disability glare caused by SR of curved curtain wall. The study established qualitative and quantitative evaluation method on the disability glare through it conducts both a measurement of illumination with the meter for the real building which have a curved curtain wall, and the computational simulation with RADIANCE V1.02 for the building and the modeling area.

This study will contribution of the reduction of disability glare using by the methods in this study for the architect, the design professional and the other people concerned disability glare in CW. Key words; Specular reflection, Disability glare, Curtain wall, Light pollution, Environmental impact of building