Adjustable external horizontal shading slats for daylighting in office buildings in Thailand

Main Article Content

Simeon N. Ingabo
Pipat Chaiwiwatworakul
Surapong Chirarattananon


Heat reflective glass is still preferred by designers of commercial buildings in Thailand to reduce solar gain from windows. This hinders the utilization of abundant natural daylight. Shading slats can block beam radiation and also allow for illumination of interior workspaces by diffuse daylight. This study examines the effective operation and performance of adjustable external horizontal slats installed on south-facing windows in office buildings. Experiments were performed in a full-scale room and the results were used to validate a calculation program for simulation. Three slat adjustment schemes were investigated and compared in terms of indoor daylight characteristics, thermal load, annual energy consumption, and energy savings relative to the common case of unshaded windows with heat reflective glass for typical office working hours. Simulations were performed for rooms of varying dimensions and configurations to establish the energy consumption behaviors for workspaces of different sizes. The study established appropriate monthly slat adjustment angles and determined that the installation of adjustable external horizontal shading slats in office buildings could save up to 60% of total lighting and air-conditioning energy consumption compared to workspaces with unshaded heat reflective glass windows.



Download data is not yet available.

Article Details

Research Articles


Chaiwiwatworakul P, Chirarattananon S. A double-pane window with enclosed horizontal slats for daylighting in buildings in the tropics. Energy Build. 2013;62:27-36.

Ingabo SN, Chirarattananon, S, Chaiwiwatworakul, P. Application of external horizontal shading slats for daylighting through north-facing windows. SEHS. 2021;15:1-12.

Ingabo SN, Chaiwiwatworakul, P, Mettanant, V. Impact of adjustable external horizontal shading slats on indoor visual comfort in a tropical climate. NUJST. 2020;28(1):23-37.

Yao J. Determining the energy performance of manually controlled solar shades: a stochastic model-based co-simulation analysis. Appl Energy. 2014;127(15):64-80.

O'Brien W, Kapsis K, Athienitis AK. Manually-operated window shade patterns in office buildings: a critical review. Build Environ. 2013;60:319-338.

Yao J, Chow DH, Zheng RY, Yan CW. Occupants’ impact on indoor thermal comfort: a co-simulation study on stochastic control of solar shades. J Build Perform Simul. 2016;9(3):272-287.

Tzempelikos A, Athienitis AK. The impact of shading design and control on building cooling and lighting demand. Sol Energy. 2006;81(3):369-382.

Nielsen MV, Svendsen S, Jensen LB. Quantifying the potential of automated dynamic solar shading in office buildings through integrated simulations of energy and daylight. Sol Energy. 2011;85(5):757-768.

Li DH, Tsang KW. An analysis of daylighting performance for office buildings in Hong Kong. Build Environ. 2008;43(9):1446-1458.

Chaiwiwatworakul P, Mettanant V, Fathoni AM. Energy analysis of the daylighting from a double-pane glazed window with enclosed horizontal slats in the tropics. Energy Build. 2015;128:413-430.

Chaiyapinunt S, Worasinchai S. Development of a model for calculating the longwave optical properties and surface temperature of a curved Venetian blind. Sol Energy. 2009;83(6):817-831.

Chaiwiwatworakul P, Chirarattananon S, Matuampunwong D. Energy saving potential from daylighting through an external multiple-slat shaded window in the tropics. Int J Renew Energy Res. 2012;2(3):376-383.

Chirarattananon S, Hien VD. Thermal performance and cost-effectiveness of massive walls under Thai climate. Energy Build. 2011;43(7):1655-1662.

Hien VD, Chirarattananon S. Triangular subdivision for the computation of form factors. Leukos. 2005; 2(1):41-59.

Perez R, Ineichen P, Seals R. Modeling daylight availability and irradiance components from direct and global irradiance. Sol Energy. 1990;44(5):271-289.

Nabil A, Mardaljevic J. Useful daylight illuminance: a replacement for daylight factors. Energy Build. 2006;38(7):905-913.