Integrating Daylighting with Task-Ambient Lighting for Enhanced Energy Savings in Office Spaces


  • Simeon Nyambaka Ingabo The Joint Graduate School of Energy and Environment, King Mongkut’s University of Technology Thonburi, Bangkok 10140 Thailand.
  • Pipat Chaiwiwatworakul The Joint Graduate School of Energy and Environment, King Mongkut’s University of Technology Thonburi, Bangkok 10140 Thailand.



Daylighting has been widely studied as a fundamental aspect of spatial illumination and energy efficient façade design. Effective installation and control of shading devices diminishes the adverse effects of prevailing climatic conditions on building envelope performance and reduces resultant lighting and cooling energy consumption. Task-ambient lighting as a free-standing approach has also been proven to reduce lighting energy consumption compared with typical general ambient lighting. This study estimates the energy saving potential of integrating daylighting through fixed external horizontal shading slats with task lighting. Spot measurements were taken in a test room to validate a daylight calculation program. Full year indoor work plane daylight simulations were performed for office spaces of different floor areas and varying window to wall ratios. Indoor daylight quality was assessed using the Useful Daylight Illuminance metric and three different task lighting schemes explored.  Lighting energy savings of 10% to 90% were estimated under the three schemes in comparison to similar office spaces with common unshaded heat reflective glazing.


Tagliabue, L. C., Buzzetti, M. and Arosio, B. 2012. Energy Saving Through The Sun: Analysis of Visual Comfort and Energy Consumption in Office Space. Energy Procedia. 30: 693-703.

Nielsen, M. V., Svendsen, S. and Jensen, L. B. 2011. Quantifying the Potential of Automated Dynamic Solar Shading in Office Buildings Through Integrated Simulations of Energy and Daylight. Solar Energy. 85: 757-768.

Oh, M. H., Lee, K. H. and Yoon, J. H. 2012. Automated Control Strategies of Inside Slat-Type Blind Considering Visual Comfort and Building Energy Performance. Energy And Buildings. 55: 728-737.

Ghosh, A. and Neogi S. 2018. Effect of Fenestration Geometrical Factors on Building Energy Consumption And Performance Evaluation of a New External Solar Shading Device in Warm And Humid Climatic Condition. Solar Energy. 169: 94-104.

Yao, J. 2014. An Investigation into the Impact of Movable Solar Shades on Energy. Building and Environment. 71: 24-32.

Aries , M. B. C., Veitch, J. A. and Newsham, G. R. 2007. Physical and Psychological Discomfort in the Office Environment. Symposium of the Dutch Light and Health Research Foundation. 45-50.

Chaiwiwatworakul, P., Mettanant, V. and Fathoni, A. M. 2016. Energy Analysis of the Daylighting from a Double-Pane Glazed Window with Enclosed Horizontal Slats in the Tropics. Energy and Buildings. 128: 413-430.

Chaiwiwatworakul, P., Chirarattananon, S. and Rakkwamsuk, P. 2009. Application of Automated Blind for Daylighting in Tropical Region,” Energy Conversion And Management. 50: 2927-2943.

Datta. G. 2001. Effect of Fixed Horizontal Louver Shading Devices on Thermal Performance of Building By TRNSYS Simulation. Renewable Energy. 23(3-4): 497-507.

Ingabo, S. N., Chaiwiwatworakul, P. and Mettanant, V. 2020. Impact of External Horizontal Shading Slats on Indoor Visual Comfort in Tropical Climate. Naresuan University Journal of Science and Technology. 28(1): 23-37.

Atzeri, A., Cappelletti, F. and Gasparella, A., 2014. Internal Versus External Shading Devices Performance in Office Buildings. Energy Procedia. 45: 463-472.

Alzoubi, H. H. and Al-Zoubi. A. H. 2010. Assessment of Building Façade Performance in Terms of Daylighting and the Associated Energy Consumption in Architectural Spaces: Vertical and Horizontal Shading Devices for Southern Exposure Facades. Energy Conversion and Management. 51(8): 1592-1599.

Tzempelikos, A. and Athienitis, A. K. 2007. The Impact of Shading Design and Control on Building Cooling and Lighting Demand. Solar Energy. 81(3), 369-382.

Kralikova, R., Andrejiova, M. and Wessely, E. 2015. Energy Saving Techniques and Strategies for Illumination in Industry. Procedia Engineering, 100: 187-195.

Veitch, J. A., Newsham, G. R., Boyce, P. R. and Jones, C. C. 2008. Lighting Appraisal, Well-being, and Performance in Open-Plan Offices: A Linked Mechanisms Approach. Lighting Research and Technology. 40(2), 133-151.

Newsham, G. R., Arsenault, C. D., Veitch, J. A., Tasco, A. M. and Duval, C. L. 2005. Task Lighting Effects on Office Worker Satisfaction and Performance, and Energy Efficiency. Leukos. 1(4) 7-26.

Jones C. C. and Gordon. K. L. 2004. Efficient Lighting Design and Office Worker Productivity. Proceedings of the 2004 ACEEE Summer Study on Energy Efficiency in Buildings. 22-27.

Ingabo, S. N., Chirarattananon, S. and Chaiwiwatworakul, P. 2021. Application of External Horizontal Shading Slats for Daylighting Through North-Facing Windows. Science, Engineering and Health Studies. 15: 21040002.

Chaiwiwatworakul, P., Chirarattananon, S. and Matuampunwong, D. 2012. Energy Saving Potential from Daylighting Through External Multiple-Slat Shaded Window in the Tropics. International Journal of Renewable Energy Research. 2(3): 376-383.

V. D. Hien and S. Chirarattananon. 2009. “An Experimental Study of a Façade Mounted Light Pipe,” Lighting Research and Technology. 41(2): 123-142.

Chirarattananon, S. and Hien. V. D. 2011. Thermal Performance and Cost Effectiveness of Massive Walls Under Thai Climate. Energy and Buildings. 43(7) 1655-1662.

Hien, V. D. and Chirarattananon, S. 2005. Triangular Subdivision for the Computation of Form Factors. Leukos.5(2): 41-59.

Harrold, R. and Mennie, D. 2003. IESNA lighting ready reference: A compendium of materials from the IESNA, 9th ed., New York: Illuminating Engineering Society of North America.

Nabil, A. and Mardaljevic, J. 2006. Useful Daylight Illuminance: A Replacement for Daylight Factors. Energy and Buildings. 38: 905-913.




How to Cite

Ingabo, S. N., & Chaiwiwatworakul, P. (2021). Integrating Daylighting with Task-Ambient Lighting for Enhanced Energy Savings in Office Spaces. Journal of Energy and Safety Technology (JEST), 4(2).