Sunlight is a free gift of nature that provides the most quantity of light than any other source. Sunlight harvesting can be tapped in building so as to illuminate the building at zero cost of lighting. However, most buildings have not yet adopted mechanisms that can tap it and direct it to light a building naturally hence they end up incurring very high costs when it comes to power consumption specifically in lighting.
This research has been conducted on the „Adoption of Daylighting to Minimize the Operating Costs of Lighting, A Case Study of ADD Building.‟ The objectives of the study were to identify the challenges that lead to inadequate daylighting in ADD building, to identify different strategies which are used to enhance daylighting in buildings, to establish which among the identified strategies are the most suitable for daylight retrofitting in ADD bottom four levels and how they can be incorporated in the building and lastly to establish the cost implications of the proposed daylighting strategies.
As established from the field study, the challenges that lead to inadequate daylighting in ADD bottom four levels were that ADD building is a deep plan building which makes it difficult to daylight, it has many concrete partitions which are indirectly proportional to the quantity of light penetrating inside the building, it lacks an electric lighting control integration system hence artificial lighting is consumed even when there‟s broad daylight and also, it has one switch controlling the lighting sources of a large zone hence, all the lighting sources are turned on even when only a small section of the space is occupied. This leads to unnecessary consumption of artificial lighting.
The researcher was able to identify daylighting strategies used in buildings like the use of light shelves, skylights and light monitors, use of tubular daylight devices e.g. solar tubes, use of heliostats, adoption of growth screens, use of fiber optic cables, use of reflective or pale painted surfaces and interior décor, use of daylight responsive electric lighting controls and also increasing the number of the windows in the building. Through the consideration of the cost implications of these strategies, the researcher was able to propose the use of light shelves and solar tube strategies as the most cost effective strategies with a short payback period and few maintenance cost. The incorporation of this strategy was represented in drawings and Bills of Quantities in the Appendices attached.
From the study, the researcher found that the building size, its location and depth affect the amount of natural light that penetrates inside it, the number of opaque partitions in a building are indirectly proportional to the amount of useful natural light available in the interior spaces, the surfaces finishing of a space influence the amount of daylight available to the particular space, the building orientation, massing and consideration of environmental factors during design influences the natural light available inside the building and also that natural light increases worker productivity, it enhances aesthetics, reduces environmental pollution by reducing photo pollution , has the best color rendering properties than any other source of light and finally reduces the energy consumption for lighting in a building.
From the above, study, the light-shelf strategy required Ksh 5,082,900.00 for its installation and would have a payback period of 0.54 years (6.5 months) while solar tube strategy would require Ksh 609,780.00 to install and recoup the same in 0.63 years (7.5 months).The researcher concluded these as most suitable daylighting strategies for the building‟s bottom four levels. The adoption of these daylighting strategies would lead to more daylighting in ADD building‟s bottom floor hence saving the cost of lighting in the building.

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