The authors consider the problem of design of external stationary sun protection devices, namely, modified multi-component units that are especially effective in the hot and sunny climate of Lebanon. Apart from their sun protection properties, the proposed units demonstrate effective light-reflecting characteristics in the clear sky environment. These properties substantially increase the value of the daylight factor. The value is mainly increased inside buildings, or in the areas that are located far from sources of natural illumination. The authors propose EF, a new efficiency factor to be taken into account in any calculations of the daylight factor. This factor depends on the shape of the sun protection device installed above the window of the storey below the one under consideration and at a distance from the device under consideration and the window in question. As a result, the new proposals increase the quality of the internal environment and may result in energy saving due to the reduction of the artificial lighting period.