The impact of building features on the energy demand for electric lighting systems

With the growing worldwide concern about energy consumption, we are witnessing to a more extensive demand for more energy efficient solutions. A great saving potential has been identified in buildings and new directives and standards are being issuing to bind the integrated energy performance or new or renovated buildings to prescribed limits. As fa as electric lighting is concerned, an important role is played by the adoption of control strategies which have the aim to reduce consumption by means of, for instance, daylight integration or lighting switching based on the real or expected occupancy of spaces. The influence of different control strategies and different building features on lighting enery demand is investigated in the paper. The analysis has been carried out through the use and comparison of two simulation tools: one simplified calculation method, recently proposed by the European Standard EN 15193, and a freeware software named Daysim. The influence of some building features, such as room depth, window size and exteriro obstructions, on lighting energy consumption in the case of manual control or daylight dependent control are evaluated with the aim of providing architects with rules of thumbs to quantify the impact of design decisions on lighting energy cinsumption.