Natural light controls and guides in buildings. Energy saving for electrical lighting, reduction of cooling load

The residential sector is responsible for approximately a quarter of energy consumption in Europe. This consumption, together with that of other buildings, mainly from the tertiary sector, makes up 40% of total energy consumption and 36% of CO2 emissions. Artificial lighting makes up 14% of electrical consumption in the European Union and 19% worldwide. Through the use of well-designed natural lighting, controlled by technologies or systems which guarantee accessibility from all areas inside buildings, energy consumption for lighting and air conditioning can be kept to a minimum. The authors of this article carried out a state of the art on the technologies or control systems of natural light in buildings, concentrating on those control methods which not only protect the occupants from direct solar glare but also maximize natural light penetration in buildings based on the occupants׳ preferences, whilst allowing for a reduction in electrical consumption for lighting and cooling. All of the control and/or natural light guidance systems and/or strategies guarantee the penetration of daylight into the building, thus reducing the electrical energy consumption for lighting and cooling. At the same time they improve the thermal and visual comfort of the users of the buildings. However various studies have also brought to light certain disadvantages to these systems.