The biological effects of light and energy efficiency
Biologically effective light is not automatically energy-efficient. In order to support the circadian rhythm of people and to create healing, motivating or calming effects, lamps and luminaires are used where the most efficient emittance of light is initially not focused upon. However, the quality of light and energy efficiency are not contradictory.
The quality of light must be compared to energy efficiency. The Energy Saving Ordinance (EnEV) of the German federal government stipulates minimum requirements for the efficient operating energy consumption of lighting installations. The energy consumption of rooms and buildings can be evaluated with criteria and usage framework conditions as defined in DIN V 15899, and if a lighting concept corresponds to both quality requirements then economic and ecological aspects are not contradictory. Use of the EnEV however must not lead to lighting quality being neglected.
How is energy saving potential created?
Intelligent light control offers the most potential for saving. Up to 75 % can be saved compared to standard lighting systems with lighting controlled according to daylight, time and occupancy. Economic lighting solutions must be fundamentally flexible and adaptable according to existing building characteristics, and in order to illuminate areas with differing light requirements it is important that lighting concepts consist of several components. In addition, luminaires and lamps should you have a high light output ratio and light should be dimmable. Modern lamps are also extremely durable and thus also cost-efficient.
An ideal lighting system in terms of intensity, color temperature and dynamics tracks the natural course of daylight, and light management systems are capable of simulating natural daylight and regulating room lighting so that the right light in the right quantity is available at all times for promoting a sense of well-being.
Daylight increases human activity and supports well-being. When working in closed rooms, this must be replaced by artificial light, and with the OSRAM EASY Color Control System for example, lighting can be controlled so that light intensity, color temperature and dynamics correspond with natural daylight. Control of luminaires is very harmonious so that modifications are not immediately perceived, but the impressive results are all the more significant: The performance capability, motivation and efficiency of workers increases.
The OSRAM lighting expert Dieter Lang forecasts for the future that indoor lighting will be adapted to times of the day and yearly seasons in all office and residential buildings. "This means in windowless rooms light could be left on for longer in summer and be dimmed down somewhat earlier in winter to simulate natural lighting conditions outside." Much energy can already be saved with today's control technology. "When the sun is shining outside and a lot of light enters the home, daylight sensors dim down the artificial lighting or switch it off completely," explained Lang. The same thing happens thanks to a motion sensor if somebody is not at his workstation for more than a few minutes, and in this way about 30 % of electricity costs can be saved. The investment pays for itself rapidly. In the more distant future, technology may well enable light to be adapted individually for each workstation, because an ideal light situation for all work locations does not exist.
"A 60-year-old needs 60 % more light than a 25-year-old," continued Lang. And while an early riser likes it very bright and early in the morning, late people in the evening leave the light bright for longer as they are more productive during this time. The right proportion of light for each individual – if Lang has his way this vision will soon be transformed into reality.
Accent lighting: Appealing and motivating
Accent lighting increases the attraction of rooms, and people find such lighting situations inviting, lively and friendly, in contrast to purely direct and indirect light. Accented wall surfaces on the other hand increase the level of personal well-being.
In one of the most extensive surveys of its type, researchers from the Light Right Consortium in New York came to the result that good light improves productivity. 9 to 31 % of people at workstations illuminated only with direct distribution systems evaluated this as being unpleasant, whereas 91 % of people found systems comprising direct and indirect lighting including wallwashers as being pleasant. If such workstations were also individually dimmable, then workers were seen to be more motivated, persistent and alert. They also worked with more precision.