Energy efficient dim-evening lighting and dynamic daylight-control adjusted for geographical orientation: Effects on energy consumption and user satisfaction in a post-occupancy-evaluation of a new psychiatric hospital

During the development of LED, we have seen a major change in light quality, spectral composition, and energy-performance. This has fundamentally affected the general lighting environment. In some areas, the lighting has improved, in other areas it has worsened. LED has a number of positive properties during daytime: giving more short-wave light, better color rendering, and with less energy consumption. In the evening hours, the LED gives rise to a number of challenges: too high levels of evening light intensity; too much short-wave light; increased glare, that can impair the lighting environment in the evening and at night. The fact that higher lumen-efficiency and higher light levels are implemented without user input might be one of the reasons we have not seen the expected energy savings in daily operation. The current use of LEDs does not take human physiological system into consideration regarding sleep, energy and mood.

To meet this challenge, the project introduces dynamic controlled light and dim-evening-lighting, characterized by intelligent control of the LED-lighting according to the geographical orientation during the daytime (06 – 14) and reduced dim LED-lighting during the evening time (14 – 22). The project collects data on energy consumption, user satisfaction, treatment processes, sleep quality and medication usage.

The project expects to find increased satisfaction in a more "homely and relaxing environment" and energy savings during operation, as maintenance, longer lifespan due to lower illuminance levels, etc. The project compares test department to a similar department (control).