What is Daylight Harvesting for lighting applications
Daylight harvesting, or daylight response, is an automatic lighting control strategy in which interior electric lighting adjusts to maintain a target level, reducing energy costs. It is most effective in areas that consistently receive ample daylight, such as lighting adjacent to windows or near skylights.
Image: In this example, you will see that as daylight contribution increases, the lighting fixtures automatically reduce electric light output to save energy.
A large number of case studies show that daylight sensors can save 30–35% of energy in settings near windows. Beyond these advantages, controlled daylighting can also result in soft savings through increased productivity and health of occupants.
From an energy-saving and sustainability perspective, daylight harvesting remains a viable lighting control strategy and a key mandatory requirement in prevailing commercial building energy codes.
Daylight Harvesting with IQnext
IQnext IoT platform is integrated with lighting partner/OEM fixtures for a simple plug-n-play solution and software driven controls and optimizations.
Unlike conventional lighting control systems (such as DALI, KNX etc), in the IQnext integrated daylight harvesting solution you don’t have to spcify complex set of planning & commissioning, such as - specifying expensive hardware control systems, draw up low voltage wiring schemes or costly power packs. It is a thing of the past! Just design, specify the lighting fixtures as usual and indicate which fixtures require daylight controls.
Representation of the integrated daylight sensor in lighting fixture. The actualsmay vary based on the lighting product of the OEM partner.
Commissioning is also very simple. Lighting fixtures specified comes with sensors that are factory integrated, pre-calibrated for most typical lighting applications right out of the box – just plug in the fixture. If your space does require some fine-tuning in the field, tuning are easily adjusted using the IQnext’s web based software interface.
How does the Daylight Harvesting with IQnext work
When daylight enters a space, there is an opportunity to save energy by using daylight sensors to reduce electric light output on a relative, compensating scale. A good daylight control design should leverage daylight contribution without disrupting occupants or sacrificing lighting quality.
Once you have installed the sensor-integrated fixtures supplied by the Lighting OEM partner and powered them with AC power the daylight sensors operate automatically using control algorithms.
Sensors & algorithms are factory pre-calibrated for most typical lighting applications and, in most cases, do not require additional commissioning. If the unique demands of the space require some fine-tuning can be done post commissioning using the IQnext software web interface.
Once the IoT/wireless lighting fixture are commissioned, each lighting fixture is a part of a lighting zone. Further each zone is assigned a lighting rule. (Read more about lighting rule here
If the given lighting fixture is part the zone in which the lighting rule has the daylight sensor “enabled”, (refer to the lighting rule section on the map operations page), the daylight sensing will be activated.
Recommendation on setting the light level in occupancy state with daylight sensor
- Measure light levels when there is no daylight in the room (at night or with the blinds closed).
- Position a light meter beneath the sensor on a work surface and take the meter reading.
- In the rules page, set the lighting % for occupancy state at the desired level.
- When daylight is present, if you not satisfied with the lighting levels after the daylight harvesting , you can adjust the compensation of the lighting fixture using the IQnext platform using the individual lighting control.
- The algorithm works on a continuous daylighting concept. It involves smooth, continuous dimming from low end to high end in order to maintain the desired light level. Continuous daylighting adjusts lights based on the amount of daylight that’s always in the space, ensuring that the minimum light level is achieved without over-lighting the space.
- The minimum electrical light output is limited to 10% (i.e. the lighting fixture will never go below this level, irrespective of ambient daylight present)
- The adjustments of electric light will be seen only with there is a daylight change for a sufficient time period. This is done so that any abrupt changes in outside condition (such as passing clouds etc.) do not affect the light output.