Reducing CO₂ emissions automatically

Climate change entails a number of consequences – and the full impact that these will have on our future continues to be unknown. So what is its main driver? The answer is, of course, CO₂ emissions. Caused by the consumption of fossil fuels such as oil, coal and gas, the topic is preoccupying politics, the economy and society at this time like barely any other. In addition, the realisation is growing that reduced energy consumption will strengthen self-sufficiency with respect to resource-rich countries. And of course, it will ultimately save money.

Switching presence and motion detectors

The idea behind this concept is easy to understand: People often forget to turn off lights and other devices whenever they leave a room. It's a particular concern in non-residential buildings like offices, educational institutions or healthcare facilities. This is because users generally do not have to bear the costs for running these facilities themselves. However, even in private-sphere applications such as outdoor lighting, there's no need for artificial light to be shining continuously at full power.

Demand-driven constant light control

Presence detectors with presence- and daylight-dependent constant light control (Fig. 2) go a whole step further: They not only switch the artificial lighting on and off, but also dim it. And they do so according to a predefined brightness setpoint and the daylight that is already present. The lights only shine as brightly as needed. The energy is supplied only to the extent that it is really required – completely in line with the slogan already mentioned above.

Constant light control makes sense in areas exposed to normal or above-average levels of daylight in particular. Today, it is primarily presence detectors for DALI and DALI-2 that perform this control function, because the industry standard clearly surpasses the possibilities of analogue technologies. In addition, grouping for this is easy with the aid of software (and directly via smartphone with ESYLUX), as is subsequent reconfiguration. The end user also benefits from extremely flexible lighting management.

Constant light control with offset

A presence detector achieves constant light control using a light sensor. For this reason, at least one detector is always required to control the light individually in a specific room zone. In rooms exposed to daylight on one side, for example, the need for artificial light between the window side and interior area is quite different. This would call for individual control in both zones. However, it is often neither economical nor efficient to use another detector in this scenario.

The concept of offsets was developed for this purpose, which improves the energy efficiency of constant light control even when only one detector is used (Fig. 3). Offset control was previously described in detail in the last issue of ESYWORLD. To summarise the concept again here: With offset, lights far away from the window and lights near the window are each assigned to a different group. The detector with the corresponding offset function dims the luminaires near the window more and earlier than the lights far away from the windows, reducing energy consumption even further.

Human Centric Lighting used in an energy-efficient way

All the previous examples refer to traditional lighting with a fixed light colour. However, over the past few years, a more modern type has become increasingly popular in the form of Human Centric Lighting: Dynamic, daylight-like colour and brightness gradients that, as scientifically proven, improve vitality, wellbeing and health, among other benefits. Human Centric Lighting, also called biologically effective light, requires a higher illuminance for this purpose, and is also recommended by the current EN-12464 standard for healthy lighting in workplaces.

Multidisciplinary control with a multi-sensor system

SymbiLogic demonstrates how a better quality of life can be achieved in an energy-efficient way. This kind of "combination" can be found in another application that admittedly has nothing to do with lighting – nevertheless, it serves as a good example of how multidisciplinary demand-driven building automation works. We're referring, of course, to the ATMO series presence detectors. At their highest configuration level, they control not only the lighting in a KNX system, but also the air conditioning or ventilation system with the help of actuators.

Presence-dependent switching of 230 V devices

However, KNX systems cannot be installed everywhere. Simpler solutions are therefore also needed for the demand-dependent control of 230 V devices such as ventilation systems. One such energy-efficient alternative is purely presence-dependent switching by means of presence detectors with a separate switching output, also called HVAC output. The ON/OFF presence detectors of this kind that are manufactured by ESYLUX can be recognised by an additional "plus" in the name.

Time-dependent control

We've already mentioned a number of different automation triggers here, including presence, light, temperature, humidity and air quality. But there's one important trigger we still haven't covered: time. After all, this too can help to further improve energy efficiency – in cases where different operating modes can be activated depending on the time, for example. Outdoors, it can also be an effective way to reduce light pollution at night – and thus counteract another environmental problem.

Semi-automatic push button operation

All the examples show the different ways in which demand-driven automation using presence and motion detectors can improve building energy efficiency. The advantage is always the same: In principle, the user does not have to worry about anything. One question remains, though: If people forget to switch off the light so often, why should detectors with a push button input exist at all? Well, on the one hand, users sometimes want to decide for themselves when to switch on the light, or override automation by scene, as is the case with lighting systems with ESYLUX Light Control or DALI-2 systems.

However, a push button can also be advantageous in terms of energy efficiency. Presence and motion detectors generally only switch off lighting and other devices after a lag time has elapsed. Even if this duration is only set to 1 minute, for example, if the user actually remembers to switch the light off, the push button still makes it quicker to accomplish this. And even if they do forget to switch it off… at least you know that's covered, too.