Change current country? Asia | Pacific English Australia | English Ireland | English

Reducing CO2 emissions automatically

Demand-driven building automation solutions for increased energy efficiency

Lighting, ventilation, standby consumption: Many devices in buildings increase energy costs and therefore contribute to environmentally harmful CO2emissions. Demand-driven control by means of intelligent sensors can improve this situation in many cases – and the options for doing so have increased over time. Here's an overview with some examples.

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.

Alongside switching to renewable forms of energy, more efficient use of energy is the order of the day. Increased energy efficiency leads to a reduction in the extraction and consumption of fossil fuels, which protects natural resources and slows down climate change. "Use energy only when it is really needed" is the watchword for demand-driven building automation using presence and motion detectors – and it's proving more valuable today than ever before.

Fig. 1: Even the use of a simple presence detector that switches depending on presence and daylight significantly improves the energy balance.

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.

The most basic way of preventing this is to use motion detectors and switching presence detectors (Fig. 1). These devices only switch on nearby lighting in insufficient ambient light conditions whenever people are in their vicinity, and switch it off again as soon as the area is no longer occupied, or once daylight provides sufficient brightness again. It sounds simple – and it is. In addition, the automatic limitation of lighting to times when people are actually present reliably makes use of the high service life of LEDs.

Fig. 2: The presence- and daylight-dependent constant light control of a presence detector is the best form of daylight utilisation. At VDU workstations, it adapts to a brightness setpoint of 500 lux.

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.

In order to make the advantages of Human Centric Lighting energy-efficient, ESYLUX has developed SymbiLogic technology (Fig. 4). SymbiLogic transfers the principle of constant light control to the biologically effective light by means of adaptive HCL light control: It takes the daylight that shines in as a point of reference and adapts to a dynamically changing brightness setpoint. Ordinarily, the artificial light does not have to shine at full strength. In addition, the lighting is of course switched on or off according to the presence or absence of people in the area.

Fig. 5: A prime example of multidisciplinary energy efficiency: the multi-sensor ATMO presence detector for KNX at its highest configuration level. Among other things, it has an air quality sensor for energy-efficient improvement of the indoor climate.

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.

This is possible because of their additional sensors for temperature, humidity and air quality (Fig. 5). Regular air exchange is especially important in well-sealed buildings, but also in rooms where many people are present at the same time. Since this is often forgotten about in non-residential buildings, ATMO presence detectors take care of the task automatically. But even in this regard, they only let the air conditioning or ventilation system work as intensively as the current room atmosphere actually requires. In this way, they ensure energy-efficient operation and also do away with the need for multiple individual solutions due to their multi-sensor technology.

Fig. 6: Many people only think of presence detectors as lighting control. However, many other devices can in fact be switched depending on presence and thus save energy.

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.

The presence-dependent switching of devices is not limited to the typical case of ventilation; monitors, printers, electrically height-adjustable desks and many other devices with standby consumption can also be easily and reliably deactivated in this way (Fig. 6). In DALI presence detectors and in lighting systems with ESYLUX Light Control, this is done fully or semi-automatically via special DALI actuators.

Fig. 7: Time-dependent operating modes can reduce both energy consumption and light pollution. In the example, the twilight switch mode provides prestigious lighting in the early morning and evening hours. At night, on the other hand, the light only comes on when there is movement – and then goes off again automatically.

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.

The DEFENSOR outdoor motion detectors demonstrate how this is possible. In addition to the standard operating mode, two time windows with a different operating mode can be set (Fig. 7). For example, it would be possible to select twilight switch mode for the two time windows in order to provide prestigious lighting for a commercial building in the early evening and morning hours. In contrast, the fully automatic motion detector mode could be used as standard and thus also at night between 10 pm and 5 am. This saves energy – and at the same time avoids insects being continually attracted by artificial lighting.

Fig. 8: Presence and motion detectors with push button input enable simple override. If the user forgets to switch the light off, the detector does it automatically. And if the user switches it off themselves, that's even better!

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.