Smart Shading with KNX

Whether it's your own home or an office building, the temperature inside should always be pleasant to increase your sense of well-being. Of course, energy is needed for this – heating is needed in winter and cooling in summer.

At the same time, legal requirements must be kept in mind: the new version of the Building Energy Act (GEG) that came into force on 1 January 2023 in Germany stipulates that new buildings must not exceed an annual primary energy requirement of 55 per cent of the primary energy requirement of the reference building. Before that, this value was still 75 %. In plain language, this means that saving energy should remain at the top of the agenda for all homeowners and property owners.

The internationally accepted benchmark for a low-energy house is a heating energy requirement of no more than 70 kilowatt hours per square metre per year.

Every new building must currently meet this requirement, which is why new buildings are basically automatically low-energy houses. However, the efficient insulation of modern low-energy houses can cause overheating in summer, which in turn can lead to high energy consumption for cooling the building. This is where automatic shading comes into play, preventing the building from heating up.

To avoid overheating of buildings, it is imperative to install shading that works automatically. Regardless of the presence of the users, shading such as blinds or awnings, should be extended and retracted without human intervention.

An intelligent KNX shading control system not only helps to optimise the indoor climate in summer, but also offers a decisive advantage in winter: the targeted use of solar heat gain.

Thanks to a smart control system, blinds and shutters remain open on cold days until the desired room temperature is reached. This means that natural solar heat can be used indoors, reducing the need for heating. As soon as the sunlight fades or the temperature drops, the shading is automatically adjusted to keep the stored heat in the room for as long as possible.

The advantages at a glance:

• Energy savings – less heating required thanks to passive use of heat
• Enhanced comfort – automatic adjustment without manual intervention
• Sustainability – optimal use of natural resources for an energy-efficient home
• Smart integration – perfect combination with KNX for holistic building automation

Data-based control and optimisation

With KNX, weather data such as brightness, wind speed, rain, outside temperature and the position of the sun can be incorporated into the shading control. This data-based control enables precise and needs-based adjustment of the shading, which further optimises energy consumption. For example, the shading can be automatically activated when the sun is shining brightly and deactivated when it is shining weakly, in order to make use of solar gains in winter.

Comfort and user-friendliness

KNX systems not only offer energy efficiency and comfort, but are also highly user-friendly. Users can easily operate their shading systems via central touch panels, apps or voice control. This ease of use helps to ensure that the shading is used optimally, which in turn reduces energy consumption and increases living comfort.

Sustainability and future-proof investment

Integrating KNX not only reduces current energy consumption, but also increases the overall sustainability of the building. Having been on the market for over 30 years, KNX systems are future-proof and can be easily expanded or customised thanks to over 500 providers of KNX-enabled products. This makes them a long-term investment that offers both environmental and economic benefits.

Active systems such as roller shutters provide good shading as well as good insulation in winter and do not require wind and rain protection.

External blinds and venetian blinds provide very good shading and allow a high level of light to enter through the slat adjustment. However, automatic wind protection is essential.

Textile blinds can be installed outside or inside. They are visually appealing and partially translucent. However, they usually need to be protected from wind and rain when used outside. Awnings also belong to this group. There are special, robust models that are rainproof and are used in the catering industry, for example. However, these models also need to be retracted during storms.

Passive systems include structural components and solar-control glass. The latter consists of reflective or absorbent glass that provides additional sun protection.

A few components are essential for a functioning shading solution with KNX. These include a KNX power supply that can also supply auxiliary power if necessary, a weather station and blind actuators.

A GPS receiver or a conventional time switch is required for so-called astro functions, i.e. a control system that is guided by the time or position of the sun. Logic modules are useful for adding your own circuits to the automation.

The components GPS/time switch and logic functions are already included in some KNX weather stations or KNX actuators.

When planning and installing a KNX-based sun shading system, some preparatory work is required. First, the building's facades need to be defined and the angles measured. For this, Google Maps, for example, can be used to determine the building's coordinates.

On each façade, a perpendicular should be determined that corresponds to the sun's azimuth angle. The angle of incidence depends on the window size and the depth of the reveal and should be sketched if necessary. The maximum angle of incidence is 180 degrees for large windows and no reveal.

It is important to sort all shadings of the building according to the facades. For round buildings, it may be useful to divide them into segments, depending on the setting options of the weather station and the logic. It should also be taken into account that more shade is created on the lower floors, e.g. by trees or other buildings.

Positioning and installation of weather stations

The positioning of the weather station on the building should be carefully determined and the compass direction checked and corrected if necessary. The auxiliary voltage and surge protection must be ensured. Since almost all external shading requires wind protection, the limit values should be requested from the manufacturer or installer of the shading. Rain protection can be useful for awnings.

Setting the shading functions

The brightness limit values should be set so that a sunny day is recognised from around 40,000 lux and shading is sensibly activated from 20,000 lux. Useful delays, such as a switch-on delay of 5 minutes and a switch-off delay of 20 minutes, including generous hysteresis, should be set to avoid excessive movement. If possible, azimuth and elevation (sun height) should be used and set individually for each façade. With blinds, adjusting the slats depending on the height of the sun (elevation) allows light to enter and the façade to be opened while providing shading.

Which device handles the automation?

The automatic shading can be located in the software of the weather station or the actuator. So either the weather station or the actuator handles the shading. Regardless of where the intelligence is located, you should ensure that the user can deactivate the automatic system by adjusting the shading themselves. The automatic shading can be customised by manually moving the blinds and scenes, which is popular with users. Only protective functions such as wind, rain and frost alarms always have priority.

Check whether the available actuators have an automatic shadingfunction. This function is extremely advantageous because it allows the shading to be adjusted automatically. If the user adjusts the shading manually, the automatic function is deactivated, allowing flexible and individual control. When purchasing or recommending devices, make sure that they have such an automatic function.

When using venetian blinds, slat adjustment based on the elevation of the sun is an important aspect. This setting ensures optimal light incidence while also allowing the façade to be opened while still providing sun protection. Precise adjustment of the slat angle makes it possible to supply the room with sufficient daylight without increasing the room temperature through direct sunlight.

By selecting the right actuators, you ensure that your solar shading system is efficient and user-friendly, resulting in an improved living and working environment.