Room automation
As a room automation is that portion designated discipline of the building automation system that performs the cross-trade automation functions and tasks within the rooms of buildings. The room automation is thus an integrated system that combines the once separate systems for lighting or sun protection control as well as room climate control. The advantages of this integration lie on the one hand in the simplified operation by the user, on the other hand in a significant improvement in energy efficiency. The second aspect in particular gives room automation great importance due to increased energy prices, as studies and standards show that the energy requirement in non-residential buildings can be reduced by over 40% with the help of room automation systems.
Room automation
Classification within building automation
The increasing importance of room automation was met by DIN 276 - costs in construction - in 2006 by including it as a separate cost group 484 within the framework of cost group 480 “building automation”. Figure 1 shows building automation with its subsystems
- Building management system (also GLT or SCADA ),
- (Plant) automation system (also DDC-GA ) including control cabinets and
- Room automation system.
In addition to the original meaning for cost estimation and billing, the picture also shows the relationship between the subsystems. These relationships are of a communicative nature and serve to exchange data between the systems. While the communication between room automation and system automation is mainly about demand-based system control, the interfaces between both automation systems and the management system are mainly used for visualization, operation or trend recording.
Hardware structure
In contrast to plant automation, a room automation system generally extends over all areas and floors of a building. This fact has an impact on the basic structure of a room automation system. A room automation system is generally more decentralized and consists of a large number of communication-capable devices, each with a specific scope of performance. A room automation function is therefore only implemented through the interaction of several devices.
For example, constant light control (see below) is only possible through data exchange between a multi-sensor for brightness and presence and a dimming actuator. If the user is to be given an override option, this is done via a third device, the room control unit (see Figure 2).
Communication protocols
In the past, so-called bus systems were mostly used to enable reliable communication between the devices. The most important open and standardized bus systems within room automation are EIB / KNX and LON . BACnet can be considered as a third standardized system , although this system is still not widely used in room automation. The first-mentioned systems have the advantage that they work in free network topologies so that the devices do not have to be wired in a line structure.
Today, however, more and more manufacturers are relying on radio systems because they are easier to install and cheaper. In this way, apartments and houses can still be automated afterwards without tearing open walls. The most important protocols are ZigBee , Z-Wave , HomeMatic , EnOcean , KNX-RF, DECT , Bluetooth and WLAN . While Bluetooth and WLAN do not penetrate walls as well with their frequencies in the 2,400 MHz range, other protocols do better in the frequency range of around 868 MHz and 1,900 MHz. At 50 to 100 meters, DECT is the furthest in buildings. DECT offers only a few sensors and actuators, and these cannot be connected to other systems. On the other hand, ZigBee, Z-Wave, Enocean and HomeMatic offer an extensive range.
System structure
The backbone of a room automation system, i. H. the connection between floors and parts of the building is usually a TCP / IP-based network ( LAN ) today , as all the bus systems mentioned have a corresponding protocol definition. Because of the advantages of a free network topology, a twisted pair cable is selected for cabling the devices on the floors, which can optionally also carry the required power supply for the devices. IP routers form the transition from the backbone to the floor segments. Figure 3 shows such a system structure in which all subsystems use the common backbone.
Room automation functions (according to VDI 3813-2)
Overview
From a functional point of view, a room automation system basically consists of the linking of sensors and actuators with certain functions. If you now represent all three groups as blocks, you get the following basic diagram.
This method of representation has become the standard in building automation standards. B. used in ISO EN DIN 16484-3 or EN 15500. The VDI guideline 3813 sheet 2 "Room automation - functions", which is currently in the green print, also uses this representation. The terms of this guideline are used below to explain the room automation functions. Similarly, LonMark Deutschland eV has created company-neutral tender texts that are compatible with this guideline.
A particular advantage in this context is that the representation of LonMark International as so-called functional profiles largely corresponds to the representation of the VDI 3813 guideline. Sensors, actuators and controllers that correspond to the function blocks can also be found here. The most important application functions of room automation are described below.
General Features
Time programs
Time programs can vary room functions at set times and e.g. B. adapt to the expected use of space. Time programs to increase energy efficiency fit u. a. the operating modes of the room temperature controller or switch off the lighting. In principle, all room functions should be able to be switched via time programs so that a wide range of user requirements can be met.
Attendance evaluation
Room automation systems automatically detect the presence of people via presence or multi-sensors. With this information, the functions for lighting, sun protection or room climate control can be operated in a particularly energy-efficient manner, since comfort criteria with increased energy consumption only have to be met when people are present.
Control via room usage types
Certain settings for lighting, sun protection or room air conditioning functions can be saved together in the form of room usage types (including "scenes") and called up at any time. The user can also manage complex room situations at the touch of a button, e.g. B. in lecture rooms, simply master. The corresponding devices must have a memory for this.
Functions for lighting, glare protection and daylight use
Constant light control
A sensor for detecting the brightness of the room, e.g. B. within a multi-sensor, ensures the exact adjustment of the lighting level to the work task. The dimmable actuators required for this are offered by modern room automation systems for all common lighting. Thanks to the optimal use of daylight, the constant light control, especially in connection with the presence detection mentioned above, is able to save over 50% of the light energy.
Daylight switching
The "little brother" of the constant light control can be used wherever the lighting can only be switched. A sensor in the room is also required to detect the brightness. If the daylight falls below the required room brightness, artificial light is automatically switched on in one or more levels and switched off again when the proportion of daylight increases. The combination with presence detection is also recommended here. The savings potential is up to 45%.
Automatic light
In rooms without sufficient daylight, e.g. B. in hallways or sanitary rooms, energy can be saved by only switching the lighting on temporarily. The presence detection provides the sensor data required for this. An adjustable switch-off delay ensures lighting comfort. The savings potential is heavily dependent on the frequency of use.
Sun control
External blinds and, to a certain extent, awnings also provide thermal protection for the building. Internal blinds, vertical slats, etc. Above all, ensure that there is no glare at workplaces. Both are therefore indispensable - despite the inevitable reduction in the amount of daylight. The automatic sun function, in conjunction with the corresponding weather data, ensures that the external sun protection always takes an adjustable position when a certain radiation intensity is exceeded. After an adjustable delay time has elapsed, the sun protection automatically moves back to the end position or at least to a horizontal slat position when the sky is overcast for better daylight supply. The internal glare protection is i. d. Usually not automated because the perception of glare has to be assessed individually.
Slat tracking
The slat tracking is the consistent further development of the sun automatic. If the radiation intensity is high, the sun protection moves to a position that is cyclically adjusted to the position of the sun. In this way, the daylight supply is maximized while maintaining the glare protection. From an energetic point of view, the combination with constant light control is recommended, as this can react continuously to the optimization and thus another 10% of the lighting energy can be saved.
Shading correction
Surrounding buildings or their own building parts cast shadows on the facades, which temporarily makes the glare protection function for the blinds in the shade unnecessary. The blinds should be open during this time for better daylight supply. For this function, the sun protection actuators of a room automation system must be equipped with a shading correction that works in conjunction with the automatic sun control or slat tracking. The function is sometimes also called the annual shading diagram.
Twilight switching
In outside or entrance areas and for illuminating a building, the following applies: Light is only required when it gets dark. Since the time varies according to the season, the twilight switch automatically ensures the optimum switch-on moment. In addition to the lighting, the sun protection can of course also be positioned depending on the twilight.
Weather protection
Weather protection functions prevent damage to the sun protection system. Sensors for temperature, precipitation, wind speed and direction provide the necessary weather data. The protective functions for wind, precipitation or ice formation ensure that the sun protection is retracted in good time before damage. Even motorized windows can be included in the protective function, so that damage from penetrating rainwater is avoided.
Functions for room climate control
Energy level choice
To increase energy efficiency, the energy levels comfort, standby, economy (night reduction) or building protection can be selected individually for each room, each of which is assigned its own setpoint. Switching can take place via time programs, manual control buttons or presence detection. A particularly energy-saving variant is to switch from economy to standby mode using the timer in the morning and to have the setpoints raised to the comfort level using presence detection. In this way, over 20% of the heating and cooling energy can be saved.
Start optimization
If, in addition to the current energy level, the room temperature controller is informed of the next and the corresponding time via a time program, the controller is able to determine the optimal heating time of the room based on additional information such as the room and outside temperature so that the desired Room temperature is available exactly at the selected time. This function, which avoids premature heating, is an extension of the energy level selection and is called start optimization.
Window surveillance
When the windows are open, the window monitoring system automatically switches to the building protection energy level in order to avoid wasting energy. The status of the windows is read in via the corresponding contacts. The savings that can be achieved are up to 10% of the heating and cooling energy.
Setpoint determination
Depending on the energy level, the room temperature and the desired temperature specified via a central specification or through local operation, a room temperature controller must be able to determine the correct setpoint specification of the control algorithm. In addition, the setpoint can be gradually increased at high outside temperatures (summer compensation) in order to avoid excessive differences to the room temperature.
Temperature control
The actual control of the room temperature by determining the correct actuator position for heating or cooling is carried out using the temperature control function. In most cases, PI controllers are used that are able to eliminate static control deviations.
Fan control
Airborne systems, e.g. B. fan coil units have fans for air transport. The amount of air can usually be adapted in several stages to the required heating or cooling output. The appropriate fan speed is selected based on the difference between the actual and the set room air temperature or analogous to the actuators of the heating or cooling register.
Air quality control
If the rooms are supplied with fresh air via mechanical systems, such as central or facade ventilation systems, the amount of supply air is adapted to the indoor air quality to save electrical energy for the fans. In its simplest form, the presence evaluation is used as a criterion in order to increase the volume flow from a minimum value in terms of building physics to a standard value when occupied (air quality control). In contrast, the highest energy efficiency is only achieved when the air quality is measured using CO 2 or mixed gas sensors and the supply air volume is regulated to maintain a fixed air quality (air quality control).
Night cooling
Cool night air can be used to cool down the room air if windows or facade flaps can be opened with motors or if fan convectors with supply air flaps are available. This function should be carried out individually for each room with the help of the measured local room temperature and the outside temperature in order to achieve an optimal reduction.
Thermal automatic
Sunlight entering through the window causes heat to enter the room, which is welcome or unwelcome depending on the room temperature. In unoccupied rooms, the automatic thermal system now takes control of the sun protection to support heating or cooling processes. In this way overheating can be avoided in summer and the heating can be relieved by solar gains in winter.
Energy efficiency through room automation
The high energy consumption for air conditioning and lighting in non-residential buildings requires good insulation and modern system technology with heat recovery , in particular energy-efficient control technology. The BDI study published by McKinsey in 2007 states: “In the building sector, levers for reducing consumption and increasing energy efficiency (...) make the greatest contribution to avoiding greenhouse gases. The overall renovation of old, not energy-efficient buildings results in a clear improvement than the mere implementation of standards for individual parts of the building. "
From the point of view of room automation, saving energy means above all avoiding waste! Cooling or heating with the window open, the lighting switched on when there is sufficient daylight, heated but unused rooms are an expression of such energy wastes that are eliminated by a room automation system. To do this, it records the necessary conditions in each room, such as room occupancy, temperature, brightness, window position, etc. and then optimally coordinates the heating or cooling, ventilation, lighting and sun protection. In this way, both the desired comfort conditions in occupied rooms and the operational readiness of unoccupied rooms are maintained with maximum efficiency. In terms of control technology, this means that in a first optimization step, which is carried out independently by the room automation, waste of energy is avoided and the optimized energy requirements are then passed on to the system controller as a target value. In the second step, the energy supply is then optimized within the automation stations (see Figure 5).
A study carried out on behalf of LonMark Germany at the Biberach University of Applied Sciences in 2007 shows that a room automation system can reduce the energy requirements of an office or school building by over 40% thanks to the integrated energy-efficient automation functions (see section).
The effects of building automation and thus also of room automation systems on the energy efficiency of buildings is standardized in DIN EN 15232. For this purpose, the automation functions are divided into 4 BA efficiency classes:
- BA efficiency class A: highly energy-efficient BA systems
- BAC efficiency class B: further developed, partially integrated BAC systems
- BAC efficiency class C: Standard BAC systems
- BACS efficiency class D: non-energy-efficient BACS systems
The VDI 3813-2 guideline contains an exact assignment of all room automation functions to the corresponding efficiency classes. This z. For example, the specialist planner can reliably identify all room automation functions required for a desired efficiency class according to DIN EN 15232 (see web links).
Flexibility of use through room automation
Office or administration buildings in particular are expected to be able to adapt to the changing requirements of different tenants or new process or work organizations. Because this changes the division and use of space, a room automation system in these buildings should be able to accompany this change without requiring rewiring.
What is not possible with conventional technology can be perfectly implemented with the help of an axis-flexible room automation concept. To do this, the room automation system only needs to be designed so that each building axis can be operated independently. In principle, a system distributor in this case accommodates all sensors and actuators of stationary field components (e.g. window contacts, dew point monitors, light outlets, sun protection motors, actuators) for a fixed number of axes - regardless of the actual room allocation. The resulting variable rooms are equipped with a room control unit and room-oriented sensors (e.g. multi-sensor). With this concept it is only necessary to ensure that the desired control functions (see section above) are in sufficient number, i.e. H. per formed space, are available. For this reason, it is advisable to arrange the control functions on the room-oriented devices. The axes can be grouped into rooms while the building is in operation using software and can therefore be varied at any time without having to intervene in the cabling.
Increased productivity through room automation
Scientific studies, e.g. B. BOSTI (Buffalo Organization for Social and Technological Innovation), have been showing since the late 1960s that people's productivity and job satisfaction can be increased by 15% compared to average environmental conditions through an ideal work environment. This is largely due to parameters that are influenced by a room automation system: lighting, temperature and air quality. It follows that, for reasons of productivity, a room automation system should be just as natural as ergonomic office equipment.
Interface to the plant automation system
The arrow marked with the number (2) in Figure 1 represents the interface between the room automation and the system automation. As already mentioned in the section on energy efficiency, both systems work largely independently. The interface is therefore primarily used to transfer the already optimized energy requirement values of the rooms to the system controller in a suitable manner in order to ensure that the required energy is provided economically. Since the number of data points is small, integration of the two systems is usually not particularly complex. If the systems are based on different communication standards, a corresponding gateway must be provided.
Interface to the building management system
The arrow (1) in Figure 1 shows the communication relationship between the room automation system and the building management system. The main purpose is the data exchange for visualization and operation, for alarm management, for archiving as well as the maintenance of calendars and timers. The number of data points is high, especially in the case of extensive visualizations. The OPC software interface or the BACnet / IP protocol are particularly suitable for communication .
literature
Norms:
- DIN 276-1: Costs in construction - Part 1: Building construction , Berlin, 2006
- VDI 3813-1: Room automation - Part 1: Basics , Berlin, 2007
- VDI 3813-2: Room automation - Part 2: Functions , Berlin, 2009
- DIN V 18599: Energetic evaluation of buildings - calculation of useful, final and primary energy requirements for heating, cooling, ventilation, hot water and lighting , Berlin, 2007
- DIN EN 15232: Energy efficiency of buildings - Influence of building automation and building management , Berlin, 2007
- DIN EN ISO 16484-3: Building automation systems ( BA ) - Part 3: Functions , Berlin, 2005
Technical literature:
- Building Network Institute (Ed.): GNI Handbook of Room Automation - Building Technology with Standard Systems , 1st edition, Zurich, 1999, ISBN 3-8007-2349-2
- LonMark Germany eV (Ed.): LonWorks Installation Manual - Practice for Electrical Engineers , 2nd Edition, Berlin, 2004, ISBN 3-8007-2575-4
- Kranz, Hans: BACnet 1.4 building automation , 2nd edition, Karlsruhe, 2006, Promotor Verlag, ISBN 3-9224-2009-5
- Wirtschaftsförderungsgesellschaft der Elektrohandwerke mbH (Ed.): Handbook Building System Technology - Basics , 4th edition, Frankfurt am Main, 1997
Individual evidence
- ↑ a b Becker Martin, Knoll Peter: Investigations into potential energy savings through the use of integrated open building automation systems based on the analysis of DIN V 18599 and prEN 15232 , Biberach University, 2007, study on behalf of LonMark Germany eV, Aachen
- ↑ DIN EN 15232: Building automation - Influence on energy efficiency , Berlin, 2007
- ↑ Radio protocols: Z-Wave, HomeMatic and RWE in comparison . Connected home. Retrieved October 24, 2014.
- ↑ ausschreiben.de
- ↑ lonmark.org
- ↑ Costs and potentials of avoiding greenhouse gas emissions in Germany , McKinsey & Company, Inc, 2007, Berlin, study commissioned by BDI initiativ - Economy for Climate Protection
- ↑ Brill Michael, Margulis Stephen T., Konar Ellen and BOSTI: Using office design to increase productivity , Buffalo, NY, 1984
Web links
- Download the LonMark brochure Automating energy efficiency (PDF; 501 kB)
- Download the short version of the LonMark study by the Biberach University of Applied Sciences
- Download the BDI study on the costs and potential of avoiding greenhouse gas emissions (PDF; 952 kB)
- Download the spega information on energy efficiency according to DIN EN 15232 and VDI 3813-2 (PDF; 553 kB)
- Functional profiles of LonMark International
- Website of the BACnet Interest Group Europe eV
- KNX Association website
- Website of LonMark Germany eV
- Website of the Intelligent Living Initiative
- Siemens room automation system website