Integrated Building Management - Weather Forcasting

Weather forecasting

Needs

While in the past control systems were largely "responsive," modern buildings require control algorithms to be more and more "predictive." The difference is that responsive systems react after they have detected a deviation from the desired conditions, while predictive systems factor forward-looking information into their control algorithms. A responsive system will, e.g., detect a drop in room temperature below its setpoint, and as a result switch on the heat generators to compensate for it. A predictive system will try to determine environmental influences on the room temperature, and bring up the heat generator as required, before the room temperature even drops.

This is of special importance in times where energy generators are designed for low supply temperatures, without much spare capacity: Failing to react early enough may result in non-ideal room conditions which persist long enough so as to make the building tenant feel uncomfortable. On slow reacting heat distribution systems such as underfloor heating or concrete core activation, this effect is even more pronounced. Using future weather conditions is a great and effective way to improve control quality, energy efficiency, and tenant comfort. Refer to the "Insights" section for details.

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Solutions

In all the above scenarios, the information about future weather conditions plays an essential role for energy efficiency and tenant comfort. As with many classic BMS system, the CentraLine solutions allow connection of weather stations through open protocol interfaces. However, this may be a costly and not necessarily accurate way of determining future weather conditions.

The CentraLine Niagara-based products HAWK, EAGLEHAWK, and ARENA BMS Supervisor offer an additional approach: They can access weather forecast data from Internet weather providers offering information on present and forecasted weather conditions (temperature, humidity, rain, cloudiness). This data can be used in the control algorithms to drive applications in the most energy-efficient way.

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Weather Forcasting

Products

SUPERVISION

ARENA X

ARENA AX is a web-based supervisor for HVAC systems and non-HVAC systems (e.g., Lighting, Shading, Security, Life Safety, etc.). Open systems based on standards such as BACnet, LONWORKS, OPC, Modbus, M-Bus, KNX, SNMP, and others can be directly integrated in the supervisor.

SMART INTEGRATION

HAWK

Smart integration platform, with BACnet (IP and MSTP) incl. B-BC certification, LONWORKS (FTT-10A and IP), Modbus, M-BUS, DALI, KNX, EnOcean, integration of CCTV, security and fire/smoke control.

HVAC PLANT CONTROL

EAGLEHAWK

Integrated building controller, with BACnet (IP and MSTP) incl. B-BC certification, LONWORKS (FTT-10A and IP), Modbus, M-BUS, DALI, KNX, EnOcean. Integration of lighting, shading, and other buildings applications.

Insights

Predictive control using future weather data is especially important if any of the following conditions apply:

1. Whenever big building storage masses play an essential role in heating or cooling the building. This is true, e.g., in "concrete core activation" applications. Building masses are heated up or cooled down at night when energy is cheaper. The concrete releases the stored heating / cooling energy slowly to the rooms the next day, which allows starting the heating/cooling later, thus saving expensive "peak hour" energy. However, you need to avoid cooling the concrete if the next day would be a cold day anyway: As cooling energy is stored in the big masses, a massive amount of heating energy would be needed to compensate for the cold walls, ceilings and /or floors plus the cold outside temperature.

2. Whenever the difference between supply temperature and desired room temperature is small. This is typically the case in modern underfloor heating or cooling applications. In such applications, it can take hours to compensate for a 1 K drop in room temperature, so you would look for a system which factors in future climatic conditions to supply heating or cooling energy before the room temperature is adversely affected.

3. Systems where buffer tanks are used to store heating and cooling energy. These tanks are typically loaded when energy is cheap, to use the stored energy the next day for conditioning rooms without using energy generators. You need to avoid loading the buffer if, on the next day, the climatic conditions would not require the energy. Otherwise, you will waste energy, as buffers unavoidably lose their energy over time.

4. In systems where a single buffer is used for both heating and cooling energy, the situation is even more critical: Future weather conditions need to be known to determine if the buffer should be used as heating or as cooling buffer. Failing to determine this reliably results in the need to "reverse" the load (e.g., from cold to hot water), causing a massive waste of energy. 5. Systems where the generators for heating or cooling energy are dimensioned such that there is no (or not much) spare capacity. The compensation for a 1 K drop in room temperature can take hours, so you would look for a system which factors in future climatic conditions to supply heating or cooling energy before the room temperature is adversely affected.

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