The Building Operating System (BOS) Themis
THEMIS (THermic and Energetic MonItoring System) is a NON-INTRUSIVE monitoring network targeting building energy performance. THEMIS embeds a fork of the EmonCMS software as a grapher and for data storage. EmonCMS is a NoSQL database dedicated to real-time monitoring based on connected objects. Its code is open source.
The diagram below represents the general architecture of the THEMIS ecosystem, structured around an Advantech 4G smartflex cellular router/gateway…..
This architecture implements two types of radio frequencies: 868 Mhz and 169 Mhz and offers the possibility to interface with an industrial RS485 bus (modbus), a standard communication protocol popular in industrial environments, such as boiler rooms of tertiary buildings. This makes THEMIS a powerful data aggregator, benefiting from the high efficiency of the MQTT protocol (Message Queuing Telemetry Transport). Thanks to the 169Mhz band, THEMIS is able to equip large buildings with wireless sensors.
On a single building or on a set of buildings, THEMIS is able to gather in real time existing measurements from available facilities and extra ones from new sensors, storing all the feeds in the same NoSQL chronological database. The aim is to capitalize physical data in order to provide a coherent digital material to intelligent algorithms so that they can quantify the building behaviour and optimize energy management.
THEMIS offers a wide variety of measurements: indoor and outdoor temperature, humidity, CO2, instantaneous electrical power, gas pulses, heat metering…
THEMIS can simulate thermal losses related to air leakages, and can estimate the actual performance of the building envelope, in order to assess the difference with the prescribed performance.
The system was heavily tested on the field during an operation funded by the social landlord Allier habitat, with measurements carried out over one year on three pavilion-type dwellings in order to evaluate different thermal insulation techniques from the outside.
Given the precision of its monitoring, THEMIS makes it easy to distinguish what is relevant to uses (ie related to the residents’habits or behaviours) from what is specific to the building’s performance, as shown by the following illustration, where we can identify at a glance the energy consumption due to the use of an air conditioner.
During summer, THEMIS can calculate absolute humidity and produce psychrometric diagrams in order to identify the discomfort.
With such software tools, THEMIS is the perfect equipment for engineering departments specialized in energy efficiency. It is also very relevant in the field of maintenance.
The following dashboard details the circuits’monitoring in a gas boiler room. The green and red curves represents respectively the outside temperature and the flow temperature in the circuits. The pumps’activities appear in orange, while the openings and closures of 3-way valves are represented by vertical lines, blue for openings and black for closures.
The second graph is typical of a 3-way valve failure. We can see repeating opening orders while the temperature in the circuit remains the same. A replacement has to be achieved as soon as possible.
The first graph illustrates a normal behaviour : at night, hot water supply is reduced.
The third graph represents the heat regulation on a poorly insulated building : while modeling the building’s behaviour, the artificial intelligence concluded that, when outside temperature was below a certain threshold and when heat injection in the circuit was stopped during the night, indoor temperature dropped too much between evening and morning. In those cases, the decision taken is to keep the building warm at night in order to ensure a basic comfort in morning time, when office work resumes.
In the future, with on board artificial intelligence algorithms and intelligent control functions, THEMIS will be able to act as a multi-energetic smartgrid controller, in a decentralized and autonomous perspective
The THEMIS system will become the reference controller for dromotherm technology.
