BEMOSS Overview
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BEMOSS™ is a Building Energy Management Open Source Software (BEMOSS™) platform that is engineered to improve sensing and control of equipment in small- and medium-sized commercial buildings. BEMOSS™ aims to optimize electricity usage to reduce energy consumption and help implement demand response (DR) programs. This opens up demand side ancillary services markets and creates opportunities for building owner/operators. This in turn can help accelerate development of market-ready products like embedded Building Energy Management (BEM) systems and device controllers for HVAC, lighting and plug loads. BEMOSS aims to offer: scalability, robustness, plug and play, open protocol, interoperability, cost-effectiveness, as well as local and remote monitoring, allowing it to work with load control devices form different manufacturers that operate on different communication technologies and protocols. Currently, BEMOSS supports the following prevalent communication technologies: Ethernet (IEEE 802.3), Serial (RS-485), ZigBee (IEEE 802.15.4) and Wi-Fi (IEEE 802.11); and protocols: BACnet, Modbus, Web, ZigBee API, OpenADR and Smart Energy Profile (SEP) protocols.
BEMOSS™ offers the following key features:
- Open source, open architecture – BEMOSS™ is an open source operating system that is built upon VOLTTRON™ – a distributed agent platform developed by Pacific Northwest National Laboratory (PNNL). BEMOSS™ is designed to have an open architecture to make it easy for hardware manufacturers to seamlessly interface their devices with BEMOSS™. Software developers can also contribute to adding additional BEMOSS™ functionalities and applications.
- Plug & play – BEMOSS™ is designed to automatically discover supported load controllers (including smart thermostats, VAV/RTUs, lighting load controllers and plug load controllers) in commercial buildings. Once devices are discovered, BEMOSS™ can then monitor and control them and perform the desired functions.
- Interoperability – BEMOSS™ is designed to work with load control devices form different manufacturers that operate on different communication technologies and data exchange protocols. These include both new commercially available products that operate on Ethernet, Wi-Fi and ZigBee, as well as legacy devices that operate on serial communications using Modbus RTU and BACnet MS/TP protocols. Currently, BEMOSS supports the following prevalent communication technologies: Ethernet (IEEE 802.3), Serial (RS-485), ZigBee (IEEE 802.15.4) and Wi-Fi (IEEE 802.11); and protocols: BACnet, Modbus, Web, ZigBee API, OpenADR and Smart Energy (SE) protocols.
- Cost effectiveness – Implementation of BEMOSS™ is deemed to be cost-effective as it is built upon a robust open source platform that can operate on a low-cost single-board computer, such as Odroid. This feature can contribute to its rapid deployment in small- or medium-sized commercial buildings.
- Scalability and ease of deployment – The BEMOSS™ software platform is designed with a multi-layer architecture where multiple single-board computers hosting BEMOSS™ can communicate among each other and to a master controller to monitor and control a large number of load controllers in a multi-floor and high occupancy building. This makes it possible for a building engineer to deploy BEMOSS™ in one zone of a building, be comfortable with its operation, and later on expand the deployment to the entire building to make it more energy efficient.
- Ability to provide local and remote monitoring – BEMOSS™ provides both local and remote monitoring ability with role-based access control.
- Security – In addition to built-in security features provided by VOLTTRON™ including agent authorization & authentication, encrypted multi-layer communication and agent validation, BEMOSS™ provides additional enhanced security features.
Buildings consume over 40% of the total energy consumption in the U.S. According to U.S. Energy Information Administration (EIA), a vast majority of commercial buildings are relatively small. As shown in the figure below, about half (49.9%) of all commercial buildings are 5,000 square feet or smaller in size. Medium-sized commercial buildings (between 5,001 to 50,000 square feet) constitute almost the other half (44.0%). These buildings typically do not use Building Automation Systems (BAS) to monitor and control their buildings from a central location. This is primarily due to the unavailability of low-cost and simple BAS that can function without the presence of a building engineer on-site. BEMOSS™ operating system has been designed to target small and medium-sized commercial buildings to address this gap.
Figure 1. Percent of total commercial buildings and floor space by size of buildings (Source: EIA - Commercial Building Energy Consumption Survey (CBECS))
With respect to load types, there are three major loads in commercial buildings: HVAC, lighting and plug loads. According to the data from EIA published in 2008 , electricity use by HVAC equipment, i.e., space heating, cooling and ventilation accounts for 30% of the total electricity consumption in buildings. Lighting loads constitute the majority share of electricity use at 38%. Electricity use by plug loads, i.e., office equipment, computers, etc. accounts for 6% of total electricity use in buildings. Other loads include water heating, refrigeration, elevators, etc. The figure below illustrates electricity use in buildings by load type.
Figure 2. Electricity consumption by end use for all buildings (source: EIA)
BEMOSS™ is designed to control these three major loads in buildings: HVAC, lighting and plug loads. Selected Load controllers with communication features for each of these target load categories are supported by BEMOSS™.
- For HVAC systems, smart thermostats, variable speed drive controllers, RTU controllers and VAV controllers are the most popular control devices (RTU = rooftop unit; VAV = variable air volume).
- For lighting loads, dimmable ballasts (both stepped dimmed and 0-10V dimming ballasts), Wi-Fi light switches, and lighting load controllers that can control the entire lighting circuit can be used.
- Plug load controllers that can control the entire plug load circuit and smart plugs can be used as controllers for plug loads.
Various technologies are available that allow communications between BEMOSS™ and associated load controllers in a building. These include wired technologies, like: Power Line Communication (PLC), Ethernet and Serial (RS-485); as well as, wireless ones, like: ZigBee, Wi-Fi, Z-wave and EnOcean.
The full version of BEMOSS™ supports the following prevalent communication technologies: Ethernet (IEEE 802.3), Serial (RS-485), ZigBee (IEEE 802.15.4) and Wi-Fi (IEEE 802.11), as summarized in the Table below.
Table 1. Communication technologies supported by BEMOSS™
Devices communicating using the same communication technology may utilize different data exchange protocols. For a building energy management system, there are many protocols that are popular or becoming popular. These are open standard protocols like: BACnet, Modbus, KNX, M-bus, Web, OpenADR and Smart Energy (SE); as well as proprietary protocols like: LonWorks and DALI.
The full version of BEMOSS™ supports the following protocols: BACnet, Modbus, Web, OpenADR and SE protocols, as summarized below.
Table 2. Data Exchange Protocols Supported by BEMOSS™
The BEMOSS™ architecture is illustrated in the figure below for a small commercial building with a few load controllers of each type. In this architecture, only one single-board computer (e.g., Odroid) embedded with the BEMOSS™ software platform is used to enable monitoring and control features of all load controllers in the building. This embedded system can communicate with different types of load controllers, i.e., thermostats, lighting load controllers and plug load controllers, and sensors/power meters via wireless signals (either Wi-Fi or ZigBee). Local and remote monitoring and control via a smart phone or a tablet are also enabled.
Figure 3. BEMOSS™ system architecture for small buildings with a few load controllers
For multi-floor buildings with larger number of devices, BEMOSS™ can be set up to deploy its multi-layer architecture feature. In this architecture, as shown in the figure below, a BEMOSS™ node is responsible for monitoring and control devices on one floor. Each BEMOSS™ node communicates with each other and also communicates with the BEMOSS™ Core. The BEMOSS™ Core is responsible for supervising the overall system operation, managing multiple BEMOSS™ nodes, and allowing local and remote access for monitoring and control of all devices in buildings.
Figure 4. BEMOSS™ system architecture for larger buildings
BEMOSS™ is a robust open source operating system for building energy management that is built completely using open source software tools. The entire BEMOSS™ system comprises of four layers: User Interface (UI) layer, Application and Data Management Layer, Operating System and Framework layer, and the Connectivity Layer. In addition to these, there are also parallel BEMOSS™ databases that help with the storage of all information pertaining to BEMOSS™ and help smooth its functioning. The figure below depicts the overall system architecture.
Figure 5. BEMOSS™ software architecture
The BEMOSS™ UI layer has two components: user interface and user management. BEMOSS™ web UI is a dashboard type interface with visuals and graphs to show current settings of devices in each zone. Authenticated users can also control these devices through an on-site interface. Regarding user management in BEMOSS™, role-based access control is implemented to allow different levels of access to different individuals. For example, building engineers will have full authority to adjust set points and schedules of loads in buildings, while tenants will have limited access to view current status and historical load data, or control selected loads in specific zones. In BEMOSS™, this role-based access control is achieved using access control lists.
This layer embeds algorithms to allow monitoring and control of hardware devices interfaced with BEMOSS™. Examples of possible applications include demand response, price-based management, planning and scheduling, behavior pattern analysis, load management, as well as alarm/notifications. Apache Cassandra is selected for storing BEMOSS™ time-series data in a distributed fashion. A relational database management system (PostgreSQL) is used to satisfy the need to store the metadata for identifying users, devices, and process controls.
In this layer, VOLTTRON™, a distributed agent platform developed by Pacific Northwest National Laboratory (PNNL), is chosen as the software platform for BEMOSS™. As shown in the figure below several BEMOSS™ agents have been developed, including device discovery agent, monitoring agent (e.g., sensor agents), control agent (e.g., thermostat agents, lighting load agents and plug load agents), network agent, platform agent and OpenADR agent. All agents communicate over an Information Exchange Bus (IEB). The entire BEMOSS™ system is also designed to allow email/SMS notifications using IFTTT (If This Then That).
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Device discovery agent - is responsible for detecting the presence of devices in a building, querying their model numbers, identifying their APIs and launching a control agent to monitor/control the discovered device. With this approach, there is no need to manually identify each device beforehand using an approach, like bar code or QR code.
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Control agent - includes thermostat agents, lighting load agents and plug load agents. These agents are automatically generated to monitor, communicate and control hardware devices after they were discovered by the device discovery agent. Once a control agent is initiated, it is assigned particularly to one hardware device.
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Monitoring agent – is a sensor agent that communicates with sensors and/or power meters. Similar to control agents, monitoring agents are automatically generated to monitor and communicate with sensors and power meters after they are discovered by the device discovery agent.
This layer takes care of the communication between the Operating System and Framework layer and all physical hardware devices. To allow BEMOSS™ to communicate with hardware devices that use different communication technologies, data exchange protocols and have device functionalities (different device API’s), the BEMOSS™ team created several API interfaces. Each API interface allows BEMOSS™ agents to communicate with a group of devices based on their unique API’s. Basically, API interfaces provide a translation service for BEMOSS™ agents so that agents can get readings and send control commands to devices (without knowing their API’s) using simple function calls: getDeviceStatus and setDeviceStatus.
The current release "BEMOSS™ V2.0" utilizes API interfaces for USNAP compatible Wi-Fi devices, WeMo devices and Philips Hue, BACnet Lighting and Modbus VAV and RTU.