Seton Hall is a high-rise building with seven single-gender floors set up in a rectangular fashion that houses both first-year and upper-class students. Seton rooms are fashioned for double and triple occupancy. At capacity, Seton accommodates 459 students. The scope of this project is 286 dormitory rooms.
Prior to the installation of the wireless energy management system (WEMS) the room temperatures were controlled by a thermostat on the 2nd floor of an 8 story building. The thermostat controlled all the rooms above that 2nd floor room, i.e. room 201 controlled the temp in 301, 401, 501, 601, 701 and 801. The maximum temperature the student on the 2nd floor could control was 85 degrees. There was no basic control for the room temperature except to open the window when temperatures were too hot. The WEMS installation was completed in August of 2018. The access time needed in each room was approximately 15 minutes. The room equipment portion of the installation was completed in less than one week.
Technology and System Architecture
The wireless system deployed uses the EnOcean® standard which is internationally ISO certified and IEC standardized. This is the first and only wireless standard that is also optimized for energy harvesting solutions, i.e. self-powered devices (no batteries). This international standard lays the foundation for fully interoperable, open wireless technology comparable to standards such as Bluetooth and Wi-Fi. As such, the proposed WEM devices are fully compatible with all major bus wired bus systems.
The thermostats with built-in occupancy sensors, powered by ambient light, and embedded with an EnOcean chip were securely mounted in each room. The other room component included a relay wired into the existing electric resistance heater. The devices communicated wirelessly back to an “Ebox”, which converts the EnOcean signal to BACnet over IP. The devices were preprogrammed by the vendor so as to simplify on-site installation, commissioning, and authentication.
An Intellastar T-245 unit provides the main control for the site and is connected to the EBox’s and electrical meter via BACnet and Mod Bus. The components are built on advanced, secure architecture. The T-245 provides all of the advanced control, analytics and fault detection, including temperature, occupancy, and weather data; plus reporting and automation for fault detection, Time of Use Pricing, and Demand Response.
The software used with the T-Star controller was customized for Niagara University. It provides visualization of data with dashboards via a web browser interface so that users can set and change occupancy schedules and view performance on PC’s, tablets or smart phones. As detailed, below the software also provides real-time data supporting fault detection and diagnostics, smart alarming, smart grid, energy modeling analytics, and demand response. (See Graphic #3, p.8 in this case study)
The team behind the development of Intellastar and software has a strong background in building automation systems (e.g. Niagara and Tridium platforms). In addition to HVAC control the Intellastar platform supports associated wireless applications including lighting and plug load control, and metering, i.e. one single gateway.
Radio Frequency Transmission
The Radio Frequency (RF) system uses a mesh network based on the IPV6 protocol. This RF system is designed to provide unlimited communication between devices and gateway(s) to optimize network transmission performance. This “self healing” network allows up to 1,000 points per gateway (compared to 120 points for most network controllers). The RF runs on a 902 MHz EnOcean protocol which is converted to BACnet over IP via the Ebox. The T-Star unit in turn, uses the existing Ethernet LAN (or can use cellular) to communicate out to user devices (i.e. laptops, tablets, smart phones). The transmission does not rely on WiFi and therefore bandwidth and interference are not a concern. Likewise, WiFi and “cloud” security concerns are eliminated. The vendor and facilities personnel worked closely with the campus IT department to coordinate the various IP aspects.
Typical of most university IT requirements, there were tight restrictions for “cloud based” wireless systems. It is a big plus the Intellastar gateway system uses HTTPS (latest IP) and sits behind the owner’s firewall. Remote access for trouble-shooting and analytical support and service is provided through a VPN. (At the customer’s preference, data can be stored in the cloud.)
Although this case study is based on electric heat, the WEMS approach to occupancy- based control is also applicable to PTAC, RTU / AHU, and hot water / steam applications.
Project Financial Results and Energy Savings
The system vendor actively assisted NU with securing the National Grid Custom Incentive, reducing the project cost by 38%.
An energy analysis performed by National Grid projected annual savings of 237,577 kWh, or $18,056.
Simple payback (after incentive): 4.3 years
Comparison of meter data for Jan Feb 2019 compared with previous year indicates kWh savings of 32% (see Graphic #2, p.7)
This project received an energy conservation award from National Grid.
More detail relating to this case study is available here.