Wireless Pneumatic Thermostats help UCSD reach sustainability goals

  • October 16, 2013
  • Case Study

October, 2013 - The University of California at San Diego (UCSD) takes pride in practicing what it teaches – particularly when it comes to sustainability – and has a track record that leaves little doubt about its commitment. UCSD received the highest sustainability rating given to U.S. college and university campuses by the Sustainable Endowments Institute and is on target to surpass the University of California system’s goals to reduce greenhouse gas emissions to 2000 levels by 2014, and further reduce them to 1990 levels by 2020. One strategy the University uses to meet sustainability goals is to incorporate energy efficiency into every new building and renovation project, thus lowering operating costs, reducing environmental impact and saving money. UCSD installed wireless pneumatic thermostats (WPTs) in McGill-Mandler Hall to allow for centralized control of temperature set points through the existing building automation system (BAS). This project will reduce electricity use in the building by an estimated 27% annually and reduce natural gas use by approximately 51% annually. McGill-Mandler Hall is a concrete building with two multistory towers and a shared basement. The building, home to the UCSD Department of Psychology, is used mainly for research and includes lab, vivarium, classroom and office spaces. McGill-Mandler Hall is open seven days a week and is typically occupied from 8 am to 6 pm, with frequent after-hours occupants in the research areas. Six air handlers meet the building’s ventilation needs. Chilled water and high temperature hot water from the UCSD campus plant provide cooling and heating. The building HVAC control system is an electric/pneumatic hybrid. In early 2011, as part of a monitoring based commissioning (MBCx) program, Eaton Energy Solutions provided a thorough evaluation of McGill-Mandler Hall’s HVAC system to identify opportunities to maximize operating efficiency and meet the needs of building occupants. Engineers identified a number of HVAC inefficiencies including the following:

  • the majority of pneumatic thermostats were out of calibration;
  • occupants and facility staff were manually controlling pneumatic thermostats and zone temperatures;
  • air handler fans were operating 24/7;
  • supply air temperature set points were constant throughout the year; and
  • some of the air handler outside air economizers were not functioning properly.

Cypress Envirosystems’ WPTs offered a number of features that addressed these inefficiencies. Wireless HVAC Retrofit Traditionally, manual pneumatic systems are replaced with new wired direct digital control (DDC) systems. However, WPTs can provide most of the energy benefits of a traditional DDC installation at a fraction of the cost and with minimal occupant and wiring disruption. WPTs utilize a building’s existing pneumatic system, replicating the functions provided by traditional pneumatic thermostats, while providing the added benefits of communicating zone-specific temperature and HVAC system information to a central control hub. The key benefit of WPTs over the existing system in McGill-Mandler Hall is that the WPTs allow both manual occupant control and centralized control of temperature set points. Facility managers can remotely monitor thermostat settings and zone temperatures, make changes, establish automated schedules, and diagnose problems through the centralized BAS. The installation of the WPTs and components took about one month, and commissioning and programming took an additional month. The 250 existing pneumatic thermostats were removed and replaced one-for-one with WPTs, which were connected to the existing pneumatic piping, calibrated, and programmed. Wireless repeaters were installed at intervals throughout the building to support the transfer of the wireless signals from the WPTs to a Cypress Envirosystems Green Box Controller. Three Green Box Controllers were installed and tied-in to the Johnson Controls’ BAS via a LAN line. WPTs were installed throughout the building to control the spaces served by five of the building’s six air handlers. The sixth air handler serves the McGill Hall basement, where the pneumatic system was previously retrofitted with a DDC system that is also controlled by the BAS and was not retrofitted during this project. To complement utilization of the new WPTs and address other problems identified in the MBCx process, a number of other supporting upgrades were included in the project: (1) installing new variable frequency drives (VFDs) on the air handler fans; (2) programming the Johnson Controls BAS to communicate with the new WPTs; (3) installing and calibrating three new outside air economizer dampers; and (4) programming the supply air temperature set point resets, occupied and unoccupied space temperature set points, and schedules for the spaces served by the WPTs. As a partner with Cypress Envirosystems, Eaton Energy Solutions provided and installed the WPTs and components and performed the air handler upgrades with assistance from UCSD facility staff.   Project Costs and Savings Estimated annual energy savings from the project are anticipated to be 538,900 kWh and 57,000 therms. This represents an annual reduction in total building electricity use of 27%, natural gas use of 51%, and energy cost savings of about $94,900. The majority of the project energy savings come from the reduced demand for heating and cooling, as well as reduced run hours for the air handler fans. The total project cost was approximately $295,700 before rebates were applied and $14,600 after rebates. The Energy Technology Assistance Program rebates covered 32% of the project cost, and the UC/CSU/IOU Energy Efficiency Partnership Program (administered by SDG&E) is expected to cover 63% of the total project cost. The project’s simple payback is 0.2 years. Without rebates, the simple payback would have been 3.1 years. The balance of the project cost will be covered by a low-interest revenue bond that will be repaid with energy savings. In addition to energy savings, the facility is likely to realize maintenance cost savings by being better able to identify and correct operational problems. Components of the wireless HVAC system 1)    Cypress Envirosystems Deadband WPTs replaced existing traditional pneumatic thermostats one-for-one throughout the building. 2)    Cypress Envirosystems Repeater picks up the signals from the surrounding WPTs and directs them to the Green Box Controller. 3)    Cypress Envirosystems Green Box Controller communicates with the building’s Johnson Controls Metasys BAS. 4)    Johnson Controls Metasys System controller box. The Cypress system has been integrated with the building’s pre-existing Johnson Controls BAS and allows the BAS to log data and control the WPT system. Demand Response In addition to energy savings, the University anticipates using the WPT system to implement demand response strategies. Previously, the HVAC heating and cooling setpoints were set by occupants. The new WPT system provides increased capability to monitor and control space temperature setpoints, which will allow implementation of a demand response sequence that conditions every zone as if it were unoccupied during a demand response event. This will cause the zone temperature setpoints to widen from 70 – 74 degrees F (occupied setpoints) to 66 – 78 degrees F in offices and 68 – 76 degrees F in labs (unoccupied setpoints). Cypress Envirosystems Cypress Envirosystems saves energy and improves productivity in existing plants and buildings, using state-of-the-art non-invasive and wireless technologies to minimize disruption and cost, delivering payback of 18 months or less. Cypress’ products include Wireless Pneumatic Thermostats, Wireless Gauge Readers, and Wireless Steam Trap Monitors.

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