RTU Savings Research Project RTU Savings Research Project: Findings and Recommendations Regional Technical Forum February 3, 2009 Mark Cherniack Howard Reichmuth New Buildings Institute

RTU Savings Research Project Phased RTU Research program –Phase 1: Identify the known savings and cost- effectiveness data; establish priorities for Phase 2 research –Phase 2: Conduct the Phase 1 recommended research activities –Phase 3: To be determined by outcome of Phase 2; an expanded field test was envisioned

RTU Savings Research Project Phase 2 RTU Research Project Bench test controller/sensor issue Apply field measurement and service protocol to RTUs Develop an annual savings methodology based on the measured data Review existing utility RTU program data Propose a Phase 3 work plan

RTU Savings Research Project Review Existing Data Set 70% had the controller being tested 1% used enthalpy sensors with unknown drift and calibration, although only dry- bulb sensing is necessary in our climate 56% had only a single stage of cooling wired, which significantly curtailed economizer use 73% used single changeover point (one outdoor sensor and no return air sensor), 27% used a differential changeover strategy

RTU Savings Research Project Phase 2 RTU Research Project Bench Test Economizer control problem identified Tested specific Honeywell controller/sensor combo Found 6-10 degF deadband in sensor-limited economizer cooling Honeywell verifies sensor finding Recommendations made for new sensor

RTU Savings Research Project RTU Savings Research Project Bench Test

RTU Savings Research Project RTU Savings Research Project Bench Test- Honeywell Sensor Specs Analog circuit based on C7400 circuit Microprocessor based control with +/- 1 degree F hysteresis 10 to 20 mA output signal to economizer logic module 4 OR 20 mA output signal to economizer control; At 4 mA not OK to economize, 20 mA OK to economize C7650C7660

RTU Savings Research Project RTU Savings Research Project Bench Test Recommendations Ensure that the old Honeywell sensor is not being used in new HVAC units coming in through utility HVAC EE programs Notify a wide band of HVAC market stakeholders Establish benefits of adding the new sensor to utility RTU field service protocols Consider regional bulk sensor purchase

RTU Savings Research Project RTU Savings Research Project RTU Field Measurement & Service Protocol 9 initial sites recruited; 5 have little cooling load. 3 sites provided sufficient signature data for analysis and consideration Metering was more than sufficient for the minimum monitoring package Analyzed three preliminary Bonneville sites

RTU Savings Research Project RTU Savings Research Project RTU Service Protocol Thermostat reset and/or replacement Measured airflow through the evaporator Economizer system check Additional control potential Refrigerant charge check/adjustment as needed

RTU Savings Research Project RTU Savings Research Project RTU Monitoring RTU total power RTU fan power Gas burner status Damper position Condensate flow Outdoor air temperature (2 measurements) Return/mixed (4 measurements) temperatures Supply air temperature

RTU Savings Research Project RTU Savings Research Project RTU Monitoring Results RTU Electric Signature

RTU Savings Research Project RTU Savings Research Project Anatomy of an RTU Energy Signature Cooling balance point temperature ‘Flat’ low temperature slope Cooling slope

RTU Savings Research Project RTU Savings Research Project RTU Monitoring Results RTU Gas Signature

RTU Savings Research Project RTU Savings Research Project RTU Monitoring Results % Outside Air Map

RTU Savings Research Project RTU Savings Research Project RTU Monitoring Results Economizer Control Temperature Map

RTU Savings Research Project RTU Savings Research Project Bonneville Unit Hourly Max Power vs Temperature

RTU Savings Research Project RTU Savings Research Project RTU Monitoring Results Economizer Effect

RTU Savings Research Project RTU Savings Research Project Annual Savings Methodology Average daily site temperature Daily RTU energy [electric/gas] signature Histogram of site daily normal avg 5 degF bins (consistent with Bonneville data) Signature x histogram = daily RTU energy Normalized annualized RTU energy is annual sum of daily RTU energy

RTU Savings Research Project RTU Savings Research Project Annual Savings Methodology # 1 Finding: With a few weeks pre- and post-data on a regularly operating building, an estimate of annual energy use and therefore savings, can be reliably made. Data needs to be studied in detail to gain confidence in interpreting the results.

RTU Savings Research Project RTU Savings Research Project Keys To Annual Savings Methodology 4 diagnostic graphs are needed for a high confidence energy savings estimate –Mode by power map = accurate kW savings –% outside air map –Economizer temperature control map –RTU energy performance map

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site 895 Initial RTU Performance Map

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site 895 Daily RTU Energy Profile

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site 895 RTU Performance Map

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site kWh savings RTU Annual Energy by Temperature Bins

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site 897 RTU Performance Map

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site kWh savings RTU Annual Energy by Temperature Bins

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site 899 RTU Performance Map

RTU Savings Research Project Preliminary Bonneville Site RTU Data Site kWh savings RTU Annual Energy by Temperature Bins

RTU Savings Research Project RTU Savings Research Project Recommendations - Phase 3 Apply measurement/monitoring protocol-- >> To all remaining Bonneville existing sites >> In all new field monitoring projects including the Premium Ventilation Package and Bonneville’s upcoming field monitoring project [60+ sites?] Current models should be reconciled to existing/new unit level data Subset monitored annually at least 5 years Fan power savings are very important: 24-hr operation More aggressive economizer control: pre-cooling