Management Committee December 3, Johnson County Community College Retrocommissioning Report

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1 Johnson County Community College Retrocommissioning Report Management Committee December 3, 2014

2 What is Retrocommissioning? Retrocommissioning is a systematic process to improve an existing building s performance. Using a whole-building systems approach, retro commissioning seeks to identify operational improvements that will increase occupant comfort and save energy. Why did we identify the COM and GEB buildings? They are among the oldest buildings Have the most opportunities for improvement Have high visibility and traffic Cost for the Study $49,210

3 Retrocommissioning Objectives Identify operational deficiencies Identify energy conservation opportunities Identify system performance improvements Result: the most in-depth investigation of College Commons (COM) and General Education Building (GEB) and both chilled water plants and respective distribution systems to date, including cost-effective improvement recommendations to achieve campuswide energy conservation objectives.

4 COM and GEB Key Findings Air distribution systems are adequate: outdated and inefficient air distribution systems (early 1970s), well-maintained, most controls have been updated to Direct Digital Control (DDC) Poor Chilled Water (CHW) control: Air Handling Unit (AHU) chilled water control valves are primarily antiquated and inefficient 3-way type Insufficient ventilation: Outside air dampers are manually closed to conserve energy rather than provide adequate ventilation air. Ineffective heating systems: Variable Air Volume (VAV) terminal boxes are obsolete and difficult to maintain, approximately 80% were identified with deficiencies Existing VAV box deficiencies, particularly non-functional electric reheat directly contributes to comfort problems, and results in significant system energy waste year-round control sequences increase airflow (cold air) and perimeter heating must overcome not only envelop heat loss, but also cold air entering occupied spaces from the air distribution system.

5 Chilled Water Plant Key Findings Good Equipment, Antiquated: Equipment is well-maintained in both plants, both plants have ample CHW capacity, but plant design and control are not optimal. E.g., variable speed chillers efficiency lost due to lack of condenser water relief Underutilized Thermal Storage: West plant underground thermal storage is only active from 11am 6pm, thus limiting potential utility cost savings Operation Provides Insufficient CHW for Cooling: During peak cooling days chiller capacity is limited to 80% of capacity to avoid higher peak electrical demand, in turn the campus CHW loop supply temperature increases and air handling units have difficulty maintaining space temperature setpoint Air-Laden CHW System: East plant utilizes an ineffective air/dirt separator, impacting system performance and longevity A comprehensive chilled water optimization project would significantly improve operation of both plants & achieve substantial energy savings, including better electrical demand management and the ability to better meet cooling demand at each building.

6 CHW Distribution System Findings Poor CHW Distribution Scheme: System consists of Primary/Secondary/Tertiary (building) pumping and inefficient 3-way control valves and building return mixing valves Poor CHW Control at Loads: Chilled water short-circuits /bypasses the AHU load resulting in system inefficiency that is commonly referred to as low T syndrome Lack of CHW in remote buildings: System pressure effects inherent with current control valve installations cause imbalance of chilled water demanded (first buildings steal flow from those down the line) High Pumping Energy: While Variable Frequency Drives (VFD s) exist, they are used primarily for soft start only A comprehensive chilled water distribution optimization project would significantly improve chilled water flow to each building, achieve substantial utility savings, and improve building comfort.

7 CHW System Recommendations Project Components Cost Utility Savings Maint. Savings Total Savings Payback Ch Chilled Water Plant Optimization $326,447 $67,616 $0 $67, ## Ch Chilled Water Thermal Storage Optimization $6,688 $7,785 $0 $7, ## Chilled Water Distribution Optimization $756,485 $129,393 $7,245 $136, ## Install Spirotherm Air/Dirt Separator $96,923 $14,181 $0 $14, ## $1,186,543 $218,975 $7,245 $226, CHW Plant Optimization: (Ultra-efficient CHW plant control strategies): all variable speed pumping (primary and condenser water flow), chiller sequencing, condenser water reset; chilled water reset; sequence cooling tower fans, level campus CHW load across both plants Thermal Storage Optimization: Expand hours of operation and regulate discharge flow to reduce electrical demand and improve building comfort CHW Distribution Optimization: New Pressure-Independent Control Valves at All Building AHUs, balanced AHU flow, reduced pumping energy, improved system T (efficiency), and improved flow/comfort at remote buildings New air/dirt separator at East Plant: Address aeration problems, increase efficiency 12-15%, improve system heat transfer

8 CHW System Implementation Comprehensive project maximizes performance improvement: The CHW plants and distribution systems require a comprehensive approach to ensure performance. Considered independently, the strategies recommended will not produce similar energy savings or operational improvement. Continuity key to achieving performance objectives: The recommended scope of CHWS improvements is complex, traditional design and construction methods are poorly suited to achieving operational improvement and energy saving objectives due to fragmented accountability for performance goals. A turnkey approach best ensures project success: Integrating engineering expertise with implementation of energy-saving strategies for continuity in meeting performance requirements, plus system commissioning and expertise to optimize system performance following implementation; a single entity accountable for project performance and energy savings.

9 Conclusion Well-maintained but older, inefficient HVAC systems. System investments will improve building occupant comfort and drive further energy savings with positive paybacks. Investments in Chilled Water optimization to be recommended as part of capital plans for FY