ASHRAE Journal - May 2010 - 46

Hospital Retrocommissioning
By Tom Hanlon, Member ASHRAE; Ed Tinsley, P Member ASHRAE; and Tim Staley, P Member ASHRAE .E., .E., ercy Hospital in Fort Scott, Kan., opened in August The selected ECRMs primarily addressed air terminal 2002. The hospital floor area is 177,500 ft2 (16 490 minimum flow settings, air terminal occupied and unoccupied m2) and operates 70 inpatient beds (the hospital is scheduling, return air fan speed controls, insufficient cooling licensed for 170 beds). The hospital was concerned with its tower capacity, variable volume heating water distribution, operating cost and energy consumption profile in light of the building exhaust control, excessive pressure drop caused by continuing economic challenge in delivering health-care ser- balancing valves, mixed air damper sequencing, control loop vices. The Mercy Healthcare System tuning and simultaneous heating and engaged an energy services firm to cooling. Some of the projects identified provide technical retrocommissionwere addressed by hospital personnel, ing and facility analysis services to typically those involving minor system Name: Mercy Hospital evaluate and improve the operating adjustments and management of the Location: Fort Scott, Kan. efficiency and effectiveness of the hospital operating controls. Other Year Built: 2002 hospital’s systems, aimed at improved projects required engineering design, Size: 177,500 ft2 energy performance. construction and technical commisTotal Project Cost: $207,789 The firm developed a process of sioning services. Estimated Annual Cost Savings: detailed overall building performance The most significant contributors to evaluation. The first step was to develop the excessive energy consumption and $181,310 a baseline assessment of the operating energy cost for Mercy Hospital were Actual Annual Cost Savings: $392,000 performance of the Fort Scott Mercy simultaneous heating and cooling Utility Cost Savings: $2.16/ft2 Hospital in comparison to similar facosts associated with high minimum cilities. Mercy Healthcare System had airflow rates and improper control developed a system-wide benchmarking of its facilities and, as sequences. By aggressively reviewing each air terminal in the indicated in Table 1, the Fort Scott facility was well above its facility and reducing the occupied/unoccupied airflows to the average of $2.85/ft2/year ($30.68/m2/yr). Although only three minimum allowed by code, and increasing the temperature plus years into operations, the facility was operating at nearly difference (bias) by which the air terminal switches from double Mercy’s average energy costs. cooling mode to heating mode, significant energy savings Initially, a Phase I investigative technical retrocommissioning were achieved. Figures 1 and 2 further demonstrate how these effort was completed that identified and evaluated approxi- savings were achieved. mately 130 energy cost reduction Before After Remarks Savings measures (ECRMs). Based on capital costs, economic returns, Electricity Consumption (kWh) 7,808,800 5,249,800 32.8% and impact on environmental Average Peak Demand (kW) 1,230 929 24.5% quality, the hospital narrowed the Mercy Average: list to approximately 24 ECRMs Electricity Consumption (kWh/ft2/yr) 44.0 29.6 32.8% 32 kWh/ft2/yr (Table 2) for implementation. The 2) Average Peak Demand (watts/ft 6.93 5.23 24.5% Phase I process included thorough air and water flow testing, Natural Gas Consumption (MMBtu) 43,114 23,523 45.4% a detailed analysis of the initial Mercy Average: 2/yr) 2.43 1.33 45.4% Natural Gas Consumption (Therms/ft 1.23 Therms/ft2/yr airflow schedules versus the curTotal Energy Consumption (MMBtu) 70,137 41,457 40.9% rent space use, investigations of Mercy Average: control system operating strateEnergy Use Index (kBtu/ft2) 393 233 40.6% 232 kBtu/ft2/yr gies, verification of proper equipTotal Energy Cost ($/yr) 916,182 540,058 41.1% ment installation, and a detailed Mercy Average: assessment of major equipment Energy Cost Index ($/ft2/yr) 5.16 3.04 41.1% $2.85/ft2 (chillers and boilers) operating schedules. Table 1: Baseline and post-retrocommissioning energy analysis.

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May	 2010
ASHRAE Journal - May 2010

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