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    • Foreword and summary – Electrifying heat in an existing hospital
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    Foreword and summary – Electrifying heat in an existing hospital

    Pabio Posted on

    Executive summary

    The American Society for Health Care Engineering (ASHE) funded a decarbonization feasibility case study at Providence St. Peter Hospital (PSPH) in Olympia, Washington, to verify the technical and financial feasibility of achieve carbon neutrality for scopes 1 and 2. at the PSPH.1 This facility was chosen as a typical large inpatient hospital that represents a reasonable benchmark for the healthcare industry. The unique operation and characteristics of hospitals, such as the need for steam for sterilization, make them more complex to electrify than many other commercial buildings.

    Two major challenges are addressed in this study: (1) determining pathways to achieve electrification of the heating plant while maintaining a resilient energy supply and supporting full service operation and (2) determine the impact on electricity utility supply to achieve beneficial outcomes. electrification. The objective of the PSPH is to eliminate scope 1 emissions linked to combustion by electrifying the existing heating plant: two dual-energy boilers. This goal also includes shutting off the supply of natural gas to eliminate associated upstream methane leaks and supplements the 100% renewable electricity already purchased by the hospital.

    The approach to assessing and decarbonizing PSPH was to carefully analyze existing conditions, energy consumption and peak heating demand by end use. The next step was to identify approaches to reduce heating loads through investments in certain technologies and consider the overall impact. A calibrated energy model was developed in accordance with ASHRAE Guideline 14, Measuring Energy, Demand and Water Savings, Requirements to fill any data gaps and to further support energy and financial.2 The recommended strategy is based on a systems thinking approach to address as many demand-side energy-saving measures as possible to reduce plant load. The installed heating capacity is 25 million British thermal units (Btu) per hour (MMBtu/h) or 7,327 kilowatts (kW), and the measured peak load was 20 MMBtu/h (5,861 kW), which can be reduced to 11 MMBtu/h. h (3,224 kW) if all demand-side measures are implemented. The reduced heating load will allow greater flexibility on the domestic hot water (DHW) distribution side in terms of smaller pipe sizes and lower temperatures. The target maximum household waste temperature is 140 F to achieve efficient heat pump operation. However, this depends on the level of implementation of demand-driven measures, particularly with regard to improving envelopes. Once the distribution system upgrade is complete, the heating plant will be able to be equipped with air source heat pumps as the primary source of thermal energy for normal operation and supplemented by a heat recovery chiller and 100,000 gallons of storage of household waste.

    Implementation of the decarbonization strategy must be gradual and may take several years depending on available resources.

    The recommended phasing is as follows:

    • Demand-side upgrades (nine-year duration).
      • Implement air-side heat recovery improvements.
      • Add insulation and glazing upgrades.
      • Improve systems using processing steam (kitchen and sterile processing areas).
      • Continue implementing other energy saving measures.
    • Distribution system upgrades (1-2 year duration).
      • Migrate loads to existing DDD pipelines once demand-side upgrades are complete.
      • Replace steam lines with domestic heating lines (starting in spring to have seven months of low heating demand before cold winter weather sets in).
    • Replace steam converters with heat exchangers for service hot water loops.
      • Add a variable primary pumping system for DDDs.
    • Plant system upgrades (three to five years duration).
      • Add a south extension or penthouse to the power station to house the air source heat pumps.
      • Upgrade electrical infrastructure, add generators, and add heat recovery to the generator duct.
      • Install air source heat pumps.
      • Take the boilers out of service.
      • Install thermal storage or microgrid in boiler footprints.

    There are two somewhat unique features at PSPH that simplify the electrification and decarbonization process. First, the hospital does not have humidification because the marine climate does not require it. The relative humidity data analyzed demonstrated compliance with a minimum relative humidity of 30% during all hours with excursions below 30% for less than 12 hours per year. The relative humidity did not fall below 20%. Second, the domestic hot water (SHW) system operates at 120 F, which simplifies providing domestic hot water from the HHW loop rather than running a hotter HHW loop or applying a system autonomous heat pump. Although it is more common to operate SHW systems at 140 F per Centers for Disease Control and Prevention guidelines, no Legionella problems have occurred at PSPH at lower temperatures.

    The resilience strategy involves maintaining on-site diesel fuel storage capable of supporting generators and boilers in the short term. The generators will be upgraded to include engine jacket water heat recovery to meet heating demand during a power outage during the plant upgrade. Heat recovery effectively transforms the generators into a combined heat and power system providing both electrical and thermal energy to the hospital during outages. The boilers will remain in place until operational competence is achieved with heat pump installation and generator heat recovery. Current testing and backup power consumption represent approximately 4% of annual on-site combustion emissions. Resilience solutions such as thermal storage and microgrids will be re-evaluated to replace boilers as technology evolves.

    Microgrids are being implemented today in a few hospitals that can be referenced for this study and should align with the timeline of this project. For now, on-site fuel storage is accepted as a resiliency solution as it is a small source of emissions due to low operating hours and helps eliminate the need for natural gas connection which leads to methane leaks.

    The study examined four potential scenarios for the hospital between 2024 and 2041, based on a regulatory framework from the recently adopted Seattle Building Emissions Performance Standard.

    1. Scenario 0 This is a status quo case in which the hospital accepts a one-time fine of $7.5 million and makes incremental capital improvements over time.
    2. Scenario 1 is the minimal disruption scenario that replaces only the existing dual-fuel boilers with two electric resistance boilers plus supporting generators and leaves the rest of the systems in place.
    3. Scenario 2 implements demand-side energy-saving measures on 100% outside air systems, electrified process loads with heat pumps or stand-alone electric boilers and a host of other energy-saving measures energy on the demand side. An air source heat pump plant would then be implemented to support the heating load of 16 MMBtu/h (4,689 kW).
    4. Scenario 3A adds in-envelope energy-saving measures to replace single-glazed windows and uninsulated or partially insulated wall insulation. The envelope measures reduce the heating load to 11 MMBtu/h (3,224 kW).
    5. Scenario 3B has been broken down to isolate the impact of insulation upgrades, as it is a costly upgrade with a low return on investment.

    A third-party cost estimate was developed to inform the three decarbonization scenarios. A detailed list of systems, components and materials is described in Chapter 7, Capital Equipment and Costs. The capital cost for Scenario 1 was estimated at $57,711,000, or $79/ft.2for scenario 2, was estimated at $62,171,000, or $85/foot2for scenario 3A, was estimated at $80,425,000, or $110/foot2and for scenario 3B, it was estimated at $68,400,000, or $93/foot.2. For reference, a complete tenant improvement (TI) on a hospital costs between $100/ft2 and 150$/ft2. However, the square footage represents the entire hospital, 733,000 feet.2. Additionally, IT focuses almost exclusively on improving infrastructure, which is atypical for IT.

    A cost model using $2,024 was constructed for a 17 year period which compiled the capital cost, energy cost and carbon fines using cost estimation, energy models and an estimate of ‘a future carbon fine in Olympia, Washington, based on present-day Seattle. Fine structure of the building emissions performance standard. The cost results are compiled in the following figure.

    Providence St. Peter Host Cost Model Scenarios from 2024 to 2041 | Costs per square foot for BAU ($62, $10, $20) Scenario 1 ($85, -, $79), 2 ($69, -, $83), 3a ($65, -, $110), 3b ($65.-.93) in utility costs, carbon fines and capital

    The 17-year total cost of ownership for each case is:

    • Scenario 0: $67.2 million ($92/ft2)
    • Scenario 1: $124.2 million ($169/ft2)
    • Scenario 2: $112.6 million ($154/ft2)
    • Scenario 3A: $130.0 million ($177/ft2)
    • Scenario 3B: $118.4 million ($162/ft2)

    The most cost-effective fully electrified solution is Scenario 2, although it still costs $45 million more over 17 years than Scenario 0, the status quo scenario. It should be noted that this study does not include rate increases or utility incentives. Additionally, the cost of some capital equipment, such as heat pumps, may decline as the market evolves. More details on costs are available in section 2.4.

    Pabio
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