Powering Care, Cutting Carbon: The Peace Island Model

Decarbonizing healthcare (or any other building) requires two things. First, they must not have any on-site combustion (e.g. they must be all-electric). Second, they must get their electricity, including for use when an external utility fails, from renewable sources.

While this obvious formula is simple, it is by no means easy.

Recognizing the simple equation, more jurisdictions around the country have begun to require new buildings to be all-electric. More healthcare owners are choosing to build new all-electric buildings. Many tout being the “first” all-electric hospital.

One of the tragedies of human endeavors is forgetting to learn from history. In this instance, we have a broad base of experience in designing and operating all-electric hospitals.
This short paper is a brief case study of one of these all-electric hospitals. We intend this to be the first of a series of case studies of existing all-electric hospitals, each focused on one that has been operating for some amount of time. Each will focus on those systems that are generally derived from combusting fossil fuels – space heating, water heating, cooking, sterilization, humidification, and “emergency power.”

The case studies in this series will take it as a given (but watch out for a different paper, making an argument for shifting to a new paradigm) that healthcare buildings must have “emergency power sources” and that they must be diesel generators, and that like the one mistake in a Navajo weaving, make the balance of the all-electric hospital perfect.

Background

Peace Island Medical Center (PIMC) is a Critical Access Hospital located in Friday Harbor, Washington. The medical center opened in 2012 and includes 10 Inpatient Beds, Emergency Services, Imaging, Surgery, and an Ambulatory Outpatient Clinic with a Cancer Care Center. The hospital is approximately 33,600sf and the clinic is approximately 6,400sf. The climate in this location is Mediterranean with warm, dry summers, and cold, rainy winters. It is ASHRAE Climate Zone 5C.

The basic thermal energy system consists of ground source wells, water-to-water heat pumps, radiant heat, chilled beams, four pipe fan coils in the healthcare areas, and natural ventilation in public and clinic spaces.

Thermal Energy Systems

Natural Ventilation to Reduce Thermal Energy

The hospital reduces need for thermal energy by maximizing the use of Natural Ventilation. The building has operable windows in the clinic rooms, giving clinic patients individual control over their environment. The design fully aligns with the Facility Guidelines Institute (FGI) (2010 edition) and ASHRAE Standard 170 (2008 edition) outside air requirements, surpassing the criteria outlined in ASHRAE 62.1 (2010 edition). The design team, working closely with the Washington Department of Health (DOH), conducted comprehensive bulk airflow calculations to evaluate the effectiveness of natural ventilation. The Department of Health was actively involved throughout the design process and ultimately approved the use of operable windows within the clinic. Due to the rapidly warming climate, higher recent temperatures have forced the owner to evaluate mechanical (electric) cooling units in previously naturally ventilated areas.

The architectural design similarly maximized the use of Passive Design Strategies to reduce thermal energy needs and enhance natural ventilation. The building structure is oriented along the east-west axis to manage solar heat gain. High-performance envelopes and decentralized systems tailored to specific loads contribute significantly to reduced need for supplemental thermal energy.  Surgery and Inpatient Bed spaces use a Variable Air Volume System, allowing reduction in air volumes and significant fan energy savings. Occupancy sensors enable partial HVAC and lighting shutdown in unoccupied spaces to save energy. Heat Recovery Ventilators reclaim heat from exhaust air to pre-heat outside air efficiently.

Space Conditioning Energy

PIMC incorporates a Ground Source Heat Pump (GSHP) system. The system consists of water-to-water heat pumps that reject cooling to or extract heating from a closed loop well system.  The well system includes twenty-two wells that are 300 feet deep in which a single closed loop polyethylene pipe was U-looped through each well.  There is up to 2.5 Tons of cooling or 30,000 Btu/h of heating available from each well from the circulated water.  The HVAC system includes separate chilled water and heating water loops, each with two dedicated heat pumps. This allows for simultaneous heating and cooling and eliminates the need for any chillers, cooling towers, and combusted heating.

Generally, one heat pump will serve the entire building. A second heat pump provides redundancy and needed boosts during peak load situations. The hospital also has a 100% capacity electric backup boiler as a safeguard against potential system failures.

When interviewed, facility staff report that this system requires much less maintenance labor and parts, due to the very simple nature of the system.

Water Heating Energy

Electric water heaters serve the entire facility.

Sterilization and Humidification Energy

PIMC is currently using point-of-use electric steam generators for sterilization and humidification. Appropriate isolation of these systems is important.

Water quality poses challenges, especially total dissolved solids, which increase the risk of calcification.

Additionally, the enforcement of the new ST 1.0.8 standard for sterile processing necessitated the use of a Reverse Osmosis (RO) system. Ultimately, the RO system was replaced by DI filter system due to the large amount of water usage to flush the RO system. Water treatment is relatively expensive.

There are also issues with the current placement of humidification and dehumidification equipment in ceilings, especially in operating rooms, making maintenance more difficult. To address these challenges, future hospitals should consider designing accessible placement of such equipment for easier maintenance.

Cooking Energy

The hospital has no cooking systems. All food is brought in.

Emergency Power Energy

PIMC currently relies on a diesel generator for emergency power. The generator is hugely oversized, capable of sustaining the entire hospital for 17 days during a power outage. In the past 12 years, the diesel generator has only run approximately 12 hours per year (not
including testing). The longest power outage has been approximately 30 hours.

To enhance operational efficiency and resilience, PIMC is exploring the integration of solar and battery solutions. Due to the very small loads, a solar/storage system, operating year-round in accordance with new NFPA Codes could probably be economically feasible.

Energy Performance and Costs

The mechanical systems for PIMC cost approximately $65/sf to construct. Average construction costs for similar systems at the time were approximately $75/sf.

The estimated annual electricity use for PIMC is around 1,300,000 kWh, resulting in a calculated Energy Use Intensity (EUI) of approximately 111 kBtu per square foot per year. This figure is significantly lower than the national average for U.S. hospitals, which stands at around 250 kBtu per square foot per year. PIMC’s EUI is performing only 11% higher than the high-performance benchmark of 100 kBtu per square foot per year set by the Targeting 100! initiative, which aims to reduce energy use in buildings by 60% below the average baseline.

Benchmark Comparisons

Facility Type	EUI (kBtu/sf‑yr)	Source / Notes
Average U.S. Hospital	~250	National average from 2003 EIA CBECS (ACEEE, flexmonitoring.org)
Targeting 100! Goal	≤ 100	60% below average baseline
PIMC (estimated)	111	All-electric Hospital

 

PIMC’s all-electric system and efficient operation place it among the most energy-efficient Critical Access Hospitals in the country.

Facility staff estimate that their ongoing maintenance costs are reduced, compared to a conventional design, because the systems are so simple and have so few parts. The facility has one facility FTE. ASHE’s 2010 study measured one FTE/31,000 sf. This building is easily handled by one person/40,000 sf.