The building of a net-zero hospital

Deep within the Mojave Desert in the remote Fort Irwin community of Southern California, soldiers prepare for deployment at the Army’s premier combat training center. Every year, the installation has the mission of receiving and training visiting rotations of battalion and brigade-level units, ranging in size from 4,000 to 6,000 soldiers.

During a rotation, this transient population can almost double the size of the fort’s community. The training setting is known for its ability to use tactical systems and munitions, instead of simulations, creating a highly complex, fast-paced, hazardously realistic environment.

Here, a design team was tasked with planning a 216,338-square-foot mission-critical hospital that could better support the health care needs of more than 10,000 soldiers and their families than the 50-year-old facility it replaced.

The team worked at an accelerated pace through requirements from multiple stakeholder agencies to envision and create the Weed Army Community Hospital — the Department of Defense’s (DOD’s) first hospital to achieve LEED Platinum certification and one that is on track for net-zero and carbon-neutral energy performance.

Highly efficient

About 40 miles from the closest town, with the hot sun beating down, the facility would need to be highly efficient and resilient with dependable utilities to survive the harsh conditions and isolated location.

Primary design objectives included providing modern health care, tailored to support the remote military community and training environment; conserving resources with efficient and reliable systems; and providing self-sufficient health care with minimal environmental impact to the community.

To best provide a full range of high-quality health care services, the current and future needs of the community were assessed to arrive at a complementary program that included outpatient clinics for primary care, women’s health, behavioral health, surgery, optometry and occupational health. Supporting diagnostic and treatment areas include emergency, radiology and pharmacy departments.

Inpatient functions include a medical-surgical ward with 10 single-bed inpatient rooms and a maternity ward featuring five single-bed labor, delivery, recovery and postpartum rooms, one cesarean section suite and a nursery.

The emergency department (ED) has multiple exam rooms to treat a range of patient types and conditions, as well as a trauma room. Adjacent to the ED entrance is a helipad constructed to receive military and civilian medical evacuation aircraft. With the nearest trauma center more than 110 miles away from Fort Irwin, emergency and urgent surgical capabilities were imperative.

As the program came to life, the design team followed the military’s world-class directives, incorporating evidence-based design principles to improve the health, well-being, and safety of staff and patients. The spaces include staff respite areas, family member accommodations, patient controls, ample daylighting and limited travel distances. Additionally, the design team incorporated principles to promote a heathy indoor environment and connect patients to the outdoors.

Patient rooms, working spaces and guest areas feature abundant natural light and panoramic views of the mountains and surrounding terrain. An outdoor dining area overlooking the summit and a healing garden were design considerations for reducing stress.

Assessing energy options

To meet the DOD’s expectations and the project’s expedited timeline, a critical initial step of the design process was to provide concepts for preliminary evaluation so the military could visualize design options, consider respective comparative data and sign off on decisions. Using an efficient charrette process and a building information modeling (BIM)-based parametric platform, the team challenged traditional linear workflows of a typical schedule, completing design in 40 percent of the time customarily allotted for a complex DOD project of this size.

BIM technology facilitated the integration of multiple project teams, creating a real-time environment where team members could work in tandem to generate a unified deliverable. The ability to do quality controls and program validation, coupled with an innovative approach to scheduling, helped streamline the design process.

Early in the concept design, the team narrowed down a dozen different configurations to four distinct options, all of which supported the medical program. Energy models of each option were assessed on how well each design accomplished the project’s energy conservation targets. Without this rapid decision-making process, valuable design and sustainability accomplishments would have been lost.

The first task of the concept design effort was to create a baseline energy model that met minimum efficiency standards to benchmark potential energy savings of the various strategies and conservation measures considered in the design.

During architectural and mechanical systems’ design, both energy modeling and life-cycle cost analysis (LCCA) procedures were used to ensure a healthy, environmentally friendly and cost-effective facility. The energy model was used to define the energy consumption patterns to prioritize reduction efforts in the design. LCCA was used to compare savings from a proposed design strategy or conservation measure with any added costs, such as maintenance. The combined use of energy modeling and LCCA validated decisions adopted in the design, including efficient HVAC, reflective roofing material, natural lighting, windows and clerestories to provide day lighting, shading devices to minimize solar radiation heat, light-colored paving to reduce the heat island effect, optimal building orientation for solar radiation and a partially underground first floor.

Energy-efficiency measures

The energy model was used by the team to analyze preliminary initiatives that balanced future savings with upfront costs. The team adopted the following major energy-efficiency measures that added less than 2 percent to the overall project cost and had a payback of less than 10 years:

Condensing boilers and controls. The use of condensing boilers with low return water temperatures maximize boiler efficiency by effectively capturing the latent heat of the exhaust gases. Condensing boilers have a larger initial cost but a lower life-cycle cost when reduced energy consumption is considered. This measure also includes the addition of premium efficiency motors.

Chiller plant. Water-cooled chillers with cooling towers were found to be the most life cycle cost-effective, even when considering the added water consumption and maintenance.

Air-handling units. Air handlers with oversized casings and low-flow velocities are designed to reduce power. Additionally, premium efficiency motors with variable frequency drives are specified on all supply and return fans.

Lighting design. Using refined design criterion with maximum efficacy light sources and controls significantly reduces energy consumption. Occupancy controls are used to turn off lights in unoccupied areas. Additionally, dual-lighting levels are an option in many spaces.

Fenestration. High-performance insulated glazing was chosen to optimize energy savings for the Fort Irwin climate. The solar heat gain coefficient equaled the ASHRAE standard recommendations, but the assembly rate of heat loss was double the ASHRAE standard with a U value of 0.28. The fenestration percentage was reduced with punched windows, and with spandrels and metal panels at the curtainwall.

Insulation. The payout for the improved insulation values is longer than the 25-year LCCA, but it is within the life of the building, and the added cost can be justified. At R-38 for the roofs, R-22 for the walls and R-19 for the floors, the building met or exceeded ASHRAE standards for the Fort Irwin climate.

Water conservation. Water conservation was perhaps the most important energy-efficient measurement, considering Fort Irwin’s desert environment. The installation of low-flow fixtures reduced water usage by about 30 percent, or about 1.6 million gallons annually, which will reduce hot water usage and save an estimated 4,314 therms per year.

Passive design strategies impacted the major architectural design choices related to building massing, orientation and siting. Hospital massing decisions were made early and reflect the clinical program of inpatient, outpatient, diagnostic and treatment zones. The energy consumption patterns differ between these three zones, while each contributes to the total-use pattern.

With the DOD goal of reducing dependence on fossil fuel, the design team seized the opportunity to use earmarked funding for renewable energy to push beyond the defined minimums, resulting in expanded sustainability targets. The project team made every effort to embody the military’s emphasis on responsible use of fiscal and environmental resources and attain energy-efficient operations well below the national median hospital average.

To best take advantage of the site’s natural resources and positively impact the life of the hospital, solar power generation and water efficiency measures were early design considerations. Ultimately, a solar thermal hot water heating system and a ground-mounted solar photovoltaic array were included, enabling energy self-sufficiency and targeting utility incentive rebates up to $1.5 million.

Passive strategies and conservation measures were expected to decrease energy use by 33.2 percent below a minimal code standard design. These conservation measures were expected to have a positive environmental impact by reducing greenhouse gas emissions by more than 4,656 metric tons per year below the code compliant baseline and save more than $300,000 a year in energy costs. Added expense for these measures amount to less than 1 percent of the overall project budget and are projected to have a simple payback of less than five years because of energy savings.

Leading up to the design phase, there were several changes in how the military viewed energy sustainability in construction — evolving from certifying their own design and construction, and transitioning into a third-party LEED model of sustainability assessment.

In addition to earning LEED Platinum status from the U.S. Green Building Council, Weed Army Community Hospital will be the first military hospital in the country to generate its entire energy needs from clean power sources and renewable energy systems. Research has suggested strategies for how hospitals could significantly reduce energy expenses, but few have yet to achieve the level of energy savings that Fort Irwin will. As such, this hospital will act as a model for future military health care facilities.

Testing and verification

A Total Building Commissioning approach was initiated in the design phase to verify and document that the performance of the hospital and its systems met the design intent and requirements of the client. This involved the early engagement of a commissioning authority for involvement through pre-design, design, construction, occupancy and warranty phases. While Total Building Commissioning is a team effort, having continuity of a commissioning authority from beginning to end proved beneficial.

The systems and equipment to be commissioned were determined during project scope development, along with the commissioning team’s roles and responsibilities. Commissioned systems include mechanical, electrical, plumbing, renewable energy systems, fire protection and fire alarm systems (along with their interoperability with the mechanical, electrical and security systems), telecommunication/data distribution, integrated security systems and certain aspects of the building envelope, including the roof and curtain wall.

Two commissioning reviews of the construction documents were completed prior to bid, and commissioning specifications were provided for inclusion in the project manual. During the construction phase, submittal reviews by the commissioning authority helped identify missing information related to the startup and testing requirements. The pre-functional checklists were completed and distributed to the team during submittal reviews. Functional performance tests were finalized during the installation validation and distributed to the trades for their review and comment prior to test execution.

Weekly commissioning progress meetings helped maintain coordination between all team members and helped identify and track issues that could affect system functionality and project schedule. During the latter stages of the systems’ installation, field verification of the completed pre-functional checklists took place.

As the team moved into the six- to seven-month functional testing period, systems were first tested at the component level, then at the system level and, finally, at the systems-interoperability level. The testing effort culminated in a final integrated systems test, where normal power service was disconnected by the utility provider and the team looked for unintended loss of function in the building systems.

As the team entered the functional testing period, the general contractor, with oversight exercised by the commissioning authority, finalized the hospital operations group training schedule, the associated syllabuses and agendas, and training staff resources. They communicated the results to the project team and the hospital’s building operations group for their review.

In the three months prior to occupancy, extensive training sessions on the building systems were conducted and the operation and maintenance manuals were reviewed to confirm the reference material to support proper operating and maintenance (O&M) of the facility.

One month prior to occupancy, extensive testing of the life-safety systems and their interoperability with the mechanical, electrical, lighting and security systems was completed. The infant protection system’s interoperability with the fire alarm and the security systems was tested several times during the last two weeks of the project.

The team accomplished proof of repeatability, a necessary step for the Army’s Medical Command to gain building occupancy. After occupancy, additional testing was completed related to the photovoltaic system and the heating boiler plant. Finally, the commissioning authority worked closely with the hospital’s operations group to ensure the O&M requirements of the facility were well understood. This support to the hospital’s operations group continues today.

The commissioning authority returned to the hospital twice during the first year of operation to assess functionality during occupancy and perform follow-up testing. They have remained in contact with the facilities group, monitoring its progress in learning the facility and assisting where possible.

Weed Army Community Hospital recently passed the first full Joint Commission evaluation with exceptional marks, a high achievement for such a complex facility situated in an extreme environment.

Such an environment requires constant operational vigilance to protect the facility from the effects of power instability, as well as negative impacts of water quality and its potential for impacting complex mechanical systems. Building utilities must function correctly and be in concert with one another.

As facilities become more complex, reliance on complicated automated control systems increases, requiring both integration for information sharing and interoperability for proper function. The burden of proper integration falls heavily on the facility operators.

Commissioning’s validation of design intent and client requirements put the final touches on this incredible journey to bring world-class health care to the Fort Irwin community and has helped make Weed Army Community Hospital a very popular place on the installation.

Positive experiences

Since opening, there has been an increase in positive health care treatment experiences, with patients providing feedback stating they love the new facility because of the grand nature of the building, the comfortable spaces, and the focus on staff and patient wellness.

To date, Weed Army Community Hospital has received numerous local and national awards, including the Chief of Engineer’s Honor Award for Conceptual Design for demonstrating exceptional innovation in military medical facility design.

Last year, the hospital received an American Institute of Architects (AIA) Orlando (Fla.) Award of Merit for exemplary “built architecture,” and, again, in 2018, it won an AIA Award of Merit for sustainability. The hospital also was recognized by the U.S. Green Building Council, Los Angeles Chapter, as the Municipal Project of the Year and for its LEED Platinum certification during the 2019 Municipal Green Building Conference and Expo. 

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Keith Holloway, AIA, is vice president and director of architecture/operations at RLF Architecture Engineering Interiors in Orlando, Fla.; and James E. Thornton, CxA, CEM, LEED AP, is senior commissioning engineer and national discipline lead, commissioning, buildings and places for AECOM’s design and consulting services group for the Americas, Houston. They can be reached at keith_holloway@rlfae.com and Jim.Thornton@aecom.com.