Green by Design
In July, the first phase of a new full-service healthcare campus (the first hospital built from the ground up in 25 years in King County, Washington) opened its doors to the public. The campus was designed with two key challenges in mind: to create an architectural design that aligned with patient and community needs and to create medical buildings that significantly cut energy usage across the new campus.
The design team at CollinsWoerman succeeded on both accounts: The Swedish/Issaquah medical center campus located in Issaquah, Washington, is now considered the most energy-efficient medical campus in the region—and possibly the nation—and the project has been embraced by the community.
Focusing on sustainability
Hospitals spend more on energy per square foot than any other commercial building type, according to the American Society of Heating Refrigerating and Air Conditioning Engineers. Hospitals have unique and intensive energy use requirements, such as the need for lighting and heating 24 hours a day, and significant energy consumption used by ventilation systems, sterilization of tools, laundry, food preparation, and use of other medical equipment. Energy savings not only improves overall sustainability and environmental impact, but has the potential to dramatically lower a hospital’s bottom line.
Using guidance from the AIA 2030 Commitment, the hospital set an aggressive, low-energy usage goal of achieving an EUI of 150 kBtu/sf/yr. Mechanical system performance at 150 kBTU/sf/yr (equivalent of the power needed for 2,200 midsized American homes per year) is 43% less than a typical hospital in the northwest and would place this hospital in the top tier of energy-efficient hospitals in both the region and the nation.
Additionally, the hospital planned to achieve an ENERGY STAR rating of 75 or higher at completion and one year after occupancy (on the rating system’s 1–100 scale, a rating of 50 indicates average energy performance, while a rating of 75 or better indicates top performance). Compared to peers nationwide, buildings that perform in the top 25% consume about 35% less energy on average than typical structures. Data relevant to achieving this merit will be tracked in the initial year of operation. At this point, an estimated score of 90 is anticipated.
Planning the design
Early in the design process, the project team participated in design meetings to gather ideas for how to achieve the project’s sustainability and energy efficiency goals. The use of building energy simulation software determined which efficiency measures would be most useful to meet the project goals.
Through this process, it was determined to orient the hospital to get sun on three sides with a basement area that receives daylight—a benefit for staff and patients. Research has shown that the human body best recovers from illness in environments that include an abundance of natural lighting, so this layout was ideal. In addition, high-performance glazing in energy-efficient frames and the use of exterior/interior shading devices result in less artificial lighting and energy consumption.
Achievement of these energy goals requires special features and systems for the architectural, mechanical, and electrical components of the building, but also significant consideration for the site and the facility’s greater impact in the community.
Creating the site
This new facility was built on a previously cleared site, and no trees were removed to construct the buildings. Like all new projects, the development added some impervious area to the environment, but efforts were made to consolidate the building footprint and stack floor plates within height limitations to reduce the overall building footprint and associated impervious space. Additionally, by adding a single level of below-grade parking, the project required 50,000 square feet less impervious area.
Similarly, substantial excavation for two floors of below-grade space placed another approximately 75,000 square feet of area beneath that footprint.
The landscape for the project is predominantly drought-tolerant and is 100% native or highly adaptive to the Pacific Northwest. Plants were carefully selected for their hardiness and ability to take prolonged periods of cold, rain, and snow, as well as dry and warmer summer conditions. All landscape areas have a fully automatic irrigation system, which utilizes current weather data to automatically adjust the system to prevent over-watering and provide maximum efficiency.
Creating form and shape
The building layout includes two major amenities that provide environmental benefits: a multilevel atrium and a 15,000-square-foot adjacent, internal courtyard.
Joining the medical office building and the hospital together with the atrium reduced the exterior envelope without significantly compromising daylighting or view, while creating a central, unifying space.
A planted courtyard acts as both a light well and a filter for fresh air intake. This space provides daylighting into the center of the atrium through a south-facing curtainwall. Fifty-four patient rooms over the top three floors and two levels of corridors are circled around the courtyard and provided with daylight access. The prevalence of natural light reduces the need for artificial light and reduces energy consumption.
The decision to use below-grade space resulted in both reduced overall building envelope and performance—less heat loss and gain in the more temperate soil surround.
High-performance glazing, shading, and heat-resistant external walls, beyond state requirements, were employed on both the medical office building and the hospital to reduce loads and energy consumption of the HVAC systems. Large windows provide natural daylight to interior spaces and are positioned with consideration to direct summer sun exposure.
Durable materials, such as brick and precast and cementitious rainscreen panels, were selected as primary cladding materials and constitute more than 60% of the exterior surface. Exterior skin decisions and design detailing minimized the use of galvanized steel and copper at exterior locations in order to protect the local aquifer from contaminated ground water runoff.
The project also features a 16,212-square-foot green roof designed to sustain a healthy growing condition for the vegetative cover and provide additional storm water holding capacity. All other roofs are light-colored or have light-colored stone ballast cover, which reduces heat absorption.
Mechanical systems: heating and cooling
An innovative system called a heat recovery chiller (HRC) recovers heat from exhaust air and processes in the hospital, and uses the recovered energy to meet up to 80% of the building heating and domestic hot water requirements. The HRC significantly reduces the amount of natural gas that would otherwise need to be burned in order to meet the heating demand. When the building demand for heating is larger than the HRC can provide, condensing boilers with efficiencies greater than 90% are used to back-up the HRC and provide peak heating.
Three 500-ton chillers provide cooling for the hospital. The chillers are equipped with screw compressors and variable speed drives—a new technology that offers the highest efficiency available on the market and 40% energy savings compared to a code baseline chiller. Also, pressure independent control valves and high-efficiency variable speed pumps were used on the chilled water system to
optimize the efficiency of the chillers and minimize pumping energy.
Recycled and reclaimed products
Although the use of recycled materials was not a priority for this facility, recycled and reclaimed products were incorporated where appropriate. Approximately 58% of the structural steel used in constructing the building was post-consumer recycled content and 20% post-industrial recycled materials. Additionally, all Douglas fir and teak materials were from 100% post-consumer sources, which allowed the project to gain its aesthetic benefit and prevent impact on old growth forests.
Built by comprehensive planning and design processes, the medical center is designed as an innovative, sustainable, and flexible complex that combines extensive green building practices into a high-performance medical setting. The project team was able to integrate advanced technologies and processes that significantly reduce energy consumption, lower overall operating costs, and enhance patient care at the same time. HCD
Phil Giuntoli is a Principal and leader of the healthcare practice at CollinsWoerman and can be reached at firstname.lastname@example.org. James Walker, is a Senior Associate at CollinsWoerman and can be reached at email@example.com.