By Meghan Hall
Market demand for high-rise multifamily (HRMF) product has taken off in Seattle as the City attempts to keep up with its current rate of population growth. In 2018 alone, more than 10,000 high-rise residential units were at varying stages of the entitlement and construction throughout downtown Seattle, South Lake Union and the First Hill neighborhood, accounting for a large portion of new dwelling units in the region. With large-scale development playing a pivotal role in the Puget Sound, Seattle-based architecture and design firm Weber Thompson and Rushing, a multidisciplinary firm focused on mechanical, electrical and plumbing engineering, partnered to examine how future iterations of the environmental code will impact HRMF design and development. The report, drafted by Myer Harrell, director of sustainability at Weber Thompson, Alexandra Ramsden, Rushing’s director of sustainability, and Nathan Miller, a senior energy analyst at Rushing, came to a somewhat surprising conclusion: Even as the Seattle Energy Code (SEC) continues to change every three years, HRMF product should be able to keep pace with future environmental standards without the need for groundbreaking new technologies.
“Washington State updates their energy code very three years, so there’s this pattern that you get into that you kind of know what’s required for a building, but by the time you figure out that out, it’s time for the next code to kick in,” explained Miller. “Clients don’t just want to know about this code cycle, they want to think about their projects three or four or ten years down the line. This is our attempt to start looking forward and start the discussion about what types of technologies or design changes might be integrated into this building type.”
The City of Seattle is targeting carbon-neutral operations by the year 2050, and the State of Washington is aiming to reduce its energy use by 70 percent for new buildings from the 2006 code by 2030.
The report, entitled “Pursuing High-Rise Multifamily Energy Efficiency in Seattle” and published in May of this year, maps the progression of SEC compliance between now and 2030, and does so in two steps: by examining Energy Use Intensity (EUI) targets for future code cycles and identifying Energy Conservative Measures (ECMs) that will aid developers in meeting those targets. Weber Thompson and Rushing selected Nexus, a residential tower designed by Weber Thompson (and MEP completed by Rushing) currently in-progress. The 41-story tower includes 382 for-sale condominium units and was selected because it is currently under construction and was designed under the 2012 Seattle Energy Code and the Seattle Building Code.
According to Ramsden, Miller and Harrell, few studies have been completed regarding the impact of energy code development on the design and development of HRMF product, in part because of the rapidity at which code changes and because previous code cycles were not as intense in their updates.
“There’s definitely a sensitivity statewide, to not put burdens or restrictions on increasing the housing supply,” said Miller.
“We’re looking at Washington State’s overall goals, and frankly the nation’s goals on how to get closer to addressing climate change,” added Ramsden. “I think if you were to ask many energy experts, they would argue that we are still moving too slowly given the state of our world.”
The report begins with the prediction that in order for HRMF project teams to meet state and city energy targets in upcoming code cycles, HRMF buildings will need to utilize best building practices in envelope improvements and heating and cooling systems, incorporating features such as reduced wall-to-wall ratios, using extensive photovoltaics on roof and wall surfaces, and tapping into new or “off-the-shelf” technologies. However, in a surprise to the authors, the study found that the expectations for future code compliance are not as challenging as anticipated. Many of the ECMs that resulted in code compliance are readily available to developers, including electric boilers, heat pumps for space heating, building envelope air tightness measures and reduced unit ventilation.
“If you don’t consider the Green Building Standard, then you can get pretty far along in the code cycles, pretty much through 2030, without anything exotic or scary looking for lack of a better term,” said Harrell. “That was a little surprising to us; at least on the current trajectory, it wasn’t as scary as we sort of imagined.”
The Green Building Standard, adopted in 2016, additional allowable building height and development potential means that project teams must also design buildings that perform 15 percent better than the SEC. The study also found that in addition to basic energy code compliance, the adoption of the Green Building Standard means that for developers and property owners to meet lower energy thresholds, additional ECMS would need to be incorporated into building designs during the 2027 and 2030 cycles.
“The Green Building Standard is the City’s approach to the urban landscape and the density associated with that,” said Ramsden. “That is related to density because with higher floor area ratios, they have to pursue a higher level of energy efficiency and green building. Because [HRMF] is a specific construction type, it is more challenging in some ways; integrative design is becoming more and more critical.”
Some of the ECMs to meet that threshold include energy recovery ventilation, triple pane glazing, reduced plug loads, rooftop and photovoltaic panels of more than 5,000 and 8,000 square feet respectively.
Harrell, Ramsden and Miller did acknowledge that improvements in energy efficiency will also be limited by human behavior, other building code requirements and functional design.
“In the design of all of our structures, we’re also looking at the quality of life of the occupants of the building,” said Ramsden. “While energy efficiency is incredibly important, aspects such as glazing are also essential. Connecting occupants to the outdoors and views, these are all measured health benefits.”
HRMF product also faces other limitations, such as smaller floorplates and lot sizes, as well as less room to accommodate energy efficient technologies such as solar panels. And, there will come a point at which the energy efficiency of a building will also be dependent upon efforts made by the building’s occupants.
“You can’t just expect that everything is getting more and more energy efficient,” said Miller. “Our behaviors change, and sometimes that offsets some of those great technological advances.”