Developments in several downtown areas of Seattle have the opportunity to increase their Floor Area Ratio (FAR) and building height through the Green Building Standard (GBS).
To achieve the Seattle Green Building Standard (aka Director’s Rule 20-2017) and be granted additional FAR, there are two distinct requirements that must be met:
- Achieve a 15% energy improvement over the 2015 Seattle Energy Code C407
- Achieve a third-party certification from an approved program (LEED NC, LEED for Multifamily Midrise, Living Building Challenge, Passive House)
Despite the perceived challenges in meeting these requirements, the housing pressure in Seattle leaves little question whether multifamily developers should consider the GBS opportunity. Building a larger multifamily building that addresses the housing demand (thanks to the FAR bonus) while also benefiting from economies of scale can significantly increase the value of an investment.
Determining when and how to meet the GBS for multifamily projects can seem overwhelming, but it is not as daunting as it appears. Our experience with multifamily projects, energy modeling, and green building rating systems has culminated in a logical sequence to assess the requirements and find the path forward. And most of the feasibility work can happen prior to submission for a Master Use Permit (MUP) so developers can go through the MUP process with a clear decision on whether to attempt the FAR bonus through the GBS.
Let’s take a closer look at the requirements:
GBS Requirement #1: Meeting the 15% Performance Target
Of the two requirements, the most significant hurdle is the Seattle Energy Code requirement. A 15% improvement over an already stringent energy standard will require time and effort to understand; and should be undertaken prior to submission for final Master Use Permit (MUP) approval.
Conventional wisdom among multifamily project designers is that the larger building envelope will require a significant investment to meet the 15% performance target. As the envelope is likely the largest investment in a project pro forma, many developers (incorrectly) assume that they cannot afford the increase to first-costs. And then this misconception inhibits developers from moving further. A simple review of physics demystifies this assumption.
Most single family and small-scale residential projects have a low volume-to-skin ratio; there are 6 sides that are exposed to climate, meaning that the envelope has a significant impact on energy performance. For these projects, investing in the envelope is indeed needed to hit high-performance targets.
However, a larger multifamily development is essentially a series of stacked residential units in which most sides of the unit are not exposed to the exterior. In fact, most units feature only one wall of exterior exposure with the other sides sharing a wall with another unit to the side, above, or below. So for multifamily buildings, there are diminishing returns on envelope upgrades such as added insulation or triple pane windows. Given that annual average temperatures in Seattle are relatively mild, there is not a significant load induced on HVAC systems through the envelope of a larger multifamily building.
So if the envelope should not be the focus in achieving a 15% energy improvement over code, what should?
Rather than to focus on the loads on a project, the team should focus on the energy-consuming features of the building.
For a multifamily project, these are: ventilation loads; the heating/cooling of ventilation air; lighting; and domestic water heating systems. Through improvements to these systems it’s possible to meet the 15% improvement target through readily-available equipment that can easily be incorporated into a project pro forma.
Ventilation loads can be managed through Dedicated Outside Air Units (DOAS) and exhaust fan heat recovery. Lighting loads can be reduced through LED lights installed throughout the building/parking. Domestic Hot Water loads can be reduced via efficient central systems rather than unit by unit (which also saves unit floor space). Cooling loads can be eliminated or reduced through well-placed operable and/or Variable Refrigerant Flow (VRF) units.
As upgrades to these systems are likely not contained within a standard project pro forma, the developer needs to know the cost of these systems and balance them against the benefits of additional FAR. As FAR will affect MUP approval, this cost/benefit study then needs to be conducted prior to submission.
The good news is that this study can be undertaken through energy modeling simulations based on a few floor plans and elevations. Through energy modeling, the systems mentioned above can be tested to determine the lowest first-cost combination of upgrades that can be used to meet the 15% energy performance target.
GBS Requirement #2: Selecting a Green Building Rating System
Once a target of 15% is reached, there are four options to achieve the second requirement of the Seattle Green Building Standard, which is to achieve third-party certification. Those options are LEED v4 for New Construction Gold Rating; LEED v4 for Multifamily Midrise, Gold; Passive House; and Living Building Challenge.
Selecting the right certification for multifamily developments is straight forward thanks to the first requirement, which is to hit the 15% performance target. If you must invest in MEP equipment to meet this target – and the envelope has little to do with this – then a green building rating system should be selected that rewards energy improvements rather than one that focuses on prescriptive envelope improvements.
The four standards are described below, and ranked from best to worst in relationship to multifamily projects seeking the GBS FAR bonus:
- LEED v4 for New Construction Gold Rating (Preferred Option):
LEED v4 for New Construction (LEED NC) mirrors the energy performance modeling process of the GBS outlined above, meaning that compliance modeling for LEED NC matches code submission requirements. Achieving the 15% performance requirement of the GBS will also be rewarded with a high number of LEED EAc1 points which is where most multifamily projects fall short. Further, given that most projects that attempt the GBS will be in dense urban areas with excellent access to transportation, several site selection credits may also be easily achieved. The combination of points accrued through these two factors makes achievement of Gold well within reach.
Additionally, with the recent changes to LEED NC v4.1, many of the past complaints about difficulty in achieving other credits such as Material and Resource and Indoor Air Quality credits has been reduced, so there is greater flexibility in the strategies to achieve a Gold certification.
- LEED v4 For Multifamily Midrise, Gold:
Envisioned by the USGBC as combination of the best in single-family home requirements (prescriptive envelope requirements) and the best in USGBC’s new construction program (performance-based targets), this rating system contains the most requirements that must be tracked and vetted of all the GBS options. In addition to focusing on the envelope, a LEED v4 for Multifamily Midrise Gold rating will require several site inspections during the envelope installation, and will add a LEED for Homes Rater and a LEED for Homes Provider to the list of consultants needed on the project. This focus on the prescriptive requirements means that the owner will need to invest more in the envelope, and while these envelope improvements may cost less than the cost of MEP upgrades needed to hit the 15% improvement, they will not gain much improvement against the 15% performance target, meaning that upgrades in MEP will still be needed.
- Passive House Institute US
The Passive House rating system centers the design process on using as little energy as possible by incorporating passive design strategies that focus on the building envelope. The Passive House rating relies on meeting the prescriptive requirements within the ENERGY STAR program for multifamily developments, as well as specific energy reduction targets for the envelope which will require: significant investments in the building envelope beyond what is needed for LEED v4 for Multifamily Midrise; additional site inspections for the envelope; detailed pressurization and compartmentation testing; and that an PHIUS+ Certified Multifamily (MF) Verifier is added to the team, making this the third most expensive rating system option for multi-family projects.
- Living Building Challenge:
The Living Building Challenge (LBC) is a leading-edge rating system that requires projects to produce as much energy as consumed within a given year. This performance target is essentially 100% reduction for a standard project, dwarfing the 15% energy target of the GBS. Thus, this is the most difficult of all the rating systems to achieve and is not viable for owners who wish to achieve additional FAR without altering and revisioning the project pro forma or revisioning a standard design, development deliver processes. If you would like to achieve this rating, please call us; we’d love to guide you through this process! You might also be interested in the LBC pilot program in Seattle.
The best option for a multifamily project attempting the FAR bonus of the GBS/Director’s rule, with the lowest first-cost implications is the LEED for New Construction, v4 Gold certification.
While negative perceptions of LEED NC v4 are often cited as the number one reason why owners elect not to attempt the GBS, the LEED NC v4 rating system has been around the longest, has the largest number of multifamily certifications in the US, and it has the cleanest review process of any of the approved options.
The Director’s rule presents an ideal opportunity for multifamily developers to improve the pro forma of their projects while also supporting the climate action goals of the region – a win/win. Hopefully by demystifying the 15% energy efficiency target, and simplifying the decision-making process around third-party rating selection, this post will help more developers to take advantage of the opportunity the Director’s Rule presents.