Mosler Lofts

Mosler Lofts Green Story- by Mithun

Sustainable Sites

Situated at the north end of Belltown across from the historically vibrant Seattle Center, the 150-residential loft tower offers environmental quality as an urban lifestyle choice for downtown Seattle’s growing live/work community. From inside to out, the project includes a number of green features that have been a major selling point for buyers.

The site itself is enhanced by the building’s different setback (a departure from city building code) that reclaims six feet at the street level for pedestrians. The building steps back only once more (rather than twice as required by current zoning laws) and creates additional planters and landscaped terraces along the building’s face that add to the pedestrian experience. As a result, the design minimized the building’s footprint and maximized the developer’s investment.

The project also integrated the site through its makeover of Clay Street. Designated as a Seattle “Green Street,” the right-of-way formerly did not have a design direction or precedent. With this project, the design team proposed the removal of diagonal, on-street parking in favor of parallel stalls and additional open space that has created a more pedestrian-friendly environment with wider sidewalks and landscaping. Planted with a grassy swale, it also helps with stormwater management, attenuating runoff and allowing it to infiltrate and recharge the soil.

The building’s extensive glazed sides have both functional (i.e., daylighting, passive heating) and aesthetic (i.e., views, connection to the surrounding site) sustainable qualities. The north roof area tilts to the south to maximize the efficiency of a future solar array.

The project capitalizes on its central location from which residents can walk, bike, bus or drive. Access to public transit is steps away. Bicycle storage and a changing area are provided in the garage. Each resident is given a free membership to use the hybrid Flexcar available on site. Parking is underground to maximize the use of the site, but to decrease dependency on vehicles, the site does not mandate parking. The garage also includes an alternative fuel recharging system.

Lauded as the most provocative residential high-rise in Seattle since WWII, the 12-story concrete, steel, and glass building respects the character and scale of the neighborhood while promoting the sustainable direction of the future.

Towards Zero Energy

As a residential building, most of the thermal load comes from exterior climatic conditions versus interior equipment loads.

The building’s extensive glazing helps maximize passive heating during the winter. Operable windows, patio doors, shading from balconies, and interior sunshades temper heat gain during the summer. Thermal mass of concrete, brick and CMU elements help insulate the building from thermal extremes. Windows achieve Energy Star levels through the use of thermal breaks, Low-E coatings, aluminum spacers, and argon gas infill. Limited solid-wall areas are insulated up to R-79.

Every residential unit also has individual control of its heating and cooling, allowing the south side to be cooling while the north side may require heating. All multi-occupant spaces use carbon monoxide sensors to alert the ventilation system when additional air changes are required. In the parking garage, CO sensors control the ventilation system so fans run only when needed.

The north roof area tilts to the south to maximize the efficiency of a future solar array. The entire roof area is super-insulated (R-45) and contains extensive planting areas to reduce thermal gains and losses.

The large glazing areas enable much of the building to function without artificial light. Each of the 150 lofts has 10-foot-tall windows that allow maximum daylight to penetrate the units. Approximately 85 percent of the building’s regularly occupied spaces have a daylight factor of two percent. All multi-occupant spaces use occupancy sensors to control lighting, turning lights off when not needed. Energy-efficient compact fluorescent fixtures are used throughout the public corridors and strip fluorescent lights are used in the parking garage. LED lights are used for a variety of exterior lighting.

An investment in renewable green power has been made to offset 35 percent of the building’s electrical use for two years.

Additional energy-saving design strategies include modulating the façade, over-sizing roof overhangs, and incorporating vegetation at the street level and throughout the building. The building also incorporates high efficiency boilers, chiller unit with no CFCs, and reduced-energy elevator system.

Local & Regional Materials

Although the density of units is high, the proportionate material use is low. Wall area was minimized through innovative open plans to provide simple, flexible living spaces. Loft ceilings are exposed, untreated concrete, which saved more than 100,000 sf of metal stud, gypboard, and painted assembly (equivalent to 242 metric tons of embodied carbon).

The materials and finishes—brick, pre-cast concrete, glass and steel—were selected based on durability, health-related factors, and proximity to the site. More than 40 percent of materials used on the project were extracted and/or manufactured within 500 miles of the site. Pre-assembled steel decks were trucked to the side and hung, minimizing waste, time and on-site labor. FSC certified wood floors are used in all residential units. Green seal carpets are installed in corridors to limit pollutants in living spaces.

A waste management plan was developed for construction, and diverted more than 75 percent of construction waste from landfills.

Sustainable Water

The project site was previously unvegetated and impervious. The project has introduced many stormwater management improvements to the site.

Forty-three percent of exterior street level area has been converted into landscape and 18 percent of the roof area into gardens. The drainage system directs stormwater from paved areas into landscape beds on street level, and retains rainwater in landscaped roof areas. This provides water for plant use and reintroduction into the hydrologic cycle through infiltration and evapotranspiration. Both methods also slow stormwater, reducing peak flows and removing suspended solids. The swale along Clay Street allows an additional infiltration opportunity for stormwater to recharge the soil.

The project also utilizes high efficiency, low water-use irrigation. The selected plants are low maintenance and well adapted to both the local climate and the microclimates of the site.

Inside the building, water conserving fixtures such as low-flow toilets, low-flow showers, Energy Star dishwashers and washing machines allow residents to minimize their water use.

IEQ & Comfort

Residential loft units were conceived and designed as a simple “drawer in the city”—emphasizing openness, space, light and views. Their end walls are all glass. More than 60 percent of the building area is daylit.

Operable windows, glass patio doors and massive sliding glass walls offer opportunities for natural ventilation, cooling, warming, views and varying levels of participation in the surrounding city. Fifty-five percent of the building can be ventilated or cooled with operable windows. Most units feature at least one deck, balcony, terrace or townhouse stoop.

A rooftop garden provides a community outdoor experience for residents with 2,643 sf of vegetated space and 2,319 sf of open space, including a barbeque area, conversation circle with fire pit, and party or gathering spaces for groups or couples.

In addition to the green roof terrace, thoughtfully-designed common facilities, such as the welcoming lobby with an original Ann Gardner sculpture; a two-story, richly appointed library and art gallery; living room-style shared spaces; a business center; workout area; and café create a sense of community.

Collective Wisdom & Feedback

Developers often are under the false impression that going green costs too much. For this project, market forces and an enlightened team shifted the client’s goals dramatically toward a sustainable outcome.

Early on, focus groups were enlisted to determine a marketing strategy to reach young, urban professionals. Prospective buyers were asked about issues that would shape the building’s design. The design team randomly inserted questions that referred specifically to sustainability, such as energy performance, indoor air quality, use of recycled materials, etc. Results showed that the target market was especially interested in green issues.

Spurred by the strength of this response, the client commissioned further studies, delving deeper into buyer demand for a sustainable building. Sustainability issues continued to score high! Working with the contractor to determine pricing, the design team assisted the client in cementing a distinctly green point of view.

The team used the LEED checklist and credit templates to track and calculate sustainable strategies. Engineers performed various calculations (energy modeling, green roof stormwater detention, LCA, etc.) to determine viability of various strategies.

Built results will be tested one year after occupancy. Electric and gas pulse meters will provide the raw data to compare actual energy consumption to modeled consumption. A resident survey has been developed and will be administered one year after occupancy to test the residents’ comfort. Post-occupancy commissioning will be performed to ensure systems are functioning as designed. Energy data will be collected and analyzed to determine if systems are performing as planned.

Regional/Community Design

As Seattle’s first LEED- and Built Green-certified condominium tower, the project provides a model for sustainable urban living. With less than a handful of lofts remaining to be sold, the project’s success demonstrates that green also can be profitable.

The 12-story concrete, steel, and glass residential tower with elegant uptilted roof adds an iconic signature to the neighborhood’s skyline.

Almost 6000 sf of retail space activates the building’s façade, providing opportunities to engage the community.

The project’s makeover of Clay into a “green street” reaches beyond its borders, creating a pedestrian link between Belltown and the Seattle Center and enhancing the walkability of the neighborhood for all to enjoy.

Social Equity

Few projects in Seattle have created more of a “buzz,” beginning with its blog-centric marketing campaign — a vital and conversant blog culture that continues among residents, their friends and the homeowner community.

Residents support a healthier way of living not just in the urban area, but also in areas outside of downtown. They do this by all paying a regular homeowner’s fee, a portion of which supports the purchase of green power.

This project has attracted homeowners passionate about design, the community and the environment — including a disproportionate number of architects, designers and the producer of an Oscar-winning environmental documentary. The project and the positive publicity received thus far have served as a touchstone for broader conversations about building quality, enduring or sustainable values and the place of “green” in Seattle’s urban residential landscape.

1) Future Proofed for Photovoltaic Panels
2) Natural Daylighting & Views in all Units
3) High Performance Window Wall and Glazing System
4) Water Conserving Fixtures
5) Regional Material Use
6) High Efficiency Chiller Unit no CFC’s
7) High Efficiency Elevator System
8) High Efficiency Boilers
9) Rooftop Recreation Areas
10) Green Roof
11) Energy Star Appliances
12) Use of Certified Wood
13) Enhanced Commissioning Systems
14) Underground Parking
15) Flex Car
16) Bicycle Storage & Changing Area
17) Stormwater Management
18) CO2 Monitoring
19) Recycling Collection & Storage Area
20) Evapo-transpiration
21) Swale / Water Infiltration