Howell Lofts goes to market this week. The first public open house will be Sunday, January 29th from 1- 4pm. Howell Lofts looms large for us for a number of reasons. Notably, it is the first new housing project that we’ve completed since the bottom fell out of the market three years ago. It is our first project to use some of the new parking flexibility of the new multi-family codes, which helped provide a more pedestrian friendly street presence for the project. It is also our first project designed for Built Green 5-star, the highest level of certification available through that program, and one of only ten homes in King County built to this level of performance in 2011. Howell Lofts will be a significant test for how well the current home sales market will reward an ambitious green project and how it will respond to our unconventional parking solution.
Howell Lofts is built on a little sliver of land, 23’ wide by 138’ long. A 100 year old house sits on the corner with a long strip of backyard that faced Howell street. We short platted the land into 4 small lots, remodeled the old house and then developed the three remaining lots into townhomes. Parking, as always, is a significant issue with small infill development. In our case, our goal was to create buildings that were welcoming and that contributed to the pedestrian environment. Given the site configuration, we were forced to choose between a streetscape dominated by garage doors, or less parking than is typical for new housing. Reducing our parking count allowed us to create small courtyard entries for the units that would otherwise be filled with parking. Avoiding curb cuts also allowed us to preserve two large specimen trees in the right of way.
The neighbors, however, were not thrilled to hear of our plans for providing less than 1 parking stall for each unit, as this would put pressure on the already over-subscribed street parking in the area. To resolve the issue, we approached the Union Gospel Mission next door and made a deal to lease some surplus spaces in their parking lot. In the end, we got the building design that we wanted, the neighbors got our cars off the street, and UGM gets income to help with their mission.
The project is laid out with the units facing south onto Howell street. Large windows are grouped along this south façade to capture natural light and passive solar gains in the winter. The large trees we preserved provide shading in the summer. The homes have about twice the amount of glazing as a typical home, and most of the windows are operable in order to provide good ventilation in the summer. In addition, the stairways are designed with open risers to facilitate vertical airflow & allow for convection currents to pull out hot air in the daytime & push down cool air for nighttime flushing.
The limited space on the site required layouts with a very compact (20’x20’) footprint. We designed the units with a split level entry and a switchback stair so that minimal space was given over to hallways and entry circulation. While the footprints are relatively small, the zoning allowed us one more story than a typical townhouse project, so in the end we got units that are quite generous. Each unit has 3br/2.5ba and a rooftop deck.
The
developer, Jonathan Mckee, sensed that the lull in the construction market was
a great opportunity to try something ambitious, and he set us a goal to
certify the building to the highest green standard. The project team had regular weekly meetings
throughout the design process to continually optimize the building and to
grapple with the simultaneous challenges of digesting the Built-Green
requirements as well as those of a brand new energy, stormwater, and land use
codes.
One of the
biggest challenges that we faced is that 5 star projects have to meet an energy
performance 30% better than what is required by code. Moreover, since the energy code baseline is based
on an assumption that the project has significantly less glazing than we were
using, we had a lot catching up to do. We used very high performance windows and a premium insulation package,
which got us part of the way there. Air leakage,
it turns out, is actually the biggest source of energy loss, and it can be hard
to eliminate because the sources of leakage are so manifold and dispersed. To help tighten up the envelope we used Knauf
Ecoseal, a form of sprayed caulking that gets applied to every joint in the
framing and seam of the plywood. A
blower door test at the end of framing helped us find little cracks before the
building cavities got closed up.
 |
Window U Value = 0.18. The blue color is the Knauf Ecoseal
|
Tight building envelopes make for great energy performance but also create a couple new challenges. Leakage is bad from an energy standpoint, but air exchange is necessary for healthy interior environments, so we needed to provide a supplemental mechanical ventilation system. Each unit is outfitted with a heat recovery unit that brings in a constant supply of fresh air. Exhaust air is run through a heat exchanger that transfers the outgoing heat to the incoming air, retaining about 80% of the heat energy.
 |
| Rainscreen battens ventilate behind the siding |
Tadashi
Shiga, our energy consultant, had organized an informal co-op to
connect builders with suppliers of the products needed for efficient green buildings. Through this network we were able to source
high performance window, mechanical, and insulation packages at significant
discounts.
Project
Team:
Developer: Jonathan Mckee
General
Contractor: Roger Penner, Pluma Homes LLC
Project
Superintendent: Lorne Gunther
Architect: David Neiman Architects in collaboration with
Thomas Isarankura of Baan Design
Structural
Engineer: Todd Valentine, HSV Engineers
Civil Engineer: Brian Darrow, Blueline Group
Civil Engineer: Brian Darrow, Blueline Group
Built Green
/ Energy Consultant: Tadashi Shiga,
Evergreen Certified
Real Estate
& Marketing: Ron Rubin, Seattle Land
Broker
Five Star Built Green Features
Energy savers:
- Triple Glazed Windows, oriented for passive solar gain in the winter, shaded by trees in the summer, have a U-Value of 0.2, about twice as efficient as a typical window.
- BIB insulation package provides complete fill of cavities providing much higher performance than conventional batt insulation.
- Airtight construction methods including sprayed sealants at the framing level and airtight drywall reduce air infiltration to about 20% of what is seen in a typical project. Project has been blower door tested to confirm energy performance.
- Fresh air intake and exhaust provided by a Heat Recovery Ventilator, which strips the exhaust air of its heat and transfers energy to the incoming fresh air. The HRV system retains about 80% of the heat that would otherwise be exhausted to the outdoors.
- Super-high efficiency on-demand boiler and domestic hot water supply heat on an as-needed basis, preventing energy losses from storage tanks.
- TED 5000C Energy monitor allows real time monitoring of energy use and tracks use over time.
- Overall energy performance is modeled at 30% better than energy code (rated HERS 70).
Indoor air quality and comfort:
- Low VOC paints, floor finishes, cabinet finishes, insulation, sealants.
- No formaldehyde in interior millwork including cabinets, trim, plywood.
- Heat recovery ventilator provides a constant supply of fresh air.
- No carpet. Flooring is entirely tile and concrete.
- Radiant floor hydronic heating system. Ahh.
- Stairwells with open risers and operable windows create a stack effect to increase natural ventilation in warm weather.
Durable exterior:
- A rainscreen cladding system provides a ventilated cavity between the siding and the building paper to increase the longevity of the exterior finishes and protect the structural framing against long term moisture intrusion.
- Commercial grade TPO membrane roof with standing seam sheet metal parapet caps.
- Exterior fiberglass entry doors with integral sill pans.
Resource efficiency:
- Recycled countertops, tile, pavers, fencing, drywall, steel, concrete.
- Open space is entirely pervious pavers and drought tolerant landscaping.
- Rain barrels provide for rainwater capture.
- Low flow faucets and showers reduce consumption by 30%.
Urban design solutions:
- The existing house on the site was saved and remodeled.
- An existing garage on the site was deconstructed & substantially recycled.
- Two large specimen trees were preserved and made into project features. The tree canopies provide summer shading for the south facing windows and the rooftop decks.
- Parking for the project was provided partly by leasing spaces from the Union Gospel Mission next door, freeing up the open land for pedestrian courtyards instead of parking stalls.
- All units feature rooftops decks, providing much needed private open space with expansive views of Lake Washington.
Fantastic write-up, and fantastic project, David. I walk by it frequently. Joe Nabbefeld
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