Overlook Clipper Mill LEED-Silver Homes in Baltimore Bring Contemporary Style to an Historic Mill

In many ways, residents of the Overlook Clipper Mill will experience the best of both worlds: sleek, modern styling set within a nostalgic backdrop of historic mill architecture; vast parkland views yet proximity to city life and public transportation; and green, energy-efficient living without sacrificing open floor plans and expansive windows. The duplex homes are part of the Clipper Mill mixed-use development, an area that once housed a major contributor to Baltimore’s industrial economy—­textile production—­and has been transformed into a complex of artisan spaces, offices, and residences located next to a light-rail stop and an extensive hiking trail network. When completed next month, the 38 houses, ranging from 1,700 to 2,500 square feet, will be the first LEED-Silver homes in the mid-Atlantic region.

Under a Planned Unit Development (PUD), the City of Baltimore has provided money for the infrastructure of the mixed-use site (offset by an increased tax base in the redevelopment community) purchased by development company Struever Bros. Eccles & Rouse (SBER) in 2002. Now, with community support, the project has been recognized for achieving excellent land-use practice with the 2008 Urban Land Institute Award of Excellence, in addition to being listed on the National Register of Historic Places.

And historic it has been already. The brownfield development has restored the historical characteristics of the property while infusing residential, modern design into the city’s long-standing architectural contexts. For many interested home buyers, this is their first opportunity to live in a green community, while for Baltimore residents, it’s also the chance to own a contemporary home.

“Baltimore tends to be quite traditional in residential offerings, so it was a deliberate choice to go modern,” says Charles Alexander, AIA, project architect and principal of Alexander Design Studio, which was chosen for its reputation of successfully blending contemporary style into old neighborhoods.

A variety of site elevations demanded designs suitable for uphill, downhill, and side-hill locations, without having too many plan variations in order to meet the financial need for repetition. Alexander Design Studio achieved this with two basic plan types: a one-car- and a two-car-garage unit. Residents enter the two-car plan at the lowest level, a design that fits well in side-hill and uphill site conditions. The one-car plan has the garage at the main living level with living spaces wide open at the rear. The result is a seemingly large variety from unit to unit and interesting spaces between them, even though there are only two models.

Site topography wasn’t the only hurdle. Designers had to preserve the homes’ desired modern design—namely, large expanses of glass and an open floor plan—while still meeting requirements to reach the LEED-Silver rating, an essential target for SBER.

“Any home can be designed to be energy efficient, but these homes were a bit of a challenge due to the amount of glazing designed into the project to give homeowners that beautiful, unobstructed view of Baltimore,” says engineer and building systems consultant Srikanth Puttagunta of Steven Winter Associates, the LEED consultants on the project.

The dwellings have nearly twice the window-to-wall ratio as a typical home, and it was key that energy efficiency wasn’t lost to the design. To inhibit energy loss, the builder specified Jeld-Wen Tradition Plus clad IG low-E windows with argon gas fill, and focused on building a tight envelope.

For all exterior-wall applications, the builder used CertainTeed Optima blown-in-blanket insulation, which allows for Grade I installation and has a higher thermal performance than standard fiberglass batts, according to the manufacturer.

The modern design’s open layout also required forethought as to where to hide the wiring, plumbing, HVAC chases, and duct runs. To preserve energy performance, ducts and water lines were not installed in exterior walls. Instead, columns were boxed out to hide all of the wiring and piping, duct risers were hidden in the back of closets, or the interior walls were widened.

“We had to be very clever relative to the location of bathrooms and other utility-intensive spaces to keep the open look,” says Alexander. “We solved the wiring issue with chases routed into the bottom of the beams that are covered by metal flat bars that fall in line with the industrial look.”

The builder also chose to put an all-electric air-source heat pump for the upstairs space conditioning system to avoid running a gas line for a furnace up to the bedroom level, another complexity associated with an open floor plan.

“Simply supporting a floor plan that is so open is a challenge, concerning green design,” says Puttagunta. “In the past, we would have used large beams to carry this load, but as we focus on sustainable lumber, we are looking at the use of smaller, quick-growth trees.”

Steven Winter Associates also worked with the builder on optimizing the framing layout of the homes to eliminate waste. When possible, framing techniques such as ladder bracing, three-stud corners, and right-sized headers were used to eliminate unnecessary framing.

All usable wood cutoffs were saved and stored for future bracing during construction, rather than trashed. Materials that could not be reworked into the project were sorted and sent for recycling.

All of the homes will further cut energy and water use with Energy Star–rated Bosch kitchen appliances, low-flow Kohler bathroom fixtures, Noritz tankless water heaters, and compact fluorescent lighting.

The homes also are prepped for excellent indoor air quality with a central vac, low-VOC paints, and exhaust-only ventilation throughout the house and in the garage.

Finally, SBER partnered with WindCurrent to offer wind-powered electricity to the 38 homes through wind credits. At about a penny/kilowatt extra, the homes will cost an additional $250 per year for the difference of electricity powered from a wind generator versus a traditional one. The appeal to buyers is their homes rely less on foreign oil for electricity and will be less affected by future price increases.

In addition, different jurisdictions around the country are offering home-owners attractive incentives for alternative energy sources. In Baltimore County, there is a tax waiver on property tax for the first 10 years, up to $110,000 per year. For the 38 residences, SBER is set to provide homeowners with 12,000 kWh of renewable energy certificates from WindCurrent, enough to offset the carbon impact of each home’s electrical use for one year.

According to the builder, meeting both the design and LEED goals added about 30% to the cost of the project.

With Phase I at the 42% sold mark, Overlook Clipper Mill stands out as a true exception to the state of the housing market. Balancing a few of the edgier green technologies with safer—though potentially more limiting­—approaches has been key to this project being so well received.

“We were not necessarily striving for technological innovation at the houses,” says Jennifer Goold, development director at SBER. “I believe every house, if well thought out and carefully planned, can be green, and we wanted to show that.”

Shannon Larsen is a freelance writer in Denver.

PROFILE:Charles Alexander, AIA
Principal
Alexander Design Studio

With a long family history in the construction industry and a strong background in innovative design, Charles Alexander was on the green bandwagon long before there was one. Along with a bachelor’s degree in architecture from Cornell University and a master’s in architecture from Yale University, Alexander brings a flexibility of approach and the desire to create strong designs.

“We have always done green designs, we just didn’t know it at the time,” he says. “Solar orientation, daylighting, natural ventilation, local materials, minimal site disturbance, preferences for urban infill sites—these have all been traits of our work for some time.”

Established in 1993, the company has continued on this path, becoming well versed with new lighting technologies and incorporating solar systems for both hot water and heating in current projects. The company also has gained a great deal of experience with wind turbines, SIPs wall construction, and ground-source heat pumps.

“Our hope is to really conquer the integration of all these components, so that the green aspects of our work are truly working in concert for maximum benefit, as well as maximum value.”

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Bathroom Fixtures

Water-conserving Kohler products were used in the bathrooms. The Symbol faucet shown here, an upgrade option, is available with a low-flow aerator. The standard toilet model is the Sterling Karsten Elongated Toilet with Dual Force technology, which offers dual flushing options of 0.8 gpf or 1.6 gpf and saves up to 6,000 gallons of water per fixture, per year. 800.456.4537. www.kohler.com.

Siding

The homes feature James Hardie’s HardiePanel fiber-cement siding, which is durable and low maintenance, and resists fire and winds up to 150 mph. The vertical siding includes PrimePlus sealer and primer. 888.542.7343. www.jameshardie.com.

Windows

To balance the high window-to-wall ratio, which generally increases heat loss and solar gain, the builder used Jeld-Wen’s Tradition Plus clad IG low-E 272 windows with argon gas–filled glazing that have a U-value of 0.31 and a solar heat gain coefficient of 0.33. 800.535.3936. www.jeld-wen.com.

HVAC

Using a natural-gas furnace with a two-stage 16-SEER air conditioner for lower levels and a two-stage Ruud 17-SEER/9.75-HSPF heat pump for upper levels, the split system recognizes that heat rises and cool air falls, and acts accordingly. The furnace, the Ruud Achiever 90 Plus with Contour Comfort Control, offers a minimum of 94% AFUE. 479.646.4311. www.ruud.com

Decking

Used for its durability, resistance to termites, fungi, and fire, ipe hardwood reduces frequent forest cutting because it will last more than 40 years untreated and up to 100 years with deck oil applied to the surface. Ipe Decking never mixes the 20 South American subspecies, which compromises the durability and beauty, and the company purchases only from managed forests. 877.232.3915. www.ipedepot.com.

Insulation

The Optima blown-in-batt system from CertainTeed provides one of the highest R-values possible in typical side-wall applications (R-21 in this case). In the attic, the fiberglass insulation provides R-38 and allows for Grade 1 rating of insulation installation. The blown-in system completely fills any voids around wires, pipes, and electrical boxes, resulting in a seamless, thermally efficient, sound-reducing blanket around the home. 800.200.8990. www.certainteed.com.

Roofing

This Magna-LOC 16-inch standing seam aluminum roof panel by Metal Sales Mfg. Corp. reflects sunlight for greater energy efficiency and complements the home’s contemporary design. The roofing offers a long life span with little required maintenance, and it accommodates from ½ inch to 6 inches of blanket insulation and has a concealed clip designed for thermal movement. The 22- or 24-gauge panel can be applied over open framing or a solid substrate. 800.406.7387. www.mtlsales.com.