THE conversion of a huge Hoboken warehouse building into condominiums and the nearly completed restoration of a small 1860 farmhouse near the Delaware River are two very different sorts of projects. But they share an intriguing goal: creation of 21st-century “green” homes in history-laden structures without stripping the buildings’ original character.

In Hoboken, the developer Lawrence Bijou is moving forward with a bold plan by the Manhattan firm of SHoP Architects to graft a zinc-faced addition onto an 80-year-old brick warehouse once used to process coconuts. The project, which will create 30 one-, two-, and three-bedroom condos, will be the first residential apartment structure on the Jersey waterfront built to the standards specified by the United States Green Building Council for achieving its “silver” rating.

In the historic hamlet of Rosemont — population 49 — the Victorian farmhouse and its four barns have been restored by the developer Lise Thompson, whose two-year-old company, Conservation Development of Hillsborough, made the project its first “green” effort.

Ms. Thompson calls the 2.4-acre property, now on the market for $2.45 million, a “new-old hybrid,” and the farmhouse a “historic green house.” The expanded house provides 4,956 square feet, with an additional 690 square feet in a finished attic.

The L-shaped white clapboard house and traditional red barns, along with a quaint 7-by-10-foot well house and a fetching iron corn crib, are part of an archetypal pastoral enclave, alongside a flowering-tree nursery.

Mr. Bijou’s Coconut Building, on the other hand, is at the unadorned corner of Garden and 14th Streets in the northeast section of Hoboken, the latest sector of the city to be undergoing gentrification. The site is close to a ferry stop and PATH and light-rail stations; and the main shopping-and-restaurant area along Washington Street is also within walking distance.

The Garden Street Lofts, as the condo complex will be called, will have a “green” roof, planted with sedum to provide natural cooling and capture rainwater. Construction materials will be recycled and as chemical-free as possible, and the building design is aimed at energy conservation, Mr. Bijou said.

For the old part of the building, with its exposed masonry walls, structural columns and 12-foot ceilings, the architects designed more traditional interiors. In the addition, however, they gave apartments a sleeker, more contemporary look to complement the zinc paneling on the facade.

The addition, shaped like the figure 7, is to be linked to the existing five-story structure, extending two stories higher.

Mr. Bijou said he envisioned that his project would become a “visual bridge joining old and new.” The symbolism pertains not only to the expanded building itself, but also to the whole historic waterfront in Hoboken, which is being transformed by new construction, he said.

Ms. Thompson, whose background is in restoration architecture, said she had also sought to blend old, new and green in Rosemont, a part of the historic and preservation-minded Delaware Township in Hunterdon County, about halfway between Manhattan and Philadelphia.

“The real challenge was keeping the aesthetics, the historical aspects and the green aspects all at the forefront at the same time,” she said. A trustee of the state chapter of the Nature Conservancy, Ms. Thompson, 47, is married to Robert J. Brander, a builder and designer of fine furniture and homes, who was her partner on the farmhouse project.

While Mr. Bijou in Hoboken said he had focused “first and foremost” on making his project as green as possible, Ms. Thompson said she had been forced to mediate between historic and eco-friendly concerns.

“Sometimes, we had to ask ourselves: What is ‘green?’ ” Ms. Thompson said. “For example, we intended to go for an Energy Star rating, but they won’t give that unless you replace original windows.

“We were committed to restoring the house as fully as possible. So we kept all the original glass, and every single piece that needed to be replaced, we did so with antique glass.

“The fact is that preserving the house is itself ‘green,’ because it avoids further development and sprawl — but there are tensions between being green and authentic restoration, and we had to resolve them as best we could.”

Ms. Thompson noted that the house had been outfitted with energy-efficient storm windows and screens and that they had been mounted flush so as to be barely visible and not interfere with the architectural lines of the house. In addition, the original window pulleys were replaced so that spray foam insulation could be installed tight to the window frame.

“This is a magical house,” she said. “The moment you see the front porch, with its ornate arches against the backdrop of brick-red barns, you’re transported into the past. We wanted to preserve that, and keep the house healthy.”

The preserved Hoboken building will have street-level retail shops, and its apartments will range in size from 1,100 to 2,300 square feet. Prices are to begin in the $600,000s.

Mr. Bijou, who previously renovated another smaller warehouse in Hoboken known as the Hostess Building, said energy-conserving features and systems in the Garden Street Lofts should reduce condo owners’ utility bills by up to 20 percent, compared with apartments of the same size in nongreen buildings.

The builders used nontoxic paint and new wood from nonthreatened sources, as certified by the Green Building Council, in both Hoboken and Rosemont.

On top of that, meticulous records were kept of the Rosemont reconstruction, and a history of the land dating back to the 17th century was compiled for the eventual owner.

In Hoboken, a commissioner from the United States Green Building Council must review every step and every piece of documentation about materials used in the rehab process, before granting a level of certification — in this case a silver rating.

Correction: March 18, 2007

The “In the Region” article in New Jersey copies on Feb. 18, about the conversion of two old buildings in New Jersey into up-to-date residences, misstated the area of Hoboken in which one of the properties, the Coconut Building warehouse, is located. It is in the city’s northeast section, not the northwest. The article also misidentified the shopping area nearest the property. It is Washington Street, not Hudson Street.