Answer: The one standing.  
     So says Carl Elephante, Director of Sustainable Design at Quinn Evans Architects.  Last year, the National Trust for Historic Preservation released a study, “The Greenest Building: Quantifying the Environmental Value of Building Reuse,” with data that supports this contention. The report uses Life Cycle Analysis (LCA) to compare the relative impacts of building renovation and reuse versus new construction. The description of the study says that it “examines indicators within four environmental impact categories, including climate change, human health, ecosystem quality, and resource depletion.” 

copyright, National Trust for Historic Preservation

According to the study, wrecking a building and replacing it with a new one comes with very high environmental and economic costs. Let’s look at what how these costs apply to the wrecking of the historic Orth House at 2320 Colfax Ave. S.in order to build the Lander Group’s new four-story apartment building:
     First is the cost of destroying the existing structure. Wrecking the Orth House (and its neighbor at 2316) will cost the developer approximately $30,000 each.  Add to this cost, the waste of the building materials of the house. The Orth House, a large 6,000+-square-foot house, is estimated to weigh 180 tons, not including the foundation (John Jepsen, Jepsen, Inc.). The Orth House was built in 1893 of lumber from Minnesota’s virgin forests.  This irreplaceable resource will be hauled off to a landfill, never to be used again. The plaster, lath, windows, and mechanical systems will similarly be trashed.  Yes, some of these features could be removed for salvage; however, the sad fact is that staircases, doors, and windows in a house of this size and vintage cannot easily be fitted into an existing structure. To reuse them, one would have to custom build a structure they could fit into. And what’s the point of that when they are already serving their purpose in the existing house?

The Orth House today.

Second is the cost in labor and materials to build the new structure. New construction consumes many resources. The developer’s claim about energy savings makes no sense because new construction consumes so much energy upfront in producing new materials. (U.S.Green Building Council) The proposed apartment building is not one that uses a variety of “green” features and technologies, but a run-of-the mill structure.  Recycling bins and bicycle racks do not a green building make. In fact, according to the Trust’s study, when replacing an average existing building with a new, more efficient building, it still requires as many as 80 years to overcome the impact of the construction.

The Orth House c. 1900

Recycling existing buildings is essential to creating sustainable cities.