Friday, December 14, 2007

NTHP on Sustainable Stewardship

press release from the front lines...

Washington, D.C. (December 13, 2007) – Richard Moe, president of the National Trust for Historic Preservation, tonight called for historic preservation’s “essential role” in fighting climate change, in a speech following his receipt of the National Building Museum’s prestigious 2007 Vincent Scully Prize.

Construction and operation of buildings, Moe noted, contributes 48% of America’s greenhouse gases – nearly double that of cars, trucks, trains and airplanes – and even construction of the greenest new building contributes to global warming. Despite that, Moe said, the most talked about solution to global warming is building new, greener buildings, often destroying an old one in the process. “We can’t build our way out of our environmental problems. We have to conserve our way out. That means we have to make better, wiser use of what we’ve already built.”
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Read Moe's speech here. It is, not surprisingly, great, as the NTHP has been a leader on this issue long before LEED.

and don't forget to check out NTHP's Sustainability Resources

Wednesday, December 5, 2007

Concept Model of Demolition Energy for Existing Buildings

We have our embodied energy model down pat. But when we're looking at teardowns, that's only half the equation. The ACHP report also provides a concept model for demolition energy, or "the amount of energy needed to raze, load, and haul away construction materials."*

The concept model provides a second table for demolition energy. The math is simple. Demolition Energy = Gross s.f. multiplied by the demolition energy of materials per s.f. of construction for buildings of similar size and construction type in table 2.

TABLE 2 Demolition Energy of Construction Materials for Existing Buildings

Small Building Size (5000-15000 s.f.)
Construction Type:
Light (e.g. wood frame)............3100 BTU/s.f.
Medium (e.g. steel frame)..........9300
Heavy (e.g. masonry, concrete)...15,500

Medium Building Size (50,000-150,000 s.f.)
Construction Type:
Light (e.g. wood frame)............2400 BTU/s.f.
Medium (e.g. steel frame)..........7200
Heavy (e.g. masonry, concrete)...12,000

Large Building Size (500,000-1,500,000 s.f.)
Construction Type:
Light (e.g. wood frame)............2100 BTU/s.f.
Medium (e.g. steel frame)..........3600
Heavy (e.g. masonry, concrete)...10,500

Now, many (most) homes don't even register on the "small" scale above. But seeing as how demo energy decreases as a building size increases, we think we're being conservative by using numbers meant for 5000-15,000 s.f. buildings to calculate the demo energy of an typical single family home. In other words, the actual energy expended is probably higher.

So, back to our "model" home: 3000 s.f. frame house X 3100 BTU = 9,300,000 BTU. If the same home was made of brick, we're looking at 46,500,000 BTU. Add that to the existing embodied energy, and you're on your way to making a solid case for preserving homes from an energy conservation perspective.

* You are a NTHP Forum member, right? You should be. The journal is great and members can pick up the ACHP report on embodied energy in the pdf file cabinet. Go now!