I was on the 20th floor of a hi-rise condo under construction in Tribeca, gazing out the concrete slab and walls, steel studs and gypsum board. I realized that there was very little carbon in any of these materials and it occurred to me that perhaps it's time to take a look housing developments (one and two-story, not hi-rises) with respect to carbon.

Would it be appropriate to look at a development of stick-built houses as a collection of "carbon-sequestration units"? Is there an argument to be made that building out of wood sequesters a significant amount of carbon?

Using some data from DOE, a 2700SF house contains 13,800 board-feet (BF) of lumber (I suggest ignoring the question of whether a 2700SF house is green in and of itself for now). At 12BF per cubic foot, that's 1,150cu.ft. of wood. At 25lb/cu.ft. (a real rough estimate for oven-dried wood), that's 28,750lb or over 14 tons of wood. Assume 50% carbon content and you have 7 tons of carbon or the equivalent of 25 tons of CO2 in a house. I expect these values could change under some scrutiny.

It certainly wouldn't offset all the carbon emissions attributable to the house over its lifetime and my cursory analysis is ignoring a bunch of other inputs and outputs (such as where and how the wood was harvested and what occupied the land before the house was built). Has anyone done a formal study of whether stick-built construction has any positive attributes viz. carbon emissions or sequestration?

I am surprised at your observation.

The world cement industry is 5-10% of all CO2 emissions.

Similarly steelmaking is a CO2 heavy activity. And the steel probably comes from a long way away.

I haven't looked into whether a concrete and steel house is as CO2 intensive as a wooden one. Perhaps the gain (if there is one) is that a concrete and steel house should last a lot longer than a wood one.

*that said* they are tearing down concrete buildings put up here in the 60s (London). They cannot take the constant wet-and-drying-out cycle that our climate puts onto them. Whereas a brick building (the norm for housing construction) dries out-- the houses on my street are nearly 200 years old (but they are incredibly energy inefficient).