The argument for conservation
Over time I have become convinced that the overarching issue for achieving sustainability in buildings is reducing the energy used to operate them. Other issues are of secondary importance, and may even prove to be counterproductive, by diversion. This is the primary lens through which I see my work. "Green" and "Sustainable" can be slippery terms: to set the frame around what it is we are trying to do and to establish the basis for decision-making, I am going present my understanding of the case for reduction of operating energy, first and foremost.
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The graph below shows the well-known global use of CO2, projected use into the future, and in this case, a variety of changes each of which reduce the usage by one “wedge.”
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This is where CO2 emissions come from, here in the US, where we are at the top of the CO2-per-capita list: buildings are our largest source, by far.
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Energy is very closely equivalent to CO2, because our building’s energy sources are not renewable.
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So why can't we just build more clean power plants?
This graph is from the Passive House Institute US, and is based upon projections in a study by Shell Oil. It shows total global energy use, historically and projected into the future. Each fuel is identified. The red is the gap projected in this scenario. Regardless of the definitive accuracy of the future amounts ascribed to each fuel, it seems clear enough that increased efficiency must play a significant role. We are not getting there fast enough waiting for technological silver bullets.
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Next, this graph shows that the energy and CO2 shown in the pie chart above come from operating buildings – from keeping them warm, cool, and lit – not from building them. The energy used in building them is not significant when compared to the energy used in operating them, even over a modest 50-year expected life.
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And finally, this graph, from the DOE, showing US national energy use by sector, which closely matches the CO2 emissions pie chart above. This graph breaks out the relative demands of the various energy-using parts of a building, and helps us understand where the largest problem lies: in the energy used to heat our buildings.
