| Traditional U.S. building structural systems are time-tested and reliable, but all have drawbacks, regarding their environmental impact. One seldom-considered but important aspect is the Carbon Dioxide Equivalent (CO2e) emissions generated by their use. We will review the CO2e emissions of steel, concrete, masonry, and wood construction as well as building construction, in general. We will discuss how to reduce the emissions in practical ways, and what materials to avoid completely. Many people think that the emissions of buildings over time due to energy usage is large compared to the initial carbon emissions of construction. This is not always the case - it varies with construction type, envelope performance, energy type, and other factors. There is a methodology to determine the approximate annual heating energy usage for a building system based on R-value, airtightness, and location. We will review this procedure, and then compare CO2e emissions from construction to annual emissions due to heating energy, for standard construction systems. |