A couple years ago I met an old friend whom I had gone to school with many years ago. During our college years we both guided canoe trips for a camp in the Minnesota Boundary Waters, then I lost track of him. It turns out that he studied glacial geology and became a drilling engineer, conducting ice core studies on glaciers throughout the world. He told me about a project in Antarctica examining ice formed 700,000 years ago. From these examinations it's possible to learn what gases were in the earth's atmosphere in the past and their percentages. And by examining the oxygen isotopes in the ice you can tell what the temperatures were in different times in history.
I asked if he thought the current global warming is just another cycle in the history of the earth or the result of human activity. He said the scientific community he works with believes the current warming trend is our responsibility because it has progressed so rapidly over such a short time—faster than any other period in the earth's history. When asked what he thinks we should do about it, he said we need to stop burning carbon-based fuels.
It's now two years later and Al Gore's movie “An Inconvenient Truth” is out and more people are accepting that global warming is real. The news media has helped to drive this message home over the past six months, too, though many people probably don't sense the urgency of the situation the way my friend does.
At RESIDENTIAL CONCRETE magazine, though, we know how we can reduce the amount of carbon dioxide (CO2) we are putting into the atmosphere—everyone should live in a concrete house, because they require less energy to heat and cool. In the United States approximately 45% of our energy supply goes to residential uses; approximately 60% of that is for heating and cooling.
R-Value, energy efficiency (the amount of air that leaks through a house), and the thermal mass of a material are the three primary ways to judge how energy will be saved or lost in a building. Concrete turns out to perform well in all these areas, especially when combined with insulation on the inside, middle, or outside of a wall. Almost every concrete home-building system has shown that you can save 60% or more of your heating and cooling bill compared to standard “stick-built” homes. So 60% of 60% of 45% amounts to a lot less CO2 being pumped into the atmosphere.
Oh, but what about the argument that portland cement produces a lot of CO2 when it's manufactured? Well, that's true, but when sand, aggregates, and waste products like fly ash and slag are added to portland cement to make concrete, the amount of CO2 produced per cubic foot of material is comparable to other construction materials. The heating and cooling of buildings is where the most energy is consumed and the most CO2 produced, and that's where concrete excels, more than any other building material.