The construction industry builds and rebuilds various infrastructure facilities. During the lifecyde of infrastructures, many materials and much energy are consumed, and the main factor of environmental impact, CO2 is released in the process, from the point of construction, usage, maintenance, all the way up to demolition. Some estimates indicate that the environmental impact from the construction industry, including manufacturing sectors that produce the materials being used, accounts for about a third of the entire industry. The flow of energy consumption and CO2 emissions in the construction is illustrated with a figure, and it shows that the energy consumption is deeply related with CO2 emissions. In order to measure their environmental impact, estimations of CO2 emissions in bridge construction have been based on methods that are similar to energy analysis.