The city will save about $1.5 million as a result of its recent refinancing of a $12.6 million bond, according to Mayor Scott D. Galvin. The savings will be realized over the remaining 12 years of the 20-year bond, which was used to fund construction of the new high school. Robert W. Baird & Co. was selected for the refinancing with a low bid that provided the city with a new interest rate of 2.22 percent, Galvin said. The city undertook a similar refinancing last summer through which it will save $465,765 over 13 years. “We are in a low-interest environment, and our strong bond rating allowed us to take advantage of these rates and deliver a substantial savings for our taxpayers,” Galvin said. Woburn has an Aa2 bond rating from Moody’s Investor Service.