Three decades of the extremes of Philadelphia's winters and summers take their toll on a building - even one considered to be environmentally state-of-the-art when built.

That's why construction workers have begun what will be a seven-month task of resealing the shiny, black glass panels that make up the distinctive exterior of Peco Energy Co.'s headquarters at 2301 Market St.

Some passersby began to notice the work last week, especially after construction crews removed and began disposing of several large PVC-like pipe structures that decorated the plaza area around the building.

Peco spokesman Michael Wood said the decorative pipes are not public art; they were added about 10 years ago as part of the renovation of the lobby and complement an industrial motif inside.

Ultimately, Wood said, Peco officials decided the exterior pipes had become too much of an obstacle to maintenance. The building "reskinning" project, he added, became a convenient time to redo the plaza.

Wood said Peco did not want to release the cost of the project because the work was competitively bid and involved proprietary information. The general contractor is C. Erikson & Sons.

Basically, Wood said, the work on the 30-story Peco tower is the equivalent of caulking the seams and windows of your home - except that workers will be squeezing out beads of sealant 10 to 15 feet long.

Workers will move along each panel seam on the building's faces, clean the surface, and apply two parallel beads of a special Dow Corning combination sealant-adhesive. Wood said a section of flat, tape-like gasket is then pressed into the sealant and allowed to cure in place.

Because the tape is colored to match the Peco Energy building, the installation will not change the building's appearance or require modifying the panels themselves.

Wood said the work, which is to be completed in July, will extend the life of the building's exterior, and reduce the loss of heat and cooling and the infiltration of water from outside.

Contact staff writer Joseph A. Slobodzian at 215-854-2985 or jslobodzian@phillynews.com.