Denver's historic Equitable Building strives to meet 21st Century energy goals

The city of Denver has set goals for buildings to become more energy-efficient and less polluting . Built in the late 19th century, the landmark Equitable Building is undergoing a behind-the-scenes transformation to meet those goals in the 21st century.

The building, on the National Register of Historic Places, is switching from the downtown steam-heat loop, which has warmed the nine-story structure since its opening in 1892, to a new natural gas system. Most of the work being done to make the 133-year-old building more energy-efficient is taking place inside, behind the exterior that features Colorado granite blocks and bricks, terra cotta ornamentation and a Palladian-style window, which has three separate sections.

But a big part of the update, a 22,000-pound boiler plant, is on t