If you're planning to follow Werner Schmidt on his famous "dirty tour" of the United Nations headquarters, here's what I suggest: Bring your hazmat suit. The bow-tied former German diplomat is the spokesman for the U.N.'s Capital Master Plan, a $1.9 billion, 10-year makeover that will rescue the building from its present dilapidated and hazardous condition.

Built between 1949 and 1952 according to 1938 New York City building codes, U.N. headquarters threatens the health of its workers and the local environment alike. The heating facilities are now 35 years past their original life expectancy; asbestos is ubiquitous; high-pressure steam pipes pose a constant risk of fire, and the building has no sprinkler system. In the winter, so much heat leaks from the building's iconic outer curtain wall that snow rises, carried on the warm air currents, and the building steams.

The makeover is, according to Schmidt, a logistical "nightmare"; some of the 4,000 staff and 8,000 annual conferences are to be moved to two nearby buildings, one of them a prefab structure that will be erected on the North Lawn adjacent to Manhattan's East 47th Street, near where the flags of the U.N.'s 192 member nations wave.

The Capital Master Plan promises a number of real improvements. The thin glass of the curtain wall will be completely replaced with thicker, more energy-efficient double panes; offices will be outfitted with daylight sensors to automatically adjust lighting and cut back on energy consumption; solar panels will be installed (although their exact use has yet to be determined); and some of the storm water will be trapped and used to water the plants and the North Lawn. When the overhaul is complete, the U.N. hopes to be rewarded with Silver Leadership in Energy and Environmental Design (LEED) certification. And Werner Schmidt has his own private fantasy as he gazes out over the lawn: a flock of sheep grazing there -- and maybe an occasional juicy lamb chop.