The Terraset Elementary School is a rare example of an underground school. It's part of the Reston neighborhood — a planned green community in Northern Virginia. I visited the school recently — the roof now resembles a meadow, complete with trees and skylight structures that appear like pyramids rising out of the grass. The school is actually set on a knoll in 14 wooded acres. The top of the knoll was shaved, the structure built, and soil was placed over it.
The earth covering provided natural insulation. When combined, the benefits of being underground, the school's depressed floor slab and the circular classrooms were expected to give the building a "high thermal mass" which would all but eliminate the effect of outside temperatures.
The challenge was to reduce the effects of naturally produced heat from people and lights. Year round cooling became the major maintenance and design task with the need to offset heat loss at the perimeter. Solar collectors were expected to play a primary role in both heating and cooling.
In order to fund the cost of the solar energy system, Fairfax County applied to the National Science Foundation for a grant to cover the $625,000 cost. The grant was turned down. The County schools found an unlikely financial backer in Fahd Ibn 'Abd al-Aziz Al-Saud, then crown prince of Saudi Arabia and now king. The Saudis donated the money needed to fund the school's solar panel network.
While the design of the school has provided insulation that saved thousands of barrels of oil, the solar collectors failed to live up to expectations. Built for Saudi Arabia's hot but stable climate, the panels cracked under Virginia's fluctuating temperatures. The panels leaked so much that, in the winter, icicles would form over the entrance way and drop unexpectedly. The hazards of the network and the costs of repairing the panels finally prompted the County to remove the solar panel rack. The other aspects of Terraset's energy conscious design continue to provide savings in energy costs every day.