Most wood floor pros are a little wary of installing wood floors below grade, and this wood floor takes that to a whole new level: The 11,000-square-foot ash sports floor was installed 16 feet below grade over solar-powered, geothermal, cast-in heating pipes. The facility is sunk into the courtyard of the Gammel Hellerup school in a suburb of Copenhagen, Denmark. Architect Bjarke Ingels, a Gammel Hellerup alumnus and Wall Street Journal's 2011 Innovator of the Year, designed the complex to be highly functional, efficient and environmentally friendly. Both the interior and exterior serve as gathering places for students, with lots of seating placed on and around the roof. The arched ceiling, which replicates the path of a ball thrown from one end of the court to the other, reduces the height-or depth in this case-of the building overall, reducing the amount of soil that had to be displaced and maintaining the views from the surrounding buildings. The displaced soil was sculpted into outdoor soccer fields that insulate the network of geothermal-heat storage pipes used to heat the underground facility. Skylights around the ceiling's perimeter take advantage of daylight and reduce the amount of energy needed for lighting and heating. The white-pigmented Junckers Unobat 45 sports floor system and the light cross-laminated beams also keep the interior from feeling like a dark basement. All of these details work together to bring a modern, earth-conscious sensibility to the 119-year-old school.