The chief designer of the "Hamburg House" yesterday revealed the pavilion's secret in keeping visitors feel cool during the summer - a ground source heat pump.

Hamburg is highlighting its "passive house" -- using as little energy as possible while still keeping the pavilion operating at its full potential -- as its ecological contribution to the Urban Best Practices Area.

The pavilion doesn't have an air conditioning system, while the pump lets heat flow in a natural way throughout the house via pipes, keeping the house cool in summer and warm in winter, Christine Reumschussel told reporters at the pavilion yesterday.

The design takes advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems, she said, adding that on top of the pavilion there is solar power generating equipment which is the main source of the electricity used.

The pavilion can keep room temperature at 25 degrees Celsius all year round, and its energy use is only 10 percent that of an ordinary building.

The 3D Wish Tree running through the entire building serves as a tour guide to visitors, showcasing the future urban life Hamburg residents want and the government's response to the wish. Interactive programs give visitors a panoramic view of Hamburg.

Editor: Hu Min