A brace of curious Teutonic names come with the new HQ for supplier of portable measuring technology Testo, on the banks of the Germany’s Titisee, designed by Sacker Architects with A Henne Ch Korn. Testo wanted the building to blend into its Black Forest surroundings with high thermal efficiency. The architect went to cladding firm Wicona to develop the L-shaped glazed units that overlap and widen at the top to create its distinctive, sculptural facade, combined with horizontal bands of smooth limestone. The system has both fixed glazing and concealed vents and was all constructed off-site to ensure quality and save time. External slatted blinds reduce solar gain, and where triple glazing has been installed, U-values are as low as 1.3W/m2K.