Drieklimatenkas (Three-Climate Greenhouse), Hortus Botanicus Amsterdam

The Hortus Botanicus Amsterdam dates from 1638 and already had a major historic glasshouse, the Palmenkas of 1912. To house plants from different climates it added a modern greenhouse, completed in 1993. The commission went to Moshé Zwarts and Rein Jansma of Zwarts & Jansma, who had just designed the Dutch contribution to Expo '92. The building cost 2.5 million guilders and was financed through the foundation then running the Hortus on an interim basis, with contributions from the City of Amsterdam, the university and the Friends of the Hortus.

An opening by Queen Beatrix planned for 25 August 1993 was called off because of a dispute over VAT. The greenhouse nonetheless served for more than thirty years before a thorough renovation was undertaken. The works, led by the same practice, now called ZJA, began in February 2024 and kept the building closed for over fifteen months. Visitors returned on 2 June 2025, and the official opening took place on 10 September 2025 as part of Amsterdam's 750th anniversary. The Arcam architecture guide dates the renovation to 2020, which probably refers to the start of the design work rather than to construction.

The greenhouse covers about 1,500 m² and, according to the Arcam architecture centre, ranges from four to eleven metres in height; the Dutch Wikipedia article gives fourteen metres at its highest point. Its polygonal plan and stepped roof planes, which fall from the tall glazed wall along the Nieuwe Herengracht towards the garden, give it an outline that recalls a Bedouin tent.

The structure rests on a slender primary steel frame laid out in two main directions, part of which stands outside the envelope like an exoskeleton. Beams and cables carry the roof loads, reducing the number of columns and leaving wide spans inside. The secondary framework uses cheaper standard components from commercial production greenhouses. During the renovation the original steel was kept, the single-glazed façades were replaced with insulating double glazing and the roof was re-covered with triple-layer ETFE air cushions. The house is heated without gas through a heat-and-cold link with the H'ART Museum, and rainwater is collected for reuse.

Originally, glass partitions separated three climates: subtropical, tropical and desert. The 2024–2025 renovation reorganised the building into three parts: tropical forest, desert and a new section devoted to the Cape region of South Africa.

The interior layout was entrusted to the landscape architects of BOOM Landscape and the studio Designwolf. The refreshed tropical zone has an upper walkway that lets visitors look down into the canopy and a six-metre waterfall built from recycled Amsterdam roof tiles. The desert regains its familiar red wall. The Cape room, spacious and sunny, holds what the Hortus describes as the first and most extensive collection of South African plants in the Netherlands, illustrating the richness of a biodiversity hotspot. The overall aim is to show how plants have adapted to a climate and fit into an ecosystem.

The greenhouse stands on the north side of the Hortus Botanicus in the Plantage district, about a hundred metres from the 1912 Palmenkas, so a walk through the garden moves from an Amsterdam School glasshouse to late-twentieth-century architecture. Allow at least an hour for the three climates, the tropical walkway and the garden's other glasshouses, including the butterfly house and the orangery. In cold weather the Cape section offers a bright contrast to the humid tropics. The H'ART Museum, the Hortus's energy partner, is close by, as is the Wertheimpark.