(abridged version Bonas Essay) L.J. Heijdenrijk (1932-1999) The work of Leonardus Justinus Heijdenrijk, which was always produced in collaboration with his closest colleagues, can be placed primarily in the tradition of the Dutch structuralists whose work was initiated by the philosophies of Aldo van Eijck. The new ideas were expressed in the Forum volumes around 1960 and are characterized by the search for an expandable structure based on a geometric grid of cells. The emerging demand for flexibility and possible expandability gave rise to expressive, spatial clusters. This offered a counterpart to the autonomous building with fixed building lines and unbroken facades. The clusters are based on the repetition of certain spatial units. Heijdenrijk's housing plans were also influenced by the ideas of N.J. Habraken from the SAR (Stichting Architecten Research). Habraken developed foundations for the construction of so-called carrier housing in which the housing unit is divided into a structural carrier with basic facilities and into a variable built-in package tailored to the occupant. His ideas, like the philosophies of Van Eijck, arose from dissatisfaction with the impersonal housing of the post-war period. The aim was to relate housing construction to the residents again, so that they could influence and identify with their own home and living environment. Another great source of inspiration for Heijdenrijk was the modern De Stijl artist Piet Mondrian. Not only did he show this in his own use of color, he also devoted himself to the establishment and operation of the Mondrian House in Amersfoort. He applied Mondrian's use of color and abstract compositions in various projects such as Het Nieuwe Lloyd in Amsterdam. Heijdenrijk studied architecture at TH Delft and immediately after his graduation in 1961 came to work at the office of ir. G.J. van der Grinten in Amersfoort. A few years later he and Van der Grinten formed the Maatschap voor Architectuur en Stedebouw, and from 1970 the firm was called Environmental Design. The management expanded, first with L. Manche and with Wim Raven, then with Stemerding and with Jansen. The firm focused, as the name implies, not only on architecture but also on urban and office districts or traffic intersections that together define the human living and working environment. The sustainable handling of materials that the firm pursued was exemplified, among other things, with the commissioning of the 18th century, vacant Elleboogkerk in Amersfoort. In 1984 the firm split and Heijdenrijk, Manche and Raven worked together for a few more months. Then in the same year the Stichting Architecten Kollektief Heijdenrijk was founded by the triumvirate of Heijdenrijk, Hans Hermes and Wim de Lange. Hermes (b. 1940) had been trained at the Academy of Fine Arts in The Hague as an interior designer. He also took part of the course at the Academy of Architecture in Amsterdam. De Lange (1938), after completing HTS, trained as an architect at the Academy of Architecture in Arnhem. The three architects worked in self-constructed national monuments in Amersfoort such as the Elleboogkerk and the Aardappelpakhuis De Nieuwe Beelding. Three years after Heijdenrijk's death, Hermes and De Lange retired and the collective disbanded in 2002. The firms' commission portfolio is remarkably rich and includes many building types. Various forms of school construction have been realized such as elementary school, secondary schools and complexes for TU Twente and for the Agricultural College in Wageningen. The collective also contributed to the development of church construction with modern church buildings in Swalmen and in Eindhoven. With the construction of residential complexes such as the experimental district Sterrenburg III in Dordrecht, the residential mound Apenrots in the Haagse Beemden in Breda and the various dwellings in the Kattenbroek district in Amersfoort, the bureua has been able to realize striking housing. The oeuvre also includes such diverse commissions as a test farm in Lelystad, a social employment facility in Amersfoort, juvenile prisons in Amsterdam and in Nijmegen, and numerous competition entries, the most famous of which was for Amsterdam's Town Hall in 1967. Participation in this competition brought Heijdenrijk international publicity because he was selected out of eight hundred entries to participate in the subsequent closed competition with seven candidates. This subsequently earned him third prize while Viennese W. Holzbauer received first prize. Heijdenrijk's design involved a structuralist plan based on the repetition of a small, square module into a large whole. The town hall complex was conceived as a small city in which the council chamber was the center. The building height varied so that a varied, expressive roofline would emerge. In addition to private housing construction, Heijdenrijk and Van der Grinten worked in the early period on several low, modern church buildings in which in each case the churchgoers were placed around the centrally positioned altar. Both in Venlo, Leersum, Swalmen, Amsterdam-Noord and Eindhoven, the churches have a more or less square plan with a flat roof or with a pent roof. Housing Heijdenrijk took an idealistic stance particularly in the field of house building, which, like his contemporaries Jan Verhoeven, H. Klunder and Witstok, emphatically opposed the contemporary way of building that had arisen in the preceding reconstruction period. The main criticism was that the builders had a poor understanding of the living ambitions of the (future) residents. The endless rows of dwellings built from the ground up, along with the accompanying living environment, only met the actual living requirements to a limited extent. The municipality provided traditional zoning plans that often already included streets, blocks of houses and the other facilities, so that the integral coherence was lacking. However, because there was a housing shortage for a long time, the houses, good or bad, were involved anyway and discontent revealed itself unclearly. In Amersfoort, at the initiative of the then alderman Fons Asselbergs, the Kattenbroek neighborhood was built in the late 1980s on the basis of an urban plan by Ashok Balotra. This surprising residential district is distinguished by the unusual housing and by the parcellation in which poetic metaphors were decisive. The aim was to build cheaply and at the same time provide good architectural quality. Heijdenrijk is one of the architects who were allowed to build houses there. Most famous are the ruined houses on Autumn Square where the standard shells are wrapped in an irregular masonry facade with crumbly edges of dark brown brick. School building The buildings of the TH Twente were designed by several architects based on an overall plan by Van Embden and Van Tijen. Heijdenrijk cs were commissioned to design the Complex for Applied Mathematics and the Computing Center (1973), a major task that allowed the firm to distinguish itself pre-eminently. The building is constructed with a basic cluster that is linked in various ways to create four parallel strips. Between these are larger spaces with computer and lecture rooms. In 1990, the new administrative center for the Agricultural University in Wageningen was completed to Heijdenrijk's design. Here, two corridor buildings were placed parallel with a large, high semi-public meeting space between them under a glass roof. The elevator and air bridges to the corridors hang in this void, giving the hall a dynamic character. In addition to numerous articles in professional journals, ED and Kollektief Heijdenrijk issued two self-published books titled Environmental Design (1974) and Houses within Own Skin (1998). These books show and briefly describe a variety of projects. Education: TH Delft/-1961