Michele Jagtenberg woont sinds half september op de Krakeelhof (Jacoba van Beierenlaan). Ze is net begonnen met luchtvaart- & ruimtevaarttechniek, is lid geworden bij Virgiel en viert komend weekend haar achttiende verjaardag.

Ze is HJ, net als bijna de helft van het huis. Acht van de achttien bewoners zijn namelijk nieuw. In dit huis zijn er dan ook geen speciale taken weggelegd voor HJ’s.


Professor Michiel Haas’ company is currently housed in a wooden barrack with single pane windows in a forest near Naarden. The large white villa that housed Haas’ consultancy company, Nibe (Netherlands Institute for Building biology and Ecology), burned to the ground last year and the new building – seemingly very esthetic and ecologic at the same time – is still under construction. Meanwhile Haas, casually dressed in jeans and a blue sweater, keeps his chin up and patiently explains what the environmental load of buildings is all about.

A poster on the wall, dedicated to the environmental index, claims: ‘One number says it all’. To make the index more tangible, the poster lists about twenty buildings with indexes varying from 143 to 819. The higher the index, so much better the building. The index partially corresponds with intuition. The winner thus far has a score of 323; it’s an office for Rijkswaterstaat in Terneuzen, built with a wooden skeleton and using recycled wood on the facade, with plenty of solar panels on the roof. That sounds more ecological than Amsterdam’s unemployment office housed in a renovated school and monastery, a spacious ensemble but hard to heat, whose index ranks a mere 143.

Currently, Haas says, 83 percent of a building’s environmental load consists of energy use, 16 percent of materials and 1 percent of water usage and pollution. Haas expects that with a greening of energy in the next fifteen to twenty years, the material share in the environmental load of buildings will increase to 48 percent: “Materials are our next problem after energy.”
Haas, who lectures on sustainable materials at the faculty of Civil Engineering and Goesciences, founded the basis for the environmental index with his thesis in 1997. With it, he had designed a method to bring all environmental impacts of building materials under a common denominator. “For each material we calculate the total life cycle analysis, from the winning to the final product. We include the environmental impacts of production, installation, use, waste and recycling.” As an illustration, a table on insulation materials shows that sheep’s wool has the lowest environmental cost and polyurethane foam the highest. Haas and his coworkers at Nibe published four handbooks of sustainable building products on different building materials: construction materials, installations, facades & roofs, and finishing materials.
Alas, the books are not yet a common sight on builders’ desks. Haas thinks that contractors are not very interested because they assume that sustainable buildings are more expensive. “That is an absolute fallacy,” he says. “The initial costs may be higher, but the exploitation costs are much lower because of the lower energy use.”

But things are starting to change now that the government has set a lower limit for sustainable procurement of 200 for the index of new buildings in 2010.
The environmental index is the quotient of the so-called hidden environmental costs or ‘shadow costs’ of a similar building built with 1990 technology and the environmental costs of a building or a plan under study multiplied by hundred. In other words: a building with an environmental index of 200 has half the ecological impact of what a similar building in 1990 would have had. Hidden environmental costs are the theoretical costs one would need to reach ecological neutrality.

Striving for half the ecological impact within a generation, as the Brundtland report (1987) proposes, in the perspective of a doubling of the world population and a five-fold increase in wealth, implies decreasing the environmental impact by a factor of twenty, or striving for an environmental index of 2,000.

According to Haas, the maximal attainable index is currently about 1,000 to 1,500. For further improvement other building materials and practices will need to be developed.
That is where TU Delft comes in. Haas would like to start a sustainable building laboratory on the campus that functions both as a showcase for sustainable developments and as a lab where measurements over longer periods of time can be performed. The ‘black box’ near the faculty of Architecture would have been suitable, but it too went up in flames a couple of months ago. 

Editor Redactie

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