The Grid: LITERALLY

The Expo Haarlemmermeer conventional hall was built in 2002 for the Floriade, a massive horticultural exhibition held every ten years in the Netherlands. At 19,000 panels and nearly 30,000 square meters, it may still hold the record as the largest photovoltaic roof in the world. Whether actually the largest or not, the 2.3 MWp installation is certainly among the most interesting. The building was a turnkey project built by Siemens AG and implements a wide range of their solar power technologies. The design is simple, rational, efficient, adaptable, and without attitude: except maybe the decision to paint the superstructure yellow – a clear take on the ‘electric grid’ - get it? Yeah. A project overview from Siemens can be found here: www.pvresources.com/en/top50pv/floriade.pdf.

Today, the building is used as an expo and convention hall. When I visited, it was the site of a huge French-themed flea market complete with accordion players, cancan girls (a suitable-for-all-ages version) and decidedly non-French concession stands selling herring, oliebollen (Dutch donuts), and vlaamse frites (Flemish fries). The near two hundred vendors sold vases and porcelain figures (mostly not fit for the curio-cabinet), stamped brass ashtrays, clothes, old tools, and broken electronics. I added to the milieu as the crazy man staring in wonder at the ceiling...

The objects of my fascination were the photovoltaic panels twenty-five feet overhead. The key idea here is that the glass and polymer laminate solar panels actually are the building envelope, not simply external attachments or embellishments over a conventional roof structure. The panels are also semi-transparent, admitting 17.5% of available light into the exhibition space, which turns out to be more than enough for good visibility. The space doesn’t feel dark at all. For it’s massive size, it’s a very lightweight structure and the thinness of the supporting columns is very impressive. It was also quite comfortable inside the building compared with the cool Fall weather outside. 

The building has an interesting relationship with the surrounding landscape design. A rolling ground plain comes in under the building canopy, creating an intermediate condition for half the building as a sheltered terrain. People can both walk and drive in and out of the space.  The overlapping and blending of architectonic and topographic conditions demonstrates a Dutch attitude toward ecological context as an equally malleable component of the human-fabricated environment. The lightness of the building’s literal footprint draws a clear parallel to the lightness of its ecological footprint.

One of the clear goals of the project was to limit construction costs to a bare minimum and to develop a system for rapid assembly. For this reason, the project employs an almost “off the shelf” constructional approach using existing greenhouse technology. Large-scale greenhouses have a long tradition in the flower and vegetable growing industry of Holland and so it was natural to adapt the form for this purpose. The project integrates a new level of technological innovation and performativity with existing construction methods and standard materials. The project is groundbreaking yet shows the synergy possible in layering new technologies and design ideas upon existing precedents.

 The decision to place panels in peaked-ridges allowed for the greatest density of collection surface on the roof relative to structural integrity and lightness, but also presented challenges. In short, the output of a directly linked solar assembly is limited by the output of its weakest performer. In the afternoon, most of the power is generated by the panels that face west: if the east and west were linked up in the same circuit, the east facing panels, with less sun exposure, would be a drag on the performance of the west facing panels. Instead, the two halves are fed separately through their own inverters, which convert the direct current generated by the panels into alternating current used by the grid, and then to separate transformers, which ramp up the voltage to grid standards. The result is a system where each sub-component operates at it’s own maximum efficiency throughout the day without draining the other. Building tectonics and the engineering of photovoltaic systems have to be closely coordinated: they interlock and inform each other.

Should this project even be in the Netherlands? It’s routinely cloudy here throughout the year, the high latitude makes for lower intensity light, and the days are quite short in winter. Yes, this is true: certainly a place with more sun would have profited far more from the investment. Not every Dutch building will be a photovoltaic building in the future. Obviously, the photovoltaic industry has not reached grid-parity in energy production costs, and it is clearly more cost effective to use wind power for electricity in the Netherlands. Still, the building is proof of the strong commitment made by the Dutch to explore and implement a huge range of new technologies in design: something we can all profit by.

This kind of meta-structure and the environmental relationship it fosters has wide-ranging potential. Distribution centers, malls, and big-box retail are all conventional ideas that can be redefined. The Wal-mart of the future will be an amazing place. Further afield, the canopy system could define a new type of development – mixed-used urban places for living, light industry, and manufacturing powered by intrinsic energy sources. We could throw this idea at Arizona and southern California. It could be used in extreme desert environments to create performative shading structures: modern-day caravanserai, deployed as nodes of activity on the suburban plains. The possibilities are pretty exciting. As technologies improve, the aspect of the roof can change (perhaps to an ETFE canopy with imbedded thin-film solar), and the program below can be imbued with greater programmatic complexity. Whatever the future holds, at Haarlemmermeer, a precedent is successfully established.