From February 17-26, visitors strolling through Fort Mason Center, on San Francisco’s north shore, were likely to happen upon a conspicuously out-of-place structure. Nestled between two historic pier warehouses, was the Das Haus (“The House”) pavilion, a traveling exhibition showcasing some of Germany’s cutting-edge clean energy and green building technologies.
The *Das Haus tour is presented by the German Chamber Network as part of the German government's Renewable Energy and Energy Efficiency Export Initiatives. At a presentation I attended on February 23, Meredith Marsh, the Das Haus project coordinator, said the pavilion was inspired by Germany’s winning entries in the 2007 and 2009 Solar Decathlon, a competition sponsored by the U.S. Department of Energy.
“Following the back-to-back wins,” Marsh said, “the German government decided to have the pavilion designed as a way to showcase and promote the different technologies, and have it be able to travel more efficiently and faster than the solar-powered houses for the Solar Decathlon competition, which actually are full, operating solar homes.”
Manfred Hegger, an architect and faculty adviser to the two Solar Decathlon student teams from Germany’s Technical University Darmstadt, designed the Das Haus pavilion with his wife, Doris Hegger-Luhnen, and their firm Hegger + Hegger + Schleiff.
The Das Haus tour launched in Atlanta, in October 2011, and visits New York City (July 10-19) and Washington, D.C. (July 31-August 9) this summer before wrapping up in Denver, in October. The exhibition will make 10-day stops in 12 cities in the United States and Canada over 13 months.
Here are some highlights of the clean energy and green building technologies on display at the exhibition:
Thin-film solar panels and smart solar controls system:
The pavilion is outfitted with thin-film CIS (copper-indium-selenide) photovoltaic (PV) panels on the roof, façade, and louvered panel systems. Thin-film panels were selected, Marsh explained on a tour of the pavilion, because they are better able to harvest diffuse light and can operate at higher temperatures than traditional monocrystalline PV panels.
Electricity generated by the rooftop panels and the solar-paneled louvers enters the solar controls systems as DC (direct current) and charges a bank of lead-acid batteries. Electricity produced by the modules on the façade is converted to AC (alternating current) by the inverter for use by the LED lighting, a laptop computer, and other features in the exhibit.
Passive house standard enclosed room:
Much of the Das Haus pavilion is an open-air exhibition. However, a small enclosed room (probably best avoided by the claustrophobic) is built to the exacting passive house standard – defined by super-insulated, well-ventilated yet airtight construction. The voids between the windows’ triple panes are insulated by Argon 90 gas; cork-insulated oak frames secure the glass. A low-emissivity coating lets in ambient light while blocking heat. The door, outfitted with three layers of weather stripping, was substantial and dense – pulling it shut felt like sealing a castle door.
A heat-recovery ventilator (HRV) ensures that the room maintains a relatively constant, comfortable temperature. An intake duct on the roof draws in fresh air; exhaust air is expelled by a vent in the floor. Before heat from the exhaust airstream can escape to the outside, it is captured by the HRV and used to pre-heat incoming fresh air.
LED lighting systems and high-efficiency appliances:
Lighting in the pavilion is provided by solar-powered light-emitting diodes (LEDs). Motion-activated LED fixtures in the enclosed room ensure that lights don’t shine when the room is unoccupied. The enclosed room’s small kitchen is equipped with a high-efficiency coffee maker and refrigerator.
Valve-regulated lead-acid (VRLA) battery system:
The pavilion’s VRLA batteries are designed to interact with solar systems, as explained by the Das Haus self-guided tour (PDF):
Their gel electrolyte allows hydrogen and oxygen to recombine into water during charging, eliminating the need for periodic water refilling as with traditional flooded cell batteries. The battery’s closed system is virtually maintenance free and safely diffuses and releases excess gas in the event of an overcharge, reducing overall room ventilation requirements. Gel technology batteries are also more robust, offering greater resistance to extreme temperatures, shock and vibration, and can be installed either vertically or horizontally without the risk of leaking electrolyte.
Advanced insulation methods:
An interactive exhibit within the pavilion displays cross-sections of several advanced wall construction and insulation methods [see p. 1 of the Das Haus self-guided tour (PDF)]. The thin walls of the pavilion’s enclosed room, for instance, use vacuum-insulated panels (VIPs) – a reflective foil membrane encases a rigid, clay-based core in a near-vacuum space. Marsh conceded that the VIP system is more expensive at the outset. Installers must be careful, she noted, not to puncture the foil membrane, which would compromise the panel’s performance. But the upfront cost is outweighed by superior performance and niche applications, from a placard at the exhibit:
By limiting the transfer of heat with a vacuum system, VIPs are up to ten times more efficient than traditional insulation types, yet are up to ten times thinner. They are ideal when space saving is essential and high performance is desired, such as interior retrofits and historic building facades for which exterior insulation would compromise the aesthetic integrity of architectural elements.
*Note: The Das Haus pavilion presentation and tour took place on February 23 after “The Net-Zero House – Propelling Green Building Concepts into Mainstream,” a half-day conference hosted by the German American Chamber of Commerce. I shared highlights of the conference in a post published on February 28.
