From my experience, when you take a typical wall – vapour barrier (petroleum) impregnated wood (carcinogens), rigid insulation (petroleum), building wrap (petroleum) and gypsum board (carcinogens) – you’ve consumed a ton of BTUs and chemicals to make a rather unhealthy wall. The work of pfeifer_kuhn architekten is grounded in the belief that insulation is not neccesary for functional, comfortable and energy efficient buildings. That the utilization of a handful of effective strategies working in concert results in extremely low-energy architecture. Günter calls this approach das kybernetische prinzip|the Cybernetic Principle:
1. Activated Structures
2. Air Collector
3. Energy Garden
4. Effective Zoning
5. Process Energy]
Thermally coupled walls are not new to architecture – though in recent years there has been a surge in use. Activated structures can be achieved in a number of ways including radiant floors and walls, geothermal loops and hollow structural members. While radiant flooring is fairly common in the U.S., radiant walls are a little less familiar on this side of the Atlantic. By weaving thousands of meters of PEX-like tubing, thick concrete walls can be activated to heat or cool a space. Recent examples include Peter Zumthor’s Kunsthaus Bregenz and SANAA’s Zollverein School. By activating a building’s mass, air ventilation for heating and cooling is significantly reduced or eliminated. Downsized mechanical systems are cheaper to install, operate and maintain – especially if they’re not needed at all. To take advantage of this system, the structural walls and slabs must be exposed – no wall to wall carpets and definitely no ACT, to which most architects are quite agreeable.
If you are familiar with a trombe wall or have sat in a car during summer, you have a basic understanding of an air collector. Glazing encloses an uninsulated solid mass (wood, concrete, masonry) which results in 3-12″ wide micro-greenhouse. In winter, this air cavity is superheated and produces pre-heated air for ventilation. In the summer, vents at the top and bottom of the wall can be opened, inducing stack ventilation to cool the building. Air collectors operate functionally as a double-glazed facade, with the added benefit of heating the uninsulated mass – allowing the designer to take advantage of a massive wall’s thermal lag. Translucent glazing is typically selected as it diffuses solar radiation better than clear glass.
An energy or winter garden is a centrally located, passively heated space within the building envelope. Sunlight warms the energy garden and is absorbed into the building structure. Warm air collected in the energy garden can be vented to cooler spaces within the building. Winter gardens were successfully used as part of the passive heating strategy for Foster’s Commerzbank in Frankfurt. These spaces provide an acoustic buffer to outside noise and also allow natural light to penetrate deep into the building. The three voids on the south facade of the Institut für Umweltmedizin und Krankenhaushygiene are energy gardens. Each void is a large atrium surrounded on three sides by offices. In the summer, these spaces naturally vent the whole building. The IUK operates 70% more efficiently than standard labs.
The correct zoning of functions within a building allows for optimizing of systems. This can be manifested as seldom-used areas being thermally isolated or by grouping functions with a similar heating demand. Also inherent in this is finding the best massing, orientation and positioning of thermal storage walls/slabs within the enevelope. Energy efficient buildings seldom have numerous re-entrant corners, many are boxy, but by utilizing devises such as atria or energy gardens, the form of the building can be simple while allowing a complex plan or section. The project above is the Faller PharmaServiceCenter, a pharmaceutical packaging plant in Binzen, Germany. The grey facade is uninsulated concrete walls around the factory and the light brown facade is uninsulated brettstapel in the administration zone. The wood was utilized for the office as it radiates stored heat energy at a faster rate than concrete or masonry, and has the added effect of a non-offensive pre-finished interior. The factory zone has a primary cooling demand and it was determined that the building could be cooled simply by using the thermal storage of 12″ thick concrete walls to absorb the process energy from the folding machines. The entire facade is wrapped in profilit, creating a luftkollektor. This project exemplifies the kybernetische prinzip – and provides a great model for how incredible industrial architecture should be.
Lighting, appliances, computers and people give off heat. This excess heat can be used to offset heating demands in other locations. Back in 2008, Jernhusen was planning a project to capture the process energy generated by 200,000+ daily passengers at the Stockholm Central Station, in order to heat an adjacent building.
These examples are my recollections and interpretations from working for this firm. Strategies like this involve a lot of coordination and verification through the design and construction phases, but can pay huge dividends in the end. While I haven’t been able to incorporate many of these strategies into projects in the states, it is my desire to see low-tech, sensible and well-designed green buildings here in the northwest.
Also, if any building simulation gurus have found accurate and inexpensive dynamic thermal modeling programs, I’d be interested in hearing about it.