Building façade Save energy thanks to plasterwork

Almost nothing is impossible: the latest trends in façade technology.

by Jürg Zulliger 10 Nov 2015
Recycled material, solar panels, wood: multifunctionality is in demand in façade technology. Photo: Luca Schenardi.

Navy blue, frog green and orange instead of gray, beige and white: colorful highlights have become fashionable in architecture over the past few years. The new desire for color began on doors and windows, and soon spread to entire façades. Benedict Loderer, architect and founder of the magazine Hochparterre, is critical of this development. A “bunch of colorful M & Ms” won’t make architecture successful. Shades of color should be harmonized. He maintains that there is no contemporary color palette, just fashionable colors “used by bad architects for creative convenience.”

In fact, a façade must be more than esthetic: it has functions to fulfill, like withstanding the weather and protecting against condensation, mold and algae. And a façade’s energy impact is increasingly important today, in particular for thermal insulation and solar energy. Architects align façades to the sun and integrate additional panels and collectors. These either produce electricity directly (photovoltaic panels) or are used to heat water (solar thermal collectors).

A world first in Brütten

A project that unites design and functionality is currently being built in Brütten by building contractor Walter Schmid AG for the Umwelt Arena Spreitenbach. It’s the world’s first energy self-sufficient apartment building. The new construction has a strikingly unusual façade, with its surface and roof covered by high-quality, non-reflective photovoltaic panels. Cedar loggias and window frames provide an optical contrast.

The façade converts sunlight into electricity, which is stored and reused directly on site using the latest technology. “It influences the appearance of the building, offers weather protection, and provides energy as well,” explains the architect René Schmid. One hour of sunshine a day should be enough to secure the building’s energy needs for 24 hours. The nine-apartment building requires no electricity or other external energy sources. The apartments are scheduled for occupancy in early summer 2016.

Colored solar collectors

Such advances are only possible now that research and mass production are making photovoltaic panels cheaper and more efficient. Mass-produced panels are only slightly more expensive than the modern laminated glass often used in construction. But does the technology limit an architect’s creative freedom? Not any more. The colored solar collectors made by Doma Solartechnik, a subsidiary of Ernst Schweizer AG in Hedingen, for example, offer many new opportunities. Made in four basic colors, they permit stylish designs over large areas. Doma’s headquarters in Satteins, Austria, meets all its energy needs using self-generated, renewable energy, and was awarded the European Solar Prize.

The Doma collectors come in a variety of designs and can be manufactured in different sizes. So façades and roofs no longer cause heat loss in the winter, but make a significant contribution to the production of solar energy. “The larger a building’s surface area, the more efficient and cost-effective it is,” explains Xavier Breitenmoser, solar façade product manager at Ernst Schweizer AG. The industry has made significant progress in recent years in being able to supply color photovoltaic panels as well. Developers and architects must weigh up costs, efficiency and esthetics.

Neuchâtel – key center of photovoltaics

As a general rule, panels with lighter shades tend to be more expensive than standard products and generate less energy than darker colors. “As long as the difference amounts to only a few percent, most architects find this choice acceptable,” says Breitenmoser. Experts speak about building-integrated panels, which is an area researchers are working on intensively now. Neuchâtel is a key center: the EPFL photovoltaic lab and the Centre Suisse d’Electronique et de Microtechnique (CSEM) are located here. Both are leaders in the field.

Crystals control energy balance

An innovation by architect Dietrich Schwarz sounds like something from the future: the GLASSX technology largely initiated by him integrates crystal-like materials into façades or glass, benefitting the building’s energy balance. Depending on the temperature at day or night, the crystals melt or solidify, and either absorb or release heat during these phase transitions. Thanks to this, technology planners can now contain the problem of overheating typical in modern glass houses better than in the past. For example, GLASSX technology was used at Neugrün, Canton Aargau, Switzerland’s largest timber-frame residential estate. In winter, crystals in the façade help save some 10 to 15 percent of heating energy.

This Swiss innovation has made the leap from research to practice. “Externally the building components look like translucent glass elements. They can be used for larger as well as smaller buildings,” says Martin Schröcker of GLASSX. Solar products make many things possible that recently looked like science fiction. Research is taking place on new technologies to cover roads, parking lots and public spaces with photovoltaic systems. This would not only improve sustainability and energy efficiency, but also help to create shade, such as for parking lots.

The new flexibility when it comes to color lets collectors blend harmoniously into the townscape. Green panels would no longer be recognizable as such in a public park. Alongside a dynamic future for the solar industry, home design also has many more options now.

One-fifth of the building

The façade determines the look of a building and protects it from the weather and heat loss. Thermal insulation thresholds have been set down in law for new-builds and façade renovations. Tip: more elaborate constructions often pay off provided building work is carried out carefully. A “back-ventilated façade,” for instance, separates the insulating materials from the outer cladding. This helps save energy. For a single family home, the wall construction – including external cladding – makes up around 20 to 25 percent of the overall building costs.

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