Inventive elements conserve energy, exude lightness

by Christopher Brinckerhoff | November 1, 2019 12:00 am

Naturally Ventilated Façades

In relation to climate façades, those on the Amvest building have an uncommon feature; they are naturally ventilated. Like other climate façades, they have an outer layer of glass, interstitial space and inner, double-layer of glass. But, instead of mechanically ventilating the interstitial space, New York City-based Rietveld Architects LLP[1] designed them to ventilate naturally with open bottoms and tops with adjustable aluminum lids.

Rijk Rietveld, partner at Rietveld Architects, says, “If it’s really warm outside, then temperature sensors open the lids on top, and then the air, by its natural heating up, rises. The hotter it gets, the more speed it takes to get out of that space, and it doesn’t heat up so much the inner façade. In the reverse, in the winter, when the sun is not so hot, the lids close completely and the space between the outer fa­çade and the inner façade warms up. Then the façade works as a radiator; how cool is that?”

Aluminum for the climate façade lids, curtainwalls and curtainwall fins was supplied, fabricated and installed by De Groot en Visser BV in Gorinchem, the Netherlands[2]. De Groot en Visser also supplied and installed the glazing.

Chain Mail Curtains

Another way the climate façades conserve energy is by blocking sunlight with chain mail curtains. When the sun is shining on the east façade in the morning, the curtains on that side, triggered by light sensors, close and block 42 percent of the light from the inner, double-layer of glass. In the evening, the reverse happens and the curtains slide across the west side and close. De Groot en Visser supplied and installed the chain mail curtains.

In terms of its minimal building footprint, the Amvest building has five floors with 20,000 square feet contained in a 45-foot by 135-foot space. At ground level, underneath the building, there is space for foot traffic circulation. Furthermore, the building sits along the shore of the Entrepothaven Entrepot Harbor, where it cantilevers 50 feet over the water’s edge.

Structural Trees

To pull off the minimal footprint, Rietveld Architects developed a design with structural support provided by four primary structural steel columns. They are angled to the north and south of the building and are somewhat shaped like trees. The columns begin with a large trunk at the base of the building made of 1 1/2-inch-thick plate steel. As they go further up the building, they branch out into two, and then again four, angled branches. At the top of the building, the columns transition into smaller branches that are strengthened with metal webs in between them.

From the fourth floor of the building, which is supported by the structural steel tree columns, the structural load transfers down the sides of the building via structural steel window frames. Every 9 feet, the steel frames hang from the fourth floor down to support the third floor.

“The steel trees hold up the main roof, and everything is hung from that,” Rietveld says. “In a traditional building, they would have to have a much bigger building for the amount of people in there [80 to 100 people]. Those steel trees also contribute to the building’s lightness. Because there are only four trees in the whole building and the rest of the building hangs from the façade, you see no columns. There’s no concrete in it, and that’s the nice part; it makes it all very light. Also, it feels like there’s no effort in it.”

See-through Staircases

Another deft design move that contributes to the buildings’ minimal footprint and contemporary lightness and openness occurs at a central chamber of staircases, where occupants can see through parts of the building and outside. Fire partitions surrounding three, side-by-side, triple scissor staircases are made from five-layer, fire-rated glass. The transparent stairwells traverse four floors and continue to the top of a raised roof above the fourth floor.

But Rietveld Architects’ inventive design presented a potential problem. In the event of a fire, the structural steel tension rods hanging from the fifth floor supporting the staircases would expand so much that the glass firewalls would crack. Rietveld Architects’ solution was to use a heavy specialty steel, called Invar steel, for the tension rods. Invar steel expands/contracts minuscule amounts, at rates not close to those of conventional structural steel. Structural steel and Invar steel was supplied and installed by Moeskops Staalbouw BV in Bergeijk in the Netherlands[3].

Solar and Geo-storage

The building uses small amounts of power from utilities; some of its power comes from solar arrays on top of the owner’s apartment buildings to the north and east of it. All of the buildings have green roofs to reduce solar heat gain. Additionally, they are interconnected with underground pipes in a geo-storage system that maintains cold and hot temperature pockets 300 feet below the surface in a network of locations, and re-circulates the cold and hot air back into the buildings in opposite seasons.

Development-wide Design

Rietveld said the overall design concept for the headquarters matched that of the whole development, Cruquius Eiland, which includes the office building, four apartment buildings, and plans for eight more buildings. Rietveld Architects designed two of the completed apartment buildings as well.

“The expression is all about lightness,” Rietveld says. “We wanted to give the office building a feeling that it can overcome gravity. The apartment buildings have glazed white brick, so they really connect to the office building. It’s sort of a white village with a lot of glass.”

Source URL: https://www.metalarchitecture.com/articles/inventive-elements-conserve-energy-exude-lightness/

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