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March 10, 2016

ETFE Football Stadium Will Soon Be Minneapolis Showcase

Originally published on Green Building Elements

When it opens this summer, US Bank Stadium in Minneapolis will feature the only ETFE (ethylene-tetra-fluoro-ethylene) roof on a sports facility in the United States. This resilient and transparent material, long used in Europe, will now provide Minnesota Vikings football fans with a comfortable experience inside the stadium and a clear view outside, even if the outdoor temperature is far below zero degrees Fahrenheit.

us bank stadium logo shutterstock_306699017In contrast to the preponderance of opaque domed stadiums in this country, some 60% of the Vikings’ facility has been covered with ETFE, not only letting in daylight, but allowing fans to gaze skyward and enjoy the view. Add to this, this dramatic stadium features five of the world’s largest operable glass doors, which can be opened if the weather outside is pleasant. These gargantuan doors measure 55 feet in width, angling from 75 feet to 95 feet in height, and weighing approximately 57,000 pounds each. Of note, the large door system also contains five smaller doors which can be used when the large doors re closed due to inclement weather.

Journalists were invited to sample

GRM Vikings ZT__8035As the stadium nears completion, a diverse group of journalists — specializing in everything from architecture to sports — had the opportunity to visit this 1.75 million sq. ft. structure, including 248,000 sq. ft. of ETFE roof, and listen to very articulate presentations from many on the design and development team, including leadership from the Minnesota Vikings.  I found no shortage of good stories to report, most which will follow later this month. Here I report on the old stadium, the new stadium, and this remarkable material, ETFE.

In other stories, I will report about:

  • Sustainability practices in design and construction
  • Strategy behind  this projected $1.1 billion inner-city facility
  • Economic impact & surrounding development
  • This development is a showcase for others to follow

The old stadium model

Minneapolis, known for its very cold winter weather, previously featured the Hubert H. Humphrey Metrodome, built downtown in 1982. It was the ninth oldest stadium in the NFL, featuring a fiberglass fabric roof, self-supported by air pressure. It was the third major sports facility to have this feature (the first two being the Pontiac Silverdome and the Carrier Dome).

vikings metrodome shutterstock_108070454

Preparation for the demolition of the Metrodome began the day after the final home game for the Minnesota Vikings on December 29, 2013. Demolition began January 18, 2014.

For those wanting a glimpse, here is how the roof to the Metrodome came down.

The new stadium model

usbankstadiumOwned by the Minnesota Sports Facilities Authority (MSFA), the multi-purpose US Bank Stadium is scheduled to host Super Bowl LII in 2018 and the NCAA Final Four in 2019. Some leap from the starting line!

Designed by Dallas-based HKS Architects, the US Bank Stadium features the largest transparent ETFE roof in North America, spanning 240,000 square feet. This will be the only stadium in the nation with a clear ETFE roof.

Vikings ETFE & cane IMG_6142Because of the angles of the roof, ETFE material on the south side accounts for 60% of the entire roof, while hard metal deck on the north side will account for the remaining 40%. 

ETFE basics

ETFE is a co-polymer resin which is extruded into a thin film. The light-weight material is transparent but can be treated to be translucent. It is durable and resistant to corrosion. In an architectural application ETFE is typically used in a multi-layer pneumatic system.

Longevity of ETFE

Vikings ETFE IMG_6211

ETFE beginning layer

This material does not degrade with exposure to UV light, atmospheric pollution, harsh chemicals, or extreme temperatures. The material has withstood extensive testing within extreme environments and is expected to have a 30 to 50-year life expectancy, requiring minimal maintenance. Presently, the true life-cycle of ETFE is not known as the oldest applications are just hitting the 30-year mark with little to no replacement of system components.

ETFE weight & strength

us bank stadium 2 Berg-150707-0965Despite its light weight (1/100 the weight of glass) ETFE is reported to handle snow/wind loads well. In sheet form, it can stretch three times its length without losing elasticity. Support rods are used with the stadium roof panels.

Cleaning ETFE

The surface of the foil is non-stick and non-porous, which allows the natural action of rain to clean the surface. Deposits of dirt, dust and debris remain unattached and are washed away in the rain, meaning ETFE effectively self-cleans with virtually no need to clean externally.

As Amy Wilson has written on Architen, “Originally invented by DuPont as an insulation material for the aeronautics industry, ETFE was not initially considered as a main-stream building material, its principle use being as an upgrade for the polythene sheet commonly used for green house polytunnels.

“The advantages of its extraordinary tear resistance, long life and transparency to ultra-violet light off-set the higher initial costs and 20 years later it is still working well. It wasn’t until the early 1980s, when German mechanical engineering student, Stefan Lehnert, investigated it in his quest for new and exciting sail materials, that its use was reconsidered.”

Indeed! Just take a look at this showcase taking place near the Mississippi River.

Images: Metrodome via Shutterstock; usbank stadium sign via Shutterstock; all other images via the Minnesota Vikings

March 4, 2016

International Wastewater Systems: SHARC Recovering Heat From Sewage

Originally published on CleanTechnica

We understand what’s involved in recovering renewable heat from the Earth by deployinggeothermal recovery technologies. Now it’s time to become familiar with another untapped renewable energy resource: wastewater thermal energy.

Sewage happens to be an energy source flowing beneath the surface of almost all modern cities. Not only is it plentiful, it’s free and mostly untapped.

That is, unless you’re Lynn Mueller, CEO of Canada-based International Wastewater Systems (IWS). His company has developed an innovative heat exchange system which recycles heated wastewater and returns it as a heat source.

With a payback that happens over a short time, a growing number of building developers are inquiring after the installation of IWS’s SHARC (sewage heat recovery) and Pirahana systems. IWS offers heat recovery solutions for space and domestic water heating in the winter, as well as for air conditioning systems in summer.

The company also provides engineering assistance, project feasibility assessments, cost estimates, and technical support, as well as third-party energy analysis studies to evaluate the capability of incorporating sewage heat recovery into a project.

“When you think of sewage, you think it’s just a cost for everybody involved to deal with it, but about 30% of the energy in the world ends up going down the sewer pipes every day,” he said in a January 6 interview with MidasLetter. “So our system has developed a cost-effective way to recover that energy. I like to refer to it as the world’s most ultimate renewable energy, because you really use the same energy every day: you use it, it goes down the drain, you recapture it and you use it again.”

This is not a new undertaking for IWS. In 2014, the company announced it had been selected to provide its state-of-the-art sewage heat recovery technology as a component of the Sechelt sewage treatment facility.

At the time, the LEED gold standard Wastewater Treatment Plant was slated to be be the first of its kind in North America. This video shows the SHARC unit being installed at the Sechelt Sewage plant.

Case studies show the SHARC system allows for significant energy and water savings over the life of the plant by recapturing energy that would have otherwise have been wasted and would have just gone down the drain.

About that project, Sechelt Mayor John R. Henderson said, “This will be the largest infrastructure project in the District’s history. The facility will ensure wastewater treatment capacity for Sechelt for the next 20 years (with provision to add capacity incrementally for up to 50 years more!). The facility will meet the highest Provincial standards for water quality, energy efficiency and resource recovery. It will be the first of its kind in North America, giving Sechelt opportunities to demonstrate and market to others.”

How SHARC Works

SHARC Wastewater heat recovery CanyonSpringsWP-960x344IWS’ Sewage SHARC  uses raw sewage as a medium to produce hot water, heat, and cooling for large residential and commercial buildings. The sewage is used before it gets to the plant, with all of the solids removed. It is put through a heat exchanger and utilized to produce 140°F water for domestic potable use.

Mueller said this process is 500% efficient; every dollar spent gets $5 worth of efficiency. The SHARC system will last for about 30 to 40 years, thereby becoming extremely valuable over its lifespan. In fact, he said buildings can recover the money spent on the systems in three to 10 years.

PIRANHA Retrofit System

IWS Pirhana As-featured-in-banner16-copy-960x344-copyIn addition to the SHARC, IWS also offers a retrofit version of the technology known as the PIRANHA. While the SHARC is custom-built or constructed with new buildings, Mueller said the PIRANHA is a prepackaged unit that comes in 50-kw-per-hour and 100-kw-per-hour models. This version can easily be put into a building’s mechanical room and have the sewer line looped into it. Mueller said it was originally produced to help the European market improve its energy footprint by 25 percent, something it legally must do with each update of a building.

Mueller’s background in geothermal heat pump technology helped him understand it was possible to use sewage as a source of energy instead of using holes in the ground. IWS has now been at it for five years and marketing its SHARC product for two. In the last two years, IWS has made installations across three continents—Australia, Europe, and North America.

Current Project: Gateway Theater

Richmond, Vancouver, BC: at the Gateway Theater, a 50,000-sq-ft public facility. The city had a carbon-reduction plan in place and needed to reduce the facility’s emissions by 50 tons per year. It chose to use the SHARC, thus becoming the first wastewater recovery system at a public facility in Canada.

“Levi Higgs, the city’s corporate energy manager, told HPAC Engineering that before adopting the SHARC, the city undertook a couple of studies and found there was a large amount of potential for a heat- recovery system at the Gateway. This was attributed to the large pumping system next to the theater. Mueller made a proposal that Higgs called “very cost competitive,” and the city has seen some great savings since the installation in April 2013.

““Right off the bat, we saw about a 30% reduction in our natural gas use with the SHARC system,” Higgs said. “We did some upgrades at the facility … and those coupled with the SHARC, we were able to push savings to about 45%.””

This YouTube video tour shows some of the Gateway Theater installation.

“We can produce all the domestic hot water without using a gas boiler,” Mueller said to HPAC Engineering. “Cost is comparable to a gas boiler, and it’s more efficient than the best gas boiler on the market. To give you an example, we did a roughly 200-unit building here in Vancouver, B.C. The greenhouse-gas savings amount to about 900 tons of carbon a year, just by cycling that heat from 200 units. We use heat-pump tech to move the heat.”

The infrastructure may be pricey, but the ROI is fabulous.

Images and video via IWS

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