Feed Laws

Vertical Axis Wind Turbines

September 9, 2013
Paul Gipe

Questionable Turbines and Siting Give Architects, LEED, Green Builders, and Wind Bad Name

It’s not bad enough that we have the Koch brothers and their sycophants on an anti-renewables rampage, or the administration touting a “100-year supply of natural gas”, that we need purported “green” wind turbine manufacturers snookering architects into throwing up poorly designed wind turbines willy-nilly—some of which will use more energy than they produce.

With “friends” like these, who needs enemies.

The problem came to a head last year when the Distributed Wind Energy Association (DWEA) formally asked the U.S. Green Building Council to amend its flawed scoring system for “on-site” renewables. DWEA has yet to receive a response.

In the meantime, vendors continue to peddle uncertified wind turbines for roof top installation to architects who don’t do sufficient due diligence on the products before applying them to the LEED rating system.


Leadership in Energy and Environmental Design (LEED) is a rating system by the U.S. Green Building Council (USGBC) designed to reward architects, builders, and owners for integrating energy efficiency and “green” practices into new and existing structures. The rating system has been in use for more than a decade and has gone through several iterations.

Nearly everyone agrees that LEED and USGBC have pushed the boundaries of what is a well-designed and energy efficient building in North America. Criticism of the system has focused on the ability of architects and builders to game the system, maximizing LEED points while not necessarily meeting the intent of designing and building for maximum energy efficiency and comfort.

The Problem

Architects, and even some renewable energy advocates, argue that LEED’s purpose for including renewable energy in the scoring system was as much about educating the building industry and the public on how renewables can be integrated into design and construction as about actual performance. Some have suggested that because wind turbines are highly visible and kinetic, they are a better educational tool than solar photovoltaic (solar PV) panels that just sit there quietly doing their job.

And therein lies the problem.

Few in the wind industry would complain about LEED if vendors, architects, and builders would simply not call these whirling devices wind turbines but something more descriptive of their actual function: whirligigs, doo-dads, or decorative arts come to mind.

The purpose of a wind turbine is to make electricity in a cost-effective and environmentally sound manner. Poorly sited and poorly performing wind turbines installed on or close to buildings generate little or no electricity in comparison to properly sited wind turbines.

Non-operating or poorly performing wind turbines mounted on a building like so much architectural ornamentation are a costly and counterproductive form of greenwashing.

Poorly performing wind turbines violate the public’s reasonable expectation that wind turbines deliver on the green energy hype used in promoting a building design. Worse, such installations play into the hands of renewables’ enemies who love nothing better than to point out when a wind turbine doesn’t deliver on its promoter’s promise.

The LEED Rating System

USGBC’s LEED rating system encompasses many building types and both new and old construction. There are several categories of construction projects that might include renewable sources of generation.

The category for new construction and major renovation includes New Construction and Major Renovations, Schools, Healthcare, Retail, and Homes.

There is also a category for Core and Shell Construction. Many commercial real estate developers only build the core and shell of a building. Future tenants then determine the design and construction of the interiors to suit their needs.

There are five categories in the principal LEED rating system: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, and Indoor Environmental Quality. Each category has a different weighting with a total of 100 points in the rating system. To qualify for LEED Platinum a building must win more than 80 points.

To encourage the use of renewable energy, LEED points are awarded for both renewable energy used on-site and for off-site purchase of Renewable Energy Certificates (RECs). One of the most glaring flaws in the existing LEED system is that no LEED points are awarded for generating renewable energy off-site.

This omission severely restricts what architects and building owners can do to responsibly develop renewable energy. RECs date from a time, decades ago, when there was little opportunity to develop renewable energy locally or even regionally. In those dark days, to use renewable energy you had to buy it from some distant project, often owned by a utility company or its unregulated subsidiary.

Thus, USGBC currently limits architects and builders to either installing solar photovoltaics or wind turbines on-site—and often this means on the building—or participate in what some critics decry as a sham transaction to buy their green energy credentials with RECs and green tags.

Worse, the current LEED weighting system awards far more points for on-site renewable energy than for buying RECs relative to the amount of renewable energy needed.

 Projects can win up to six LEED points with on-site renewable energy in an existing building by meeting only 12% of the load. To win as many points with RECs, the project would have to buy 100% of its energy from an off-site green producer.

Under LEED’s Core & Shell Rating Systems a project can win 4 points if it meets 1% of the buildings load with on-site renewable energy.

Fortunately, USGBC has recently approved changes to this provision, granting only 1 point for meeting 1% of the building’s load, and granting up to 3 points for meeting 5% of the load. That’s not the only change underway. USGBC has also adopted changes to how points are awarded for new construction as well. Equally significant, USGBC’s changes, which take effect this fall, remove the distinction between on-site and off-site generation, allowing the use of generation from community-owned projects and leased equipment. To qualify, the renewable generation must be in the same utility service area, and the ownership or lease must be for a period of 10 years.

These are significant changes, a long time coming, and may signal that USGBC is serious about addressing abuses.

Examples of Abuse

There are several examples of promoters exploiting the existing LEED system to sell their wares. One is Wind Sphere.

Wind Sphere

This wind turbine is promoted by the same company that previously touted its “wind cube”. As late as 2012 the company was advertising its outrageously expensive Diffuser Augmented Wind Turbine (DAWT) as a means to win up to 8 LEED points.

The vendor says that the wind turbine alone costs $150,000 to $225,000. Installation is extra! This puts the Wind Sphere in the range of $13,000 per kilowatt of installed capacity—five to six times more than a commercial wind turbine, and twice as much as most small wind turbines. Despite this, the vendor says the turbine will pay for itself in three years because federal subsidies will allow building owners to write off 50% of the cost and win LEED points besides.

While the specifications on the Wind Sphere are not as outlandish as on their previous Wind Cube, they remain wide of the mainstream, to say the least.

To my knowledge, no Wind Cube or Wind Sphere has ever been installed on a building that has used it to win LEED points. Nevertheless, it is using the LEED rating system to hype its overpriced product.

Urban Green Energy

Another firm exploiting LEED is Urban Green Energy (UGE), an importer of Chinese-made Vertical Axis Wind Turbines (VAWTs). The company promotes using its turbine for “buildings seeking certification under the LEED 2009 for Core & Shell Rating Systems.” They go on to note that “UGE wind turbines contribute toward satisfying EA Credit 2 On-Site Renewable Energy.”

UGE is probably most well known for installing fourteen turbines on the Philadelphia Eagles’ stadium at Lincoln Field. While the stadium is not LEED certified, the architects and the team are promoting the installation as “the gold standard in stadium greening.”

One writer characterized UGE’s wind turbines as mere “eye candy,” while the solar panels were the “workhorses” of the installation. She went on to quote Eagles president Don Smolenski saying, the turbines are “a visual representation of our commitment to sustainable efforts.”

These statements imply that UGE’s VAWTs were installed on the stadium more for their visual statement than for the energy they would produce.

Venger DNA

It’s one thing if the flamboyant owner of a football team wants to tout his green credentials, but it’s an entirely different matter if a medical research center—dependent upon public donations—installs 18 Savonius rotors because they look like a double-helix.

18 Venger V2, Oklahoma Medical Research Foundation’s (OMRF), Oklahoma City, Oklahoma.

Little substantive information is available on Venger’s installation atop the Oklahoma Medical Research Foundation’s (OMRF) new building in Oklahoma City. The reputed $1 million project was made possible by a grant from the McAlester-based Puterbaugh Foundation—money that could have been spent on either real wind turbines generating a significant amount of electricity or on much needed medical research.

The building won LEED gold for its efforts. The foundation considers the un-certified turbines “the crown jewel of the environmental features” of the new edifice. Ironically, the exact same wording was used by the Nature Conservancy at its LEED Platinum building in Indianapolis, Indiana that features three Savonius rotors.

Venger is one of two spinoffs from the defunct Helix wind turbine company of San Diego, California. The company says the turbines at OMRF will produce 85,500 kWh per year. While the projected generation is optimistic it remains well within reason. In a world where most VAWT suppliers grossly overestimate how much electricity they will produce, Venger’s estimate is quite modest.

Unfortunately, the turbines are very expensive—if the reputed cost of the project is to be believed. The turbines cost $12,000 per kW of installed capacity: five to six times that of modern commercial wind turbines and twice what most small wind turbines cost. And this is assuming we use Venger’s rating of the turbine at 4.5 kW at a wind speed of 20.5 m/s.

Small wind turbines certified in the US by the Small Wind Certification Council are rated at 11 m/s. At a wind speed of 11 m/s Venger’s V2 is claimed by the company to produce less than 1 kW.

If we rated the Venger V2 at a more reasonable power output, the relative cost of the turbine jumps to an incredible $45,000 per kW. That’s 20 times what a commercial turbine would cost or 10 times that of typical small wind turbines per unit of rated capacity.

Using another metric, the cost of the Venger V2 is $12 per kWh of annual generation. The cost of modern commercial wind turbines, in contrast, averages about $1 per kWh.

The Venger V2 may—and this is the operative word—generate electricity that costs 12 times what a commercial wind turbine could produce it for. Or it may not. If the turbines don’t perform well, the cost of course will be much higher.

Ouch! That’s an awful lot to pay for “ornamentation” in the shape of a double-helix.


However, it is the defunct Windspire that most fully exploited the LEED rating system and took greenwashing to new levels. It’s as if Windspire’s entire marketing effort was built around gaming LEED. From Adobe Systems, to Keep Indianapolis Beautiful, to the San Francisco Public Utility Commission, architects and building owners touted their poorly sited Windspire turbines—and their LEED Platinum ratings--in the same breath.

Such flagrant exploitation of the LEED rating system should serve as a wake-up call to both the USGBC and those responsible for choosing these ill-considered installations. Far less money could have been spent to achieve the same or better energy benefits.

There are some positive exceptions, but they are few and far between.

Apogee Stadium—A Positive Example

Architects and designers are capable of using wind energy effectively. The installation of three of Northern Power’s 100 kW turbine at a new football stadium for the University of North Texas in Denton is an example of how wind can be used successfully as part of a LEED project.

The school won LEED Platinum for its Apogee Stadium where the turbines are not installed on the building but instead stand well exposed in the parking lot surrounding the stadium.

Better yet, the installation features wind turbines with a proven track record. The 21-meter diameter wind turbines are not classified as “small” by international standards and, consequently, they are not certified by the Small Wind Certification Council. Nevertheless, the turbines conform to international standards for commercial wind turbines and there are numerous installations in the US, Canada, and Britain for which there are reliable production figures.

Combined, the three turbines are expected to generate 450,000 kWh per year. This is equivalent to ~400 kWh/m2 of rotor swept area, an industry metric of performance, and a reasonable amount to expect from a wind turbine of this size in this location.

Contrast the expected performance of the three NPS 100 turbines at Apogee Stadium with the claims from Wind Sphere and Venger. Wind Sphere touts performance of nearly 800 kWh/m2 and Venger says its V2 turbines in Oklahoma City will deliver 770 kWh/m2. Both are twice what could be reasonably expected at windy site like that in Texas. These numbers are simply not credible.

While the NPS 100 turbines, at $6,700 per kW, are more than twice as expensive as commercial wind turbines today, they remain half that of the Wind Sphere and Venger turbines.

For the reported $1 million spent by OMRC, the facility could have installed 1.5 NPS 100 turbines on the grounds or in a parking lot, generating as much as 200,000 kWh per year or at least twice what Venger’s V2s are expected to produce.

Unfortunately, the NPS 100 doesn’t look like a double helix. It looks like a wind turbine.

Simple Solutions Await Action

DWEA suggested in its letter to USGBC that at a minimum, LEED only award points for wind turbines certified by the Small Wind Certification Council. This would go a long way in eliminating the use of untested wind turbines. Currently there are only five small wind turbines certified in the US. All are conventional horizontal axis wind turbines. There are no VAWTs or DAWTs that currently meet certification requirements.

DWEA also recommended that LEED only award points for wind turbines that are sited to the industry’s best practice. For a small wind turbine, best practice is to install the wind turbine so that the bottom of the rotor is at least 30 feet above all obstructions within 500 feet. This is extremely difficult to do with VAWTs.

The USGBC should also implement its new scoring system for renewable energy generation as soon as possible. They should also implement, as soon as possible, the proposed changes allowing expanded off-site use of renewable energy, such as from community-owned wind turbines. These wind turbines can then be sited to best advantage, benefitting the building owner, the community, and the LEED rating system.

It’s time that USGBC adapt LEED to offer rewards commensurate with the benefits of well-sited, cost-effective wind energy. Let’s hope that USGBC promptly takes action.

More on wind and LEED.


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