New report by the US Green Building Council covers the impact of LEED and green practices
The U.S. Green Building Council has released its LEED in Motion: Venues report, which highlights the efforts of convention centers, sports venues, performing arts centers, community centers and public assembly spaces to transform their environmental, social and economic footprint through LEED certification. The report showcases some of the most impressive green venues around the world.
“The scope and scale of the venues industry is enormous, and the leaders creating these spaces have an important role to play in reducing environmental impact,” said Mahesh Ramanujam, president & CEO of USGBC. “By incorporating green practices, venues around the world are positively impacting their triple bottom line – people, planet, profit – while inspiring and educating others to be proactive in the areas of social responsibility and sustainability.”
Venues are large contributors to the U.S. economy. The U.S. Bureau of Labor Statistics reports that the number of conventions and events is expected to expand by 44 percent from 2010 to 2020 – far outpacing the average projected growth of other industries. Annually, the top 200 stadiums in the U.S. alone draw roughly 181 million visitors, and roughly 60 million people worldwide attend a consumer or industry trade show. Waste Management estimates that the NFL, MLB, NBA and NHL generate a combined 35,000 metric tons of CO2 each year from their fans’ waste. The convention and trade show industry, one of the largest global contributors to waste, produces an estimated 60,000 tons of garbage each year.
Venues that incorporate LEED (Leadership in Energy and Environmental Design), the world’s most widely used green building rating system, into their buildings enjoy increased cost-savings, decreased annual operating costs and a higher return on investment overall. According to the 2015 Green Building Economic Impact Study, from 2015-2018, it is estimated that LEED-certified buildings in the U.S. will have saved more than $2.1 billion in combined energy, water, maintenance and waste savings.
The report highlights the green strategies and savings of more than 30 LEED-certified venues across the globe, including Orlando Magic’s Amway Center, the first NBA arena to earn LEED Gold certification using the LEED Building Design Construction: New Construction rating system, was able to save nearly a million a year, including close to $700,000 in annual energy costs alone because of LEED certification.
At one of the most renowned regional theaters in the country, The Old Globe’s 108,000 square foot complex in San Diego, green strategies were implemented so as not to disrupt the buildings’ aesthetics and primary focus on performance. Low-flow fixtures and aerators reduced overall water usage by 32 percent, LED retrofits and timer installations resulted in savings of more than 14,000 kilowatt hours per year, and an increase of recycling bins and staff education created the potential for more waste diversion.
Another prominent example is Shanghai 2010 Expo Center’s implementation of sustainable strategies such as a vegetable roof garden, rainwater recycling system, LED lighting, water source heat pumps, high-efficiency water-use fittings and irrigation, which resulted in the project achieving 82.5 percent annual total water savings and a 93 percent reduction in storm water runoff volume.
LEED is used in more than 164 countries and territories with international demand continuing to grow. According to the Dodge Data & Analytics World Green Building Trends 2016 SmartMarket Report, global green building continues to double every three years. In the next ten years, green building’s growth rate is expected to continue at both the domestic and international levels. USGBC’s recent Green Building Economic Impact Study analyzed the economic impact of green construction on the U.S. economy and found that LEED-certified buildings account for 40 percent of the green construction market’s contribution to the U.S. GDP in 2015. The report also projected that by 2018, green construction will account for more than 3.3 million jobs and generate $190.3 billion in labor earnings in the U.S.
LEED is a simple and effective program for navigating complex, sometimes competing, building and environmental issues affecting humans worldwide. Every day, more than 2.2 million square feet of space certifies to LEED. There are more than 36,300 LEED-certified commercial projects representing more than 5.4 billion square feet of certified space and an additional 53,180 projects, totaling 11.6 billion square feet of registered space.
LEED in Motion: Venues is the latest in a series of reports from USGBC designed to provide a holistic snapshot of the green building movement. The report equips green building advocates with the insight and perspective to understand the use of the globally recognized LEED rating system and to make a strong case for sustainable building activity.
Read the January 2017 issue of Construction Global here
Why engineers must always consider human-induced vibration
Human induced vibration, or more accurately vibrations caused by human footfall, often conjures images of Millennium Bridge-style swaying or collapsing buildings.
But in reality, the ‘damage’ caused by human-induced vibrations is less likely to ruin a structure and more likely to cause discomfort in people. Though not as dramatic as a structural failure, any good engineer wants to make sure the people using their structures, be it bridges or buildings or anything in between, can do so safely and comfortably. This is why human-induced vibration must be considered within the design process.
Resonance v Impulse
There are two ways that human-induced vibrations affect structures: resonant, and impulse or transient response. Put simply, resonance occurs when Object A vibrates at the same natural frequency as Object B.
Object B resonates and begins to vibrate too. Think singing to break a wine glass! Although the person singing isn’t touching the glass, the vibrations of their voice are resonating with the glass’s natural frequency, causing this vibration to get stronger and stronger and eventually, break the glass. In the case of a structure, resonance occurs when the pedestrian’s feet land in time with the vibration.
On the other hand, impulse or transient vibration responses can be a problem on structures where its natural frequencies are too high for resonance to occur, such as where the structure is light or stiff. Here the discomfort is caused by the initial “bounce” of the structure caused by the footstep and is a concern on light or stiff structures.
Engineers must, of course, design to reduce the vibration effects caused by either impulse or resonance.
Potential impacts from human induced vibration
Human induced vibration can lead to a number of effects upon the structure and its users. These include:
- Interfering with sensitive equipment Depending on the building’s purpose, what it houses can be affected by the vibrations of people using the building. Universities and laboratories, for example, may have sensitive equipment whose accuracy and performance could be damaged by vibrations. Even in ordinary offices the footfall vibration can wobble computer screens, upsetting the workers.
- Swaying bridges One of the most famous examples of human-induced resonance impacting a structure occurred with the Millennium Bridge. As people walked across the bridge, the footsteps caused the bridge to sway, and everybody had to walk in time with the sway because it was difficult not to. Thankfully, this feedback can only occur with horizontal vibrations so building floors are safe from it, but footbridges need careful checking to prevent it.
- Human discomfort According to research, vibrations in buildings and structures can cause depression and even motion sickness in inhabitants. Tall buildings sway in the wind and footsteps can be felt, even subconsciously by the occupants. It has been argued that modern efficient designs featuring thinner floor slabs and wider spacing in column design mean that these new builds are not as effective at dampening vibrations as older buildings are.
- Jeopardising structural integrity The build-up of constant vibrations on a structure can, eventually, lead to structural integrity being compromised. A worse-case scenario would be the complete collapse of the structure and is the reason some bridges insist that marching troops break step before crossing. Crowds jumping in time to music or in response to a goal in a stadium are also dynamic loads that might damage an under-designed structure.
How to avoid it
As mentioned, modern designs that favour thinner slabs and wider column spacing are particularly susceptible to all forms of vibration, human-induced or otherwise, but short spans can also suffer due to their low mass. Using sophisticated structural engineering software is an effective method for engineers to test for and mitigate footfall and other vibrations at the design stage.