Monday, June 30, 2008

Guest Column--Overview of LEED and Green Globes Rating System

By: Margaret McInerney

Overview

As the green building market increases, a growing number of states, cities and municipalities have passed green building legislation. The level of enforcement and certification varies greatly, but most green building legislation references a green building rating system. The two most common green building rating systems in the United States are the Leadership in Energy and Environmental Design (LEED) Green Building Rating SystemTM from United States Green Building CouncilTM (USGBC) and the Green GlobesTM rating system from the Green Building InitiativeTM (GBI).

Both rating systems aim to improve the built environment and emphasize design and construction practices that reduce energy consumption and water use, improve indoor air quality and minimize the impact on the natural environment. These rating systems have many similarities but a few key differences. Both LEED and Green Globes rating systems are structured similarly by awarding four levels of certification and focusing on common aspects of green building design. The LEED rating system is more expensive, but has a more balanced and comprehensive structure. On the other hand, Green Globes is user-friendly and emphasizes unique green building practices. It does not, however, necessarily demand the best green building practices.

Green building policy leaders argue over the extent of these differences when determining the appropriate rating system to reference in green building legislation. There was a recent budget debate in Virginia over whether the Green Globes rating systems should be referenced as an acceptable green building rating system in addition to the LEED rating system.
It should be noted the comparisons in this article consider USGBC’s LEED for New Construction version 2.2 (LEED-NCv.2.2) rating system and GBI’s Commercial Green Building Green Globes v.1 rating system. A new version of the LEED rating system (LEED 2009 or LEED v.3) was released for public comment in May 2008. The requirements of the LEED 2009 rating system are not considered in this article unless noted.

Brief History of Green Building Rating Systems

The first environmental certification system was created in 1990 in the United Kingdom, called the Building Research Establishment Environmental Assessment Method (BREEAM). In 1998, the USGBC introduced the LEED green building rating system, based substantially on the BREEAM rating system. The Green Globes rating system was adapted from the Canadian version of BREEAM and was released by the Green Building Initiative in 2005. There are many other available rating systems worldwide. However, LEED and Green Globes are the most common in the United States.

Today, USGBC has rating systems for new construction, existing buildings, core and shell, commercial interiors, homes, schools, retail, healthcare and neighborhood development. GBI has a rating system for commercial buildings which includes new construction buildings and existing buildings. In addition, GBI partners with the National Association of Home Builders to promote green homes.

LEED and Green Globes Similarities

The LEED and Green Globes rating systems are very similar in structure. Both systems have four levels of achievement. LEED projects can achieve the following four certifications (1) certified, (2) silver, (3) gold or (4) platinum. Similarly, Green Globes projects can achieve either 1, 2, 3, or 4 globes. Both LEED and Green Globes share a common set of green building design practices. There are six focus areas for LEED and seven for Green Globes, but the focus areas are similar in many respects as shown below.


LEED-NCv2.2 [1]
Sustainable sites (14 Points, 20%)
Water efficiency (5 Pts, 7%)
Energy and atmosphere (17 Pts, 25%)
Materials and resources (13 Pts, 19%)
Indoor environmental quality (15 Pts, 22%)
Innovation and Design (5 Pts, 7%)

GREEN GLOBES v.1 [2]
Site (115 Pts, 11.5%)
Water (100 Pts, 10%)
Energy (360 Pts, 36%)
Resources (100 Pts, 10%)
Indoor environment (200 Pts, 20%)
Emissions, effluents and other impacts (75 Pts, 7.5%)
Project management (50 Pts, 5%)
[1] The United States Green Building Council, www.usgbc.org.
[2] The Green Building Initiative, www.thegbi.org.

Both LEED and Green Globes place an emphasis on energy use. Of the sixty-nine allowable points for LEED, twenty-five percent can be achieved for advanced energy practices and thirty-six percent of the one thousand allowable points for Green Globes can be achieved in the energy category. The common energy criteria for LEED and Green Globes are building energy consumption, proper installation of energy efficient technologies, and on-site renewable energy resources.

The LEED rating system has a balanced point distribution, with four out of the six categories contributing about twenty to twenty-five percent of the potential points. While Green Globes emphasizes energy (over a third of the potential points), site and material resources only account for approximately ten percent of the rating system. This is a potential weakness in the Green Globes system. While reducing a building’s energy consumption is very important, a certified green building should not be constructed without significant consideration to its site and surrounding area.

LEED and Green Globes Differences

The two main criticisms of early versions of LEED were that it was too complex and too expensive. When USGBC first introduced the LEED rating system, the application for certification was long and complicated. All certification forms had to be submitted by mail. This was a contrast to Green Globes’s user-friendly online certification process that any building team member could complete. The newer versions of the LEED rating system are online; however, the rating system is still complicated and each building team member is responsible for different documentation. LEED registration and certification are still more expensive than Green Globes. LEED registration costs approximately $900-$3000 and certification costs approximately $1,875 to $20,000. Green Globes offers a preliminary self-assessment for $500 dollars and the certification is around $3,000-$6,000.

Another criticism of the LEED rating system is that LEED-NCv2.2 does not address life-cycle analysis. Life cycle analysis (LCA) assesses the complete impact of a building on the environment. LCA analyzes a building’s construction materials from pre-manufacturing to post-consumption. For example, the LCA of a building’s insulation would consider the manufacturer’s location, the resources needed to make the insulation and the disposal/recycling of the insulation when the building is torn down. In the current LEED rating system two buildings could achieve a sliver certification, but have very different impacts on the environment when considering life cycle analysis. USGBC has recognized this deficiency and addresses LCA in its latest rating system, LEED 2009. Green Globes incorporates a life-cycle analysis in its current rating system.
The main criticism of Green Globes is that it does not require a minimum performance level. Therefore it is relatively easy to attain the one globe certification level (350 points out of 1000 points). In contrast, LEED requires minimum performance levels in energy use, erosion control, and indoor air quality. For example, LEED requires that all certified projects create an Erosion and Sedimentation Control Plan. Since this plan is required it does not earn any certification points. However, Green Globes awards nine points for a similar erosion control plan. Green Globes does award points for specific best practices that are unique to its rating systems such as, integrating pest management, composting organic waste, monitoring carbon monoxide, and maintaining acoustic comfort.

Another significant difference between the two rating systems is their energy performance measurements. Most LEED certified projects measure energy performance against the ASHRAE/IESNA Standard 90.1-2004 which sets a baseline for building energy performance. LEED points are awarded if the building reduces energy consumption 20% to 60% compared to the standard’s baseline. However, Green Globes projects are awarded points for scores of 75 or better from the Environmental Protection Agency (EPA) Energy Performance Rating. EPA’s rating system compares the project to other similar buildings nationwide. For example, a score of 75 in the EPA Energy Performance Rating system means that the project performs better than 75% of the buildings in the U.S.

Builders have different views which rating system most effectively measures energy performance. The ASHRAE 90.1 standard is the industry accepted standard for building performance. Based on performance modeling, LEED certified buildings save approximately 25-35% on average compared to the ASHRAE 90.1 baseline standard. However, there is still a discrepancy between predicted-modeled energy performance and actual-design energy performance. While some buildings perform better than modeled a significant number perform worse. A number of LEED certified buildings do not meet the Green Globes standard of 75 from the EPA Energy Performance Rating system. In contrast, the EPA Energy Performance Rating system only awards certification to the top twenty-five percent of buildings and does not set a minimum performance level or a baseline for improvement. By using the EPA Energy Performance Rating system, Green Globes is not providing incentives to improve the performance of buildings each year.

Conclusion

The USGBC’s LEED rating system and the GBI’s Green Globes rating system have some differences. However, they share a common core of green building design practices. Both rating systems offer unique benefits and promote good building practices. Referencing the LEED rating system in government legislation will ensure minimum energy performance, good construction practices, reasonable indoor air quality, and basic building commissioning. However, for legislation to completely disregard the Green Globes rating system would ignore a number of good building practices, such as using the EPA Energy Star Performance rating system and having a user-friendly, less expensive incentive for building green. Governments should adopt strong green building legislation that encourages the best green building practices and it may be premature to limit green building certification to only one rating system.

Margaret McInerney is a LEED® Accredited Profession and is a graduate of the University of Virginia School of Engineering and Applied Science. She currently is a Senior Energy Consultant at Navigant Consulting Inc. in Washington, DC. The views expressed in this article are those of the author only and not those of any other company or organization.

2 comments:

Mark Rossolo said...

This is a great article Margaret, thanks for shedding some light on this issue. My name is Mark Rossolo and, as the director of state and local outreach for the Green Building Initiative, I regularly participate in these type of debates at the state and local level. We whole-heartedly agree with your position that governments should adopt strong green building legislative initiatives which allow for more than one rating system as we believe credible options are necessary to encourage mainstream design and building professionals to implement sustainable building practices on a more regular basis.

I also wanted to point out to you and your readers that we’ve recently taken steps to address some of the concerns you raised about Green Globes as part of the process to establish our rating system as the first American National Standard for commercial green buildings.

As part of ANSI’s established standards development process, the proposed standard version of Green Globes would require the achievement of a minimum number of points in each of the system’s seven areas of assessment. In addition, the system also features an energy section whereby CO2 equivalency is used as the basis for calculating the energy performance path. The standard, which we hope to finalize later this year, will also feature new calculators for both life cycle assessment and water consumption.

At the GBI, we always look for opportunities to improve and feedback like yours is taken very seriously as we continue our efforts to offer the best green building resources available. I'd encourage you and any of your readers to view the proposed standard version of Green Globes or to take a free trial of our Green Globes New Construction and Continual Improvement of Existing Building modules by visiting www.thegbi.org. Thanks again for your comments!

BlogMonkey said...

Margaret,

Wonderful article, and one of the few cogent explanations I've found on the pros and cons of LEED v. Green Globes.

My own experience with LEED (almost impossible) in existing home renovation/restoration has certainly convinced me another standard was needed!

.//A.

http://greeninharlem.com