LEED Certification - An Insight with Perspective

Certification Systems
The established certification systems BREEAM, DGNB and LEED evaluate the ecological, economic, and social aspects of buildings. Each system focuses on these aspects by weighting their predetermined criteria differently. They take the entire building life-cycle into account, from the design and construction phase to building operation and demolition. Meanwhile, these systems offer the possibility of certifying a wide spectrum of occupancy profiles, such as schools, hospitals, hotels, retail, etc. The systems enable the comparison of buildings in accordance with each system's specific requirements and can be applied to new construction, existing buildings, or tenant fit-outs.

The Green Building Certification Systems use minimum requirements and target values to describe the desired quality of the building features in regard to sustainability and to define the building at an early stage.

On the one hand, the systems function as tools to determine the overall building quality and on the other hand, they help the investor and his partners to find alternatives in the decision-making process. At the same time, new operational processes, design techniques and documentation requirements have to be implemented in the integral design approach required by these systems. New professions such as auditor, sustainability manager or environmental consultant, who guide the project team throughout the entire process and who provide the project team with information about all the requirements, have to be integrated into the project. Additional services and documentation, e.g. origin of materials, building simulation, life-cycle analysis, etc., as well as commissioning management, have to be provided and documented continuously.

LEED
The certification systems are voluntary in nature and are mostly based on the country-specific standards and regulations of each individual system. Thus, the American certification system LEED (Leadership in Energy and Environmental Design), by the US Green Building Council, predominantly applies the ASHRAE standards (American Society of Heating, Refrigerating and Air Conditioning Engineers) to evaluate the technical systems of the building. Since October 2011, Alternative Compliance Paths (ACPs) are available for international projects, which allow the use of local standards, as long as it can be proven that the requirements of these standards are equal or higher than those of the US standard.

Certification systems are increasingly used at an international level. In the commercial building sector, LEED is the system with the highest market penetration. Today, more than 10,500 buildings worldwide have been certified under the LEED standard and 32,000 are in the process of being certified. In regard to gross floor area, more than 40% of the projects are outside the US. The system's flexibility regarding its application to different occupancy types, an extensive marketing approach, as well as the system's adaptation to mandatory requirements by city, state and federal authorities in the US and countries worldwide have contributed to the high usage of LEED. Over the past three years, a multitude of buildings have also been awarded with LEED certifications in Germany. There are various reasons to motivate building owners and developers to certify their buildings with an internationally established system. One is that it allows the comparison of buildings across borders. Other reasons are international corporations which have a general policy that requires the certification of their properties or for inclusion in sustainable real estate funds. A final reason is tenant demand for certified buildings.

      40-49 zertifiziert     -     50-59 Silber     -       60-79 Gold     -    80-110 Platin
Figure 1: LEED Certification Label
Point requirements for the LEED Certification Levels
Source: USGBC

Beginning with "certified" as the lowest level up to "platinum" as the highest rating for a building, LEED consists of four different certification levels, which are determined by the sum of the individual points. The highest amount of points possible is 110. Of these 110 points, 100 can be achieved with the fulfillment of the Credits in the categories (displayed in Figure 3). An additional six points can be achieved in the category Innovation in Design and four in the category Regional Priority.

Prerequisites
A special characteristic of LEED are the "Prerequisites." They are minimum requirements, e.g. for the reduction of pollution from construction activities, water efficiency, protection of the building users against hazardous cigarette smoke, consideration of recycling possibilities in the waste concept or even requirements for outdoor air supply. No points are awarded for these minimum requirements, but without fulfilling all prerequisites no certification of any level can be achieved. That is why it is so important to implement these prerequisites into the design process early on and to adjust the construction processes accordingly and document implemented measures, e.g. dust prevention during demolition work. The weighting of the individual categories is already relatively equally distributed in the 2009 version, with a focus on Energy & Atmosphere and Sustainable Sites. The point allocation will be even more equally distributed in the new 2012 version.

Figue 2: Increase in the Number of Categories and Adjustment of the Point Allocation in the Rating System LEED BD&C ( Building, Design & Construction) for New Construction, Renovations, Schools, Health Care System, Retail
Source: EB

The certification systems are continuously improved and adjusted to new market developments and construction standards, both regarding requirements and target values, as well as the further development of the spectrum of user profiles. This is done to ensure advancement in technical development in order to continuously improve the quality of buildings and their sustainability aspects. The new version of LEED, which is supposed to be introduced after the 3rd public comment round and final ballot in the 4th quarter of 2012, reflects that strategy. The number of categories will be extended to include Location and Transportation, Performance, and Integrated Process. For some credits, the threshold and target values have been increased significantly in the 2012 version, in reference to current standards. This is especially the case for the evaluation of the energy efficiency, which is based on the latest version of ASHRAE 90.1-2010. The new requirements are approx. 30% higher compared to the previous version from 2007. The number of minimum requirements has been increased from 8 to 15, both by converting existing credits to Prerequisites in 2012 and through new, additional requirements, e.g., requirements for metering the water and energy usage for the building.

The total number of criteria is reduced, but at the same time, there are 17 new criteria in the LEED 2012 version.

Figure 3 The "Prerequisites" in LEED 2012 for the Rating System LEED BD&C (Building, Design & Construction) for New Construction, Renovations, Schools, Health Care System, Retail
Source: EB

Outlook
The further development of the USGBC's LEED systems towards a LEED 2012 version, leads to an extensive adjustment of the existing system structure as well as the individual requirements. The system is reacting to developments in society as well as technical progress. This again results in the creation of new design options regarding used products and materials, but also new design tools and methods such as simulation tools, or integrated design processes such as BIM (Building Information Modeling) or Cx (Commissioning).

For further Information please contact the authors:
Thilo Ebert
Ebert-Ingenieure München
eMail: t.ebert@eb-ing.com
Jochen Schäfer
Ebert & Baumann Consulting Engineers Inc., Washington D.C.
eMail: j.schaefer@eb-engineers.com
Heike Schlappa
web: www.eb-ing.com

U.S. Green Building Coucil
web: www.usgbc.org/LEED