The following research and thesis was presented to the Landscape Architecture Program at Chatham University in partial fulfillment of the requirements for the degree of Master of Landscape Architecture in April 2010. The goal of the study was to support the need to increase the landscape principles that are represented in green building certification. Buildings can be certified by the LEED Rating System and still attain none of the landscape principles deemed necessary to a healthy environment by this research.
Evaluating vegetation, site, and location-related credits achieved by LEED Certified Buildings
The green building movement is one response to the environmental impacts resulting from the built environment; it aims to reduce material consumption and waste, while improving energy efficiency and occupant health. The U.S. Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED) Green Building Rating System has become a base line for sustainable building in the United States.
Though LEED is increasing the number of high performing buildings, thus reducing the energy use and waste production resulting from the built environment, without a stronger focus on the exterior performance these certified buildings may not be providing the urban environment with the ecosystem services necessary for healthy cities. Douglas Farr, author of Sustainable Urbanism, points out that a shortcoming of the LEED Rating System is that the emphasis is put on just the building by stating that “a certified green building isn’t really a positive for the environment when it turns out to be surrounded by a massive paved parking lot” (2008, p. 29).
The thought is that there is little attention paid to site selection, preservation of existing vegetation, or the addition of vegetated area during the design of green buildings. Though the building may be energy efficient or built from recycled steel, the vegetation that was replaced by impervious surfaces represents a loss in ecosystem services and a dependence on the car to get to the building. Commuting by car long distances to a green building is contradictory to the intentions of reducing environmental impact.
Also, vegetation can reduce heating and cooling needs, clean the air, lower ambient temperature, and more (Nowak et al., 2006; Robinette, 1972), but current design practices are to replace these natural systems with mechanical ones. This increased energy and resource use only compounds the negative impacts of the building, though it is considered green.
One reaction to this shortcoming of LEED has been to develop site-related rating systems and principles for the development of healthy cities. Without research defining the lack of focus on vegetation, site, and building location in the LEED Rating System, there is nothing to support the initiatives being taken to create site-specific rating systems and to bring to the forefront the importance of integrating them with the green building movement.
The purpose of this study was to evaluate the role that vegetation, site, and location of the building play in the certification of green buildings in order to support the need for landscape-specific rating systems and their integration with LEED and other green building rating systems. For this study, the term “landscape principles” will refer to vegetation, site, and location characteristics that will be measured.
These landscape principles will specifically represent seven characteristics that represent a healthy urban environment: air quality, water quality and management, microclimate regulation, cultural services, development density, walkability, and transit (Bolund & Hunhammar, 1999; Farr, 2008; Millennium Ecosystem Assessment, 2005). The purpose will be achieved by determining if LEED certified buildings have met these landscape principles and are thus maintaining urban ecosystem services.
Quantitative measures were used to measure each landscape principle. LEED certified buildings were scored based on these Quantitative Measures of Landscape Principles (QMLPs) to determine how many high performing buildings, though certified as green buildings, are actually contributing to maintaining a healthy environment.
Seven out of the 12 QMLPs were measured using data from LEED certification, which provided data that would not be otherwise available. The five remaining QMLPs were derived from best practices and represent landscape principles that should be considered in green building design. The LEED credits were recorded as achieved or not achieved, while the additional QMLPs had values associated with their achievement, of which the calculations are described in the methods section. The results were aggregated in a table summarizing the QMLPs achieved by each building and within which category they fall. Also, a profile was created for each building in the sample summarizing the data collected and the QMLPs achieved by each building.
Total number of QMLPs achieved per building was calculated (Figure 4-1). Of the entire study sample, one building achieved zero of the QMLPs and no building achieved all 12 QMLPs. The most QMLPs achieved was ten, and this was accomplished by only four buildings.
The four buildings that attained the most QMLPs were LEED gold or certified buildings. No LEED platinum level buildings, the highest possible level in the LEED Rating System, attained the highest QMLP attainment level. Therefore, the data were analyzed based on their LEED certification levels to determine any correlations between LEED certification level and QMLP attainment level.
In general, the buildings sampled did not consider landscape principles to become certified as green buildings. The research determined an average score of 5 QMLPs for the sample. This is low and implies that landscape principles are not an important aspect of green building design. This is not unexpected, as anecdotal evidence has stated that vegetation, site, and location-related credits are lacking from the LEED Rating System. The general lack of consideration of landscape principles inspired further investigation into the results to see if there were any connections between LEED rating level and the number of QMLPs achieved, or if the measures used to determine the QMLP score impacted the results.
The data does support this relationship, but at a very low significance. When the LEED rating was compared to QMLP scores, a relationship was found, but the lack of this being a significant relationship means that this relationship will not be true the majority of the time. Therefore, this relationship cannot be used as a predictor. A building’s LEED certification level will not predict its QMLP score the majority of the time.
The research indicates and supports the need to integrate the principles of landscape-specific rating systems (such as SITES®) into LEED and other green building guidelines. Buildings can be certified by the LEED Rating System and still attain none of the landscape principles deemed necessary to a healthy environment by this study. Most recently the Green Business Certification Inc. (GBCI) has launched the Sustainable Sites Initiative™ (SITES) as the first rating system available (SITES v2) for public use to pursue certification of sustainable landscapes.
For the thesis in full, please visit to access the pdf: http://library.chatham.edu:80/record=b1116132~S0
By Deborah Steinberg, ASLA, LEED AP, Director of Sustainability Initiatives, Knox College. Research and thesis presented to the Landscape Architecture Program in partial fulfillment of the requirements for the degree of Master of Landscape Architecture – April 2010.
- Bolund, P., & Hunhammar, S. (1999). Ecosystem services in urban areas. Ecological Economics, 29(2), 293-301.
- Farr, D. (2008). Sustainable Urbanism: Urban Design with Nature. Hoboken, NJ: John Wiley & Sons, Inc.
- Millennium Ecosystem Assessment. (2005). Ecosystems and Human Well-Being: Synthesis. Washington,DC: Island Press.
- Nowak, D. J., Crane, D. E., & Stevens, J. C. (2006). Air pollution removal by urban trees and shrubs in the United States. Urban Forestry and Urban Greening, 4, 115-123.
- Robinette, G. O. (1972). Plants / People / and Environmental Quality. Washington DC: U.S. Department of the Interior.