Rooftop Vegetation: An Opportunity to Influence Green Buildings via Prevention through Design Michael Behm East Carolina University Science and Technology Building, Suite 100 Greenville, NC USA PH: (252) 329-9674 behmm@ecu.edu Abstract: Vegetated roofs are becoming increasingly popular in the United States due to their environmental benefits and their ability to earn credits in the green building certification process. With the exception of one international guideline, we find little mention of safety and health in green roofs codes and literature. Field investigations of nineteen vegetated roofs in the United States revealed unsafe access for workers and equipment, a lack of fall protection measures, and other site specific hazards. Prevention through Design strategies and the integration of life cycle safety thinking with green building credits systems are seen as methods to reduce risk to workers on vegetated roofs. Additionally, and more importantly for the larger safe green jobs initiative, safe designed vegetated roofs serve as a means to demonstrate the synergies between green building elements and worker safety that can serve as a foundation for future integration. Ongoing research and recommendations for future research are described. Keywords: Safe design, vegetated roof, green roof. 1. Introduction Vegetated roofs are recognized by urban planners as an advantageous technique for providing thermal insulation, reducing the urban heat island effect, improving storm water retention, increasing natural habitat, enhancing air quality, and providing an aesthetically pleasing environment for building occupants. The use of these architectural techniques presents potential hazards to workers involved in installation and maintenance. The hazards are not new, but there is an increased frequency of roof access required to maintain vegetated roofs compared to a conventional roof. Moreover, the integration of worker safety into green building features complements a recent National Institute for Occupational Safety and Health (NIOSH) Safe Green Jobs campaign (Schulte et al, 2010). The green movement is an entry point for new sustainable ideas (including worker safety) which can trickle down to all industries or become standard practice as has been seen by many green ideas. Green and sustainable construction practices do not currently include safe design as a method to enhance the safety record of an industry that employs 7% of the United States workforce but yet accounts for close to 20% of its fatalities.
This paper proposes that worker safety on vegetated roofs can be enhanced through Prevention through Design (PtD) techniques and offers suggestions for further research. This conference proceeding reports on 1) a search for safety and health issues associated with vegetated roofing, 2) a review of green roof codes for safe design specifications, and 3) field investigations of nineteen vegetated roof projects and the observed safety issues that could be eliminated or reduced through PtD suggestions. The growing interest in the use of vegetated roofs means that their design and maintenance have to be investigated more thoroughly in order to determine the sustainability of such systems (Emilsson et al, 2007). Dvorak and Volder (2010) concluded that as North American green roofs continue to become regulated and adopted in policy, further development of standards and guidelines are needed. Worker safety can continue to be an afterthought or the design community can embrace best practices, such as PtD, to be incorporated into these new ideas, guidelines, and standards. This paper will add to the body of knowledge by documenting what is known about the safe design of vegetated roofs in order to make recommendations for future guidance, research, and application. 2. Literature Review A comprehensive literature review was completed to determine if any research or guidance exists regarding worker safety and health on vegetated roofs. We did not find any peer-reviewed archival literature that mentioned worker safety and health in articles about green or vegetated roofs. However, we found one magazine article. Turf Magazine provided an overview of safety issues for vegetated roof maintenance. In this article, Mulhern (2008) reports that her review of numerous articles and Web sites on green roofs reveals little or no mention of safety issues. The article identifies falls, material access, and planning for emergencies as the major potential safety issue. Vegetated roofs are becoming increasingly popular in the United States for their environmental benefits and their ability to earn credits in the green building certification process. Additionally, municipalities are providing tax incentives to encourage vegetated roof installation and passing regulations that require government buildings to provide vegetated roofs. Vegetated roofs can directly provide building owners with numerous LEED credits in the sub-categories of reduced site disturbance, site development, stormwater design, water efficient landscaping, heat island effect, and innovative design (Luckett, 2009; Carter and Fowler, 2008). Additionally, vegetated roofs may count for up to 15 points under the LEED system depending upon how well the roof is integrated into other building systems (Kula 2005). To be precise in terminology and avoid confusion for the scope of this proceeding paper, the term vegetative roof rather than green roof will be used when specifically referencing the author s ideas and work. While the two are utilized interchangeable within the peer-reviewed archival literature in meaning plants on roofs, the term green
roof has been utilized to include all roofs with environmentally friendly features such as solar panels, reflective properties, wind turbines, vegetated roofs or other green technologies. Therefore a vegetated system is not the only option worthy of the green roof designation. Moreover, according to Cavanaugh (2008) a definition of green is one that considers the sustainable qualities of a roof rather than the nature of its particular components. The terms eco-roof and living roof are also frequently used to describe roofs with vegetation. However, our review of the peer-reviewed literature finds these terms used less than green or vegetated roof. Berndtsson (2010) commented that there seems to be no consistency in the use of the terminology and the different terms are often used interchangeably. 3. Methods The objectives of the research were to 1) search for documented safety and health issues associated with vegetated roofing, 2) learn about incorporation of worker safety into green roofs guidelines, and 3) to investigate design practices by visiting vegetated roofs. In addition to the literature review, we searched world and local newspapers via LexisNexis Academic Search for reports of falls, injuries, and deaths from vegetated, green, and eco-roofs. Falls would be the source of the most severe injuries and thus, if any were reported, we believed this type of safety issue would be reported in the newspapers. Additionally, we searched the internet using Google for the same. A green roof textbook author was contacted and his ideas solicited on safety issues. The author joined three green roof social networking sites to discuss the topic of vegetated roof safe design; two were green roof networks on LinkedIn and third was the Green Roof Think Tank, a Portland, OR based networking site. At the time of the social networking postings, the Singapore guidelines were located via a Google search and purchased. The following description and request was posted on all three sites. I have a small grant to study green roofs from a worker safety standpoint. I am trying to learn more about hazards and risks to roofers and landscapers which could be eliminated or reduced through better design practices and work planning. Specifically I d like to know two things from the group: 1. If you know of any landscapers or maintenance workers that have died or been seriously injured while working on a green roof. 2. If there are any guidelines for the safety design and maintenance of green roofs. I have a guide from Singapore, CS E 02:2010 Design for Safety for Rooftop Greenery, but this is the only one I could find. For the site visits, all roofs were a convenient sample. Nineteen vegetated roofs were visited in Portland (n=9), Chicago (n=5), and the U.S. mid-atlantic (n=5). A contact at the United Union of Roofers, Waterproofers and Allied Workers in Washington D.C. recommended visiting Chicago and Portland because green roofs are increasing in
popularity due to city tax incentives for green construction and roofs in particular. A contact with the local roofers union in Chicago arranged site visits. In Portland, a contact with a large construction company provided the names of a roofing company, landscape architects, landscapers, and a large developer. In the mid-atlantic, a contact at a university allowed four roof visits, and one other visit was to a green roof that was available to be viewed from public areas. Roofs were evaluated for safe design including: safe access, roof edge protection, proximity to hazardous machinery and skylights, and other hazards unique to the work (i.e., proper water access for vegetation). Discussions with landscape architects, roofers, and landscapers provided additional insight. The author s university Institutional Review Board determined the research protocol to meet exempt certification requirements. 4. Results Web-based Searches There were issues with the combined search of safety and vegetated roof terminology in the newspapers. Fall or Autumn, is a season marking the transition from summer to winter. We found no fall to lower level type safety issues in newspaper articles; however, we located several hundred discussing the Fall seasonal description with regards to vegetated roofs. We also found no safety related articles while using the word death. Rather, we found approximately 50 articles describing the death of the vegetated roof for a variety of reasons which required re-planting, removal, or the complaints about misuse of funds for such projects. We found one newspaper article highlighting labor concerns that mentioned that the worker s harnesses were not attached to anything (Simmons, 2009). In summary, we could not find any evidence that any serious injuries or deaths have occurred from vegetated roof installation or maintenance. Social Networking Results We received twelve total comments on the social networking sites. Five of the respondents referred the author to guidelines from Germany and three referred the author to guidelines from Green Roofs for Healthy Cities (GRHC). Two mentioned OSHA standards. None of the respondents mentioned that they knew of any serious injuries or worker deaths from installation or maintenance on vegetated roofs. Vegetated Roof Guidelines The Landscape Development and Landscaping Research Society in Germany, translated as Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau or (FLL), is frequently mentioned in numerous peer-reviewed articles and in discussions the author has had with industry experts. Dvorak and Volder (2010) provided a recent background of the existing guidelines for the vegetated roof industry and described FLL as a recognized source of authority regarding the design, construction and maintenance of green roofs in Europe and throughout the world. The FLL s Guidelines for the Planning,
Construction and Maintenance of Green Roofing provide guidance on fall protection, determining design loads, and fire characteristics. Fall prevention during the planning and tendering stages is mentioned. Fall protection and prevention measures from the edge and through building components such as skylights are mentioned. The guidance is written based on the philosophy found in the European Directive 92/57/EEC of 24 June 1992 on the Implementation of minimum Safety & Health Requirements at Temporary or Mobile Construction Sites in that the responsibility of the protective measures lie with the client and their appointed safety coordinator. However, unlike the Directive, design phase modifications to include or facilitate fall protection measures are not mentioned. The FLL guidelines are focused on downstream safety measures. Green Roofs for Healthy Cities mission is to increase the awareness of the economic, social and environmental benefits of green roofs and green walls, and other forms of living architecture through education, advocacy, professional development and celebrations of excellence (GRHC, 2011). They are a not for profit group based in Toronto. Three respondents from the social networking site mentioned this organization as one to explore for guidelines that might include worker safety. We emailed the education director at GRHC twice inquiring about the integration of safety into their guidelines and training programs, but did not receive a response. An owner of a green roof installation company who had gone through the GRHC training mentioned that they did discuss OSHA standards for fall protection in the introductory course. The Association of Standards and Testing Materials (ASTM) develops and publishes numerous green roof standards including one for determining the dead load of green roof systems. There were no specific mentioning of worker safety considerations (falls, access, etc.) in the summary and outline of the ASTM standards. The American National Standards Institute (ANSI), in cooperation with Green Roofs for Healthy Cities, wrote and published the standard, External Fire Design Standard for Vegetative Roofs in 2010. The National Association of Fire Marshalls created an entire website devoted to fire safety and green buildings, and it includes a vegetated roof section. See http://greenbuildingfiresafety.org/index.html. The Singapore Center for Urban Greenery & Ecology s (CUGE) Design for Safety for Rooftop Greenery provided the only recommended guidelines for worker safety and its focus was on design. According to Singapore s Workplace Safety and Health Act, similar to safe design legislation in Europe and Australia, the person who creates the risk is responsible for mitigation (Workplace Safety and Health Council, 2008). In specifying the design of a building or structure, the designer should understand how the building or structure can be constructed, cleaned, maintained, and decommissioned or demolished safely (Workplace Safety and Health Council, 2008). Therefore, the designer must study and evaluate the risks to those carrying out the proposed works and others affected by it, such as the public or people using the building or structure in the future. The CUGE standard defines for rooftop greenery in the design, installation, and maintenance phases. The design phase considerations include:
1. Building Considerations. The building s established load bearing capacity; greenery on sloped roofs; protection from falling; roof penetrations (skylights); access; fire safety; working at height; and lightning protection. 2. Service Considerations. Appropriate facilities for washing / potable water; storage provisions; and taking onto account mechanical and electrical systems on the roof in relation to the vegetation. 3. Health Conditions. Reducing the use of hazardous materials; reducing noise through scheduling; and mosquito control. 4. Plant considerations. Plant selection; plant maintenance proper tree anchorage and maintenance; height control and health of trees; and provisions for tree removal. 5. Work scheduling considerations. Features to reduce the risk of falling; prevention equipment falling from height; design to simply construction; and the use of crane and aerial platforms. Site Visits Fall protection issues were observed on 11 of the 19 roofs visited. See Table 1 below for a summary. Six of the roofs had poor access; two of these roofs are not maintained any more due to unsafe access, and another is maintained sporadically and not as frequently as the building occupants would like. Potentially fragile skylights adjacent to vegetation were observed at 2 roofs. Water access was an issue at four roofs. For example, at one 20 roof with no parapet, no anchorages and poor access through the middle of the building, a spigot was only available at ground level at one side. When the roof is to be watered, a hose will have to be lifted / elevated to the roof and someone will need to be at the roof s edge without fall protection. Understanding the work to be performed in relation to the vegetated roof is of the utmost importance. These issues can be solved by proper building design and planning; Prevention through Design is a preferred solution. Table 1. Observed Fall Protection Status on Vegetated Roofs Fall Protection Comments Freq. % 39" Parapet (100%) Very Good 5 26.3 N/A - roof in usable Very Good 2 10.5 area Horizontal Lifeline Good requires worker 1 5.3 understanding 39" Parapet (partial) Poor potentially deceptive to 2 10.5 worker Davits available Poor these are for window 4 21.1 washing and not in readily observable or usable locations None Very Poor 5 26.3 Total 19 100.0
5. Discussion As part of the Prevention through Design (PtD) initiative, the National Institute for Occupational Safety and Health (NIOSH) and its partners are developing a framework to create awareness, provide guidance, and address occupational safety and health issues associated with green jobs and sustainability efforts (NIOSH, 2011). In January 2011 the National Occupational Research Agenda Construction Sector Council created a Green Jobs Coordination Committee, which is co-chaired by the author. The specific aims of the committee are to: 1. Explore and evaluate for practicality the notion of the Leadership in Energy and Environmental Design (LEED) pilot credit initiative for integrating worker safety and health into green building (e.g., two credits for ergonomics). 2. Explore and evaluate for practicality the notion of LEED innovation credits, and how they can be amended to integrate worker safety and health to improve design concepts and address fall prevention when installing roofs (conventional and vegetated), wind turbines, and solar panels, for example. 3. Identify methods for measuring the effects of prevention through design in installation. The committee is considering the value of both an incremental and a comprehensive approach. A comprehensive approach might look like a separate stand-alone system such as that proposed by Rajendran and Gambatese (2009). An incremental approach would entail the development of new credits or the modification of existing credits to include safety and health considerations across the life cycle. The safe design of vegetated roof systems would be an example of the incremental approach. A separate credit might be considered utilizing safe design criteria as outlined by the CUGE guidelines. Alternatively, safety could be a stipulation for awarding any credit an unsafe vegetated roof is not green and would therefore not be awarded that LEED credit if certain safe design considerations were disregarded. Other researchers are also linking potential synergies between safe and green. Silins (2009) examined several green building rating systems, including the United States Green Building Council s (USGBC) LEED rating systems, to identify areas where and how occupational safety and health are addressed and where they are lacking. Silins (2009) found that none of the rating systems currently include a credit or prerequisite for including a safety plan or program, either during initial construction or renovation, or for the post-occupancy engineering and maintenance workers. At the 2009 W099 CIB, a paper provided an argument and a rationale that for green buildings to be considered sustainable, safety and health concepts must be integrated into upstream considerations (Behm et al, 2009). The authors suggested that if construction worker safety and health is not part of the green and sustainable arrangement, any additional improvements in construction safety and health would certainly lag behind environmental improvements. Without integration, green and sustainable buildings will continue to be built by a process that employs 8% of the U.S. workforce yet experiences over 20% of its deaths (Behm et al, 2009).
6. Recommendations and Future Research This research is the first of its kind in an effort to associate safe design with a specific green building element. This research focused on vegetated roofs because they are becoming popular worldwide and in the United States due to the environmental benefits, green credits, and city tax incentives described earlier. Secondly, vegetated roofs pose a potential increased risk to roofers and landscapers charged with their installation and maintenance. Thirdly, risk countermeasures can be solved with proper prevention through design strategies, such as designing the built environment to ensure safe access, fall protection measures are provided, and considering the relationship of the work to other rooftop hazards. There are several research efforts stemming from this initial work. They include: 1. Specific safe design suggestions for vegetated roofs are being developed from this initial research endeavor. A journal paper is in preparation. 2. Building designers will be surveyed to determine their views on permanent safe design suggestions and how it would affect their work and the building (aesthetics, ease of implementation, cost, value for safety, etc.). 3. The NIOSH Green Jobs Coordination Committee continues to work toward specific goals to develop a strategy and tactics to integrate with LEED and other green systems. 4. The author will be appointed to a 2011 summer research fellowship in Singapore at the CUGE to evaluate the safe design for rooftop greenery strategies and their effect on building design and life cycle safety. Additionally, vertical greenery systems (green walls) will be examined. 7. Acknowledgement This study was funded by Virginia Tech s Occupational Safety and Health Research Center through the Kevin P. Granata Pilot Program funded by the Institute for Critical Technology and Applied Sciences. The author appreciates the support of the Center and the partners who provided access to vegetated roofs. 8. References Behm, M., Lentz, T., Heidel, D., and Gambatese, J. (2009). Prevention through Design and Green Buildings: A U.S. Perspective on Collaboration. CIB W99 2009 International Conference Working Together: Planning, Designing and Building a Safe and Healthy Construction Industry. Melbourne, Australia. Berndtsson, J. (2010). Green roof performance towards management of runoff water quantity and quality: A review. Ecological Engineering. 36 (4), 351 360.
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