Evaluating the environmental, technical, and social impacts of a livin g green roof in Vicenza, Italy Mary Frisbee University Scholars Program May 2011
B ACKGROUND A green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium. They are constructed of a lightweight soil media, underlain by a drainage layer, and a high quality impermeable membrane that protects the building struc ture. The soil is planted with a specialized mix of plants that can thrive in the harsh, dry, high temperature conditions of the roof and tolerate short periods of inundation from storm events. Historically, engineered green roofs originated in northern E urope, where sod roofs and walls have been utilized as construction materials for hundreds of years. The development of contemporary approaches to green roof technology began in the urban areas of Germany over 30 years ago. The benefits of green roofs are many: reduced airborne emissions, greater sound insulation, reduced heating and cooling system needs, mitigation of the effects of urban heat islands, a cutback in storm water runoff. In addition, after massive development in recent decades, the space lef t to greenery in urban environments has rapidly been decreasing. On the one hand, greenery decreases carbon dioxide and increases oxygen in cities. And in the other, green roofs also create green spaces that, especially in dense environments, can perform i mportant roles as social spaces. W hile the advantages of green roofs are not under discussion, studies that quantify the many proposed benefits of green roofs are sparse, particularly studies on roofs that have been functioning for a period of years. In a Federal Technology Alert, The US Department of Energy Efficiency and Renewable In the United States the lack of information and education about green roofs must be addressed, if they are to be used more widely. This is especially important
INTRODUCTION The intent of this research is to test the performance of an already constructed green roof, and to check if it successfully fulfills what it promised as a project. Not all green roof projects are a complete success, as there are many issues and problems that arise from the presence of a green roof. Green roof systems are complex entities with a multitude of facets. Evaluation is not simply a question of does it work or does it not work. Research in the field of green roof constructions is in clear demand. A case study will be done on a green roof located in Vicenza, Italy. The conclusions made from this case study will contribute to the growing body of work in the fie ld. THE ROOF UNDER ANALYSIS P roject Name: San Bortolo Hospital Year of Completion: 2006 Location: Vicenza, Italy Type of Roof: Extensive & Intensive Size: 26910 sq.ft. Access: Accessible, Open to Public Architect: Enrico Dall'Osto
Plan of Plant Distribution on Roof
HYPOTHESIS APPROACH Five years after completion, does the green roof located on San Bortolo Hospital perform as a successful project? The performance of the roof was evaluated by its social, technical, and ecological vitality. The social impact of the roof was evaluated by a quantitative and descriptive analysis of people interacting with the roof. The technical impact of the roof was evaluated in terms of its energy efficiency effects on interior space, and economic impacts. The ecological impact of the roof was evaluated by the success of the life of the plants on the roof. APPROACH AND METHOD Before traveling to the roof, research was done on how green roofs have been evaluated in the past. Multiple case studies were analyzed. Through the study of different case studi es three main concerns emerged. Past evaluations were concerned with technical, ecological/ environmental, and social facets. The technical and ecological evaluation was performed through a series of questions. These questions were asked to the manager of the roof finances, a member of hospital maintenance, and the two roof gardeners. The following questions were as ked for technical evaluation.: 1. What technical advantages did the architect promise of the green roof? How did the architect promise these things, with concrete numbers or a general statement that it would be improved? 2. How expensive is it to maintain the green roof (is this what was expected)? 3. Does the hospital get any tax breaks from the government fo r having a green roof? 4. Does the hospital get a reduced rate in storm water runoff fees for having a green roof? 5. After installing the green roof was there a decrease in the amount of energy needed to heat and cool the interior of the building? 6. How has the roof aged over the past 5 years? Has there been any major issues? 7. Overall, does the roof deliver technically what the architect promised?
The following questions were asked for the ecological evaluation: 1. What did the architect promise in terms of ecological impact of the green roof? 2. Does the roof deliver ecologically what the architect promised? 3. How healthy are the plants growing on the roof? 4. Do the plants need re planting every year or are the gar dens self sustaining? 5. Is there an irrigation system? For the social impact, both qualitative and quantitative methods were used. A first hand experience of the roof was to be recorded over a period of three months. Four items were looked at through ob servation. 1. Areas of Social Density Observe and record what areas of the roof attract the most people. What seems to be the space that people want to be in? (chapel, extensive succulents, intensive gardens). Make a diagram showing the floor plan of the roof and use levels of grey tone to show differing areas of density. 2. Typology of Activity What activities take place on the roof? Patients visiting with family, patients visiting with patients, patients alon e? How has the green roof provided a setting for activity? Use photographs to show the different activities occurring. 3. Architectural Impact Now that the roof is occupiable, how has this affected the interior space of the hospital? Compose drawings l ooking at circulation and views. 4. Patient Percentage of Roof Utilization Compare the number of people occupying the roof to the number of people occupying the glass tunnel on the roof. Measure once a week for three hours for three months. The followin g questions were asked for the social evaluation: 1. What activities take place on the roof? Patients visiting with family, patients visiting with patients, patients visiting with doctors, patients alone employees taking a break ? How has the green roof provided a setting for activity?
2. Now that the roof is occupiable, how has this affected the interior space of the hospital? 3. What percentage of patients utilize the green roof? 4. What percentage of employees utilize the green roof? 5. What are t he peak hours of occupation? 6. Is the roof more active in the summer than the winter? 7. Is the roof more active on the weekends? 8. What rooms have windows that look down onto the roof? 9. May I give a simple survey to patients and staff who have ut ilized the green roof? Sample Survey: 1. Have you utilized the green roof? If so, how many times during your stay? 2. Have you viewed the green roof, either from your window or passing through the tunnel on the roof? Did you like this experience? 3. Has the green roof contributed to your healing process? 4. Is the green roof an attribute to the hospital? RESULTS
DISCUSSION After analysis, the roof was found to have virtues and problems. In terms of social vitality, the roof is very successful. While people do not typically occupy the exterior spaces, people do occupy the space with their sight. It gives over 100 patient rooms a view of a green garden space instead of a barren concrete roo f. T he benches of the glass tunnel on top of the roof served as a meeting space for people. The tunnel provides an environment not usually found in a hospita l: interior conditioned space overlooking a green garden. In terms of ecological vitality, the roof is successful. The plants are very healthy. Over the paste three years they req uire a replanting percentage approximately 20 %. The variety of plants on the roof provides color throughout the year, so the roof never appears to be dead. In terms of technical vitality, the roof is not very successful. While the roof succeeds in energy efficiency, it does not succeed in effects on interior space and economic impact. The main problem is the presence of only one irrigation system. The sedums in the extensive gardens require very little water. The flowering plants in the intensive gardens require a lot of water. In order to keep the flowering plants alive, both the intensive and extensive gardens are given the same amount of water. The inabili ty of the sedum to absorb the quantity of water it receives causes problems of leaking in the roof. The leaking negatively affects the interior of the hospital and puts a financial burden on the hospital. The problem with the irrig ation is not easily solva ble. In the future, I hope to be able to analyze more green roof projects. By gaining an understanding of the problems green roofs have, future green roofs can be constructed to avoid these issues.