Installation of a Green Roof The Use of a Literature Review, Engineering Analysis, and Life Cycle Analysis to Determine Sustainable Benefits CIVE 6900 Sustainability Science and Engineering Fall 2008 Professor Apul Presented by: Katie Puffenberger,Erik Lange,Prasad Bollineni,Zongsu Wei

School of Art, Design and Media at Nanyang Technological University

An intensive green roof on the Coast Plaza Hotel in Vancouver, British Columbia

Portion of a 10.4-acre extensive green roof on an assembly plant at Ford Motor Company in Dearborn, Mich.

Fukuoka City, Japan

Stakeholders of this Project University of Toledo wishes to update the North Engineering Building SSOE is fast tracking design plans UT Students will be benefited by aesthetically pleasing study areas Society benefits from silver standards of LEED certification

Objectives Engineering analysis for installing a green roof – Far reaching background information – Analyze possible LEED credits – Life cycle analysis

Introduction

Green Roof Developed in Germany in the 1960s Water-proof structures covering buildings Energy savings Used to combat the urban island effect. Decrease air pollution Provides habitat

Extensive Green Roof Advantages – Lightweight – Used in large areas – Low maintenance – No need for irrigation Disadvantages – Less energy efficient and storm water retention – Limited choice of plants – Unattractive during the winter

Intensive Green Roof Advantages – Good insulation – Very attractive – Energy efficiency and storm water retention – Longer membrane life Disadvantages – Greater weight loading – Need for irrigation and drainage system – energy – Higher maintenance costs

Layers of Green Roof 1.Plant layer 2.Growing Medium 3.Drainage Layer 4.Root Barrier 5.Waterproof Layer 6.Structural Support (Roof)

Types of Green Roof Plants Mosses Grasses Herbs Succulents

Contains both organic & inorganic materials. Provides fertilizers for plant growth. Provides stability to plants. Retains water for plants. Restricts weed growth. Growing Medium

Locks water Drains excess water Provided for roofs with slope angle <10° Supports growing medium Drainage Layer

Placed below drainage layer Prevents root migration Protects waterproof layer Avoids water from damaging the roof Root Barrier & Waterproof Layer

Methods and Modeling Approach

Analysis Methods Much of the modeling analysis was done using site-adjusted published figures Specific numbers were found for the North Engineering Building Roof Literature review was very important for data gathering Site drawings and roof visits were important for visualization

LITERATURE REVIEW

Insulation Effect Lowering Thermal Conductance in Roofs is the Key to Energy Savings Studies have found between 37% to 48% Energy Savings due to Insulation of Green Roofs

Air Quality Effect In U.S., there are 3,700 premature deaths per year that can be directed contributed to air pollution Reducing air pollution does not always equate to lower monetary costs Ozone, nitrogen oxide, sulfur dioxide, and PM10 (particulate matter) are examples of pollutants that have been shown to be removed by plants that have been installed on green roofs Each hectare of green roof installed has been found to remove 85 kilograms of air pollution in one year

Monetary Effect Green roofs cost approximately $150 per square meter to install Energy costs are substantially less for buildings with green roofs Cost analyses must be done on each site due to a number of differing factors including existing insulation and building configuration

LIFE CYCLE ANALYSIS

LCA Goals and Scope Goal of LCA was to quantify and clarify the environmental and monetary costs and saving of installing a green roof versus leaving the existing roof The functional unit was the entire roof The life was determined to be thirty years

LCA Scope: Boundaries Included in the LCA was energy used, monetary cost, and any pollution removed or added during the manufacture, construction, or operation phases No results in other impacted sectors or results from the maintenance or demolition phases were considered.

LCA: Life Cycle Inventory Comparison Categories (from the functional unit): – Global Warming Potential (GWP-carbon dioxide equivalence) – Monetary Costs (U.S. dollars) – Air Pollution Removal (kilograms of total pollutants) – Energy Saving (terajoules) Analysis for each category was done using a mix of process-based LCA and EIOLCA Most of the inventory was done using site-adjusted published figures Multiple outputs were evaluated from each phase within the boundaries

Results and Interpretation

A Local Case Study Toledo Lucas County Public Library

Toledo Lucas County Public Library Serving the Public since Intensive Green Roof. Green Roof Covers 0.5 acres of the roof. Consists of Turf, Shrubs, & Trees. Grid System Implemented for Roof. Uses Potable Water for Watering Plants.

Baseline Scenario Water There is approximately 5,150 square yards of roof was examined Using average annual rainfall data, this area of roof catches approximately 4,580 cubic yards of water each year. This water is currently being wasted

Layout and Drainage Patterns The 50-year, 24-hour storm was the basis of design Existing Drains will remain intact only as emergencies

Layout and Drainage Patterns The new roof shall not need to be re-sloped The roof layers and plants shall be designed to hold the design storm The saw-toothed structures shall work as they do currently

Roof Type Determination Extensive Green Roof – No supplemental irrigation – Maintenance free – Less design load Why Intensive Roof was not chosen – Difficult and expensive to reconstruct the roof – Planting media requires more maintenance

Introduction to LEED Building Rating System LEED (Leadership in Energy and Environmental Design) was developed as a national standard for building environmental minded and sustainable buildings. LEED was developed and continues to be administered by the U.S. Green Building Council. The first pilot version of LEED was released in 1999.

LEED Sections and Points per Section (Source: LEED-NCSection Points Sustainable Sites (SS)14 Water Efficiency (WE)5 Energy and Atmosphere (EA)17 Materials and Resources (MR)13 Indoor Environmental Quality (EQ) 15 Innovation and Design Process5

LEED Accreditation Sustainable Sites CreditsDescriptionPoints 5.1 Reduced Site Disturbance Local plants and vegetation used on the green roof for habitat creation and restoration Reduced Site Disturbance The green roof is an open place for students and faculties Storm Water Management Rainwater and runoff are collected on the roof Landscape & Exterior Designed to Reduce the Heat Islands The green roof helped to reduce the heat island effect. 1 *continued on next page

Water Efficiency CreditsDescriptionPoints 1.1 Water Efficiency Landscaping Water was not directed to storm sewers Water Efficiency Landscaping No potable water was used for irrigation of plants on the green roof because native plants were chosen. 1 Energy and Atmosphere CreditsDescriptionPoints 1 Optimize Energy Performance Insulating properties of the green roof reduced energy demand. 1 LEED Accreditation *continued from prior page

Life Cycle Analysis Results Impact Assessment Totals (inclusiveness of all within boundaries): Comparison CategoryInstalling a Green RoofAllowing Existing Roof to Remain Money$752,100$542,025 GWP3,766 GWP5,700 GWP Energy Saved43.5 TJ65.7 TJ Air Pollution Removal697 kg of total pollutants0 kg of total pollutants

LCA Interpretation Phase Over life cycle, monetary costs are not recovered from high installation cost of green roof Other categories evaluated decidedly favor green roof installation Tough to compare to other LCAs performed on green roofs due to unique functional unit

Take Home Messages 1.University of Toledo can benefit from the installation of a green roof, because LEED many accreditation points can be accumulated 2Cost of installing a green roof on an existing structure will not be met by energy savings costs 3.Other than monetary cost, all other areas of the LCA favored green roof installation

Questions

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