Kristin N. Moreno, EIT, SFP, LEED AP O+M Steven P. Bentz ... · LEED EB Operations and Maintenance 2009 - Sustainable Sites Credit 7.2 Heat Island Reduction- Roof Option 1: Use roofing

© Facility Engineering Associates 2010

Green Roofs

Kristin N. Moreno, EIT, SFP, LEED AP O+M

Steven P. Bentz, P.E., RRC, RWC, REWC, RBEC

www.feapc.com


Agenda

• Introduction

• Roofing Basics

• Cool Roofs

• Vegetative Roofs

• Summary


Objectives

• What is a green roof?

• What aspects of atraditional roof make itsustainable?

• What aspects of avegetative roof makeit sustainable?

• Which one do youchoose?


Green Roofs

• Sustainable is a pattern of resource usethat aims to meet human needs whilepreserving the environment so that theseneeds can be met not only in the present,but also for future generations. (Brundtland Commission)


Green Roofs

• Why should we want a “green” roof?

They are good for the environment


Green Roofs

Sustainable Roofing

Traditional Cool Vegetative


Agenda

• Introduction

• Roofing Basics

• Cool Roofs


• Summary


Roofing Basics

The basics of roof construction

What is the primary function of a roof?


Roofing Basics

Factors that influence roof service life:

- Slope & Drainage

- Attachment

- Durability

- Constructability

- Maintenance


Roofing Basics

Slope & Drainage

Early Design- Relied heavily on slope to drain water away, roof

material was often secondary

Modern Design- Relies more heavily on the waterproofing ability of the

membrane


Roofing Basics

Slope

• Economicdisadvantages of flatroof systems:

- Shortened service life

- Inconvenience ofpremature tear-offand replacement

- Loss of energyefficiency wheninsulation gets wet


Roofing Basics

Drainage

• Amount and size of drainscontrols how fast a roofdrains water

• Particularly important forProtected MembraneAssemblies

• Add overflow protection


Roofing Basics

Attachment

• Dictated by wind uplift design requirements

• US Manufacturers:

- Nailable decks, Non-nailable decks

• National Roofing Contractors Assn:

- Nailable

- Insulated

- Concrete

- Concrete (CIP, P-T, Precast)

- Wood

- Steel

- Lightweight Insulating Fill

- Cementitious Wood Fiber


Roofing Basics

Attachment Methods

- Loose-laidBallasted

- MechanicallyFastened

- Fully Adhered

- ProtectedMembraneAssembly


Roofing Basics

Material Durability

Weathering Resistance:

- Temperature fluctuation

- Seasonal extremes

- UV Exposure

Resistance to foot traffic

- Protected membrane

- Ballasted membrane

- Exposed membrane


Roofing Basics

Constructability

Must account for:

- Building location

- Height

- Type

- Use

- Occupancy

- Roof traffic

- Material availability


Roofing Basics

Constructability

Must account for:

- Material transport

- Use of asphalt

- Use of torch-applied products

- Membrane and flashing durability

- Deck type

- Interior construction

- Assembly weight


Roofing Basics

Maintenance

How visible (accessible) is damage to themembrane?

How easily is the roof maintained?

- Fully adhered or mechanically fastenedassemblies

- Ballasted assemblies

- Protect membrane assemblies


Roofing Basics

Maintenance

For ballasted and protected membraneassemblies

- What is the relationship between thedurability of the membrane and the“maintainability”?

- As the “maintainability” of the systemdecreases, the durability of the membranemust increase


Roofing Basics

• Wind uplift requirements

• Fire resistance


Agenda

• Introduction

• Roofing Basics

• Cool Roofs


• Summary


Cool Roofs

• Vegetation and reflective surfacesdecrease the effect of heat islands on theenvironment

• Heat Island- Absorption of heat fromhardscapes and its radiation of heat tosurrounding areas


Cool Roofs

• Reduced heat island effect = cooler cities

• Greater energy efficiency


Cool Roofs

Reflective Roofs

- Solar reflectance


Cool Roofs

• Common types of Cool Roofs:

- Gray or white single-ply

- Gray asphalt shingle

- White granular surface bitumen

- Aluminum coating

- White pavers


Cool Roof Considerations

• Cool roof energy efficiency savings arebased on the climate at the location of thebuilding


Renewable Energy

• Photovoltaic systems

• Wind turbine

• Solar thermal panels

• Biomass

• Wave and tidal


LEED Points

LEED EB Operations and Maintenance 2009

- Sustainable Sites Credit 7.2 Heat IslandReduction- Roof

Option 1: Use roofing materials with a solarreflectance index (SRI) equal to or greater than thevalues in the table below for a minimum of 75% of theroof surface:

Area Roof Meeting Min. SRI X SRI of Installed Roof ≥ 75%

Total Roof Area Required SRI


LEED Points



Option 2: Install and maintain a vegetated roof thatcovers at least 50% of the roof area


LEED Points



Option 3: Install high-albedo and vegetated roofsurfaces that, in combination, meet the followingcriteria:

Area Roof Meeting Min. SRI X Area of Vegetated Roof ≥Total Roof Area

0.75 0.5

Roof Type Slope SRI

Low-sloped roof ≤ 2:12 78

Steep-sloped roof > 2:12 29


Agenda

• Introduction

• Roofing Basics

• Cool Roofs


• Summary


Vegetative Roofs

Two main types of vegetative roofs

- Modular

- Built-in-place


Vegetative Roofs

Modular


Vegetative Roofs

Built-in-place

- Extensive Roof (2”-4”soil depth)

- Semi-Intensive Roof

- Intensive Roof (5” soildepth)

Extensive Roof System


Vegetative Roofs

Built-in-place vegetative roof components


Vegetative Roofs

Modular System

Built-In-Place System


Vegetative Roofs

• Views from windowsor a walk outside canrestore concentrationand reduce anxiety

• Plants cleanse the airof toxins thatadversely affect thosewith asthma-relatedillnesses


Vegetative Roofs

• Replicate natural habitat


Vegetative Roofs

• Decrease the amount of stormwaterleaving the site

• Vegetative roofs at multiple levels to catchrunoff from all areas of a building


Vegetative Roofs

• Carbon capture that mitigates climatechange


Vegetative Roofs

• According to LEED, in 2006, the commercial buildingsector produced more than 1 billion metric tons ofcarbon dioxide, an increase of more than 30% over1990 levels.

• Commercial buildings are responsible for 18% of U.S.carbon emissions.

• Any energy using facility contributes to CO2 emissions,and reportedly, the portion of energy used in buildingsinefficiently or unnecessarily is 30%.


Vegetative Roof Guidelines

• FLL Green RoofingGuidelines

• Developed by TheGerman Research,Development andConstruction Society

• ASTM is developingstandards

• International GreenConstruction Code (ICC)


Vegetative Roof Considerations

• Use plants that have more performancethan ornamental characteristics

• Use plants that can respond to varyingconditions



• Wrong type of plant on a roof could requiremore water and care



• Native plants do not always survive on arooftop



Load bearing capacity of the roof

- Weight of the soil

- Installation and storage of materials



Load bearing capacity of the roof

- Extensive Roof:12 to 50 pounds per SF

- Intensive Roof: 80 to 120 pounds per SF

- Traditional Roof: 5 to 6 pounds per SF

Photo: Daily Herald, Mark Black



• Installation & Constructability



• “Maintenance Free?”

• How visible is damage to the membrane?


Agenda

• Introduction

• Roofing Basics

• Cool Roofs


• Summary


Green Roofs Summary

Which type is right for you?

• Primary function of the roof

• Considerations

- Structural capacity of the roof

- Cost

- Climate

• Sustainable and green


Option 1:

Traditional, asphalt-based, light-colored

coating

Option 2:

Cool, reflective-surface, Single-ply

Option 3:

“Green”, vegetativeroof, plantings and

pavers

Single-PlyMembrane

Roof Replacement

Green vs. Traditional Roof

Initial cost: $20-$25/sf Initial Cost: $15-$20/sf Initial Cost: $30-$35/sf


Any questions? Please contact:

Kristin N. Moreno, EIT, SFP, LEED AP [email protected]

Steven P. Bentz, P.E., RRC, RWC, REWC, [email protected]

703-591-4855www.feapc.com

Thank You!

Documents

Kristin N. Moreno, EIT, SFP, LEED AP O+M Steven P. Bentz ... · LEED EB Operations and Maintenance 2009 - Sustainable Sites Credit 7.2 Heat Island Reduction- Roof Option 1: Use roofing