Jon Burke

2006

Mechanical

Faculty Consultant: Dr. Jelena Srebric

An In-depth Look at a Green Roof

Outline

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Building Information

Purpose

Procedure

Results

•First Cost Analysis

•Lifetime Analysis

•Additional Benefits

Conclusions

Existing Conditions

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Central Shared Use Facility

FDA’s White Oaks Campus

Silver Spring Maryland

Rendering supplied by Kling

Design Firm: Kling

Civil Firm: Greenhorne & O’mara

Owner: GSA

Existing Conditions

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

3rd Floor – Library

26,500 sq ft.

VAV System

Cold and Hot water pumped from Central Plant on Campus

Rendering supplied by Kling

Existing Conditions

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Purpose

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

First Cost Analysis

•Material and Labor

•Rainwater Quality

•Structural Support

Lifetime Analysis

•Energy Savings

•Maintenance Costs

GOAL: Find “Benefit”/sf and optimal size

How does size affect project costs and benefits?

Other Benefits

•LEED Rating

•Architectural Value

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Procedure

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Results – First Costs

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Materials and Labor

Built-up Flat Roof: $2/sf

Green Roof: $14/sf

COST $12/sf Green Roof

Results – First Costs

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Rainwater Runoff Quality

Runoff of Green Roof is Clean

Bio-Retention System

1 I.A. = 3000 sf Filter

Greenhorne & O’mara

Rainwater Quality Control

600

700

800

900

1000

1100

1200

1300

1400

25 30 35 40 45 50 55 60 65 70 75

Green Roof Size (%)

Req

uir

ed S

ize

of

Fil

ter

Sys

tem

(sf

)

$10 /sf of Filter

SAVE 69¢/sf of Green Roof

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric Results – First Costs

Structural Support for 50 psf

1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE

1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE

1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE

1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE1 2 3 4 5 6 7 8 9 9.5 10

A

B

C

MIR

RO

R L

INE

30” Diameter ($1,992) 14” Diameter ($875)24” x 24” ($3,203) 12” x 12” ($1,252)

COST $2.50/sf Green Roof

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric Results – First Costs

Total First Costs

Materials and Labor: $12/sfStructural Impact: $2.50/sfFilter System: -$0.69/sf

Total: $13.80 Additional Cost per Square Foot of Green Roof

Results – Annual Costs

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Energy Savings

Energy Savings

100

105

110

115

120

125

130

25 30 35 40 45 50 55 60 65 70 75

Green Roof Size (%)

Pea

k C

oo

lin

g L

oad

(to

ns)

SAVE 21¢/sf Green Roof PER YEAR

Annual Electric Load Reduction•2.15 kWh/sf Green Roof

Peak Cooling Load Reduction•0.6 tons/265 sf Green RoofGSA:

10¢/kWh

Results – Annual Costs

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Maintenance CostsBuilt-up Flat Roof Green Roof

Annual Maintenance

Lifetime: 15 yrs

Negligible MaintenanceLifetime: ??

Greening Rooftops for Sustainable Communities. Chicago 2003. Page 280

Results – Other Benefits

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

LEED Rating

Guaranteed•Credit 6.1: Stormwater Management – 1 point•Credit 7.2: Heat Island Effect – 1 point

Architectural Value

Conclusion

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

“Energy conservation is the foundation of energy independence.”~Thomas H. Allen (D-ME 1st)

Conclusion

Jon Burke

2006

Mechanical Option

Consultant: Dr. Jelena Srebric

Any Questions?