LEED FAN calculations Demystified
About Instructor
Bob Fassbender
LEED AP, BD+C
3+ years with Trane C.D.S
Co-founder Energy-models.com
Coded - LEED fan calculator
What This Course Covers
LEED Fan Calculation (90.1-2007)
Proper Setup in TRACE 700
Common Mistakes
After this course
Correctly Setup LEED fan calculations in TRACE 700
Use the Fan Calculator at Energy-models.com to help design buildings
Calculate LEED fan power manually
Understand when to use LEED fan Credits
Tools for the Job
TRACE 700
ASHRAE STD 90.1-2007
Fan Calculator (Energy-models.com/tools)
OR Fan calculator spreadsheet if you have made one
Key details
System Type (CV/VAV)
Design CFM
Building type (residential/non-res)
Pressure Drop Considerations
Why is this important
It’s the fan energy “you need to beat”
Fan energy can be >20% cost
Common way to lose LEED points
What are we modeling?
“Proposed Building”
Simple Pre-Designed Office Building
5 “thermal blocks”
13,500 sq ft
VAV System Supply/return fans
Fan HP ALREADY Designed
Baseline Building
90.1-2007 Office Building
13,500 sq ft
System 3
Fan HP To be calculated
1 system per thermal block
Comparing the two buildings
TRACE 700
Let’s take a trip in TRACE
How does the Fan calculation Work?
Based off Supply CFM only
TOTAL SYSTEM FAN POWER
Supply CFM calculated at 20 Degree ΔT
Follow Steps in 90.1-2007
Reasonably Long algorithm
Built into TRACE 700
But TRACE 700 takes it an extra step!
=
Total
SYSTEM FAN POWER
Complicated PROCESS?
But it takes it one extra step
Total System Fan power?
Algorithm yields power for ALL Fans in the baseline
How much Fan power does each fan get?
Same “Ratio” as the proposed
What does the Proposed look like?
Proposed Fans
Supply Fan = 5 hp
Return Fan = 3 hp
Baseline Fans
Same Ratio
Calculated based on each supply cfm
Which CFM?
Baseline building calculated CFM
Calculated using many specification in Appendix G
Different building Envelope
Different Lighting loads
Different Building Mass
NOT the Proposed building Design CFM
Let’s Look in TRACE 700
Total Fan KW
Common Mistakes
Single zone system with zones
Vs Multiple Systems
Proposed building – No True Fan Selection
Assuming “fan static” impacts Fan hp/kW in TRACE 700