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Manual J calcualtions through various methods
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SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Manual J ... The Easy WayWhen do I need it?How much detail?
How does it relate to my Scope Of Work?
Can I contract it out?Is it the gospel truth?
The whole truth?Are there shortcuts?
When can I take them?Easy, Medium, Hard,Which one’s for me?
(This is not the Easy Way... But it’s good to
understand)
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Before we begin...
What’s happening here?
(It was mentioned last week as a Change Order)
Rogelio sends me stuff like this from his iPhone so 3000 miles doesn’t matter.
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Owner Requested and Paid Change Order
Wall Removal and Stove Relocation
Couldn’t go overhead as the new gas stove is in an island = Had to cut the concrete.
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Questions From Last Week
Fireplace?
Mini SplitHeat Pump?What Size?Even with 2Room Adds?How about a
GarageConversion?Still 2 ton?
How can we reduce the heat load?
Concealed Unit or Wall
Mount?
Ducts Inside Envelope or in
the Attic?
Buyer wants
changes?
How much can a 2 ton do?
1 zone or 2?
How bad is “Oversizing?”
When to keep old equipment?
Does a Room Add
makes sense?
Manual J?Manual D?
Western Exposure?
Low E 140?
Change Order?
How tight can we get this one?
Need an ERV-HRV?
Rigid Insulation?
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Shows total square
footage.
Newest (owner’s) plan is to convert the garage
Garage only = 361
Total = 1700
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
N Note: No Windows on East, Few on West
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Infiltration
Floors
Ceiling
Doors
Walls
Glazing
Ducts
Internal Gains
Ducts
InfiltrationCeilings
Doors
Glazing
Walls
AnySurprises?
Internal gains are growing annually
....A big area
for homeowner education
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
HTM =Heat
TransferMultiplier
Every Building
Component has one
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Room by Room
& Component
by Component
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Your HVAC contractor should provide this type of
report for you ... Just as your realtor should provide you
with the CMA.
But for quick reference, let’s look at an easier way to do
Manual J
And see how close to the same answer we get ...
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Blan
k Te
mpl
ate
Fill
in Y
ello
w ..
. The
Res
t A
uto
Cal
cula
tes
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Instructions for using the Load Calc
SpreadSheet
They are in the cells
immediately to the right of
the main sheet
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Now go live to the Load Calc SpreadSheet.
Let’s see how easy it is to tell if a 2 ton mini split will do
the job!
(2 ton is the smallest they
make.)
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Let’s see which questions were
answered by doing the Manual J
Calculation
Can you identify where
Manual J addressed
each question?
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Fireplace?
Mini SplitHeat Pump?What Size?Even with 2Room Adds?How about a
GarageConversion?Still 2 ton?
How can we reduce the heat load?
Concealed Unit or Wall
Mount?
Ducts Inside Envelope or in
the Attic?
Buyer wants
changes?
How much can a 2 ton do?
1 zone or 2? How bad is “Oversizing?”
When to keep old equipment?
Does a Room Add
makes sense?
Manual J?Manual D?
Western Exposure?
Low E 140?
How tight can we get this one?
Need an ERV-HRV?
Rigid Insulation?
Always? 2
Always In Writing, Paid For Up Front
Not as bad as once thought... Especially
with inverter technology It’s Gotta Go!Always In Writing,
Paid For Up Front5-10 yrs old But
dont even consider the ducts.
J for equipmentD for DuctsTwice the load
as North
Build so that you always need Ventilation
ON Purpose
Address each component & maximize
it’s efficiency
Especially on West and East Expsure
Good load reduction especially on east and west. Also reduce leaks
We’re shooting for.5 cfm50 per square
foot of floor
Wall mount would be even more
efficient. No duct loss
Could reduce load even more with ducts inside
We think soSo did our buyer
This one, 1700 sf still has 20% extra
capacity
SavingThe PlanetOne HouseAt A Time
G r e e n E a r t h E q u i t i e s . C o m © 2010
Manual J ... The Easy WayWhen do I need it?How much detail?
How does it relate to my Scope Of Work?
Can I contract it out?Is it the gospel truth?
The whole truth?Are there shortcuts?
When can I take them?Easy, Medium, Hard,Which one’s for me?
Always, Unless you are building so tight that the smallest unit is still too big. Still a good idea
After answering the big question, the detail is needed for room to room air delivery
Yes, HVAC Sub
Dont guess, Improve the envelope or the equipment
Sort of. There are other ways and other factors.
Fudge factors and safety factors are built in.
Yes but it’s good to know the old school way
It’s America
You Choose
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