Transcript Things To Not Do When Weatherizing Southern Homes

Things To Do and Not Do
When Weatherizing
Southern Homes
Doug Garrett, CEM
Terry Brennan
Agenda for Today
• Building Science and Weatherization
• What Makes Sense in Southern
Region
• What Doesn’t Make Sense
When We Say the South
• We Mean the Hot and Humid and The
Mixed Humid Climates Zones.
• H&H zone has very little winter at all
and M-H has brief periods of cold
with mild times in between.
• You could throw in the Hot/Dry and
Mixed/Dry areas too for that matter.
North
American
Climate
Zones
Do Not Assume
• That the attic and the crawlspace are
outside of the house.
• Do not assume that it is best to make
them outside in all cases or to bring
them inside in all cases.
Do Make the Effort to
Test/Define the Air Barrier
• Is the Basement or Crawlspace part
of the Conditioned Space?
• Are there any dropped ceilings, furr
downs over kitchen cabinets, or
utility chases in the conditioned
space?
• Does the Knee Wall and the Shed
Roofed Porch have an air barrier
behind them?
Conditioned Space?
FINISHED
ATTIC
GARAGE
LIVING SPACE
F
BASEMENT
WH
SUNPORCH
Or Conditioned Space?
FINISHED
ATTIC
GARAGE
LIVING SPACE
F
BASEMENT
WH
SUNPORCH
A/C & Ducts In or Out?
• If the ducts are in the crawlspace can
we easily bring them into the
conditioned space?
• Will it help solve other issues like
decay of the home, critters living in
the ducts or IAQ issues impacting
the health of the occupants if we do?
The House Is A System
• Crawl Spaces:
• Generally It’s Best to Not Ventilate Them!!
• Outside Air Is Too Humid to Dry Anything
most of the year - And it Just Freezes
Pipes in Winter.
• Seal them air tight, use 6/10 mill vapor
barrier on the dirt, insulate the stem wall
and ventilate with conditioned air at 20
CFM/1,000 SF of floor. IRC 2000 (R-408)
allows this method of construction.
• In retrofit, at least put the 6 mill plastic
down covering the dirt!
EEBA Builders Guide
Building
Science Corp.
Required in the
South
or no termite warranty!
Termite view strip or
No Mans Land!
Photo by
the Healthy
Building Company
Do Not Assume that It’s
Really Insulated?
• Kneewalls, dropped ceilings, furr
downs in kitchens and utility rooms
may look insulated but are they?
• They often have a lot of insulation
that is in storage waiting to be put to
some useful employment in the
future.
Do Take the Time to
Address Thermal Bypasses
• Especially in the Attic
Dropped
Ceiling
Recessed
Light
Typical
Dropped
Kitchen
Ceiling
Framing &
Insulation
Knee Walls
Kneewall:
Pull the
Insulation
Back
and...Instant
Access to
Uninsulated
Ceilings and
Floors!
Note:
Insulation is
Absolutely
NOT an Air
Barrier!
Should
Uninsulated
Ceilings and
Floors Like
These be
Open to
Super
Heated Attic
Air?
Seal and Fire Block Around
Dryer Vents & Chimney Chases!!
Do Not Assume That the
A/C Is Sized Right Because
They Say It Cools
• Most A/C’s are not right sized
• Our actions and the improvements
we make change as in reduce the
cooling and heating loads
Do Take the Time to
Calculate the Right Size
• ACCA has developed the methods
for over 40 years.
• They are really on target now.
• They are actually required in the
building codes now!
HVAC Issues
• Replacing units with the same size
that is there now.
• Not improving the ducts when you
replace or repair a unit.
• Not sealing ducts when weatherizing
a home.
Some Facts About Sizing
• ACCA studies show that the average
A/C installed in the past 20 years is
150% to 200% bigger than it should
be.
• A/C contractors have been held liable
for causing mold and other indoor air
quality problems in homes and
buildings due to over sizing
equipment or improperly addressing
ventilation needs.
HVAC System:
• A/C Sizing:
• Rule of Thumb – Based on
construction practices of the ’60’s!
• 1 Ton could only cool 400 to 500
SF
• Right for construction then, not
always right for well weatherized
homes today.
• Size by ACCA Manual J and Select
Equipment by ACCA Manual S.
HVAC System:
• Manual S - Selecting equipment
far over calculated load
• ACCA Manual S says to pick
equipment that is Never More
Than the Load in BTU’s + 15%
Maximum!
• Take calculated load and
multiply it by 115%. That is your
maximum total equipment size.
Building Science for HVAC
• HVAC Role:
• Design to ACCA Manuals J8 & D
required by 2006 IECC
• Install air tight ducts, mastic
sealed
• Return Grilles – 200 CFM/SF Filter
Grille or 300 CFM/SF Non-Filter
Grille
• Use the right high efficiency filters
Building Science for HVAC
• Supply Ducts Equivalent Length =
Long- 0.06”, Med.- 0.08”, Short0.10” W.C.
• Select equipment with a Sensible
Heat Ratio (SHR) of 0.75 or less to
control indoor humidity!
• Select equipment by ACCA Manual
S, no larger than 15% over
calculated load.
1.0
Sensible Heat Ratio (-)
No moisture removal
to the left of these
points
2 rows
3 rows
4 rows
0.8
0.6
0.0
0.2
0.4
0.6
0.8
1.0
Rm K1233 - 6-30-02
100
0.03
90
T-RH (F-%)
70
0.02
60
50
0.015
40
0.01
30
OA Temperature
OA RH
Indoor Temperature
Indoor RH
OA HR
Indoor HR
20
10
0.005
0
0
0
5
10
15
Hours
20
25
30
HR (lbsH2O/lbair)
0.025
80
South
Dallas
Houston
HVAC System: Benefits
• The new A/C will operate more
efficiently.
• The new A/C will deliver greater
comfort.
• The new A/C will last longer with
fewer repairs.
• The new A/C will improve the
healthfulness of the home and the
people living in it.
Ducts and all
building
chases and
cavities used
as ducts
LEAK!
Don’t worry,
this is only a
$2 Million
dollar home
just a week
short of
completion!
Do Not Assume That Ducts Are
Tight Because They Look Tight
• I guarantee you that you can’t tell
diddly squat about how tight ducts
are by looking!
• You may guess right sometimes but
then even a blind pig finds an acorn
occasionally and that’s not reason to
start bragging.
Do Take the time to Deal with
Pressure Imbalances!!
EEBA Builders Guide
Building Science Corp.
Duct Air Sealing Examples
HVAC System:
• In a 3 Month Accelerated Aging
Test simulating 30 Years in the
field, U.S. DOE found Failure in:
–Cloth Duct Tape = 7 Days
–UL-181B-FX Tape = 10 Days
–UL-181 B-FX Foil Tape = 10
days
–UL-181-A (metallic) and
B (Flex) Mastic = No Failures!!
The Critical Air Seals Are the Inner Core and
Flange, NOT the Vapor Barrier Jacket on the
Outside!!
EEBA Builders Guide
Building Science Corp.
Leaks!
Measuring Static Pressure
Static Pressure Should be ...
• Less than 0.5”wc or 125 Pa.
combined for both supply and return.
• Add the two readings and ignore the
+ and – signs.
• Measure after duct sealing is done.
• If it is too high, add ducts and grilles
to ease resistance.
Storm Windows?
• Storm windows are not cost effective
in the South.
• They are popular with many
contractors because they are easy
and they are profitable.
• If you live where the codes require
Low E glass you should not retrofit
homes with storm windows!
Solar Shading Is The Southern
Equivalent of Storm Windows
• Installation of solar shade screens or
solar film is cost effective when A/C
is present.
• The Shade Coefficient should be 0.50
or lower.
• The measure must cover all of the
glass area, not just the operable
section.
• Permanently secure to the home.
Region Where Storm
Windows Don’t Make Sense
Unvented Gas Space
Heaters
• Try your best to replace them with
vented units.
• At least replace them with units
having an ODS.
• If you can’t replace it with a vented
unit do not tighten the house or you
can cause death or a moisture
problem.
A Few Quick Do’s and
Don’ts
• Tips and information to make it go
smoothly.
What the heck is a U factor
anyway?
• U factors = R value stated as a
decimal
• R- 4 is fraction ¼ as a decimal
it’s stated as 0.25
• So, R- 4 = U- 0.25
• R-10 = 1/10 = 0.10 as a decimal
• So R-10 = U- 0.10
• Bigger R’s and Smaller U’s are
better
Polyethylene Vapor Barrier
Optional:
Installed
Mold
Breeding
Chambers
That Concludes Today’s
Program,
Thanks for Listening!