TECHNICAL REVIEW
compared “apples to apples” across every
Things I always wanted to know about
little dollar return. In Miami, where we have
climate zone in the US.
energy and masonry (was not afraid to ask)
the largest difference, your igloo cooler
but could never find the real answer.
wall insulation gets you the equivalent of a
It leaves nowhere
to hide. Additionally, the research is leading edge in that it moves us past discussions of “R”
Q1
Starbucks Frappuccino and lemon pound What
do
save
when
you
REALLY
you
insu-
value to the ability to see the actual kWhs
late the beejebers out of the exte-
(and thus $$) differences between walls with
rior walls of a typical Florida home?
varying mass, insulation levels and insulation arrangements. It brings all discussions on wall insulation levels into clear monetary focus, putting it in the correct perspective.
A1
cake a month. In Orlando you’ll have to pass on the lemon pound cake.
Q2
As you continue to increase insulation in the exterior walls
Real Answer (as opposed to all
of a Florida home is there an optimum level
of the ridiculousness floating
beyond which you are just wasting your
around the internet)
money?
Quadrupling the insulation in your walls sounds great until you find out that it only
Super high R value wall systems don’t pay
saves you a mere $100 a year and will never
for themselves anywhere in the Florida
give you payback for the first cost of the
climate. The maximum dollar savings that
higher R value wall!
can be achieved by changing the insulation
A2
Real
Answer
(as
opposed
to what your local insulation
salesman is going to tell you)
of the exterior walls in a 2000 sf one story
In Florida your return on exterior wall
The data base is huge – nearly 22,000
home is roughly $100 per year. That’s it.
insulation starts to diminish rapidly. I always
individual analysis were run. Thousands of
And that is NOT going to pay for the $4000
knew this was generally true – but I now
Table 1: Comparison of Energy Savings of the Least and Most Insulated Walls in Florida] Total Energy $ Savings per Year Over Standard CMU w/R4 Added Insulation (2000 sf Single Story Home)
$ Savings in Miami
$ Savings in Orlando
$ Savings in Jax
Cost of Energy Upgrade
Payback Period 6 for Mia
Wall#
Wall Disc
Overall U Value
1
CMU R4
.172
0
0
0
0
0
3
ICF R20
.046
$101
$79
$96
$4,2075
41.5 yrs
energy use comparisons can be made on
plus dollars it is going to take to do it.
various wall types and climate zones. For
know EXACTLY how it is true. Insulation beyond the R4 to R8 range for mass exterior
the purposes of this article I have picked out
Table 1 was generated from the PNNL data
walls is a complete waste of money.
5 eye opening truths that specifically relate
and clearly shows the HVAC savings when
to Florida’s climate and building types. The
you change out the walls from R4 CMU to
Figure one shows the savings for various
PNNL research gives is the REAL answer
R20 ICF. The overall U value is - well – the
levels of insulation. Going from no insulation
to residential energy questions that have
overall U value. I haven’t got room for a
to a nominal R4 in Miami makes perfect
plagued masonry for the past 4 decades.
detailed answer in this article for U stuff so
sense. It costs around $240 and saves you
I am not going to go through the details of
just consider it the insulation value of the wall
$70 or so per year. Going from R4 insulation
the research – for that you can view the two
with the smaller number having the better
to R8 insulation is a marginal return of
technical reports on our website at www.
insulation.
What is clear is that approx. 4
around $53/year on an initial investment of
floridamasonry.com.
times the insulation value nets you precious
$770 for the upgraded insulation package.
SPRING 2015 7