Weather file - EcoTect - Winnipeg

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Does anyone have, or know where I can download, an EcoTect weather file for
Winnipeg please?


Chris Flood 

Chris2's picture
Joined: 2011-10-02
Reputation: 400

I'd suggest using Meteonorm and then convert the format in the weather tool in Ecotect.

Aryn Bergman's picture
Joined: 2011-10-02
Reputation: 0

There is a CWEC weather file for Winnipeg. I would suggest that you get
that file instead of using Meteonorm.

Go to :

For more information about CWEC weather files, look at the EnergyPlus
weather site

Joe Huang

Joe Huang's picture
Joined: 2011-09-30
Reputation: 406

There is also a winnepeg weather file available in EPW format that you can translate to WEA with the Weather utility in EnergyPlus. Search for 'energyplus weather' to get the link.

David Scheer's picture
Joined: 2011-10-02
Reputation: 0

knowing that

1) appendix a, section 6.1, references that "For the purpose of Section
A1.2, the base assembly is a slab floor of 6 in. concrete poured
directly on to the earth ..." meets the requirement for an unheated slab
f-factor of 0.73, and
2) section a6.3, f-factors for slab-on-grade floors, a.6.3.1 states:
"/F-factors/ for slab-on-grade floors shall be taken from Table A6.3", and
3) section a6.3.2 states: "These /F-factors/ are acceptable for all
/slab-on-grade floors/."

does the "all slab-on-grade floors" really mean any thickness of
slab-on-grade? i.e. section 6.1 references a 6-inch uninsulated slab
meeting the 0.73 f-factor requirement, but per sections a6.3.2 and table
a6.3 a 4-inch uninsulated slab (or an 8-inch uninsulated slab) would
also meet the 0.73 f-factor requirement. so why would section a6.1
specify a 6-inch slab when any slab thickness will suffice? the user's
manuals (both years) just refer to table a6.3 for f-factor values.

the state of washington has a similar section in its energy code (see
link below), page 41, table 4-2. section 1003.2 (also page 41) lists
"All on-grade slab floors as assumed to be 6 inch concrete poured
directly onto the earth." note that on page 40, table 10.1, the
f-factors decrease the deeper the below grade the slab-on-grade floor is.

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200


The heart of your query isn?t really crystal clear to me, but I?ll take a stab:

Section A1.2 says if a building official feels sections A2 through A8 do not ?adequately represent? the proposed construction, Section A9 is to be used, but A.9.2.e. curtly says no alternate procedures are permitted to find alternative F-factors for SOG floors. At first glance, it would appear the 90.1 committee might be giving any extremely meticulous building officials/reviewers/designers the run-around.

The way I see it, Section A6 in its entirety is suggesting concrete slab thickness varying from 6 inches ?doesn?t matter much.?

More precisely: ?Real-world? SOG design within the confines of any 90.1 calculations shall be restricted to the following variables:

1. The R-value of any insulation, if present

2. The configuration of said insulation, if present,

3. Whether the slab is heated

Note there are a series of variables are not brought up or either explicitly held constant, beyond slab thickness, and I understand these all can have a decent effect on perimeter conductivity:

1. What?s on top of the slab

2. Slab height relative to grade / footing exposure

3. Soil conductivity/moisture properties

For further reading, I know there are multiple white papers out there going well into depth if that?s what you?re seeking ? LBNL comes to mind as being part of some research? I personally haven?t charged myself with crunching the numbers up to this point, rather letting my software of choice do the legwork.

The reasons I would speculate that section A6.1 specifies a 6? thickness would include

1. It helps ground/quantify from what the numbers in the table are derived

2. It gives a reference to the base construction?s thermal mass ? necessary should you wish to model something different for your proposed constructions within the context of, say, an Appendix G performance rating.

3. While a strict reading of appendix A might lead one to believe all constructions used in all calculations must follow the prescribed values, I?ve only ever run into one reviewer who called into question the use of custom constructions and ASHRAE Fundamentals-derived materials/properties which do not appear within the (relatively abbreviated) Appendix A. I think the real intent is to provide a description of those constructions as defined earlier in the code ? namely envelope constructions in the context of describing either a ?prescriptive minimum? or in the context of energy modeling as the ?baseline constructions.? I do not believe the intent of Appendix A is to restrict/limit the design decisions that may be made outside of the presented materials/tables.

I?m on a bit of a limb here, but I?m speculating at what may have prompted your question? does this miss the mark?


Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

you're pretty much right on the same track. i realized after i sent it
the email only had the main question buried in the middle and i have a
side question to go with it.

main question: what is the f-factor of a 4" concrete slab?
reason for question: most architects in southern arizona specify, and
contractors build, an unheatd 4" concrete slab for standard
office/retail. 6" concrete slab for warehouses and other spaces where
heavier loads are common.

secondary question: does a building with a 4" concrete slab meet the
f-factor requirements of 90.1 per table A6.3? (unheated or heated,
unheated in my case though).
reason for question: need to demonstrate 90.1-2004/2007 compliance for
floor f-factor. unclear as to answer.

1. all of the research/other references to f-factors that i've found
also reference the 6" slab, the same research, and 90.1, and from what
i've seen/can tell they only tested at a 6" slab with 8" and 4" walls
and varying insulations.
2. the problem with calculating an f-factor, even if using ashrae
fundamentals derived constructions, per 90.1, is that calculations are
prohibited by Section A9 Determination of Alternate Assembly U-Factors,
C-Factors, or F-Factors, or Heat Capacities, SubSection A9.2(e),
"Slab-on-Grade Floors: no testing or calculations allowed."
3. which leads me back to section a6.3.2, which states in reference to
Table A6.3, "These /F-factors/ are acceptable for all /slab-on-grade
floors/." - but is it really? how does one defend a building official
or leed review comment for a 4" slab f-factor? if section a.6.3.2 is
literally correct then the f-factor for an unheated 4" slab is the same
0.73 as an unheated 6" slab. since the f-factor is based on linear feet
and not square feet this could make sense if the thermal capacity of the
thickness of the slab does not matter for f-factor. note though that
4", 6", and 8" lightweight concrete all have the same conductivity
(3.7), density (80), and specific heat (0.22) (per the 2009
fundamentals). knowing the thickness of the slab may be insignificant
to the f-factor calculation is one thing, proving/demonstrating it to a
code official/leed reviewer is another. i have asked my local code
officials (who are pe's also) and they don't know the the answer(s)
either ...

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200

Alright, we are on the same page!

Main Question Answer in short: Use the F-factor of a 6? slab as listed in the table. It?s less work for you, it?s defensible to a reviewer, and this should not significantly impact any calculations relative to the conductivity of an otherwise equivalent 4? slab.

Fleshed out responses:

1. I?ve observed the same.

2. This ?runaround?/dead-end you?re also pointing out is the first point of defense against any reviewer or local code officials who would have you do anything else. 90.1 explicitly does not permit any calculations/methodology outside of using that table.

3. So that you can sleep easy at night, note that 90.1 also draws a line regarding what constitutes a significant deviation by defining the term ?adequately represented?:

a. A1.2.b. reads (abbreviated): ?An assembly is deemed to be adequately represented if ? changes ? to the base assembly do not increase or decrease the R-value by more than 2 from that indicated??

b. This may seem somewhat arbitrary in discussion of F-factors, but you can be reasonably assured (and further defend the decision to use a 6? F-factor) that an additional 2 inches of concrete in your proposed slab construction, considering all possible concrete mixes, is very likely not going to swing the net R-value of the slab + footing by more than 2.

c. My materials charts reference (from 2001 fundamentals) lists only 2 exceptions to that statement ? they?re the very least-dense options for ?polystyrene aggregate? and ?foam concretes*,? which stand apart with a shared listed density of 20pcf. These two in the list have an ?R-per-inch? value above 1. All other values for concrete are around or less than 0.5 per inch.

d. If you have to, I?m pretty certain you can quickly calculate the net difference from a 6? slab using materials in fundamentals per above (or better yet, whatever?s listed in Appendix A for concrete), and show any meticulous reviewers/officials that the net difference in terms of R-value is less than 2, referencing A1.2.b.


* On a complete tangent, a friend of mine did a masters report on lightweight concretes in construction during my last semester, so I once got to play around once with a sample of foam-infused concrete block? That stuff is a mind bender like clear Pepsi from the 90?s! Their densities can be in the vicinity of a block of cork, for reference. Much fun playing one-handed catch with a CMU =).

Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805

Just to throw something out there since you have the motivation right now to research the topic, here?s the extent I?ve ever gone to get to the bottom of the ?F-Factor? questions. ASHRAE Fundamentals 2009 has a discussion on below-grade heat loss calculations starting on Page 18.30. They reference a 1969 research paper as a primary source of information: ?Latta, J.K. and G.G. Boileau. 1969. Heat losses from house basements.

Canadian Building 19(10):39.?

I haven?t read or researched much beyond 90.1 and Fundamentals for the very reason Nick cited as #1: the standard essentially says not to :)

I?m not sure what you?ll find if you are able to get a copy of that research paper, but I?m sure it will shed some interesting light on the topic.

Jeremy R. Poling, PE, LEED AP+BDC

Jeremy Poling2's picture
Joined: 2011-09-30
Reputation: 0