[MassHistPres] More window material

Mon Sep 28 11:39:11 EDT 2009

This is the information I got from a renovation contractor who regularly
uses blower door testing on work.

"The level of improvement depends on how bad the windows are to start with,
of course.

That being said, you can expect improvements ranging from 25 to 75
cfm at 50per window for a good weatherstripping installation and (at the
higher end)
a storm window replacement. Window replacements will yield a range a bit
higher--on the order of 40 to 100 or so."

The way I read this is that if you address a leaky window properly, you
house will get a tiny bit more comfortable and the difference between which
approach (assuming good materials with either) you will initially see a
difference.

I feel that material life expectancy and the effects of aging are more where
we should be talking about. What happens in 5 years, 10 years or 15 years
down the road is what the average homeowner is going to feel they need to be
paying attention to.

Let's all look back at the e-mail from John Warden in Arlington to see a
great response.

Cheers,
Garrett

Garrett Laws, Manager
The Copper & Slate Company
Fine Roofing and Exterior Finish Carpentry
238A Calvary Street
Waltham, MA 02453
Ph: (781) 893-1916
Fax: (781) 893-2041

Copperandslate at Gmail.com or
GLaws at hbuilders.net

On Fri, Sep 25, 2009 at 3:24 PM, Dennis De Witt <djd184 at verizon.net> wrote:

> Lee
> Such a testing facility was already built and used by Lawrence Berkley
> before 2002  See the attached report.   Maybe that's what inspired the one
> you are referring to.  In this case too it would be great if some PE could
> just summarize it into a few pages of relatively comprehensible charts and
> text.  Right now it almost need a PhD in physics to follow and the
> conclusions are not summarized out a in simple accessible form.
>
> Dennis
>
>
>
> On Sep 25, 2009, at 3:08 PM, Lee Wright wrote:
>
>  Dennis--
>
> My understanding is that the NT is sponsoring a large study at Berkley.  I
> don't recall when it's going to be available, but as I recall it wasn't
> going to be for awhile.
>
> It doesn't seem like it would be that hard for an established testing
> facility to set up and test the various approaches.
>
> I dug up this NPS study last fall . . .
>
>
> http://www.scribd.com/doc/8167584/Testing-the-Energy-Performance-of-Historic-Windows-in-a-Cold-Climate
>
> . . . but at 175 pages, much of it fairly technical, it's far from
> user-friendly.
>
> Late last year I tracked down the author--he now works for the state of
> Vermont--and sent him a note.  I just followed up with him and asked him if
> would be interested in distilling down his report to a 1 - 4 page piece that
> would include a worksheet (or reference an online tool).
>
> I'll let you know what I hear.
>
> Best--
>
> Lee
>
>  ------------------------------
> *From:* masshistpres-bounces at cs.umb.edu [
> mailto:masshistpres-bounces at cs.umb.edu <masshistpres-bounces at cs.umb.edu>]
> *On Behalf Of *Dennis De Witt
> *Sent:* Friday, September 25, 2009 2:42 PM
> *To:* MHC MHC listserve
> *Subject:* Re: [MassHistPres] More window material
>
> I agree.
> What seems to be missing is the alternative of installing high quality
> storms (e.g. Harvey tru-channel) w/ or w/out low-e.  They should have an
> infiltration number comparable to the IG replacement windows and the U value
> probably wont be much different than what you would see for the typically
> generic IG used on cheap vinyl sash.  So, you can spend maybe $150 per
> window on the storms, save the original windows (and maybe spend $150 per
> window on average tightening them up) and not have something that will fail
> in 20 years.
> Why can't the National Trust or the NPS contact this state government
> agency and get them to incorporate storm windows into their equation?  -- in
> two places a) factor them in to the "before" figure if they already are in
> place & b) offer them as an alternative to replacements for the "after"
> figure.
>
> Dennis De Witt
> Brookline.
>
>
>  On Sep 25, 2009, at 2:06 PM, Michael Smith wrote:
>
>   Our advice to homeowners is to rehabilitate existing historic single
> pane windows and install new storm windows to gain energy efficiency.  This
> seems to be a common suggestion in much of the literature on historic window
> restoration.  Comparing the infiltration rate of an old wood window with
> that of a new insulating glass, energy-efficient window, without factoring
> in a new storm window seems inconsistent with most recommendations.  Or am I
> missing something?
>  Michael Smith, Co-Chair
> Belmont Historic District Commission
>   ------------------------------
>  *From:* Chris Skelly [mailto:Skelly-MHC at comcast.net<Skelly-MHC at comcast.net>
> ]
> *Sent:* Friday, September 25, 2009 1:57 PM
> *To:* masshistpres at cs.umb.edu
> *Subject:* Re: [MassHistPres] More window material
>  I think making any assumptions on the "infiltration" factor of an old
> window demonstrates that this worksheet is misleading.   Just because a
> window is old doesn't mean it has to leak air.
>  Would we use this logic to demonstrate how much money we would save by
> buying a new car?  If comparing how much money you would save on automobile
> fuel, you would need to consider the miles per gallon of the old car and the
> miles per gallon of the new car.  All old cars don't have the same miles per
> gallon and all old windows shouldn't be treated with such a broad brush
> either.  Furthermore, the infiltration that will occur over time with a new
> vinyl replacement that warps and bends needs to be factored here as well.
>
>
> When it comes to saving energy on heating a home, infiltration is a major
> issue that needs to be addressed.   Yet when it comes to old wood windows,
> infiltration can be addressed very effectively through a number of methods.
> Methods such as installing removable rope caulk each fall are very
> inexpensive.  For those on a tight budget and faced with leaky windows, this
> can make a huge difference.  Chris.
>
> Christopher C. Skelly
> Director of Local Government Programs
> Massachusetts Historical Commission
> 220 Morrissey Boulevard, Boston, MA 02125
> Ph: (617) 727-8470 / Fax: (617) 727-5128
> Christopher.Skelly at state.ma.us
> http://www.sec.state.ma.us/mhc/mhcidx.htm
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>  -----Original Message-----
> *From:* masshistpres-bounces at cs.umb.edu [
> mailto:masshistpres-bounces at cs.umb.edu <masshistpres-bounces at cs.umb.edu>]*On
> Behalf Of *slater at alum.rpi.edu
> *Sent:* Friday, September 25, 2009 12:04 PM
> *To:* masshistpres at cs.umb.edu
> *Subject:* Re: [MassHistPres] More window material
>  Maybe someone can help me out here. I just did this worksheet for window
> replacement:
>
> http://www.dnr.mo.gov/forms/780-1363.pdf
>
> Based on my calculations, it told me that a house with 30 single pane
> windows with storms will consume 582 gallons of oil -- just for the windows
> -- and that if you install low-E replacements, it would consume just 233
> gallons of oil just for the windows. Replacing would save 439 gallons of oil
> annually.
>
> Let me tell you my assumptions and maybe someone else can try this.
>
> First, I assumed 30 windows at 32" x 62" -- each being 13.9 square feet.
> That's about the size of my second floor windows. Multiplied by 30, that's
> 417 square feet of windows.
>
> Second, I used 0.5 U-value for single pane with storms, 0.38 for
> double-pane with low-E glass. That's an agreed upon number.
>
> I used the "degree days" method in line 6, since this form is for Missouri
>  and we are in Massachusetts. The calculation says "degree days x 24 /
> 10^6". I used 6250 degree days, a number I got from an energy website. That
> changed the factor to 0.15 versus the 0.1 for Missouri.
>
> I used an energy cost of $19.73 per million BTUs. That was based on oil
> being $2.75 per gallon. It came from this website:
>
> http://energy.cas.psu.edu/costcomparator.html
>
> I treated the fuel efficiency as 100% in the calculation because the energy
> cost from the previous step already factored that in.
>
> I assumed that a vinyl replacement window costs $300 installed.
>
> Using the formula on the spreadsheet, it said that if I keep the original
> 30 windows, I will spend $1,849 in heating costs, and if I replace them, I
> will pay $641 in heating costs.
>
> If that's true, that seriously weakens the argument for keeping the
> originals pretty significantly -- if a replacement window costs $300, then
> payback period is just 7 years. If oil goes up by 45% to $4/gallon, then the
> payback period is just 5 years.
>
> One big factor is that the calculation uses something relatively new (it
> wasn't on an earlier version of the form) called an "infiltration factor".
> It is set to 1.00 for old windows, 0.14 for new windows. That seems a little
> arbitrary, and it completely changes the results of the calculation. Without
> this factor, a replacement window without low-E glass is actually less
> efficient than an original window with storms.
>
> I did some research on "low-E" -- there is some thought that it does not
> last for the life of the window, and may only last for 5-6 years before
> breaking down.
>
> Can someone else validate my numbers? Honestly, they are just not that
> believable. I have 49 windows in my house -- some of them are quite leaky,
> such as leaded glass casement windows -- with storms, though the leaded
> glass transoms above them don't have storms. I also have several windows
> without storms -- two 2nd floor bathroom windows and a casement window over
> the kitchen sink, plus a fixed window with multiple lights, plus a couple of
> 3rd floor casements that open inward. Many of my windows are larger than the
> example I used too.
>
> I use about 1,200 gallons of oil per year to heat a 4,000 square foot house
> to around 65 degrees. If I plug 50 windows into to this worksheet, it says
> 1,100 gallons of that is due to the windows, and I would save 718 gallons
> per year by replacing them.
>
> I just can't believe that on its face. Could these calculations be designed
> to justify replacement?
>
> Ralph Slate
> Springfield, MA
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