[MassHistPres] More window material

Fri Sep 25 14:41:45 EDT 2009

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]
> 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
> *******Stay Informed on Historic Preservation Topics by joining the  
> MassHistPres Email List. Visit http://mailman.cs.umb.edu/mailman/listinfo/masshistpres 
>  for more information. ******MHC offers regional training workshops  
> to local historical commissions and historic district commission  
> members on a variety of topics. ******The MHC has a new 50 minute  
> DVD for Local Historical Commissions. ******The Local Preservation  
> Update is MHC's new bi-weekly e-newsletter.  For more information on  
> any of the above, please contact me.
>
> -----Original Message-----
> From: masshistpres-bounces at cs.umb.edu [mailto: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
> ******************************
> For administrative questions regarding this list, please contact Christopher.Skelly at state.ma.us 
>  directly.  PLEASE DO NOT "REPLY" TO THE WHOLE LIST.
> MassHistPres mailing list
> MassHistPres at cs.umb.edu
> http://mailman.cs.umb.edu/mailman/listinfo/masshistpres
> ********************************

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cs.umb.edu/mailman/private/masshistpres/attachments/20090925/079bea3e/attachment.htm>