[MassHistPres] More window material

Sat Sep 26 08:16:12 EDT 2009

Just point of information, going rate for installed Harvey Tru-Channel 
storm windows with Low E glass is around $250 each. Typical cost for 
weather stripping, cord replacement, patch glazing, etc is around 
$200-300 per window.

There ought to be a whole lot more noise about storm windows. They are 
by far one of the best investments a homeowner can make.

Alison Hardy

Dennis De Witt wrote:
> 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 <mailto: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 <mailto: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> 
>> [mailto:masshistpres-bounces at cs.umb.edu]*On Behalf 
>> Of *slater at alum.rpi.edu <mailto:slater at alum.rpi.edu>
>> *Sent:* Friday, September 25, 2009 12:04 PM
>> *To:* masshistpres at cs.umb.edu <mailto: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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