[MassHistPres] Double Glazed Replacement Windows

[Dennis De Witt]

Pat

The short answer is that Brookline requires retention of existing  
windows (allowing absolute single-glazed TDL like-kind replacement per  
MGL 40c) -- because windows are important original fabric and because  
no credible economic or green argument can be made for replacing them  
vs adding good storms.

We do have one LHD with some interwar houses with steel casements.   
Because they are not easy or inexpensive to repair, and because there  
is no really satisfactory storm system for them for someone who wants  
to open their windows, we have allowed their replacement on a hardship  
basis (the hardship relating to the repair, technical, and design  
issues specific to those windows) with similar aluminum and fiberglass  
frames.  It is not fully satisfactory.  Neither alternative has as  
thin frames or muntins.  We have variously allowed both TDLs and  
single units with adhered non-flat muntins.  The former gives more  
realistic reflectivity but the muttons are too wide while the latter,  
like all non-TDLs, reflects like a single sheet of glass, with the  
funhouse mirror effect typical of IG.

I assume you know that replacements with modern (post 1980s)  
organically sealed insulating glass (IG) do not make any sense  
economically as compared to repair combined a good triple track [e.g.  
Harvey Tru-Channel].   Modern IG will always fail (cloud up) --  
typically before they have paid for themselves.  Good tight storms  
will deliver 90% of the replacement widow's efficiency at a fraction  
of the cost and will never fail.  As you may also know good storms are  
available with Low-e glass.  Low-e can be used to in such a way as to  
allow solar gain in and keep it in for winter heating economy or to  
keep solar gain out for air conditioning economy.  All except some  
expensive custom replacement windows are, as a matter of course, made  
for southern summers rather than for northern winters.  With locally  
available storms, the opposite is true.  As you may also know, wood  
framed, triple track-like storms with triple track-like lower sash/ 
screens are also available with low-e.

Dennis De Witt
Brookline


Below is an article from the Globe which I posted a while back.   
Interestingly, this particular house is in a Brookline LHD, although  
that was not mentioned in the article and does not seem to have  
impacted the recommendations.  Chris has the illustration that went  
with it.  The article is about making homes more energy efficient.   
The illustration shows the cost, savings payback periods of various  
energy saving investments.  Note the last item:

Air Sealing — payback:2.5 years
Storm doors and storm windows — payback 13-15 years
Door weather stripping — payback 2.5 years
Aircrete foam wall insulation — payback 6.5 years
Cellulose attic floor insulation — payback 9 years
New furnace of boiler — payback 8 years
Replacement windows — payback up to 33 years
		(That's longer than the lifetime of the insulating glass!  Note the  
6th paragraph from the bottom below)

These are said to be average numbers based in information from  
Conservation Services Group, a non-profit entity which does energy  
audits -- I think largely for public utilities.

When I first sent this story out Chris made the following comment:

Interestingly, I had an energy audit on my 1850 house with all original
6 over 6 windows last winter.  While they need some rehabilitation, we
have plugged all of the gaps with mortite so there is very minimal
infiltration.  I didn't tell the auditor where I worked or what I did
for a living.  I fully expected him to bring up the windows and that
they needed to be replaced but he didn't.  At the end of the audit, I
asked him about the windows.  His response, "Oh, don't replace your
windows.  You won't see savings for 30 years."

The following is the text of the article — less a deleted section on  
financing:

  So, this is the year you're finally going to bring your house in  
from the cold? You're not alone, and there's help available from many  
places to narrow the number of winterization choices to the most  
effective, and steer clear of the costly.  Despite the retreat in oil  
prices, heating fuel costs remain high - home heating oil, for  
example, is in the mid-$3-a-gallon range.

Numbers like these were the tipping point for Brookline resident  
Rebecca Mailer-Howat. Her household held off for years before spending  
thousands of dollars last month on an energy-efficient retrofit of  
their 1870s Colonial Revival. The Mailer-Howats started with an  
ecologically friendly insulation foam called Aircrete, which was blown  
inside the walls of the house, and then expanded to fill in airways  
and hidden gaps and holes. Next the family plans to upgrade its hot  
water system, and add solar panels.

"I always wanted to do it, but circumstances have indicated that we  
should hurry up," Mailer-Howat said. "And everything's just going to  
keep getting more expensive."

Like Mailer-Howat, homeowners hoping to dodge the winter heating  
bullet should get going now. But be cautious about spending large sums  
on big-ticket projects that may do little to lower your bills.

Bruce Harley, technical director at the nonprofit efficient energy  
consultant Conservation Services Group, said there are multiple ways  
homeowners can cut heating costs by themselves. He divides home  
winterization into four primary elements: insulation, air sealing,  
ductwork, and heating equipment.

"I liken insulation and air sealing to the sweater-windbreaker  
analogy. Neither one alone is going to keep you warm on a chilly day,  
but put them together and it's a really good system," said Harley, who  
has authored two books on home energy-saving projects. Filling walls  
with cellulose, foam, or fiberglass insulation can boost the house's R- 
value (the measure of its thermal resistance) from an insulation-free  
3, to a whopping 12. But air leaks - gaps, slits, and other hidden  
openings - throughout a house can defeat that improvement. "Ideally  
the contractor seals leaks as part of the prep for insulation," Harley  
said. "Of course, some contractors understand this much better than  
others."

Finding those air leaks, however, is not always easy. They are  
sometimes behind walls, along chimneys, or in dark and hard-to-reach  
spaces in the attic or in the basement where the house foundation  
meets the sill.

And, because some of these gaps can be tucked away doesn't mean they  
are small. According to Hurley, they can be "large enough to put your  
arm or head through; even newer homes often have large air leaks that  
render insulation practically useless." These gaps can be plugged with  
a variety of foams, or other insulation and even closed off with sheet  
metal.

While most New England homes are spared the expense of energy loss via  
ductwork, Harley said, sealing such pathways where they do run -  
typically in crawl spaces or garages - becomes critical to capturing  
the benefits of new insulation.

And that leaves the heat generator itself; the hardware in the  
basement. "If your furnace or boiler is more than 20 years old,  
chances are it's reaching the end of its service life," Harley said.

Homeowners can realize enormous savings by replacing old systems with  
modern, certified high-efficiency boilers and furnaces. Though they  
run into the thousands of dollars, new heating systems will yield  
immediate savings in fuel consumption, savings that can pay for the  
upgrade within 10 years.

But Harley and Berry cautioned homeowners to think twice about some  
big ticket items - chief among them are new replacement windows. Often  
the costs of the new windows far outweigh the savings they deliver.  
"When you look at the amount of space your windows take up compared to  
the overinsulated portion of wall space, it is most likely cheaper and  
more cost effective to add additional insulation to a wall," Berry said.

For far less money - as much as half the price - new exterior storm  
windows can be a smart investment in increasing the efficiency of  
aging windows, because they slow the loss of heat from inside and  
reduce air leakage. Meanwhile Harley identified other energy  
efficiency measures that don't pay off, including duct cleaning (as  
opposed to sealing), fan-fold insulation board used in typical re- 
siding projects, and anything marketed as "reflectivity" or radiant  
barrier.

These include thin insulation with foil layers and, believe it or not,  
paint. "They always have hugely inflated claims for R-value, which are  
simply not justified by physical reality, Harley said.

For some homeowners, conventional costs are not the only  
consideration. The Mailer-Howats wanted to use environmentally  
beneficial products, so for insulation, they chose Aircrete, a  
magnesium oxide expanding foam, which is fireproof and nontoxic, over  
the more common blown-in cellulose insulation. Aircrete costs $2.70- 
per-square-foot, compared to $1.40 or more for cellulose.

"We always wanted to do this, but what we wanted was something that  
made sense ecologically and environmentally, that didn't have any  
toxic complications," said Patrick L. Mailer-Howat, as workers from  
All Weather Green Insulation scaled ladders at his home in preparation  
for the installation.

"We're not bleeding heart, naive hippie children," added Mailer-Howat,  
who is chairman of Vita Bio Group, a biomass energy development  
business. "We are interested in being proactive in our husbandry of  
resources, with an outlook to a mid- to long-term future. I mean this  
is my retirement home."

On Apr 27, 2009, at 5:58 AM, Pat Patrick wrote:

> As chair of the Old and Historic Districts Commission,Marblehead, I  
> am tasked with surveying other historic commissions and boards  
> regarding to allow or to deny double glazed replacement windows in  
> our historic districts.  I would appreciate some feedback on how  
> other towns approach this matter.  We currently require true divided  
> lite, wood, single glazed replacement windows.  Exceptions are  
> allowed on a case by case basis.
>
> Pat Patrick
>
> James M. "Pat" Patrick
> OldTownRepair
> 2 Pleasant Court, Ground Floor Office
> Marblehead, MA  01945-3310
> 781-631-5145 (P)
> 781-639-8024 (F)
> pat at oldtownrepair.com
> www.oldtownrepair.com
>
>
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