Need new windows, and advice

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Go Blue!
Posts: 2
Joined: Fri Feb 11, 2011 1:19 pm

Need new windows, and advice

#1 Post by Go Blue! »

I live in a 1600 sqft, 1937 built, two story in Michigan. Most of the windows in my house, I believe, are original to the house. Over time, I'd like to replace all the windows, but I'd definitely like to replace the upstairs bedroom windows before next winter as they seem to be the worst in the house (very leaky, frost often forms on them). What I thought would be a relatively straight forward exercise in picking an "efficient" window and finding a competent installer has proven much more difficult than expected. If anyone has thoughts on the following issues, I'd be much obliged.

1) Is there a group that independently tests window/frame performance?

2) What kinds of info should I be checking on the installers? I don't know that I'd know the difference between a well installed/insulated window and a "yank the old one out, put in a new one" job.

3) Should I be looking for windows with high solar gain? This was something I hadn't considered at all until recently. Of the six windows I'm looking to replace two of each face north, west, and east.

4) I think I have a realistic expectation of cost (I'm budgeting $5K for the six windows) and am looking for comfort. Qualtitatively, is there a big difference between, say, a U - 0.25 window and a U -.125 window?


T

Skydawggy.
Posts: 1193
Joined: Mon Mar 05, 2007 10:29 pm
Location: Northern Virginia

Re: Need new windows, and advice

#2 Post by Skydawggy. »

Go Blue! wrote:I live in a 1600 sqft, 1937 built, two story in Michigan. Most of the windows in my house, I believe, are original to the house. Over time, I'd like to replace all the windows, but I'd definitely like to replace the upstairs bedroom windows before next winter as they seem to be the worst in the house (very leaky, frost often forms on them). What I thought would be a relatively straight forward exercise in picking an "efficient" window and finding a competent installer has proven much more difficult than expected. If anyone has thoughts on the following issues, I'd be much obliged.

1) Is there a group that independently tests window/frame performance?
Several. National Fenestration Rating Council (NFRC) tests for energy efficiency, his includes U-factors as well as Solar Heat Gain. http://www.nfrc.org. There is also the American Architectural Manufacturers Assoc. (AAMA) who does structural testing, air infiltration and water penetration. http://www.aamanet.org.

2) What kinds of info should I be checking on the installers? I don't know that I'd know the difference between a well installed/insulated window and a "yank the old one out, put in a new one" job.
Short answer is ask for references. Most of the better companies will not only be happy to provide them, they will encourage you to check them out.
3) Should I be looking for windows with high solar gain? This was something I hadn't considered at all until recently. Of the six windows I'm looking to replace two of each face north, west, and east.
Yes, as high a solar gain as you can get. I would look for something above.40
4) I think I have a realistic expectation of cost (I'm budgeting $5K for the six windows) and am looking for comfort. Qualtitatively, is there a big difference between, say, a U - 0.25 window and a U -.125 window?
Yes, but I don't think that's what you mean. To get a higher Solar Gain you will have to go with a higher U-factor. You will likely end up getting a window with a U-factor around.32 and a Solar Gain near .50. If that is your budget, I'd be looking at triple pane glass. As an example Sunrise makes a triple pane window with krypton gas that has a U-factor of .18 and a solar gain of .42

JScott
Posts: 508
Joined: Tue Jan 04, 2005 5:06 pm
Location: Kentucky

Re: Need new windows, and advice

#3 Post by JScott »

Krypton has gotten expensive. Try to find a Uw@0.20 with argon. The cost of your home in 1937 is probably about what the upcharge on the krypton will be.

Skydawggy.
Posts: 1193
Joined: Mon Mar 05, 2007 10:29 pm
Location: Northern Virginia

Re: Need new windows, and advice

#4 Post by Skydawggy. »

I would also recommend you get an energy audit on your home before spending a lot of money on windows. If your home is poorly insulated and you don't improve the entire envelope, windows will not be of much help. The heat will just escape by other means.

Go Blue!
Posts: 2
Joined: Fri Feb 11, 2011 1:19 pm

Re: Need new windows, and advice

#5 Post by Go Blue! »

Thanks for the quick responses all.

Ecostar:

The U-value vs. Solar gain is one of the things I'm having the hardest time wrapping my head around. Specifically, I have no idea how to determine the best V: SG ratio. I appreciate your recommendations, but how are you determining your numbers?

Also, in terms of the energy audit, I've not had the a blower test, but I've had someone look at the overall insulation and, last summer, had cellulose insulation put in the attic and walls.

Jscott:

I've heard many references to noble gases being used as insulation between glass panes. It sounds like you say no, but do others think there's really a difference between different noble gases?

Skydawggy.
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Location: Northern Virginia

Re: Need new windows, and advice

#6 Post by Skydawggy. »

U-factor and Solar Gain are indelibly linked. Think of the sun coming through your car windows in the winter. Even though it might be 10 degrees F, you still feel the heat coming through the glass. Move your car out of the sun and into the shade and the heat disappears very quickly.

All glass manufacturers offer glass with different degrees of solar gain. The range is roughly .18 to .55. If you live in a heating dominated climate, you would ideally want a window with as low a U-factor as possible but as high a solar gain. The reason is that the winter solar gain actually helps heat your house and if you eliminated winter solar gain you could actually see your heating bills increase. Why? Keep in mind that U-factor and Solar Gain are linked so lowering the U-factor also lowers the solar gain and while a lower U-factor will prevent heat from escaping your home, it will also block the solar gain. Ideally you would want a window with a U-factor of .00 and a solar gain of 100. in a heating dominated climate. Unfortunately with present technology, this is un-achievable.

Windows in a heating dominated climate would ideally have as low a U-factor as possible and also as low a solar gain. When there is a close balance between heating and cooling, we usually use high to mid solar gain windows on the southern exposure and low to mid solar gain on the rest of the house. This can vary however depending on the surroundings. If a house has a lot of trees on the southern exposure we always use high solar gain if we are in a split between heating and cooling because the trees have leaves in the summer which block the direct rays of the sun in the summer but the trees drop their leaves in the winter, so we take advantage of that free solar heat.

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Windows on Washington
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Re: Need new windows, and advice

#7 Post by Windows on Washington »

Go Blue! wrote:Thanks for the quick responses all.

Ecostar:

The U-value vs. Solar gain is one of the things I'm having the hardest time wrapping my head around. Specifically, I have no idea how to determine the best V: SG ratio. I appreciate your recommendations, but how are you determining your numbers?

Also, in terms of the energy audit, I've not had the a blower test, but I've had someone look at the overall insulation and, last summer, had cellulose insulation put in the attic and walls.

Jscott:

I've heard many references to noble gases being used as insulation between glass panes. It sounds like you say no, but do others think there's really a difference between different noble gases?
JScott and EcoStar have done a very thorough job of answering your other questions so I figured I would answer the ones that haven't yet been addressed.

The inert gases most often used in window IGUs (Insulated Glass Units) are Argon and Krypton. Argon is used more by and overwhelming majority because of its relatively low cost when compared to Krypton (1/30th the cost). Argon performs best in a glass space of 1/2" to 3/4". In gap widths of less than 1/2", Krypton performs much better and hence its necessity in triple pane IGUs for insulation.

Addressing the insulation is a start, however, does not usually address what is the more problematic aspect of home energy efficiency (air leakage).

Here is a quick summary of what a comprehensive energy audit entails:

What is a Home Energy Audit?

A Home Energy Audit is the equivalent of a full physical on your home and the systems at work. You might see a doctor for a visit if you are suffering a malady and the same rational can be applied when discussing the necessity for an energy audit.

Your home is your most valuable investment and very likely your most significant expense. High utility bills and uncomfortable rooms are the two most cited reasons for an energy audit. A full service energy audit will identify and quantify the extent of all of those issues (utilities, comfort, consumption) while examining the health and safety of the home (air quality, combustion safety, structural, and pests).

A full scope Windows on Washington Energy Audit includes the following diagnostics:
• Building Inspection
o Interior – Basement, attic, and crawlspace inspections for moisture, ductwork condition, leak pathways (air and water), and insulation condition and R-Values.
o Exterior – Inspection to assess grading, structural issues, roof venting, HVAC components, gas leak detection, and water tightness (Flashing, paint, and caulking).
• Combustion Safety Testing
o Natural draft combustion equipment (Furnace, stove, water heater, boiler, etc) will be tested to determine if the equipment is drafting properly while preventing an unhealthy and unsafe CO (Carbon Monoxide) level.
• Combustion Efficiency Testing
o Furnaces, water heaters, and boilers will be tested to examine the current efficiency of the unit and determine the necessity for replacement or service.
• Blower Door Testing
o The blower door is used to quantify the amount of cumulative air leakage the home is allowing. This testing in conjunction with the Infrared Camera examination pinpoints air leakage, insulation bypasses, and repair potential.
• Infrared Camera inspection
o Infrared cameras indicate the surface temperatures of building surfaces and, in doing so; identify the source and locations of air leakage.
• Duct Leakage assessment
o HVAC duct leakage and its severity are identified with the use of a pressure pan. The quantification of the duct leakage (cfm) can be achieved with the use of a Duct Blaster for an additional fee.
• Report and Recommendations
o All of your results will be summarized and explained in a comprehensive report that will include the testing data, analysis, and photographs.
o A detailed list of work scope recommendations will be provided to you as part of the summary results.

A Windows on Washington Energy Audit utilizes the most detailed and thorough testing available today. Our Auditors are Building Performance Institute (BPI) certified and Windows on Washington is a Gold Star Certified contractor. The Gold Star Certification provides you quality assurance that Windows on Washington is maintaining the highest standards as set forth by BPI.

Upon completion of the recommended repairs, a majority of our customers notice over a 20% reduction in utilities and immediate abatement of comfort issues. These types of repairs (insulation and air sealing) have extremely fast payback schedules (ROI) and will continue to pay you back as long as you own the home. Couple the utility reductions with the repair of nagging comfort issues and our customers wonder why they put off starting the work!


In regards to what combination of performance data is best for your home, I agree with the feedback so far that you would want to got with higher Solar Heat Gain on the South facing windows and go with as low a U-Factor on the other windows (these windows will have lower SHGC because there is a trade off between lower U-Factors and as you get windows with lower U-Factors (triple pane, multiple surfaces of Low-e, heat mirror layers, etc) the windows SHGC will drop as well)

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