Replacing coop windows why aluminum ?

As a practical consideration, you should direct the requirements question to your coop's managing agent. The building management (ultimately the board) sets the rules for your building. Those rules will be a combination of NYC building codes, landmarks rules, etc., plus anything the building decides is a requirement. (Your vinyl may fail on simple aesthetic considerations, for example.) The bylaws and proprietary lease will come into play too, since usually the exterior facade including windows is a coop maintenance responsibility and you would be stepping into their territory here.

Posters here may be able to contribute information on suppliers, and on the general building code requirements, but your specific building can dictate a lot of additional details or prevent you from doing this altogether.

We are the first to replace in our building and hence there is no statute in place (I have checked with management already). It will ultimately need board approval (and they'll decide about color etc), but id like to know going in (before getting a ton of bids for vinyl if it's not to code) what the code actually is and have been totally unable to find this. (I can find code for lot line windows but not non-lot line windows). I asked 2 major aluminum window dealers/suppliers in the NYC area if they could show/send/direct me the code and both say no/are unable to produce it. I don't doubt that it exists or mistrust them, but I like to see things with my own eyes ( esp since the vinyl has higher efficiency rating and is substantially less expensive).

Most buildings have aluminium because it lasts longer, and maintains a good look longer than vinyl. Since the managing agent apparently hasn't been advised of the board's standards, you need to get an opinion from the board before you go too far down a particular path. There were many boards that permitted owners to replace their own windows, and then had to put in window standards when the buildings became a mish-mash of styles and qualities (some of which caused leakage problems when they were of low quality or poorly installed. Walk down Fifth Ave in the 70s & 60s, and you will see the results on many buildings.

Efficiency ratings are more a function of enginnering, manufacturing quality, and installation, rather than specifically vinyl vs. aluminium.

I'm just wondering why you'd want to replace aluminum with vinyl?

Also the energy rating will depend on coatings and engineering.
Aluminum is lighter weight than vinyl.
Aluminum has (typically) a thinner profile.
Aluminum windows come commercial grade which gives you a wider frame to manage heavier/thicker glass (ie: double hung with 2 laminated glass panels and an air space).
Typically, aluminum windows have better sound isolating abilities (but who knows, maybe vinyl has caught up).

I guess it just seems odd that you would want to replace your windows with something that will look very obvious, especially if the rest of the building isn't doing it.

And I think JELD-WEN does commercial vinyl, but honestly I've never spec'd vinyl windows in the city... ever. Wood, steel, or aluminum.

Do NOT do vinyl!

Particularly on south-facing windows, the sashes literally melt in the sun. My building has been prematurely replacing the vinyl windows it installed just 20 years ago. They look terrible and the melting sags the sashes to such a degree that the locks don't even work anymore.

I like how British people call it aluminium .

Are there any aluminum windows that meet Energy Star standards? (name and model numbers appreciated)

Does anyone happen to know what the NYC code says on this (for non lot-line windows)?

NYCMatt: What specifically are they replacing them with? My current windows are 26 years old, ALUMINUM, and are horrid. They break constantly, they let in air, and they are noisy.

architecta: aluminum is better sound-wise. But not heat-wise.

Some data I found (from aamanet)
73% of the US market share of replacement windows is vinyl
2% is aluminum

So that unlucky 73% all have ugly thick windows that melt in the southern sun? And only those 2% have decent windows?! (This of course doesn't account for what's being replaced: that 73% could all be replacing faulty old vinyl windows rather than aluminum windows. However, the overall use of aluminum is very very small comparatively, and getting smaller).

There are certainly aluminum clad windows that meet Energy Star standards.

Example: http://www.marvin.com/windows/wood-casement-windows/

I'm assuming you've been here: http://www.energystar.gov/index.cfm?c=most_efficient.me_index

Yes. I assumed that Marvin's "Wood and Clad Wood" windows that meet energy star standards were wood. They are outrageously expensive (if you know any deals please lmk!!)

We are replacing the vinyl with aluminum.

Don't know why people think they are "horrid" -- it's a window just like any other.

There are a lot of aluminum windows that do meet energy star guidelines. If you do a thermally broken aluminum window, double pane with an airspace (laminated double pane if you want the sound reduction), argon filled, low-e coating (solarban is one type, they have various products) you can meet whatever "energy star" you want. It has more to do with the engineering of the window than it does with vinyl vs. aluminum. Here is a commercial heavy window that can be used in residential for over-size windows http://crystalwindows.com/HF-Series5500DH.html#anchor4. Call someone like crystal and tell them what you want or call an installer and get them to provide you with some options. Crystal is a mid-range window, I actually have the 5500 (see link) in my apartment because we have huge windows and the rest of the building is aluminum (old, crappy and similar to 2000 series). Our windows were broken, wouldn't stay open on their own, leaking heat, fogged up in areas.. the works. New windows move like butter, upgraded to stronger ballast system, and are a huge improvement. I don't know your budget or what you have in your mind as a budget but you will pay more for better performing windows, and it will be worth the investment.

And I wouldn't rely on those percentages you found because it's not accounting for where in the country the windows are going in or what they are replacing to begin with.

Sorry, I shouldn't have said "you can meet whatever energy star you want" above. What is more appropriate is that you can meet high efficiency ratings with adjustments/engineering to the window you have spec'd to you if you request it and they can provide you with the testing #s to compare to whatever vinyl windows you are looking at.