9ft h windows, floor to ceiling
In order to satisfy LEED and Energy Star requirements, our U-values had to meet the following requirements outlined in the Energy Star zone map. New York City is in the upper most reaches of the North-Central band, while the rest of New York State lies in the blue Northern Zone. Yes, the map is a little hard to discern this. We set our sights on the Exceptional Windows, to guarantee the best performance at the building's Achille's heel.
Wood, fiberglass, vinyl, and aluminum are three primary frame options to choose from. Wood and vinyl are superior choices for achieving low U-values at affordable costs, but neither were real options for us. Wood does not meet NYC Building Code for multi-family housing, and vinyl has many environmental issues associated with it. Vinyl actually has 60% of the market share as noted in this Environmental Building News article Choosing Windows, Looking Through the Options. But despite vinyl's great energy performance and typical low cost, the production and disposal of of vinyl is a toxic task, and as a known carcinogen that off-gases it is not on our list of materials that we want to go into our non-toxic building.
Aluminum has been the industry standard in multi-family housing in NYC and one day we will look back, surprised that these were ever installed. They will be reminders of a by-gone era when energy efficiency wasn't of real concern. Aluminum windows offer a more commercial and modern aesthetic, but their performance is basically lousy, even with a thermal break. With U-values hovering around .45 they are they are true energy conductors, and can not meet new Energy Star (version 3.0) mandates.
tilt and turn doors at the front balcony
So, we turned to Fiberglass. Fairly new to the market over the past 10years these windows have been in greater use in Canada and Europe and are slowly making their entry into the US market. The benefits of fiberglass are 1) their thermal performance rivals wood and vinyl so is a good option for multi-family 2) coefficient of expansion closely matches glass so their ability to stay tight within the opening over long-term is superior than other options 3) can be painted easily 4) structural capacity is high allowing for thinner frames 5) durability and life-span have been shown to be significant. A few downsides are that they have no recycled content, and recycling in the after-life only possible into aggregate, and emissions during production may be higher than other options.
There are a lot of manufacturers that offer fiberglass options, even the usual suspects. The costs compared to aluminum are similar, although a bit more pricey than vinyl. So we narrowed down the search and looked at Marvin, Pella, Serious, and Inline based on their price, and profiles. Windows really require a hands on understanding - images below are from reps that visited our office so we could get a real feel of what the windows would look like. Below is a quick chart rating each one for cost, thermal performance, overall quality and modern aesthetic.
Marvin, All Ultrex series
- cost rating : Moderate
- performance : uModerate, ranges from .29 to .33.
- construction quality : Moderate
- modern aesthetic : Moderate
- cost rating : Moderate
- performance : Moderate, with ranges from .28 to .45. Not all windows meet En.Star req's.
- construction quality : Low
- modern aesthetic : Low.
- cost rating : High
- performance : Excellent, with a range from .09 to .22, the lower the U-value the more costly.
- construction quality : High
- modern aesthetic : High
- cost rating : Medium
- performance : Excellent, with a range from .13 to .30, the lower the U-value the more costly.
- construction quality : High
- modern aesthetic : High
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