Green Means

Selecting Quality Windows

By Shannon Scott

            Selecting windows for a home involves a whole lot more than just deciding upon price, brand, and color.  With glass a major expense for any home, time and care must be taken to find two things: manufacturers that produce quality, environmentally responsible, and energy wise products; and distributors that offer competitive prices and good customer service.

            Since we’ve begun our small straw bale cottage project I phoned several window distributors in and around our area asking for Sierra Pacific brand windows, though I was open to learning about other green savvy products as well.  While many manufacturers offer claims of environmentalism, Sierra Pacific was one of the first to show genuine concern for sustainable production, from responsible timber growth to using zero VOC (volatile organic chemical) paint finishes. 

            Nu Vu Glass in Twin Falls phoned  back the same day and within two days e-mailed preliminary prices.  Mark, their chief sales rep for our area, suggested that I look into Anderson Eagle series and Weather Shield.  Nu Vu carries Marvin and several other major window brands.  Delivery to our area is included in their bids.

            After some back and forth with Mark and internet research on window configuration and brands, I narrowed it down to Marvin, Andersen, and Sierra Pacific.  Marvin definitely had nicer finish details than the other brands, but with the corresponding higher cost.  Anderson offers many options and boasts some green qualities, but ultimately I stuck with the Sierra Pacific.  The convincing feature, besides sustainably harvested wood was the no VOC exterior finish.  Now it’s up to me to find zero VOC interior wood finish products, as it doesn’t appear that Sierra Pacific offers prefinished models.

            With brand selection out of the way I had to compare glass features.  Passive solar design necessitates south window glazing that allows sun’s warmth to penetrate during winter months, while maintaining a fair level of insulation to keep out summer’s heat.  No direct sun enters south windows during summer, but the ambient outdoor temperature can still migrate inside.

            All window manufacturers post technical specifications on their websites so customers can compare glazing data.  I compared various combinations of U-values - lower numbers mean greater insular quality; SHGC or Solar Heat Gain Coefficient which indicates the allowance or disallowance of solar heat to penetrate (for south windows I want penetration, for all other sides minimal penetration); a high VT or visible transmittance for a nice clear view; and low CR, the Condensation Rating that tells how well glass resists condensation build up. 

            Deciding upon the best combination of features involves compromise.  Ideally, I could run a northern Nevada construction laboratory, build three to four identical buildings side-by-side each with slightly different glazing option combinations to see which combination of U-factor, SHGC, and VT prove optimal.  Since I don’t have the luxury of a local construction physics laboratory, I’ve got to go with available data and my best guess for optimal interior year round comfort levels and energy efficiency. 

             Higher SHGC (solar heat gain) means reduced U-value (insulation).  The slightly reduced U-value should prove negligible.  I’m weighting warmth in winter as more critical for human comfort and energy efficiency than cooling in summer.  We have relatively fewer super hot days as opposed to colder winter and spring time temperatures.  Plus, during summer months windows can be opened at night to allow in cooling high desert temperatures then closed in early morning to block out the day’s heat.  This type of physical adjustment to the building envelop is not available during winter.

            After reading charts and graphs to near delirium, I decided upon Low E² 180 Cardinal double glazed for south side windows.  These offer decent, but not great, insulation value while allowing in solar radiant heat.  For the north, east, and west faces the two better, and budget minded glazing options are either Low E²  366 i89 or Low E² 272 i89.  The final decision here will depend on price difference.  There are more heat deflecting and insulating options, like triple glazing, but they cost more.  The difference in glass quality must be measured against heating and cooling energy costs.

            Mark Birrer from Nu Vu Glass had my back on most the tech stuff.  He had quoted prices on pretty much what I had selected before I provided technical specifics.  So much of the time, unless we customers do our homework, sales forces do not ensure that we get the exact right product for our needs.  Even if you like and trust a supplier, double check technical data and specifics on everything you order.

            Frankly, I’m happy if a supplier just returns phone calls, but actually figuring tech data and then, get this, driving out to the boonies where I live to show Rob and me samples was pretty nice especially considering that our project is so small.  Mark still championed for Andersen Eagle series, which are a nice window, but ultimately we settled on Sierra Pacific.  They seem to be the underdog of window manufacturers, smaller but more humble, sort of like our project. 

            Window selection is critical for energy efficiency, comfort, aesthetics, and home quality.  Shop widely and wisely.  If you need assistance make some calls.  Nu Vu has been good to work with.  They get back to customers right away and are thinking green.  Mark showed up in Elko driving a Nu Vu Glass company Prius.  You can reach them at 208-734-9877. 

              Shannon Scott is a LEED Green Associate and green home owner, designer, builder.  You can reach her with questions or for green building help at greenmeansnv@gmail.com