Low e will certainly effect plant growth. Ultraviolet Light (UV) Ultraviolet light is comprised of three different wavelength ranges of light. UVC (200-280nm) has the shortest wavelength and most energy, but is potentially the most stressful to plants and human skin causing sunburn and can be very damaging to human eyes. Fortunately, for humans and plants atmospheric absorption eliminates the majority of UVC shortwave light. no need for a window film to block it. UVB (280-315nm) has a short wavelength, high energy and also causes sunburn in humans and plants. UVB is known to damage protein and nucleic acids in plant cells, causing decreased metabolism and decreased number of flowers. UVB can have positive effects as well.. A plant responds to the stress and sunburn from UVB wavelengths, by creating it’s own sunscreen in the form of trichomes and cretinoid. Exposure to UVB radiation is also known to reduce a plants biomass, plant height and leaf area, but increase leaf thickness. lack of UVB causes leggy plants. Finally, UVA and near ultraviolet light (315-400nm) has the longest wavelengths of UV light and can be very beneficial to plant development. Wavelengths in the UVA spectral range are included in the absorption spectrum, particularly in the 380nm range. The absorption spectrum is the range of wavelengths of light that are absorbed by green chlorophyll for photosynthesis. Additionally, research has shown that exposing plants to UVA light can also inhibit mold growth and fungal development. Far-Red and Infrared Light On the far end of the spectrum (>700nm) you find far-red and infrared wavelengths of light. Far-red and infrared light have very long wavelengths, and very little energy. Infrared wavelengths are not visible to the human eye and only can be felt as heat. We know that blue and red light is optimal for plant development, but research conducted in 1957 has shown that combining blue light and red light with far-red/infrared light (700-760nm), led to an increased rate of photosynthesis due to the Emerson effect. The protein Phytochrome is the only known receptor that is sensitive to far-red/infrared wavelengths. Plants use Phytrochrome to regulate when a plant is to switch from vegetation state to flowering, and the time of flowering, due to the length of daylight or exposure to artificial light. The appropriate amounts of far-red and infrared light can also be a very effective at promoting robust stem growth, proper node spacing, and more flowers and fruit. Too much IR radiation can also be an issue because to a plant the majority of IR radiation is felt as heat. consider the amount of light (PAR or PPFD) needed to successfully grow your plants. then decide if low e is sufficient for you. It may lack certain lighting requirements.

It sounds like the 266 is better for you. But it all really depends on orientation, climate, shade etc. There is no one answer. Even mixing windows on a house might be a good idea. The Midwest is a large area - could be Minn - could be St Louis. You might have a/c or you might not and are willing to spend some money so that you can continue to live without a/c. If you are predominately cold - then obviously a little more solar heat gain is a good idea. U value becomes the most important. If you have some heat - then low solar heat gain is important if you are unshaded and the windows get sun in the summer. I live in mixed and my North windows never get direct sunlight - SHG doesn't really matter there. Now my West windows - it would make sense to pay for less SHG. And generally in South windows, a higher SHG is a good idea to maximize winter heat gain. So the answer depends on too many things to say one is better than the other. But in the midwest, you probably want relatively more SHG. Not a simple subject and you would hope that your builder would have some guidance in your particular situation. If not your builder, then some energy consultant. It seems like an energy consultant (like Energy Star) should almost be standard on new construction since a lot of builders don't seem to care.

I ended up telling Sierra Pacific that they were the same price as Marvin & that I was going to buy Marvin. Sierra reduced my whole house price by $12,000! Hard to refuse that offer. What is the primary difference btwn SP & Marvin? Also- is there a rating that tells you how the glass will reduce the chances of fading my hardwood floors & furniture? Is there more than just LowE2 rating to tell me how well the glass helps in fade prevention or reduction?

Mrschlab, Oberon476 gives some seriously spectacularly helpful information. I wish he'd come to my house and tell me which manufacturer to purchase from for my upcoming renovation and how to get what I want with my window and door impact glass :) I am currently also in the hell of LowE, clear glass or tinted glass decision-making process. The previous owners put one SGD (two 3' panels) facing north and two more SGDs (seven 3' panels). They are CWS vinyl frame LowE366 Argon IG units that were installed in 2014/2015 on the east side of our house. Bear in mind the remaining impact-resistant windows are clear glass on the west side of the house (go figure). Those were installed in 2009 (my guess from the etching on the glass, I find no permit indicating when they were installed) I brought home this luxury vinyl sample; this is how I realized the extent of the change in the color of the natural light coming in through the LowE366-laden SGDs. Because I'm choosing a specific tone on the flooring product, I don't want the color/hue/tone changed by the windows. The LVP is a warm-neutral tone, but not yellow or honey colored LVP. I wanted to see what the LVP looks like on a sunny day, so I took it out back one morning. Then I brought it inside and set it down next to the SGD (with the LowE366). Below are the results. (I mention that the LowE366 SGDs were installed in 2014 because I don't know if the LowE366 color changes with time or if the fact that they're IG units has an effect; or maybe in 2014, CWS used an obscure LowE product-- I do not know these answers.) Also, keep in mind that the phone camera and subsequent computer image may not be an exact representation of the colors, but to my eye right now looking at the computer screen, the colors are 99% accurate. The first photo was taken in the morning sun on the east side of the house in sunny South Florida through the LowE-366 SGD. The second photo was taken when I opened the door to go out with natural sunlight on the LVP and rug below it. Is the hue of light from the sun coming into the house drastically changed by the LowE366? You be the judge. (I say YES) Also, when I look at the LVP in the afternoon on the west side of the house with sun coming in through clear glass, the tone of the LVP is yet again a natural wood tone, just like you see with the door open. I did have to close the plantation shutters on the east-facing LowE366 SGDs to control the experiment so the only incoming light came in through the clear glass of the west-facing windows. Hope my pathologically detailed research helps you make your decision :) All it helped me do was rule out LowE 366 and plan on shade for my new SGDs and windows.