Renewable Energy

Published on March 17th, 2008 | by Philip Proefrock

47

Super-Insulating Vacuum Glass

sample thermography imageIn terms of energy efficiency, windows are one of the biggest contributors to heat loss from buildings. However, a new window technology being developed by Guardian Industries could allow for windows that can provide insulation values comparable to a standard insulated 2×4 stud wall, with a new double-pane glass and a vacuum between the panes.

A thermos keeps hot beverages hot and cold beverages cold by separating the contents from the outside world with a vacuum. Heat is conducted by three modes, conduction, convection, and radiation. A vacuum prevents conduction and convection, and a reflective coating serves to reflect radiated heat back where it came from. The Guardian VIG (vacuum-insulated glass) works the same way, with a vacuum between two panes of glass, and a low-E coating to prevent radiant heat from escaping.

Ordinary single-pane window glass is not much better than an open window when it comes to insulation value. Even a good quality double-pane window only has an R-value of 3 or 4, typically. A typical 2×4 stud wall has an R-value of 12 or better. Superinsulated houses with thick wall construction and very high R-values will often use triple glazing, and will minimize the size of the windows in order to keep the efficiency of the system as high as possible and reduce the amount of energy lost through the windows.

vacuum insulated glassThe new glass provides a vacuum space between two panes of glass. To keep the two sheets of glass from being drawn together by the vacuum, low thermal-conductivity spacers are placed in the space between the two panes. (These are the small dots that can be seen in the photograph.)

While the vacuum is only about 1/100th as strong as what is typically found in an ordinary thermos, it is still far better than standard double pane glass in preventing heat loss from conduction and from convection. The only other glazing systems I have come across with close to this level of insulation value have been nanogel-filled windows, but those are just translucent, and do not allow clear vision through the glass.

The manufacturer, Guardian Industries, is reportedly hoping to have this glass commercially available by the end of 2009. More importantly, while other researchers have been exploring the idea of vacuum glass for several years, Guardian is expecting to be able to produce this glass at a reasonable cost over conventional glass.

The head of the Building Technologies Division at Lawrence Berkeley National Laboratory, was quoted as saying, “This performance level would convert most windows in heating climates into net energy suppliers, providing more energy to the home via passive solar gain (even facing north) than the window looses.”

via: BuildingGreen.com

Image Sources: Passive House Institute and Bulding Green.com

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  • Laura Catanzaro

    What is the R-value of this window?

  • Laura Catanzaro

    What is the R-value of this window?

  • http://greenbuildingelements.com Philip Proefrock

    It’s still in development, so I don’t know that there’s a definite answer for you just yet. But they were talking about center-of-glass values of R-11 to R-12 for it, and the possibility of triple pane assemblies that could give you an R-15 window.

  • http://greenbuildingelements.com Philip Proefrock

    It’s still in development, so I don’t know that there’s a definite answer for you just yet. But they were talking about center-of-glass values of R-11 to R-12 for it, and the possibility of triple pane assemblies that could give you an R-15 window.

  • http://renegadeconservatoryguy.co.uk/ Renegade Conservatory Guy

    Sounds like a great product.

    But it depends what price point this glass is at. My gut feeling is that it will be too expensive for the window industry to look at it favourably.

  • http://renegadeconservatoryguy.co.uk/ Renegade Conservatory Guy

    Sounds like a great product.

    But it depends what price point this glass is at. My gut feeling is that it will be too expensive for the window industry to look at it favourably.

  • http://greenbuildingelements.com Philip Proefrock

    Some years back, other earlier researchers were having difficulty getting a similar concept down to $15/sq ft. According to BuildingGreen, a few years ago Guardian was get the cost below $6 to $8 sq ft ($65–$86/m2), but recent technological improvements have enabled them to better that.

    “Guardian is in discussion with two major U.S. window manufacturers about use of this glazing.”

  • http://greenbuildingelements.com Philip Proefrock

    Some years back, other earlier researchers were having difficulty getting a similar concept down to $15/sq ft. According to BuildingGreen, a few years ago Guardian was get the cost below $6 to $8 sq ft ($65–$86/m2), but recent technological improvements have enabled them to better that.

    “Guardian is in discussion with two major U.S. window manufacturers about use of this glazing.”

  • Pingback: Victoria Everman :: Writer, Model, Environmentalist, Crafter, Yogi » Blog Archive » Carnival of the Green #120()

  • Christophe C

    Hi,
    a similar technic is currently used (and sold) by Velux, whereas only “cavities provide a vacuum space” (I couldn’t find more details):
    http://www.velux.ch/VELUXCommon/Resources/cache/c5b764fe-da56-45d3-91f0-727869d9e2f2_Nouveautes06-F.pdf
    (“Vitrage sous Vide”)… sorry, it’s in french.

  • Christophe C

    Hi,
    a similar technic is currently used (and sold) by Velux, whereas only “cavities provide a vacuum space” (I couldn’t find more details):
    http://www.velux.ch/VELUXCommon/Resources/cache/c5b764fe-da56-45d3-91f0-727869d9e2f2_Nouveautes06-F.pdf
    (“Vitrage sous Vide”)… sorry, it’s in french.

  • http://greenbuildingelements.com Philip Proefrock

    Thanks for the information. My French is too weak for me to confidently translate the information from that site. (Since it’s a Swiss site, the data is in metric format, as well.)

    If I’m doing the translation right, though, it’s about R-4.7, which is pretty good for a window, but not as high performance as the Guardian windows. There’s also no discussion of the maximum size that Velux makes, but as they are a residential supplier, I imagine they are not as large as what Guardian is working on. Still, it’s good to point out that other manufacturers are working with this, too.

  • http://greenbuildingelements.com Philip Proefrock

    Thanks for the information. My French is too weak for me to confidently translate the information from that site. (Since it’s a Swiss site, the data is in metric format, as well.)

    If I’m doing the translation right, though, it’s about R-4.7, which is pretty good for a window, but not as high performance as the Guardian windows. There’s also no discussion of the maximum size that Velux makes, but as they are a residential supplier, I imagine they are not as large as what Guardian is working on. Still, it’s good to point out that other manufacturers are working with this, too.

  • Christophe C

    Asaof, Uw (1,2 W/m².K) currently indicates the thermal transmittance of the window (glass+..), whereas Ug (0,6 W/m².K) is specific of the glass part (sorry for the evidence if things are the same in US, but I’ve no way to know it). If following the convertion factor given by Wikipedia (http://en.wikipedia.org/wiki/R-value_(insulation)), it roughly corresponds to R-9.4, which is terribly good, even better than triple panel glass…
    Addendum: I do not work for Velux but as Environnemental Enginner in a public structure :o)

  • Christophe C

    Asaof, Uw (1,2 W/m².K) currently indicates the thermal transmittance of the window (glass+..), whereas Ug (0,6 W/m².K) is specific of the glass part (sorry for the evidence if things are the same in US, but I’ve no way to know it). If following the convertion factor given by Wikipedia (http://en.wikipedia.org/wiki/R-value_(insulation)), it roughly corresponds to R-9.4, which is terribly good, even better than triple panel glass…
    Addendum: I do not work for Velux but as Environnemental Enginner in a public structure :o)

  • John P

    Alpen Window has windows avaliable at R15 and R20 now, from there website information.
    I bought some of there R8 glass for a project last year. The make a quality product. They stay so warm that there is no condensing on the glass in a bathroom under almost all but the worst conditions.

  • John P

    Alpen Window has windows avaliable at R15 and R20 now, from there website information.
    I bought some of there R8 glass for a project last year. The make a quality product. They stay so warm that there is no condensing on the glass in a bathroom under almost all but the worst conditions.

  • Richard J.

    I wonder how long the vacuum seals will last. Certainly my existing double-pane windows started leaking around the edges after only a few years. A partial vacuum can’t help that much.

  • Richard J.

    I wonder how long the vacuum seals will last. Certainly my existing double-pane windows started leaking around the edges after only a few years. A partial vacuum can’t help that much.

  • Mr Georges

    Mr philip, we keep on seeing press release about the guardian VIG. Can you please mail me more about this technology and if it is manual or automated? The final Price and the application of Use? if it is a big commercial project, the production is high enought to cover it? any brochure? or sample???

    Thank you for your collaboration

  • Mr Georges

    Mr philip, we keep on seeing press release about the guardian VIG. Can you please mail me more about this technology and if it is manual or automated? The final Price and the application of Use? if it is a big commercial project, the production is high enought to cover it? any brochure? or sample???

    Thank you for your collaboration

  • Sherry

    how well would these work in southern humid climates?

  • Sherry

    how well would these work in southern humid climates?

  • eliza

    Great solution! But how glass panels with vacuuumed air from the cavity will stay flat in temperature changes. Lets say in Dubai climate where AC keeep air cool inside, and outdoor air is extremally hot? Are there any invisible to human eye partitions between glass panels?

  • eliza

    Great solution! But how glass panels with vacuuumed air from the cavity will stay flat in temperature changes. Lets say in Dubai climate where AC keeep air cool inside, and outdoor air is extremally hot? Are there any invisible to human eye partitions between glass panels?

  • http://www.longislandsolarenergysystems.com Raymond Michael

    This SIVG window pane w/ 15 r factor will probably be suitable for our off grid green residential and commercial structures under design now for north America. As this product is sold in volume the cost will come down as with most products.

  • http://www.longislandsolarenergysystems.com Raymond Michael

    This SIVG window pane w/ 15 r factor will probably be suitable for our off grid green residential and commercial structures under design now for north America. As this product is sold in volume the cost will come down as with most products.

  • http://www.rethink-technologies.com Roger Faulkner

    As to how long the windows will hold vacuum: it mostly depends on the edge seals. There is no reason in principle not to make the windows re-evacuatable. The article mentions that the vacuum level is 100X typical pressure in a thermos (which is around 10^-7 torr. I’m guessing they picked the initial vacuum level so that not too much change will occur in one year.

    I did calculations years ago (on plastic extruded glazing) which showed that the energy cost to run a vacuum pump occasionally to re-establish a vacuum is very well energy justified.

  • http://www.rethink-technologies.com Roger Faulkner

    As to how long the windows will hold vacuum: it mostly depends on the edge seals. There is no reason in principle not to make the windows re-evacuatable. The article mentions that the vacuum level is 100X typical pressure in a thermos (which is around 10^-7 torr. I’m guessing they picked the initial vacuum level so that not too much change will occur in one year.

    I did calculations years ago (on plastic extruded glazing) which showed that the energy cost to run a vacuum pump occasionally to re-establish a vacuum is very well energy justified.

  • DaveCarrera4

    The edge seal is an air tight glassy compound fused to the glass sheets – nothing like the organic sealants used in traditional IG units. Therefor the life expectancy is targeted at more than the 10 or 20 years of traditional IG units. The vacuum cannot be “refreshed”. The units are pumped down and remain under vacuum for the lifetime. There is a threshold vacuum that has to be maintained in order that gas conduction is virtually eliminated, which maintains the high R-value. The low-E double silver or triple silver coating is the workhorse for reducing thermal (radiant) transfer. The pillars that hold the glass apart are a clear compound – very hard and 1mm in diameter by 0.25mm thick – which is the cavity thickness as well. The VIG will work in any climate – it is really just a calculation of energy cost to heat or cool (plus smaller HVAC) vs. the benefit from VIG. Achieving R-10 (COG) at the cost of a (less efficient) triple pane along with pending government and energy star initiatives will be the main drivers to commercialization.

  • DaveCarrera4

    The edge seal is an air tight glassy compound fused to the glass sheets – nothing like the organic sealants used in traditional IG units. Therefor the life expectancy is targeted at more than the 10 or 20 years of traditional IG units. The vacuum cannot be “refreshed”. The units are pumped down and remain under vacuum for the lifetime. There is a threshold vacuum that has to be maintained in order that gas conduction is virtually eliminated, which maintains the high R-value. The low-E double silver or triple silver coating is the workhorse for reducing thermal (radiant) transfer. The pillars that hold the glass apart are a clear compound – very hard and 1mm in diameter by 0.25mm thick – which is the cavity thickness as well. The VIG will work in any climate – it is really just a calculation of energy cost to heat or cool (plus smaller HVAC) vs. the benefit from VIG. Achieving R-10 (COG) at the cost of a (less efficient) triple pane along with pending government and energy star initiatives will be the main drivers to commercialization.

  • Stanley M Hunter

    I have an idea for what I feel will provide a very low-cost approach to vacuum-insulated glass, with an extended life. Would Guardian or some other manufacturer be interested in talking to me?

    S.M.Hunter, Ph.D

  • Stanley M Hunter

    I have an idea for what I feel will provide a very low-cost approach to vacuum-insulated glass, with an extended life. Would Guardian or some other manufacturer be interested in talking to me?

    S.M.Hunter, Ph.D

  • http://www.hd-glass.com Phoebe Wang

    The cacuum seals last for about 10 years.

    Our company Qingdao Hengda Glass in China can produce vacuum glass. If you are in need of them, please let us know.

    email:phoebe-wang86@hotmail.com
    Mob: 86-13698656961

  • http://www.hd-glass.com Phoebe Wang

    The cacuum seals last for about 10 years.

    Our company Qingdao Hengda Glass in China can produce vacuum glass. If you are in need of them, please let us know.

    email:phoebe-wang86@hotmail.com
    Mob: 86-13698656961

  • John Rhodes

    Please mail me all technical information, standard sizes available and prices relating to your companies vaccume insulated windows. I do temperature research for 25 years and I have engineered soonto be patented technologies which will create a new multi-billion dollar market for your product. Please mail to John Rhodes, 334 W. Del Norte St., Apt. # 4, Eureka, California,
    95501, Ph. # (707) 444-3183

  • John Rhodes

    Please mail me all technical information, standard sizes available and prices relating to your companies vaccume insulated windows. I do temperature research for 25 years and I have engineered soonto be patented technologies which will create a new multi-billion dollar market for your product. Please mail to John Rhodes, 334 W. Del Norte St., Apt. # 4, Eureka, California,
    95501, Ph. # (707) 444-3183

  • http://www.lokmancam.com.tr Lokman Aldogan

    Dear Mr Hunter

    We are Istanbul based Glass Company.

    I would like to invest in VIG for the future

    I would be very happy if we can talk about this technology and you can support me with your valuable ideas

    Best regards

    Lokman

  • http://www.lokmancam.com.tr Lokman Aldogan

    Dear Mr Hunter

    We are Istanbul based Glass Company.

    I would like to invest in VIG for the future

    I would be very happy if we can talk about this technology and you can support me with your valuable ideas

    Best regards

    Lokman

  • http://www.heliostat.co.kr Hanul Chung, Solar Boiler Rser

    Your insulated vacuum glass for our solar project is applicable to collect solar radiation heat energy to provent convection current. Please let us know if your product is available in size of 500mm x 1000mm and for sale.
    We look forward hearing from you soon.

  • http://www.heliostat.co.kr Hanul Chung, Solar Boiler Rseracher, PhD

    Your insulated vacuum glass for our solar project is applicable to collect solar radiation heat energy to provent convection current. Please let us know if your product is available in size of 500mm x 1000mm and for sale.
    We look forward hearing from you soon.

  • http://www.eglasscompany.com Erik

    E Glass Company is a full service manufacturer providing Low Profile Insulated Glass units. We offer a full line of Low E glass, Grid options as well as Argon and Krypton gas. We offer many more products as well such as mirrors, tempered glass, laminated glass, restorations glass and much more. If you are looking for a competitive glass manufacturer look no further give us a call today. We ship to anywhere within the United States.

    We look forward to hearing from you!

    Erik Slapp
    President
    E Glass Company
    Tel (717) 479-6745
    Fax (717) 441-3821
    http://www.eglasscompany.com
    info@eglasscompany.com

  • http://www.conservatoriesnetwork.co.uk conservatories

    Sounds really interesting. i hope that you get it soon. I bought solar grill just two days ago which save energy and also prevent from radiations.

  • Chaitraglaze1

    Chaitra Glaze Pvt. Ltd. is a joint venture, Manufacturers the needs of Modern Structural Glazing and Fabrication assignments.

    Structural Glazing Manufacturers

    For more details visit  http://www.chaitraglaze.com/

  • Laurent

    more info here:
    http://www.nsg-spacia.co.jp/spacia/summary.html

    Anybody knows more about the production? Where to get this glass from?
    thanks!

  • http://www.glennrileymeyers.comorhttp://www.ourgreenstreetsblog.com Glenn Meyers

    Check with who posted this article: BuildingGreen.com

  • http://www.luxan.pl/pl/plisy-i-duetty Mitchell

    I read this article fully about the difference of hottest
    and earlier technologies, it’s awesome article.

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