NorthernStar, DOE & Windows – A Recap

I just loved this tweet – “I really like days when Michael Anschel attends and tweets some interesting conference to which I am not invited.” Well that makes two of us, but fortunately Michael is nice enough to tweet about them. Speaking of nice, he was also nice to allow me to pull them all together to do a Twitter Recap of the Event. For those of you that may not know him, he is a principal with Otogawa-Anschel Design-Build, CEO of Verified Green and if I may say, a pretty good friendship has developed over the years.

This is a transcript of the first day which involved windows. Hopefully by reviewing this transcript you might have a better feeling for where the industry is now & make better decisions as a result. A few quick notes – the tweets are for all intents and purposes exactly what was sent. I did integrate a few “conversation” tweets into the stream where proper, eliminated the #NStar hash tag from each one & any use of “( )” so I could use them for any of my comments.

• This room is a who’s who of the window industry. Full day of discussion ahead. Thinking I should have a hash tag for this day… (And the  #Nstar tag was born)
• I’m part of the NorthernStar research team working with Department of Energy. Today’s expert meeting is all about windows.
• We (NorthernStar team) are working on a new set of Window Measure Guidelines for DOE
• First Speaker. Charlie Churcija with Berkeley Labs windows and envelope materials research group
• Homes energy usage: 32% heating. 10% cooling (Just a reminder this is for the Northern Climates & percentages vary based on your actual location)
• One quad = one quadrillion btus. Windows and lighting represent 5.1 quads out of 40 quad total
• Think of your home as a dynamic filter.
• Windows can be energy producers. We are close, but not quite there yet.
• Clarifying Tweet a little later… Mike, just checked. The windows are not energy producers. It is the structure that is holding energy.
• For our friends in the south the challenge lies in dynamic controls for cooling, but cost effective solutions still elude us.
• Single glazed windows have a u value of 1.1 and low-e windows are around .4 …. We need to be around .1 (U Value is the inverse of R Values – so in this case the lower the U value the better aka .1 = R 10 & .4 = R 2.5)
• The real challenge with low U values is the loss of solar heat gain. Single pane windows have three times the gain of low-e
• Heat transfer in windows is more complicated than people realize. And too complex for tweeting 😉
• Triple glazing. Quadruple glazings. Vacuum glazings. Think complex design and heavy. – I think high risk of failure
• Aerogel was flat out dismissed.. Ha ha. “it didn’t really catch on, so…”
• Cardinal glass rep points out windows are about a lot more than energy efficiency. Asks researchers to “get back to the real world!”
• Windows need to be hurricane resistant, allow light in, withstand the elements, and…look good!
• “A major weak point in windows are the frames.” – I fully agree
• PassivHaus instantly sparked heated comments. I still contend that it is a waste of our time, energy, and resources. (As he tweets later he prefers: Living Building Challenge. Because it cares about the impact of the structure on occupants and environment.)
• Peter Yost points out that PassiveHaus is really struggling to be relevant in climates colder and warmer than Germany’s relatively mild climates.
• insulated frames of windows developed for PassivHaus in Germany were mentioned. Manufactures question real performance value
• Goniophotopmeter 10 points if you can tell me what it is and what it is used for. 😉 (Heh heh – A photometer designed to measure the intensity of light reflected from a surface at various angles… Ok I had to look it up to)
• Energy audits and IR scans. It is very easy to generate qualitative data, but very hard to generate quantitative date.
• BrainPop! Insulated sealed track retractable blinds inside the home. Would turn window into a wall when it needs to be one.
• ResFen .. Residential design tool… Has anyone used this?
• COMFEN 4 uses the energy plus engine and it may make sense to roll RESFEN 6 into the program.
• If we replaced all the energy star windows already installed with high performance energy star units, we could save 2quads?
• Varying levels of info available for consumers for windows. Starts with looking for the EnergyStar label on the window.
• Over 70% of the US falls into the Northern climate zone for EnergyStar.
• Need help choosing the right window? Here is an excellent tool for making that decision! http://www.efficientwindows.org/
• Looking at comparative study of every window type. This really is a cold climate issue.
• Window selection on a standard 2,000sf house can have $700 per year impact on your home.
• In Phoenix, the best solution might actually be shading devices more than window performance. (I can vouch for that)
• The best window for Phoenix is going to be a double glaze low-e window with u value of .34 and SHGC of .30 (Word of warning, especially with direct sunlight to be careful with the low-E in cheap windows aka thin glass)
• Architects love aluminum frame set windows, but they are hands down the worst performance windows in any climate!
• Discussion about the value of old historical windows versus new efficient windows.
• The challenge comes in when we talk about cost. How and what do we measure.
• Stating the cost of a window is ridiculously hard. The number of options that exist swing the cost by 200%
• Subject of pricing sparks heated conversation. Researchers don’t include installation, insulation, finishing, markup, etc… (Yes & when they do it is always dramatically lower than reality if they are talking about how cost effective something is or blow it through the roof for why they have a better solution)
• Range of installation competence, wide range of product quality, range of performance… Too much to come up with rule of thumb.
• Cost effectiveness, thermal comfort, air leakage reduction, HVAC system reduction. Areas of study for new cost guide. (Insert whistling smillee here)
• Improving the efficiency of your home may result in HVAC equipment that is oversized, and using more energy! (Agreed as if it wasn’t already, and debatable)
• Adding insulation and replacing your windows can actually result in higher energy bills.
• Cardinal glass rep pointing out that window performance in places like MN doesn’t require science to prove single pane glass gets damn cold
• Six primary factors of thermal comfort design. Metabolic rate, clothing insulation, air temp, air speed, humidity, radiant temp.
• Ashrae 55-10 has the standard for thermal comfort design.
• How to measure perceived comfort of the occupant. Fascinating
• This picture is not a joke. Actual visual guide for ASHRAE thermal comfort levels http://yfrog.com/gyfu9tlj (Yeah that was to good to pass up, thus the thumbnail used for this article was born)
• When you design windows for a room you need to consider where the occupant will be in the room.
• ASHRAE thermal comfort standard does not include solar radiation – influence of the sun (and people wonder why we think that all these guidelines & standards are written by those up North)
• PPD = predicted percentage dissatisfied. – what happens when you let engineers pick a name
• Some glass types can actually get too hot, exposing occupants to hot glass.
• Don’t confuse energy performance of windows on the computer with thermal comfort of the occupant.
• Cardinal glass representative really driving home the complexity of window selection in the home.
• Field Test Report for net zero energy homes shows computer model was way off on the heating side. Ok for cooling. (Interested to know who did the modeling & where the issue lies)
• The intent of a window is to prove a view.
• Researchers hate field studies because they involve the real world.
• I wish this session was required for all window sales people and architects.
• Windows have four seasons. Winter night, winter day, swing season, summer day.
• Cardinal rep urging caution for architects designing passive anything. Comfort of the occupant is critical.
• We cannot design homes that rely on smart and engaged homeowners. (Fully agreed, along with convo on smart and engaged homeowners can better optimize performance.)
• Excellent point raised with discussion on occupant comfort. Challenges all the energy efficiency data crunchers theories.
• SHGC limiting doesn’t result in higher bills, although it might feel that way. It HVAC equipment that becomes inefficient.
• Peter Yost of Building Green is talking about window attachments now. Films, shades, awnings, etc.
• With 17 options and 24 attributes in window options the grid is too large and confusing to communicate to almost anyone.
• The window attachments folks want a label from NFRC just like the windows people (Good idea, but…)
• Window treatments, attachments, retrofits, …. Terminology is a problem.
• Interaction between window attachments and the window glazings themselves is a poorly understood area
• Peter Yost turns his home into a test home! Haha!
• Low-e interior storm? Interesting. I’d never seen one, but evidently. Larson makes these. Cool.
• Window quilt…. Fugly. Sorry Peter.
• Ahha!! This is important. The most important location for air tightness is on the WARM side.
• We would have fewer issues if we used clear glass instead of low-e coatings.
• Testing of windows may show minimal differences between assemblies performance, but surrounding materials reveal stunning difference
• Positive feedback on insulated cellular blinds. Field testing shows insulation value with both cellular and honeycomb.
• Key to cellular shade performance is the inclusion of side tracks.
• I asked about embodied energy of replacement windows. Answer was: window manufacturers refused to do it.
• The value of air movement. 10x the volume of air movement on exterior panel vs interior panel.
• Interior storms will put the condensation layer on the old wood window.
• If you want to learn more about window attachments and their performance buy the June issue of EBN – they won’t give the study away
• You can also check out
• Total estimated cost to the window manufacturing industry to get critical LCA data and input into ATHENA $335k. Too expensive? Really? (I think I ran out of whistling smillees…)
• Install a liquid applied waterproof membrane behind the jam track when retrofitting windows, and allow them to drain. (One good thing about not living way up North – no real worries about that issue)
• Do not caulk the bottom of the jamb liner to the sill
• Interesting… For replacement Insert windows BSC is suggesting you cover the lower half old jamb and sill with liquid membrane
• DuPont representative summed up exactly why DOE and Energy teams don’t understand this market in statement about window AC units “If you replace your windows why would you put a window AC unit back? Seems to defeat the purpose” (combined for readability)
• WRB sounds too much like WMD
• Curious to know how many of my followers know what a WRB is… (I do…)

Wow, and to think he didn’t even have a full charge on his phone… Thanks Michael once again for allowing us to repost them & we invite you to check out tomorrow’s transcript on the basements.

Tweet