• Field Notes 22.05.2013

    The ASHRAE folks keep stirring the pot, and it doesn’t bode well for the glass industry. I’m left wondering: How do they get away with writing proscriptive qualifications for glazing that would result in a black/white reduction in the amount of vision glass in a building, when glazing can be more effectively addressed with a little forethought and integrated design?

    I get that walls, by means of their thermal performance, directly impact the amount of heating and cooling required for a building. It doesn’t matter if the wall is glass, insulating glass, metal panels, stucco, precast or any other material, if heat can travel through it, then the HVAC systems are impacted, and ASHRAE by rights weighs in.

    But, how can they proscribe the amount of glass on a building? This would be like GANA or the precast industry proscribing what the building frames have to be in order to carry the weight and loading of the curtainwall materials being anchored to them, and then professional engineers have to design building structures to those limits. We could require A50 Steel and 5,000 psi concrete, claiming it could reduce the size of embeds and anchors. I know it’s not a well reasoned argument, but neither is ASHRAE’s claim about the need to limit vision glass.

    Besides, did it occur to ASHRAE that more HVAC capacity is required when artificial lighting loads go up? There is a correlation between increasing daylight (read: increasing glass) and reducing the amount of artificial lighting required. How has ASHRAE responded to that? How would the lighting folks respond if they had ASHRAE come in and say, “We want fewer lights, as it reduces the capacity of the HVAC equipment.”

    Limiting vision glass also reduces the human comfort factor of daylighting. That’s sometimes hard to put dollars on, but there are studies about improved productivity of workers and students occupying spaces with abundant natural light.

    One more argument: ASHRAE does not limit the area of the structure that bridges the exterior wall and is exposed to exterior conditions. All those balconies on condos are really just radiator fins. Talk about an ice maker on a cold December day in Chicago.

    Okay, enough crying: Who’s going to save us from the abyss?

    We need the architects to take a stand. An architect friend of mine said he’d be surprised if a lot of architects know what ASHRAE is, let alone what the organization’s proposed standard 90.1 related to glass requires. His office is looking into indigenous architecture for clues on how to design for the location, rather than relying on any one standard. The point is, architects have to design for the whole, and balance all types of needs from human comfort to energy usage, as they relate to HVAC and lighting. One discipline can’t outweigh any of the others. Good design is most evident when all components are molded, kneaded and coalesced into a cohesive whole: Structure, human comfort, circulation, HVAC, exterior walls, all blended together so that no one element takes precedence over the others.

    I see a lot of pleas from industry publications that now’s the time to weigh in. And, I get that. Unfortunately, many of the little guys don’t have the time or resources to devote to this fight. So they look to the industry big boys to carry the fight for them.

    Look at BEC, for example. Sure a lot of the contractors go to Vegas every spring for the BEC conference, but look at the people serving on the BEC committees. There’s a lot of representation from the manufacturers, but not a lot from the CONTRACTORS. It’s because the resources aren’t there. What about the big glazing contractors, can they step it up a bit for the industry?

    I will pass my comments onto ASHRAE. Who else will step up to the plate? Everybody remembers how Mighty Casey ended his day. Let there be joy in Glassville, instead. Hopefully, there are those among us who will not only make a plate appearance, but will smack it outta the park.

     

    Posted by Blogger @ 1:37 pm

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  • 3 Responses

    • The 40/30% WWR is for use in the prescriptive environment.
      In simplistic terms it means you restrict windows to x% of the entire wall and make sure the window has a U-factor and SHGC that matches the physical location of your building as dictated in the document.
      It’s like the building code telling you to install floor joists at 16” centers.
      The prescriptive method works well for small projects where there are few design professionals involved.
      However, it does not limit the designers from applying the performance method of calculation. In this method design professionals “trade off” energy values from walls, balconies, windows, roofing etc. you no longer are limited to any WWR. You just have to make the energy efficient math work.
      I’m not suggesting we don’t involve ourselves in the debate and hold our own corner. WE SHOULD.
      And as for rallying the troops or forming a militia….good luck with that!

    • I agree with the comment above, the 90.1 standard provides a performance path to accomadate up to 100% WWR. Regarding daylighting, the 90.1 standard requires electrical lighting controls when skylights are required in large buildings. 90.1 is concious of any added load imposed by increased window area/daylighting. Also, the fenestration industry is well represneted at 90.1 and did push back on WWR restrictions.

    • This didn’t post the first time, so I’ll try again …
      Great points, Chuck. I’ll be in the middle of it all fighting for the industry on behalf of the Glass Assoc of North America and the Aluminum Extruders Council, but as you say, we need people from all across the industry to comment. If anyone has not yet seen the detailed instructions how to comment, please feel free to contact me at culp@birchpointconsulting.com.

      One minor correction – this proposal is for ASHRAE 189.1, not 90.1. 189.1 is their standard for high performance green buildings, which makes even less sense because it ignores the negative impacts on occupants from decreasing daylighting and views. 189.1 is not used as much as 90.1, but we don’t want this to set a harmful precedent that may spread.

      Regarding sausage’s comments, yes, the glazing reduction is for the prescriptive path, and you can still use any glazing area you want in the performance path as long as you compensate elsewhere in the building. However, you will now be compared to a building with less glass, which will affect the calculation. On one hand, we can take credit for the daylighting from the extra glass, but you also have to compensate for the thermal / solar impact too (and it doesn’t accout for the non-energy human occupant aspects). In the end, you could see this cause strip windows to switch to punched openings, or curtain wall go to strip windows, regardless of whether you are in the prescriptive or performance paths.

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