PDD Handbook - Sample Item 12

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    Scott Barber

    Hi Adelina, 

    These are the types of questions that can be tricky. All the real-world considerations need to be ignored when the ARE tells you in the question a specific criteria that's important. In this example, the question says "The building's energy performance is a top priority of the client." After reading that, I would make that the top priority, and not remove anything that could impact the energy performance. The 3 incorrect choices all would impact the energy performance of the building, including Low-E windows. You can do some searching online to learn more about Low-E glazing - I'm not an expert and you'd probably learn that way rather than someone sharing a handful of facts with you. This was the first article that showed up after searching "Low-E glass for cold climates" and may be a good starting point.

    While architects in the "real world" will push against any change or substitution that would impact the design, that's not what the ARE typically (if ever) asks about. So while changing the tint of the windows may not be preferred by the architect/design team, this question explicitly states at the end that energy performance is the most important priority. Therefore, that should guide your answer 100%. 

    Hope that helps. Good luck!

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    Adelina Koleva

    Thanks so much Scott - not the first time you've helped me out!

    I got it now:

    There 3 answers that are energy-related, and 3 answers that are not energy-related. Pick the 3 that are not energy-related.

    I'll take this as a lesson in the dangers of over-studying...

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    Jorge De La Rosa

    Agree with Scott 100! Low-e glazing, in short, is the ability of the glass to reflect the heat rays from the zone away from the interior of the building. it doesn't reflect all the radiation away like a mirror, but enough of it to make it a sustainable approach to prevent heat gain in the space.

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    Jorge De La Rosa

    and also, pay attention at the answers...sometimes the choices give away the answers. if you would have selected removing the e-coating, then the savings would have been much more than 26000...yes, it would be great fr the budget, but ARE doesnt care about that, just how much the contractor needs to save :)

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    Adelina Koleva

    Jorge,

    Passive heat gain in the space should be prevented for a hot climate but would desirable in a cold one. This question is asking specifically about a cold climate, and also about the overall construction cost estimate.

    I've read all about low-e coatings in MEEB but I'm throwing that out the window. The ARE is not about that. It's about a) spotting 3 answers that have something in common given criteria #1 of the question ("energy performance"), and then selecting from essentially two choices, which both satisfy criteria #2 of the question ("construction cost.")

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    Jonathan Chertok (Edited )

    i think the help provided above is correct. taking out low-e affects building performance. tint is only aesthetic.

    the only thing i would add per your "thinking ARE" comment is to make sure you fulfill the minimum VE requirements (even if you are under by a very minimal percent of the overall budget) and even if the change seems to contradict stated owner goals. and then don't do anything to increase VE savings (even if it seems that they won't impact owner goals very much).

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    Jonathan Chertok (Edited )

    here is item 11. 

    if you choose thin brick on metal studs - retaining the original wall section (metal studs) and moving to thin brick instead of the original bid with a full width brick facade - you will be below making the VE goal by like 0.05% or 0.005% of the total budget. not 5%. 0.05% or 0.005%. basically you will be off on the order of maybe a thou +/-.

    this answer is wrong.

    the correct answer is to move to a completely new wall section (PRECAST CONCRETE) and keep the same thin brick exterior look as the thin brick on metal studs that is the other option but that barely misses the VE goal.

    so the goal is presumably to meet the owner's goal of "similar exterior aesthetic" - which you do choosing /either/ option. but if you think about the actual practicalities of bringing in a new trade, or that the owner would like to move forward quickly since they just received a construction cost estimate from the contractor (and the contractor already has a trade ready to go) - if that is not meeting their budget, or if you have any practical goals at all in mind except meeting the VE goal by an exact amount you will be wrong.

    just thought to mention it WRT strategy

     

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    Adelina Koleva

    All,

    I  finally found what I was looking for as to why low-e is used in cold climates. Hopefully this will be helpful to people out there studying:

    "Low-e glass is a good choice for a cold climate because it has a low U-value, which means that it can minimize heat loss while still allowing some solar heat gain. The low-e film or coating allows both visible and near-infrared radiation to be transmitted through the glass but prevents long-wave radiation (heat) from escaping the room."

    Thanks again for the help. After studying up and coming back to it, this question started making more and more sense. Time and reading (and of course, not overthinking it) can really help.


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