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    Michael Ermann

    Why do most architecture firms register as an LLC? 

    Sole proprietorships offer little protection if sued; If you start a lemonade stand in your front yard today without registering as a corporation, your business defaults to a sole proprietorship. General partnerships, where you and your siblings start the lemonade stand together, also offer little liability protection; Limited liability companies are registered with the state and separate the firm’s finances from the firm owner’s finances. If an LLC’s owner is successfully sued, the owner is unlikely to lose his house in the settlement—that’s what makes a corporation a corporation. If you start a small architecture firm, an LLC filing is typically the way to go. Limited liability partnerships can limit the liability of a silent partner: if your rich uncle, who has nothing to do with architecture or the running of your firm, invests in your firm in hopes of seeing a return in the form of distributions paid out from annual firm profits, and you design a roof that collapses, he has more legal protection than you in an LLP because, while he is an owner, he is not running the business like you are. S-corporations: Like an LLC but there are sometimes tax benefits for S-corps because the owners are paid as owners (and owners are taxed at a lower rate than salaried employees). Many architecture firms are registered as LLCs and then switch to filing with the IRS as an S-Corporations as they become more profitable for this tax advantage. C-corporations: Not for small or mid-sized architecture firms (more for Google and Pepsi). These are publicly traded in stock exchanges, have more than 100 owners, and are “double taxed.” B-corporations allow a company to set goals other than profitability (environmental responsibility, social responsibility, etc.).

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    Michael Ermann

    Acoustics: NRC vs STC

    Noise reduction coefficient (NRC) measures sound absorption inside a room and goes a long way to determining room acoustics. If a racquetball court sounds excessively reverberant, it is because it has a low NRC, so very little of the sound energy made in the room is absorbed or transmitted, and more than 99% of the sound energy impinging on room surfaces is reflected (for an NRC of 0.01). If you are reading this in your plush, velvet-covered smoking room, then most of the sound impinging on room surfaces is absorbed or transmitted by the room’s surfaces and very little is reflected. Maybe only 15% of the sound energy impinging on the surfaces is reflected (for an NRC of 0.85). It’s just the way you would think: thick, squishy, fuzzy materials with interconnected air pockets absorb more sound; massive, hard, dense, smooth materials reflect more sound. See this graphic.

    By contrast, sound transmission class (STC) measures sound transmission between rooms and goes a long way to determining sound isolation. If you live in an apartment and can easily hear your neighbor snoring, then you might have a wall STC of only 25. If you can’t hear her even when she’s hosting party and has the stereo cranked, you may have a wall STC of 65. Massive, airtight, and structurally discontinuous (like double-walled) barriers perform best at maintaining sound isolation.

    Click here for an image of discontinuous assemblies (bottom two rows)

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    Michael Ermann

     

     

    While both NRC and STC are measures of acoustics, they measure different things, just like temperature and windspeed are both measures of weather, but they measure different things. Generally, materials like glass fiber with high NRC values have interconnected small cells where air can pass through. The friction inherent when sound energy passes through that kind of material structure reduces the strength of the sound before it is reflected back into the room it came from. But if you separated two different rooms with only a fiberglass batt blanket for a barrier. . . you can see how those interconnected cells would allow you to hear your neighbor and your life experience tells you that a blanket isn’t a good barrier to sound transmission.

    Of course, you could design an assembly with both a high NRC and a high STC, but that would not likely be a homogeneous single-material assembly. Picture a wall with glass fiber panels mounted over 8 inches of concrete. Sound created inside the room that “sees” the absorptive panels would die quickly and be less likely to excessively reverberate. But the concrete part of the wall assembly would prevent your neighbor from hearing the argument you had with your roommate last night.

    Both NRC and STC are single-number measurements that combine low-frequency (bass content: mechanical noise, transportation noise, bump’n bass from amplified music, vowels) and high-frequency (high-pitched: hissing pipes, truck backup beepers, consonants). Because humans are less sensitive to low-frequency sound, NRC and STC give varying weights to the performance of the assembly across the frequency spectrum, bass to treble. These single-number values make for easy comparisons: acoustical ceiling tile A has an NRC of 0.75, acoustical ceiling tile B has an NRC of 0.95 so B absorbs more sound. . . floor-ceiling assembly A has an STC of 35, floor-ceiling assembly B has an STC of 55 so B is more robust at keeping the room upstairs quiet while the room downstairs has the TV blasting. But, while these single-number ratings make it easy, they gloss over the importance of knowing how a material will behave at a given frequency. This is especially problematic in the presence of low-frequency sound like an orchestra (NRC doesn’t account for how much low-frequency tuba sound is being absorbed. . . just a single number for all sound), and it doesn’t account for low frequency noise (STC is unable to tell you if you will be able to hear the roar of an air handling unit in the adjacent room, because it is just a single number). Many, but not all, materials absorb high-frequency sound much better than low-frequency sound, and many, but not all, assemblies prevent high frequency sound from passing through (speech) but don’t do well at mitigating low-frequency sound (a bus passing outside).

    So what is an architect, or acoustician, to do? If they want more detailed frequency-level information, the absorption coefficient (denoted by a lower-case alpha) measures the absorption at each octave band so we can know if the tuba’s energy will be absorbed in the concert hall when we specify a certain weight of velour curtain. And if we want to know if the window will sufficiently block the low-frequency roaring sound of the passing bus accelerating outside, looking at transmission loss (TL) will give us data at the low-frequencies and high-frequencies and everything in between.

    And while NRC measures room absorption as a convenient single number, and absorption coefficient measures it at each octave band for more detailed analysis. . . and while STC measures airborne sound attenuation between rooms, and TL measures it at each octave band for more detailed analysis. . .  impact noise measures a floor-ceiling assembly’s response to structure-borne noise. Specifically IIC measures how well the floor-ceiling mitigates impacts from footfall on the surface above. If you took no measures to address impact noise, your assembly might earn an IIC rating of 35, and most reasonably-minded downstairs occupants would judge that as unacceptable.  And if you took exhaustive steps and achieved an assembly with an IIC-65 rating, most reasonably-minded downstairs occupants would judge that as acceptable. If IIC was a person in your office, you wouldn’t like him very much. Not only is he piss-poor at rating wood frame floor-ceiling assemblies, but the code requires IIC of at least 50 for multi-family housing, and many reasonably-minded downstairs occupants would find that unacceptable.

    An assembly could have a high IIC and a low STC, meaning you can’t hear the person walking upstairs, but you can hear their stereo. And an assembly could have a high STC and a low IIC, meaning you can’t hear their stereo, but you can hear them puttering around.

    Hope that helps. –Michael Ermann, creator and author of Architectural Acoustics Illustrated , Wiley 2015. (like a Ching book for architectural acoustics. . . That illustration above was one of hundreds like it from this book)

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    Mark Baker

    Thank you Michael!

    Penn State University has several an-echoic chambers.  I was able to spend some time in one for one of the architecture classes. I must say, these are super eery / creepy spaces where NO SOUND is reflected.  Its like a space that EATS sound.

    I also must say that your arrow scale graphic is SUPER clear and helpful in explaining the understanding needed about NRC and how it applies in real life for the architecture exams.

    Mark

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    Michael Ermann

    Failing is a Feature, Not a Bug

    At the time I write this, pass rates for ARE divisions range from 42% (PPD) to 70% (CE). (You can see up-to-date pass rates for each division here.) Let’s say you’ve studied enough to achieve an 80% likelihood of passing EACH of your six exam divisions, which is exemplary and far exceeds the average test-taker. Even in that high-achiever example, with an 80% likelihood of passing EACH division, you still have less than a one-in-three chance of passing ALL the divisions on the first try. Failing some divisions is part of the process, not a detour from it. For this reason, think of failing a division not as failure, but as an expensive, but very accurate, practice test—part of the process of moving toward licensure, and nothing to be dejected about for more than a day. Unless your score suggests you failed spectacularly, sign up right away for the next available to re-test that same division. If you are a football fan, think of it as a holding call: not optimal, but a part of the game. If you are not a sports fan, think of failing a division as a long queue at airport security. It makes you feel bad, it delays you, but you usually make your plane in the end. Go here and watch what I mean.

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    Michael Ermann

    Partnerships

    General partnerships: Two or more people get together to start a firm. Partnership agreements are very important to establish who will do what, who gets credit, how profits are divided, who can put the firm into debt, what happens when one person decides to leave the firm, etc..

    Limited partnerships: partial owners in a firm with limited management roles. Your rich aunt wants to invest in your idea to start a firm, but knows nothing about architecture. You take her $15,000 to start your firm and give her 10% ownership. She's entitled to 10% of future dividends paid to owners from profits, and as a limited partner, she's not (much) liable for civil damages when the building you designed burns down and hurts someone. If you sell the firm in 20 years, she gets 10% of the sale price (after expenses); if you list it on a public stock exchange, she gets 10% of the stock; if you go broke, she gets nothing back.

    Don't confuse partnerships, which happen when people couple-up to start a company, with the ways that  firms couple-up. . . Strategic alliance is two companies hanging out together to land or execute a job; joint venture is two companies making a new baby company to land or execute a job and each one has ownership in the baby; a merger is a total combining of the two companies into a single company that now shares everything as a single, larger, firm.

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    Michael Ermann

    Are Courtyards Good for Humid or Arid Climates?

    Courtyards are a good fit in hot arid climates. where air movement (cross ventilation) is not beneficial. Let's go backward for a minute, then we'll come back to courtyards. . . 

    In hot-HUMID climates, air movement helps sweat evaporate from the skin, and evaporation makes everything around it cool so evaporation of sweat is a good thing. In those climates, because the air is already saturated with moisture, evaporation is stymied. The "sponge" that is the atmosphere is full of water and doesn't want to take any more sweat in from your skin. Air movement helps overcome the problems with evaporation in humid climates (think of a fan placed to more rapidly dry a wet floor). To promote air movement--and we only want to do this in humid climates-- we want large apertures on the windward and leeward sides of the building and we want to separate adjacent buildings by a distance at least equal to five times the buildings' heights. That way, your building doesn't block the breezes available to my building.

    In hot-ARID climates, we have no problems coaxing sweat to evaporate because the atmospheric "sponge" is dry, and happy to take more moisture from our skin. Our sweat evaporates easily in dry climates, which is why 94 degrees feels cooler in Los Angeles than it does in New Orleans. We actually sweat more in dry climates than humid ones. . . only in humid climates, the sweat STAYS on our skin. We don't need air movement to promote evaporation in dry climates, so we don't need large openings; large openings in arid climates only bring in hot air, which will increase the temperature inside our building. To our original question, courtyards are beneficial in hot-ARID climates because they position the other half of the building, on the other side of the courtyard, close to our half of the building. This blocks the breezes because typically, the distance across a courtyard is far less than seven times the height of the building. . . . but in hot ARID climates we don’t need breezes for evaporation. Courtyard arrangements help with shading because the courtyards are typically small relative to the building mass, so the portion of the building on the other side of the courtyard shades my half of the building, plus it shades the courtyard itself. Shading is important in warm humid climates but very important in warm arid climates.

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