Project Planning & Development

A corridor serving a one-story office building has two exits as drawn. The conference room has one door to the corridor. The building is sprinklered. What is the maximum length of travel from the far corner of the conference room to the conference room door?

A: 100ft, minus the required travel distance in the corridor until you have two means of egress. The first link isn't relevant to this question. From the second link table, we find that a Business (B) occupancy class sprinklered building has a maximum common path of egress travel distance of 100ft. This means that from the most remote corner of the room, farthest from the exit, our fleeing occupant must travel no longer than 100ft before having a choice as to which way she will flee. She can go left past the reception desk, or she can keep running straight down the corridor. Generally, the occupants of your building can travel no more than 75 ft before they have a choice of at least two ways to egress (this particular situation allows for 100 ft). Watch this excellent short video here. Some of you who are savants at reading plans to scale may have noticed that the dashed line here is longer than 100 ft- and is probably drawn at 140 feet in this example. So even if your conference room can be 4,900 sf by occupancy load, per the previous flash card, the travel distance may limit the size of your room (or require an egress door from the conference room directly to the outside, or a corridor reconfiguration so that occupants have a choice of two egress paths right when they leave the room, without having to travel right down the hallway).

Air-handling unit

Air-handling unit: located down the hall, cools air for delivery to the room via ductwork

Air-to-air system

Air-to-air system: fan over condenser and evaporator

Air-to-water

Air-to-water: fan over condenser, pumped water over evaporator

The following diagram depicts a building plumbing system. The blue arrow points to a pipe that brings hot water back to the hot water heater from the rooms with fixtures (not hot wastewater, but hot potable water). Why would we want to return hot water to the hot water heater? It's more efficient (less heat loss through pipes) It's safer (less likely to scald children or others not able to effectively work the fixture controls) It creates less stress on the water pumps Water in fixtures gets warm more quickly

Answer: Water in fixtures gets warm more quickly Hot water circulates, especially in large buildings, to keep warm water in the pipes adjacent to fixtures so occupants don't have to wait for the column of hot water to make it all the way from the hot water heater to a distant fixture. This arrow points to a hot water return pipe that brings hot water back to the basement where it is reheated and recirculated, even when no one is running a fixture in the building. In this case, the circulation is maintained (slowly) by natural convection as the hottest water rises and not-as-hot water sinks in the pipes. In some buildings, hot water circulation is instead maintained by an electric pump.

What is the area-weighted U-value of this wall

Answer:0.24 BTU/(hr°Fft2). Convert each component to U-value before taking the area-weighted average. Uopaque=1/20=0.05 Uwindow=1/1=1 Utotal= 0.05*80% + 1*20%=0.24 Generally we talk about total-building area-weighted U-value (rather than total-building R-value). Calculating the area-weighted average R-value first, then taking the inverse of that number will, curiously, return a different value: 0.06)! Weird, huh? If you want to practice with another, similar, problem and watch a video of me working through the answer, watch this Amber Book : 40 Minutes of Competence video.

When do architects use a Faraday cage?

Architects use Faraday cages as lightening protection. By creating a wire mesh on the roof, they can redirect lightening strikes around the building to the ground. See this diagram.

Where should I locate a "vapor barrier?"

Answer: on the warm side of the insulation, right up against the insulation. This is a complex question and one that the ARE doesn't yet understand the nuance of, because building scientists no longer use vapor barriers in assemblies to stop all vapor out-bound migration, but instead use vapor migration as a way to dry out assemblies that have become wet. However, if you see this on the exam, assume that your goal is to keep vapor from migrating out and locate the vapor barrier on the warm side of the insulation, flush to the insulation. For a warm climate that means place the vapor barrier on the outside face of the insulation For a cold climate that means position the vapor barrier on the inside face of the insulation What if you have a mixed climate, like most of us do, with warm summers and cold winters? The ARE doesn't seem to know what to do in that scenario, so that is unlikely to be encountered on the exam. To learn more, read on. . . These enclosure questions are by far the most common questions I get from those in practice—and for good reason, because enclosure is the most labyrinthian area of building science, and among the most complex. Your building skin will need to (in order of importance) Keep out rain: rain control layers Keep out outdoor air: air control layer Keep out cold/heat: thermal control layer Dry out when the assembly gets wet (and throttle the rate of vapor migration into the cavity, but contrary to popular opinion among those in our field, providing for vapor out-migration is more important than preventing vapor in-migration): vapor control layer Sometimes more than one of these functions may be handled by a single material in an assembly, and sometimes more than one material in an assembly is responsible for a single function. Let's start with rain. We'll keep the rain out with three layers: with a mechanical layer, with a capillary break, and with a raintight layer. Let's assume we're designing a wall with metal panels (but this applies to stone, brick, fiber cement board, wood siding, or EFIS as our exterior finish material). Those panels, our first line of defense, will deflect, say, 99% of the rain like a shield; water simply rolls down the panels and to the ground. Then 98% of that small portion that sneaks through the panels, will drop down through an airspace (capillary break) and be redirected through flashing to weep holes that take the rain back to the outside. Finally, the two-percent-of-one-percent that makes it past the panel shield and the airspace capillary break will encounter the raintight layer. In our example, we'll use a spray-on fluid-applied product impermeable to air, water, and vapor (think of a truck bedliner, it looks like this), but we could use a rolled-on or troweled-on fluid-applied product, a self-adhered membrane product (this), lapped building felt/tar paper this, or lapped polymeric building wrap/Tyvek, this. The lapped products don't double as air or vapor control layers—just rain control layers—because air and vapor can sneak between the lapped layers; and in the case of the building wrap, vapor can also sneak through the Tyvek building wrap itself. Even if vapor and air can pass through, rain will run down the outside of the lapped layers. For rain control, we can lap layers on a steep roof, but a low-sloped roof will require a fluid-applied surface or membrane to keep out rain. The three-layer approach (mechanical, capillary break, and watertight) won't apply to a low-sloped roof . . .just the one membrane, and it has to be water-tight and perfect. Truthfully, the roof and foundation water responses are more interesting than the wall enclosure, but everyone always focuses on the wall. Let's move to the underground foundation. Like the wall, the water control layer sits immediately outside the enclosure (concrete), between the rigid insulation and the underground enclosure, but unlike the above-ground condition, water only wants to move from the always-wet ground to the always-dryer basement. It doesn't move both ways. We have no use underground for loose lapped products that rely on gravity to shed water or materials like Tyvek that allow vapor to pass through. See here for a proper foundation waterproofing detail. On both the plan and section drawings, you should be able to put a highlighter down on the rain control layer and run that highlighter around the entire perimeter of the building, without ever picking up your marker, and be continuously in contact with an intentionally-designed continuous water-control layer. Before we move on, we have to clear up something else. While water is water is water, moisture moves through an assembly in three different ways. The first, rain, is already familiar to you, but you likely have conflated the next two. The second is water moving as humidity, and humidity moves with air. Think of every air molecule as wearing a tiny backpack that may be filled with water. A surprisingly large amount of water can move through an assembly as humidity, piggy-backing with the air leaks, so an airtight assembly, which is important for thermal reasons, is also important for humidity infiltration and in-assembly condensation reasons. The third path for water is vapor migration, which is a different process than the moisture that moves through the air as humidity. Vapor migrates through the molecules of the solid materials. It is a much slower process than the humidity-with-air mode of water transfer, and unlike humidity transfer, it can happen even if the assembly is airtight! If I asked you to build a box made of dimensional lumber, you could seal the joints airtight, and it would also be somewhat raintight, but if you spilled water on the top, after some time, there might be a water stain on the inside of the box lid as the water seeped slowly through the wood, solid molecule to solid molecule, over a half-day. Likewise, if you left a puddle of water inside the box, it would slowly dry out and now there might be a water stain on the bottom of the box. If however the box was lined on the inside with vinyl, you can imagine that the water, once placed inside the box, might not dry out for a decade or more. The vinyl-lined box is impervious to rain, air, and vapor, and the wood-only sealed box is impervious to rain, and air, but not vapor. Having dispensed with rain control, we'll move on to air control. We want our outside fresh air to enter through the mechanical system and be distributed through existing A/C ductwork, not through the envelope: the lungs should function as the lungs and the skin should function as the skin (and not function as the lungs). Lots of common materials are acceptably airtight, including interior and exterior gypsum board, taped (not lapped) Tyvek, CMU, and glass. . . however it is not the panel we are concerned about in air leaks, it is the seam between panels. For this reason, caulk, tape, fluid-applied sealant, and a keen sense of both adhesive chemistry and detailing/construction management is needed to execute a continuous air seal all the way around the building. Air leakage can be measured with a blower door test. The tighter the building, the lower the heating/air conditioning bill, and the lower the likelihood of condensation inside the assembly, because less air leakage begets less humidity infiltration. If you are using OSB as your building's air control layer, be sure to look at the technical specs: many OSB panels are air-leaky through the panel, even if their seams are sealed. Again, you'll want to run your highlighter around the plan and section at the air control layer, to ensure a continuous seal. It is not unusual for a poorly-sealed building to leak 20x the air, relative to a similar building that is well-sealed! Remember the rain control layer may also be the air control layer. . . or they may be controlled in two separate layers within the assembly. The thermal control layer, which in our example sits immediately outboard of the fluid-applied rain/air/vapor control layer and inboard of the air space capillary break, will likely be a rigid or spray-on foam, though fibrous insulation like glass fiber and mineral wool have outdoor-rated versions available too. We want to avoid thermal bridges associated with overhangs, balconies, and other places where the structure of the building extends beyond the thermally controlled interior, but some thermal bridging is likely to happen anyway, and unlike the rain and air control layers, a little bit (but not much) of necessary compromise in thermal bridging is okay. And finally, we come to vapor control. You may have been taught (and NCARB may still think) that the vapor control layer is a "vapor barrier," designed to prevent vapor from migrating into a building's assembly. . . but keeping vapor totally out isn't really a worthwhile goal because much more moisture will enter the building through air leaks (air molecules wearing backpacks of water) than will ever enter by way of vapor migration (water moving slowly through a solid). Instead we'll think about vapor control as a system to throttle the flow of vapor inward, but more importantly, to eliminate the possibility that moisture, once infiltrated into an assembly, will stay there forever. That's right: designed properly, the vapor migration system is intended to let water out, not keep it out. To do this effectively remember: never have two vapor-impermeable layers inside the same assembly. I took this photo a few weeks ago at a construction project around the corner from where I live. The fluid-applied (black) product in the photo better be an air-control-layer only, and remain vapor-impermeable. . . otherwise we could trap moisture between two vapor-impermeable layers: the black fluid-applied layer and the foil layer. because the foil, sealed at the seams, is vapor-impermeable. The building just opened this week. . . I'll be asking its occupants about moldy smells in a year or two. Foil, vinyl, melamine, plastics like white board material or polyethylene sheet, taped rigid insulation, and certain fluid-applied trruck-bedliner-type products are (practically) vapor-impermeable. Lapped products and Tyvek keep rain out, but allow for vapor migration. Frankly, unless you've screwed things up by including two vapor-impermeable layers in a single assembly, vapor control really isn't that important most of the time, especially when compared to rain, air, and thermal control. Vapor migration's vaunted place in the minds of both architects and NCARB is probably unjustified. Moisture will always get in, either as humidity, rain leaks, vapor migration, or as a byproduct of the construction process (curing concrete shedding water after the wall is sealed up, for example). Knowing that water will get in, limit the assembly to no more than one vapor-impermeable layer allowing water (once it does enter the assembly) to dry either to the inside or outside. It may even take two months to dry through the process of vapor migration (remember our wooden box?). . . but that's okay so long as it doesn't stay wet for more than ½ a year. In our example, the fluid-applied "truck bedliner," the one that is impervious to rain, is also impervious to vapor migration. Condensation occurs on vapor-impervious layers on the warm humid face when the other side of the membrane is cold. Because the vapor-impervious layer is inboard of the insulation in our example, humidity (from air leaks) won't condense on the inside of that vapor-impervious fluid-applied layer because that layer is still warm in the winter—it's inside of the insulation. In humid summers when there's mechanical cooling inside, there may be condensation on the outside of the fluid-applied layer, just behind the insulation, but that's okay too, because that layer was made to be waterproof—to protect from rain incursion—so a little bit of condensation shouldn't be a problem. It will evaporate into the air space capillary break later in the week, or drip down to the flashing and out the weep holes. The assembly I described looks like this and was also found at the top of this flashcard. Look at it for a bit until you are satisfied that It properly accounts for rain, air, thermal, and vapor control. This idea of the vapor control layer being more about letting water out is not new, and is widely accepted among building scientists. You can read John Straube's High Performance Building Enclosures (get it here, it's not available on Amazon), peruse Building Science Corporation'swebsite and follow Building Science Fight Club on Instagram to learn more, because that's a lot of content to summarize in one flash card here (I did my best, but this will be hard to follow for some of you). Why doesn't the ARE know about this? Why does NCARB continue to ask you where to locate the "vapor barrier" (but then realize that locating it on the warm side of the insulation is not that clear in a mixed climate, so the test has to let you know that you are either in an obviously all-year warm climate like Puerto Rico or an obviously all-year cold climate like Alaska). This "locate the vapor barrier on the warm side of the insulation" mantra doesn't really help you if you are in a mixed climate like most of us are, and it relies on 60-year old research that was junk research to begin with and only ever applied to old buildings that leaked lots of air, and even then, only in cold climates with humid interiors. Why does NCARB ask the wrong question? It's because of their original sin of relying solely on volunteer test question writers. Those volunteers, haven't been exposed to the building science because they are not experts, and they know the old way ("put the vapor barrier on the warm side of the insulation") because that's the way the profession understands it to be. Why does the profession have the misunderstanding? Because that's how they were tested when they took the ARE in the past. It's a self-referential cycle of errors where mistakes of one generation continue to echo well beyond when they should have been corrected. Volunteer test item writers are adequate in many topics, but when deep technical exposure to complex processes are needed, as they are here, volunteerism can fall short.

Bracing: Single diagonal, cross bracing, k-bracing, v-bracing, inverted-v-bracing (chevron bracing)

Bracing

Embodied energy

By comparing "embodied energy" between building materials, we can specify with climate change in mind. A lower value translates to a smaller energy footprint (by weight). Embodied energy only accounts for the energy required to mine, extract, process, and transport the material. . . just the upstream part. To include the operation (how much energy will the insulation save? How much energy will the photovoltaic panels make? How long will the gypsum board last? Can rubber be recycled?) one must supplement an embodied energy analysis with a life-cycle analysis (LCA). Below is a comparison of flooring options. The take-away: Note the high embodied energy of petroleum-based products (carpet and vinyl). Linoleum seems like it would be a petroleum product, but is instead made with organic materials: sawdust, jute, and linseed oil.

Types of security systems. . . .

CCTV: Closed-circuit television. Cameras record the premises for security. Types of cameras: conventional, thermal (for night vision), PTZ (Pan, Tilt, and Zoom cameras so you can cover a larger area while minimizing the number of camera installations), and domes (so the retail workers at the cash registers can't see where the camera is pointing) Access control systems: Restricts entry by pin, fingerprint, or biometric pattern identification system. Motion sensors: To detect movement with infrared rays. . . Active motion senors send out radar and let the system know when something has moved. Passive motion sensors send out nothing but monitor with a thermal camera and wait for a change in heat (because someone who shouldn't be there moved). Don't tie active sensors to lights that illuminate the suspect, because windblown bushes, small animals, and even insects can trigger a false alarm, which are verycommon. Passive sensors can be tuned to be more or less sensitive so that human movements can be detected above a sensitivity threshold, but those of a raccoon won't trigger the system. Fiber optic detection systems: a fiber optic cable is woven through a fence or wall. When the intruder climbs the cable shakes and the alarm sounds. Some of these systems can only be applied to securing the property perimeter (fiber optic detection system). Others can only be applied to securing access at doors (fingerprint access control system). Some can be used for either securing the perimeter or securing access (CCTV).

Ceiling raceways

Ceiling raceways, also sold as proprietary systems called "manufactured wiring systems": run the power to the third floor open-plan desk through the ceiling of the second floor below it. Then install a poke-through fixture. Expensive because of all the drilling through the floor, and in retrofits, this might inconvenience the office tennant, below, but is a smart out-of-sight solution if you didn't install a floor cellular raceway when the building was constructed, don't like carpet, and hate the hollow thump of raised access flooring

Chilled beams

Chilled beams: like radiators for coolth; measures are required to prevent condensation

Chiller

Chiller: refrigeration machine for cooling chilled water in large buildings. Includes refrigerant moving through the condenser, compressor, evaporator, and expansion valve and the water that interfaces with the evaporator (and condenser)

Compressor

Compressor: high-pressure hot refrigerant

Condenser

Condenser: pump that circulates refrigerant

Cooling tower

Cooling tower: for cooling condenser water by blowing outside air over it

Direct expansion (DX)

Direct expansion (DX): like a window unit; with all cooling components including refrigeration machine and fan in one box

Displacement ventilation

Displacement ventilation: mechanical cooling, supplied near the floor, with a little-bit-cold air brought in at not-very-fast duct velocities. This displaces the warmer room air near the floor and pushes it upward. Grilles in the ceiling suck out the warmer return air (also slowly). Because our skin is warm, naturally convective plumes form where the people sit, drawing warm air up toward the ceiling grille and replacing that air with the colder pool of heavy air near the floor. Benefits: uses less energy (smaller & slower fans, 65 degree supply air instead of 55 degree supply air, more hours available for the economizer cycle "free cooling" because 65 degree outdoor air can be brought directly into the space); is quieter (slower fans); and provides superior air quality (the stalest room air is the warmest, so the stale air hovers at the ceiling near the return grille, where it can be filtered and exhausted outside). Limitations: only works in rooms with high ceilings (minimum 9′); doesn't work with heating (so you'll need radiant baseboard heating for winter); doesn't do as well in humid climates (cooling air to 55 degrees removes more of the room humidity as condensation at the cooling coil than cooling the air to only 65 degrees); with high cooling loads, occupants can feel uncomfortable (with cold feet and warm head). Used for: high-occupancy rooms (lots of people so lots of stale air to be removed); theaters (tall ceilings, need quiet); cooler climates (popular in northern Europe) For an excellent video on the subject, see here. You don't need to watch for more than a few minutes if you are in a hurry. . . you'll get the point quickly. This theater, below, uses displacement ventilation. Blowing cold air from the high ceiling hard enough to mix with the air at the orchestra level would necessitate the kind of ducted air velocities that always produce too much noise. Instead, air is ducted to a concrete plenum in the sloped "leftover" wedge-shaped space beneath the seats. Air then seeps up slowly from the pressurized plenum below the seats, like this. Below the seats the ducts pressurize the plenum. Note the bored holes in the ceiling:

Think of every large piece of outdoor equipment you might need for a large building and decide where it should go on a site.

Dumpster: out of view, far from noses (smells bad), not near quiet-room windows (banging lids) Transformer: between the municipal service (electrical wires on poles or electrical wires underground) and in-building switch gear. Could be on pole, on the ground near the building 4′ from the road, underground outside building or inside building. Ugly and sometimes buzzes, so out of view if possible. If inside building often non-flammable coolant needed inside the transformer. Cooling tower: These are large. They want to be out of view and they need access to the atmosphere so they can't be indoors. They are often near the chillers they serve, but they can be remote if needed. Generator: loud, but if it is a backup generator, it will be rarely used and the noise will not be a problem. Must exhaust to outside, so typically a generator sits outside the building. If it is an indoor generator, it must exhaust to the outside.

Evaporative cool tower

Evaporative cool tower: uses evaporation of water for cooling, no fan, for very dry climates only

Evaporator

Evaporator: low pressure cold refrigerant

Fan coil unit

Fan coil unit: located in the room, cools air by blowing it over pipes filled with chilled water from a chiller

Floor cellular raceway systems

Floor cellular raceways provide both the metal part of a concrete slab's structure, the floor pan, formwork, and the wire management in a single proprietary product. See this excellent video (the link starts the video midway through because that is the best place to start).

Geothermal system

Geothermal system: More efficient because it uses the moderate temperature of earth to heat or cool water for the refrigeration machine

Put these in order from highest sound transmission loss (TL and STC) to lowest sound transmission loss:

Grout: robust sound barriers are massive. Because of the mass of the grout, this barrier serves as an effective barrier to low-frequency sound, so it can, for instance separate a mechanical room from a conference room in a way that a lighter-weight stick wall (even one with the same STC value) is not able to. Perlite/Vermiculite: the puffy Perlite and Vermiculite do a bit to absorb sound as it passes through the barrier, but not much. (Puffy, fuzzy things, when they are mounted at the face of surfaces, influences room acoustics-how the person speaking sounds to the listener inside the room. That requires a different discussion than the TL/STC and airborne sound isolation.) Air: Not as good at keeping sound from the next room out (though a CMU wall, even one with only air in the cavity, is still a robust barrier relative to less massive stick-built partitions).

What building type is most associated with chilled beam technology?

Labs are most associated with chilled beam technology. Chilled beams have nothing to do with structure. Rather, chilled beams are to cooling as radiators are to heating. They are cold surfaces in the ceiling, made so with circulating water from the chiller. They cool the air through convection and cool the occupants through radiation. Common in Europe, chilled beam technology has been slow to gain widespread popularity in the US, probably because it's complicated to install and operate, or maybe just because air systems are entrenched in the minds of MEP engineers, architects, and building owners. There is, however, one building type where the advantage of chilled beams overwhelms the inertia of the entrenched air systems: Labs, especially lab buildings in warm climates. Chilled beams, because they don't rely on moving around streams of (contaminated) air for cooling, offer an energy-efficient solution.

What are the takeaways from this graph:

Materials that involve mining or petroleum (including plastics)-and those with complicated industrial processes-require more energy to produce. Organic options (wood, cellulose insulation, linoleum, wax), simpler processes, and recycled content generally require less energy to produce.

Minisplit

Minisplit: refrigerant flows through units in rooms under high pressure for heating and low pressure for cooling; can heat and cool different rooms simultaneously.

Read the following AIA contracts. (It is probably not an efficient use of your study time to memorize them unless doing so will also help you day-to-day at work.)

Owner-Architect Agreement B101 is here (most important one to know) Owner-Contractor Agreement A101 is here General Conditions of the Contract for Construction A201 is here Architect-Consultant Agreement C401 is here *As with so much of the other content in this division, these are also important for CE, PjM, and PcM exam divisions, and to a lesser extent, PA and PDD. That is why you'll save yourself time-both in total hours of studying and in total time until licensure-if you treat all six divisions as one long six-part exam to be taken in one or two weeks. I know you are scared of this idea, but I'm certain I'm right about this.

Poke-through floor boxes vs floor cellular raceways

Poke-through floor boxes: Best for retrofits and renovations because the floor slab is already poured. The fifth floor open-office wiring is run under the floor slab, in the ceiling of the fourth floor. Then holes are bored for poke-through floor boxes with electrical receptacles and data jacks for the mid-floor desk. Click here to see what poke-through fixures look like. Floor cellular raceways: Best for new construction. The fifth floor slab is poured with a floor cellular raceway system integrated into it. If you forgot what these look like from the last flash card, click here.

Raised access flooring system

Raised access flooring systems float floor tiles on pedestals over a 12in to 24in hollow cavity. Conduit (and ducts) can then be flexibly run-and later adjusted-under the floated floor with relative ease. Obviously raised access floors increases the required floor-to-floor height. See here.

Locate the portions of the section most susceptible to thermal bridging

See image

Overhangs-for roofs, balconies, or breaking up the scale of the elevation-are difficult to seal for air. The air leaks sprout where the structure of the overhang penetrates the plane of the building enclosure at the wall.

See image

Sketch convective loops as they develop in roof and floor assemblies

See image

What is a right-hand reverse-bevel door?

See image

Shading higher southern sun requires _______ (shorter or longer?) horizontal overhangs.

Shading higher southern sun requires shorter horizontal overhangs

How can we shade windows?

South facing: deciduous trees, horizontal louvers, light shelves, shade with other adjacent building masses East- and west-facing: deciduous trees, vertical louvers, light shelves, shade with other adjacent building masses North-facing: shading not required

Split system

Split system: condenser outside, evaporator inside (residential)

If our goal is to shade the windows, which illustrates the west side of the building?

Vertical fins shade the east and west elevations, horizontal fins shade the south, no shading needed on the north

Water-to-Air

Water-to-Air: pumped water over the condenser, air over the evaporator

Water-to-water

Water-to-water: pumped water over the condenser and a different pumped water system over the evaporator

How do we bury conduit into concrete structure?

We can run steel conduit inside concrete slabs. They are placed in the bottom half of the slab (in section) to help with tension the way that rebar runs in the bottom portion of spanning horizontal concrete. The top of the conduit sits below at least ¾ inch of concrete covering and parallel conduit runs must be spaced, O.C., a distance at least three times the larger conduit outside diameter. Conduits cross at right angles. See here for an example (some of these conduit look to be closer together than allowed). We can also pour a non-structural concrete topping over the structural slab and nestle the conduit into the topping.

We use plywood shear walls in wood construction to resist lateral forces in the two vertical dimensions (X-Z and Y-Z planes). How do we resist lateral loads in the horizontal (X-Y) plane?

Wood diaphragms, usually the kind of plywood or OSB panels over joists or rafters that we need for gravity loads anyway in our floors and roof, also double as our "resister of lateral loads" in the (X-Y) plane. Think of them as shear walls turned on their sides to be horizontal. Plywood diaphragms can be seen here and here. Most wood-framed floors act as diaphragms, whether they were intentionally designed as such, or not.

Surface metal raceways

You've seen surface metal raceways on walls (they often have a metal back but a visible plastic-not metal-cover). They can be mounted on floors too. Don't specify these on floors unless you like to trip your occupants and want to ensure floors aren't cleaned properly. They are only specified when sufficiently out-of-the-way of everyday foot traffic. See here.

Calculating code stair width

You calculate the stair width-for the whole stair system-based upon the floor with the highest occupancy load. That floor's width controls all the way up and down the exit stairs, so you don't have to add cumulatively. For stairs serving one floor and fewer than 50 occupants, the minimum width is 36″. For stairs serving multiple floors, the no-matter-what minimum width (always measured between handrails) is 44″. To calculate the minimum width for your building, you'll take the floor with the highest occupancy and multiply that occupancy by 0.3 (multiply by 0.2 if sprinklered and not a fireworks factory or prison, but I'm going to use 0.3 going forward for simplicity). After you multiply the highest-occupancy floor's number of people by 0.3, that will give you a minimum TOTAL width, inclusive of all your exit stairs. You'll split that total up between the total number of exits required for your building: Occupant Load per Story: 1 to 500 people: 2 stairs; 501 to 1000: 3 stairs; more than 1,000: 4 stairs So if you have 100 people per story and four stories, you will need two exits, minimum. You'll multiply 100*0.3 to get a minimum TOTAL stair width of 30″, divided across two exits, which returns you 15″ per stair. But, there is a minimum stair width of 44″ so each stair will be a minimum of 44″ If instead you have 600 people on your third story and 100 per floor on the other levels, you'll take 600 * 0.3, which returns you 180 inches and minimum number of three exits, so 60″ per exit stair and three exit stairwells. Only stair widths within 30″ of a railing "count" as egress, so were the width of the example above more than 60″ wide, we'd need an intermediate rail in the middle of the stairs (or more likely, add a fourth stair). An intermediate stair rail looks something like this. https://i.pinimg.com/originals/09/82/64/098264fef1ba1a445aafa7f39cc395d4.gif There are exceptions for refrigeration rooms and daycares and all kinds of different rules such that you should never use my generalizations in lieu of your own code search when designing your buildings. This is just provided as a general rule-of-thumb, useful for studying, but not verified and never appropriate to replace your own code search.

How many horizontal footcandles would be measured on a table 3' above the floor on a desk surface. The fixture is hung at a height 9' above the floor, and in plan, the desk is 5' to the right of the fixture. Given: An omnidirectional point source light 9,000 candle power (cp)

Answer: 113fc

How many amps for a 2160 watt bedroom circuit in a single-family detached house? Ignore power factor. Given W=I*V

Answer: 18amps Standard voltage is 120 volts.

A ballroom dance floor measures 24 feet by 20 feet; what is its maximum occupant load? Use this code link to answer.

A: 48 occupants Many of the code table-reading questions you will face are this straightforward. . . don't doubt your answer, as the ARE code test items generally shy away from obscure exceptions. From the link table, 1004.1.2, we find that we can calculate an occupancy load of 10 sf/occupant. The dance floor (ballroom) measures 24 ft x 20 ft = 480sf 480sf / 10 sf per occupant = 48 occupants *You would be forgiven had you not seen the "Dance floor (ballroom)" and had instead mistakenly gone to just "Dance floor." That's why it's better to search for the weird word (in this case, "ballroom") when engaging case study references.

A corridor serving a one-story office building has two exits as drawn. The conference room has one door to the corridor. The building is sprinklered. The corridor has an offshoot with a dead end. What is the maximum length of the dead end portion of corridor? Use this code link to answer.

A: 50ft Search the link for "dead end" and you'll find section 1018.4 Dead Ends. Use search when faced with a case study exam question too. Where more than one exit or exit access doorway is required, the exit access shall be arranged such that there are no dead ends in corridors more than 20 feet. So the limit for a dead end corridor is 20'. . . but wait: read on and find In occupancies in Groups B, E, F, I-1, M, R-1, S and U, where the building is equipped throughout with an automatic sprinkler system, the length of dead-end corridors shall not exceed 50 feet. We are Group B, so our dead end corridor limit for a sprinklered office building is 50ft. Dead ends are generally limited to no more than 20′ (50′ if the building is sprinklered). Watch this excellent short video here. https://www.youtube.com/watch?v=xRk4bGlEUjo&t=17s

How do we best reduce the build-up of low-frequency sound in a room (for instance, rumble from mechanical equipment)? Specify materials with a low Noise Reduction Coefficient (NRC) or Position sound-absorbing materials near the corners and edges of walls

A: Position sound-absorbing materials near the corners and edges of walls. We call this a "bass trap." Low frequency sound energy-low tones from mechanical equipment like fans, transportation noise like trucks, and amplified sound like in da club—naturally build up around the perimeter and corners of a room. Sound-absorbing materials positioned near the corners and edges of walls absorbs more of that build-up. For more, see my book, Architectural Acoustics Illustrated.

How much heat loss through the wall described below (round numbers liberally)? Given Bubble wrap: R=1.7 per layer R-1 airspace R-0.9 glass Wall is 4 layers of bubble wrap, 5 air spaces (1/2" each), and two ¼" glass Use 19 degree design outside wintertime temperature for Roanoke, Virginia Wall is 375sf Qheat loss in BTU/hr = Uu-value of assembly * Aarea *∆T

A: Qheat loss in BTU/hr = 1,300Btu/hr How much heat loss through the wall described below (round numbers liberally)? Given Bubble wrap: R=1.7 per layer R-1 airspace R-0.9 glass Wall is 4 layers of bubble wrap, 5 air spaces (1/2" each), and two ¼" glass Use 19 degree design outside wintertime temperature for Roanoke, Virginia Wall is 375sf Qheat loss in BTU/hr = Uu-value of assembly * Aarea *∆T Qheat loss in BTU/hr = Uu-value of assembly * 375sf * 50 deg R=1.7*4+1.0*5+0.9*2 R=13.6 U=1/R U=0.07 Qheat loss in BTU/hr = 0.07* 375sf * 50 deg Qheat loss in BTU/hr = 1,300Btu/hr (Down from 21,000 in the previous example)

How much heat loss through a single pane glass wall (round numbers liberally)? Given Glass: R=0.9 Use 19 degree design outside wintertime temperature for Roanoke, Virginia Wall is 375sf Qheat loss in BTU/hr = Uu-value of assembly * Aarea *∆T

A: Qheat loss in BTU/hr = 21,000 Btu/hr How much heat loss through a single pane glass wall? Given Glass: R=0.9 Use 19 degree design outside wintertime temperature for Roanoke, Virginia Wall is 375sf Qheat loss in BTU/hr = Uu-value of assembly * Aarea *∆T Qheat loss in BTU/hr = Uu-value of assembly * 375sf * 50 deg R=0.9 U=1/R U=1.1 Qheat loss in BTU/hr = 1.1* 375sf * 50 deg Qheat loss in BTU/hr = 21,000 Btu/hr *I used an indoor thermostat set point temperature of 69 degrees and rounded the answer. If you used a different indoor temperature and didn't round, you will have gotten a similar, but not identical, solution.

Which flooring should be used from an embodied energy point of view?

A: Rammed earth certainly has the least embodied energy at 0.5 MJ/kg. But perhaps that's not practical for a high-traffic fifth-floor office. the next-lowest embodied energy option is stone flooring at 2 MJ/kg. . . but note that although wood, at 10 MJ/kg, has a 5x higher embodied energy per kilogram, stone is heavier-therefore we require five times as many kilograms of stone to cover the same floor area. That puts the two options at about-even: wood has five times the embodied energy per kilogram as stone tile, but stone tile weighs five times as much as wood. The takeaway: Everyone seems to forget about the weight! Intentionally misleading manufacturer's literature compounds this problem.

Design a light shelf. Draw it in section. Try to get the proportions and materials correct.

A: height of light shelf should be such that it shades room occupants from sky view B: height of top light should be as high as possible (with "A" in mind) C: extension of light shelf should be 1.4 times b if light shelf faces due south (1.7 times b if light shelf faces more than 20 degrees to the east or west of south). Figure out why that would be? (answer below). In hot climates the extension of the light shelf can be louvers to allow built-up heat to escape upward. x: to get light deep into the room (and therefore mitigate glare) sunlight should reflect off top of light shelf and then off light-colored ceiling R: because view to the sky is shaded, areas close to the window have less glare z: top of light shelf should be painted white. In cold climates, the top surface can be mirrored. Figure out why climate matters (answer below). Bottom of light shelf should also be light colored so that it doesn't contrast too heavily with the bright outdoors when viewed from within. Answer 1: the sun is lower in the sky in the east and west than in the south, especially near sunrise and sunset. To shade from the sun, we need to extend the light shelf outward farther. Answer 2: in a hot or mixed climate, a mirrored top surface would reflect unwanted heat into the occupied space.

Why are lab buildings big energy hogs?

Air quality concerns usually prohibit labs from recirculating room air back to the air handling unit. The fear is that the chemical or biologic that you spilled in your room will spread, airborne, throughout the rest of the building via ductwork. So to cool my lab building in the summer, all the inside air that had already been cooled to 70 degrees and 70 percent humidity is exhausted out to the atmosphere and replaced with new outside air that will need to be cooled and dehumidified all the way down from 90 degrees and 90 percent humidity. This is much less efficient than recooling indoor air. The graph depicts the energy use per square foot of floor area for different buildings on my university campus. Note the outsized footprint of the research buildings, which primarily stems from their inability to recirculate conditioned air.

Put these in order from most effective insulation to least effective insulation:

Answer: Perlite/Vermiculite: most insulative. Perlite and Vermiculite are puffy rocks that have air pockets for thermal resistance, and because they are rocks, they can be exposed to moisture without significantly degrading. Air: more insulative than grout! Air molecules sit farther apart from one another than grout molecules, so air conducts heat more poorly than grout (which is a good thing when using empty cavities in cold climates). Grout: pourable and cementitious, grout serves as surprisingly poor insulation, until you remember that all dense cementitious materials serve as poor insulation.

In the previous flash cards we saw how we can reduce the U-value of an assembly to reduce heat loss. How can the "A" and "∆T" values be reduced in a building assembly? Given Qheat loss in BTU/hr = Uu-value of assembly * Aarea *∆T

Answer: Qheat loss in BTU/hr = U * A *∆T Reduce the area of the building skin by designing a similar-sized building in a more compact form Reduce the wintertime inside-outside temperature differential by lowering the thermostat. This can be done with a radiant heat source, or a conversation with the owner about wearing warmer clothing.

How many footcandles would be measured 3' above the floor directly below a fixture hung at a height 9' above the floor Given: a point source light 9,000 candle power (cp) Ignore reflectance from room surfaces, dirt depreciation, etc.

Answer: 250 fc The US lighting industry has far too many metrics to easily keep track of. Measures of how much light is coming out of a lamp Candle power (CP): measure of how much light is coming out of a lamp. A 100,000 candlepower spotlight is equal to the light of 100,000 candles. Because it is an imperial measurement, it is easily converted to footcandles, which is also an imperial measurement. Candela: A more scientific measure of candlepower. For our purposes, we can use the two terms interchangeably, though the historical "candlepower" unit is equal to 0.981 candelas. Lumens: metric version of the same thing. 1 candela = 13 lumens. "Lumens" is the most common metric used in the industry, but is a bit less intuitive when converting to footcandles and a bit more intuitive when converting to lux (the metric version of how much light is hitting a surface). Measures of how much light is striking a point in a room Footcandles: how much light arrives at a point on a surface (imperial) Lux: same as footcandles, but metric. 1 footcandle is equivalent to approximately 10 lux. You don't need to memorize conversion rates

You are calculating the reverberation time in an opera house. It is the early stages of design, so you will be working with approximate area values because the space hasn't been laid out yet. You assume 10,000 square feet of floor area, 10,000 square feet of total wall area, 10,000 square feet of ceiling area, and 10,000 square feet of seating area. 2,000 square feet of the wall area will be covered by absorbing material (fabric-wrapped glass fiber panels). How many square feet of material, in total, will you be using for your calculation?

Answer: 28,000 The sound in the room will not "see" the 2,000 square feet of hard wall that is behind the soft panels, so we won't include that area. The sound in the room will also not "see" the 10,000 square feet of floor that is covered by the audience seating, so we won't include that floor area either. Seating area replaces the floor area it covers when accounting for room acoustics.

How many horizontal footcandles would be measured on a table 3' above the floor on a desk surface. The fixture is hung at a height 9' above the floor, and in plan, the desk is 5' to the right of the fixture. Given: a fixture with the following photometric curve

Answer: 85 horizontal footcandles

How many vertical footcandles would be measured at a point on a wall 3' above the floor. The fixture is hung at a height 9' above the floor, and in plan, the wall is 5' to the right of the fixture. Given: An omnidirectional point-source light 9,000 candle power (cp)

Answer: 95 fc Calculate the angle Θ SOH CAH TOA tan(Θ)= ⅚ tan-1(⅚)=Θ or arctan(⅚)=Θ. . . . Θ =40 degrees Calculate the distance D Pythagorean theorem 52+62=D2 D=61 Calculate the vertical footcandles I've included an optional video explanation below if you need more.

"Horizontal footcandles" is a measure of light arriving from ______. Above or The side

Answer: Above! Horizontal footcandles is a measure of light impinging upon a horizontal surface: as if you put the light meter flat on a table, so it measures light arriving from above. Vertical footcandles measures light impinging on a vertical surface. . . so light arriving from the side. This is a bit counter-intuitive until you know the backstory.

A good barrier for preventing sound from transmitting from one room to the other is _______. Absorptive Or Airtight

Answer: Airtight Assemblies that are massive, airtight, and structurally discontinuous do the best job keeping out the neighbor's TV noise, or keeping out the bus noise, from your apartment. By contrast, sound absorption is used to reduce the sound buildup inside the same room where the sound is made, and has less impact on the neighbor's noise. In the same way that cloud cover, temperature and wind speed are each measures of weather, but not very related to one another . . . room acoustics (sound absorption), noise control (sound isolation), and impact noise control (from footfall) are each measures of acoustics but not very related to one another. A room with high or low quantities of absorption may or may not be good at keeping sound from the adjacent room out, just as a cloudy day may or may not also be windy.

A larger room has a _______ reverberation time than a smaller room. Longer or Shorter

Answer: Longer Large rooms, rooms with fewer surfaces, and rooms with harder, smoother, less-fuzzy surfaces are more reverberant (sound lingers longer after it is suddenly stopped). The more reverberant the room, the longer the reverberation time, measured in seconds. Rooms with unamplified speech, amplified speech, and amplified music generally want to be less reverberant: they want to be smaller, with fuzzier surfaces. In contrast, rooms for unamplified music, like concert halls, generally want to be more reverberant: larger, with harder and smoother surfaces.

Which type of soil is more stable to build on? Clay or Sand

Answer: Sand Clay behaves unpredictably when it gets wet. It swells. Of course most soil boring reports detail a mix of sand and clay (and silt and gravel). It is then the proportion of clay that will determine stable soil.

The current calculation in the previous problem can be used to _______. Locate the breaker box Locate the underground power utility Reduce the amount of power used (for energy conservation) Size the wire

Answer: Size the wire

A surface with an absorption coefficient of 1.00 is considered _______. Sound-reflective or Sound-absorptive

Answer: Sound-absorptive. Sound absorption coefficient measured for the surface of a building material (⍺), ranges from 0.0 (fully sound reflective) to 1.0 (fully sound absorptive). Most sound absorbing materials have ⍺ values greater than 0.5 and most sound-reflecting materials have ⍺ values less than 0.2

Why does the advantage of chilled beams overwhelm the inertia of the entrenched air systems in lab buildings.

For air quality reasons, labs can't recirculate their air. If chilled beams are used in lieu of a ducted air system, we no longer have to exhaust that perfectly good 70 degree room-temperature air and replace it with 100% outside fresh air that needs to be mechanically cooled all the way from 90 degrees. Instead, when the thermostat calls out, "more cooling, boys!" we can circulate chilled water to the chilled beams (radiators in the ceiling that look like this). This is a much less wasteful regime, and there's no worry about your aerosolized lab spill being blown through all the rooms of the building because there's no recirculating ducted air needed for cooling. (Some small amount of ducted fresh air is still required, but those duct sizes are often small and they never siphon bad air from other rooms.)

What is an overturning moment

For the curious or confused, see here for a more detailed calculation (probably not worth memorizing but may be interesting to you).

Position the vertical louvers on the east or west face so that the "cut-off" angle of each fin shades direct sun.

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There are urbanistic and programmatic reasons why you might want to design a tall or flexible or otherwise different first floor. What is the "soft story" solution?

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When the shear wall is overly-perforated with apertures or doesn't continue uninterrupted all the way from roof to foundation:

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Sketch a convective loop inside a wall cavity

In wall cavities of widths greater than 4in, a convective loop forms as air naturally rises up the warm side of the cavity and falls along the cold side. This acts as a short circuit of the thermal barrier, accelerates the transfer of heat from inside to outside, and cancels (or even reverses) the thermal benefit of the cavity. This is especially acute in tall cavities in cold climates. Note the role of radiant heat exchange across the cavity, as the warm side "sees" the cold side and transfers its heat by electromagnetic energy. Note also the role of conductive heat exchange across the solid elements of the wall The physics of a cavity wall suggest conduction, radiation, and convection are all going on simultaneously—but for simplicity, we typically measure heat transfer through the wall in equivalent conduction terms (R-value).

What is the difference between passive and active radon mitigation?

Passive system: Caulk/sealant in foundation cracks and where the slab meets the foundation wall, and plastic sheet below the slab seals the building from the radon in the ground. Continuous, airtight plastic pipe extends from the sub-slab gravel straight up through the roof to allow an easy path for underground radon to escape without entering the house. No fan needed. Active radon mitigation: fan pulls air (and radon) through a continuous plastic pipe from below slab or crawlspace to the atmosphere, bypassing the building. We don't want the radon that is pulled out of the foundation to leak back into the building, so we seal the slab; we put the fan in the attic or anywhere else outside the the enclosure; and we discharge the radon from the pipe at least 10 feet from a window, door, or other opening (including doors and openings in adjacent buildings), at least 10 feet off the ground, and above the roofline, as close to the ridge as possible. Angle the pipe discharge away from any bulding surface to avoid moisture discharge or mildew build up on the building wall or roof. For new homes, a passive radon system should be installed (it's cheap, and if it needs to be converted into an active system later because of high radon levels, simply add an inline fan to the existing passive pipe in the attic). In areas of the country with high radon levels, new homes should have an active system installed from the beginning.

In each of these four trusses, identify which members are in compression. Which ones are in tension? Assume each of them is under a uniform gravity load and supported at their ends.

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How do we route power to desks that are far from a wall when the floor is concrete?

See Video (PPD 43)

Floor-to-ceiling raceway poles

See here for an example of a Floor-to-ceiling electrical/communication raceway pole. Thesehanging receptacles offer another from-the-ceiling option.

Conduction, convection, and radiation across a wall assembly

See image

Locate the portions of the section most susceptible to air infiltration

See image

Shear (pin) vs Moment Connections

Straighten out your arm and hold it horizontally. Now use your hand to grab the shoulder of a loved-one who is standing nearby. If that loved-one suddenly moves out of reach, does your arm fall or does it remain horizontal? If it falls, your shoulder was a shear (or pin) connection. If it still remains outstretched horizontally after your loved-one moved—if it remains cantilevered from your body—your shoulder was in a moment connection. In steel, you can recognize a shear connection because (generally) the beam web is bolted or welded to the column, but the beam's flanges are not. Shear connections resist gravity, but don't do well in the presence of lateral forces like wind and seismic. They therefore need additional lateral resistance from cross bracing or a shear wall (rigid lateral membrane) so that a hurricane doesn't push over the pin-connected structure. The nomenclature can be confusing: shear connections need a shear wall (or cross-bracing) to resist lateral forces. Importantly, shear walls or cross-bracing are not required everywhere—only in a few of the structural bays. By contrast steel moment connections (generally) bolt/weld both the flanges and web to the column and resist both vertical gravity and lateral wind/seismic. They can handle the hurricane without the benefit of shear walls or cross-bracing. The additional cost of attaching the flanges doesn't feel like it would amount to that much extra in a building's budget, at least not relative to the extra cost of cross-bracing or building a concrete shear wall. But given the skill-level of the structural steel trades, and their location high atop steel structures exposed to the elements, the extra cost of moment connections (bolting the flanges to the beam) is surprisingly significant. Plus, code life safety requirements often dictate a concrete stair tower that can "do double-duty" as the shear walls without extra cost. So most of the connections you see in the field when a steel beam meets a steel column are shear connections. . . which means that if the neighboring column were to jump out of the way, and there was no shear wall in the bay and no cross bracing in the bay, the beam would pivot downward.

Swamp cooler

Swamp cooler: uses evaporation of water for cooling, with a fan, for very dry climates only

Thermal bridging happens when structure short circuits the insulation and spans clear across the assembly, touching both the inside and outside.

Thermal bridging across rafters melts the snow first

Thermal bridging happens when structure short circuits the insulation and spans clear across the assembly, touching both the inside and outside.

Thermal bridging is present, but not nearly as serious a problem, in wood. Concrete or steel offer more problematic paths for heat transfer. This double stud door frame provides a "thermal break," a way to separate the structure of the inside and the outside of the door into two different planes, separated by an insulated space.

Underfloor raceway ducts

They're called "ducts" in this context, but they carry electrical and data wires rather than air. They can sit beneath, or flush to, the floor. Expensive, disruptive, and not very popular anymore in favor of moving power in the ceiling below, under-carpet, or cellular metal floor raceways. See here for an example of ducts for raceways.

With an eye toward carbon emissions, what should you select as structure: steel or concrete?

This is, again, a difficult question. Concrete is heavier per-unit-volume, but we use sooo much more volume of concrete in a concrete building than volume of steel in a steel building (plus a non-negligible amount of steel rebar inside that concrete too). The real problem, though, is that embodied energy is only part of the story when selecting for climate and carbon. The process of making cement directly produces carbon dioxide when calcium carbonate thermally decomposes, leaving behind lime and carbon dioxide; this is separate from carbon emissions associated with the energy used in cement production. The takeaway: That seemingly-tiny concrete bar on the graph belies a thorny problem: Concrete contributes 1/12th of all the carbon that humans spew into the atmosphere. If concrete were a country, it would rank third-behind only China and the US-in carbon emissions! The convention of measuring embodied energy by weight (instead of by volume or by square foot or by building), coupled with the focus on embodied energy rather than on carbon emissions, must be one of the biggest wins for the concrete industry-or any industry- ever. I don't know that they orchestrated that convention, but they milk it to make concrete seem benign when architects do a quick google search. I'm not sure that NCARB understands this, but you should.

Vierendeel Truss

Truss without triangles-only right angles. Useful if you don't want angled truss components to interfere with windows, but for it to function as a truss, the connections at the top and bottom chords have to resist moment forces and are often beefy and expensive. They look like this. Herzog and deMeuron's Jenga building in New York achieves its cantilevers with two-story concrete Vierendeel trusses. You can see them on this short time-lapse construction video.

Under-carpet wiring system

Under-carpet wiring systems: imagine laying something that looks like tape, but is actually flat insulated electrical conductors aligned edge to edge. Only 0.03 inches thick, so you can't feel it under the carpet when you walk on it. Obviously the least expensive solution and obviously the one with the least impact on floor-to-floor heights. Doesn't work as well for large, complicated floors because with higher power needs comes the need for thick electrical boxes that can't lay flat under your carpet. See this video at this timestamp (you don't need to watch all of it and you are encouraged to watch it at 2x speed).

In which condition does an exit (stair) need to be pressurized to keep smoke out? Buildings made of combustible construction types (wood (Type V) construction) or Underground buildings

Underground buildings have stairs that must be pressurized. The egress path (the path for getting out in an emergency) has three parts, 1.Exit access (for simplicity, think of that as the corridor from the room to the stairs) 2.Exit (the stairs) 3.Exit discharge (door from the stairs to outside) We want occupants to be safe—or at least safer and more protected from fire and smoke-when they reach the exit (stair), even if they are not yet out of the building. One of the ways we do that, is to pressurize the stair with a giant fan at the top that is activated by the building's smoke detector. With the stair pressurized, smoke is less likely to fill the stair. This type of system is required in the following building categories: 1.In tall buildings--it takes a long time to walk down 100 floors, especially if others are joining you at each floor and clogging things up, and we need you not to choke from smoke inhalation on the way down. . . We pressurize the stair so it doesn't fill with smoke. 2.In underground buildings—you need to move up to make your way outside safely, but smoke rises, so we don't want you moving up to a too-smoky-to-breathe higher floor. . . We pressurize the stair so it doesn't fill with smoke. You can see an example of such a pressurization fan by looking up the next time you are in a stairway of an underground building or tall building. It looks like this. The diagram of it looks like this.

Variable vs constant cooling coil & variable vs constant ducted air speed & variable vs constant fan & variable vs constant pump

Variable vs constant cooling coil & variable vs constant ducted air speed & variable vs constant fan & variable vs constant pump: how much control over the rate of flow. Variable generally offers more comfort control and more energy-efficiency, but more complex equipment

So what did we decide for the flooring: stone-tile or wood?

We have to ask ourselves more questions first. What was given as "stone" is an average, but in embodied energy analysis, knowing the specifics is annoyingly important. Look at the difference within "stone." Then we must account for the variance associated with transportation. Stone has weight, and heavy things require a good deal of fuel to transport. Is the stone tile mined locally, or is it shipped from India? The takeaway: The flaw of averages strikes again! To get embodied energy right, you'll need to do a lot of research (manufacturers and suppliers notoriously use this to greenwash). I think your design time is better spent researching low-energy operations (VRF HVAC, daylight harvesting, roof albedo, insulation, low-e windows etc.) and only after that's buttoned-up should you research low-energy materials. . . but I don't know that NCARB shares my priorities on this issue, so we're studying embodied energy now.

When given a chance, how you decide what is the least expensive construction technique?

What you see most often on construction sites is usually the least expensive option. OSB sheathing is more common, and less expensive, than plywood sheathing Plywood is more common as formwork, and less expensive, than insulated concrete forms (ICFs) Vinyl siding is more common, and less expensive, than wood siding Asphalt roadway is more common, and less expensive, than concrete roadway And so on. . .

So we should choose wood, right? Let's choose wood.

Wood must be finished, and paints, lacquers, and chemical finishes of all kinds have an embodied energy problem: But again, measuring these by kilogram may be a bit misleading: how many kilograms of finish does it take to cover a square meter of wood flooring? We'd want to calculate that, add the embodied energy of the wood itself, and compare the total (wood + finish) to stone. The take-away: paints, lacquers, finishes, resins, and epoxies include high embodied energy content (they often off-gas too). Consider a no-finish option when possible, like an exposed ceiling, or an alternative like sandblasting, or shou sugi ban (but note that I used this burnt wood technique on my shed and the char streaked any clothes that brushed up against it. . . so I wound up applying a clear stain on top of the burnt wood anyway!) To see, go here (second to last photo, bottom-right of photo).

Are wind loads higher at the top of tall buildings?

Yes, wind speeds increase with the height above the ground (but gustiness—circulation of wind in eddies—decreases with height). Wind is notoriously difficult to account for in tall buildings. The high pressure (windward) side takes on a "pushing" lateral load, while the low-pressure (leeward) side takes on a suction pulling load in the same direction. This can cause the building to "gallup," vibrate, and sway in ways that prove unnerving for occupants in higher floors. The downwind pattern formed by the building's disruption of wind flow, called "vortex shedding," can create a force perpendicular to the wind direction and dislodge windows. To limit the structural impact of winds on a tower, soften the corners in plan (rounded or chamfered, rather than right angles), taper or set back the building plan as it rises, twist the building as it rises, provide large apertures in the building's windward face that allow the wind to pass through at some floors, or position a heavy damper in a top floor to counteract the natural vibration of the building. See this digital model. Most of these strategies will also reduce the canyon effect wind speed on the city streets below as well. For more, go here.

How many lavatories, water closets for boys, water closets for girls, and water fountains are required for a middle school with an occupancy load of 1000 people? Use the internet liberally.

You'll want to visit the IBC here to check with Table 2902.1. On the exam, this will be provided in the question, or more likely, in the case study material. Lavatories: 20 (1 per 50 occupants) Water closets for boys: 10 (1 per 50 occupants) Water closets for girls: 10 (1 per 50 occupants) Water fountains: 10 (1 per 100 occupants) With few exceptions, you must assume that 50% of occupants are women and 50% are men, so 500 of each for this example. Here we assume Educational (E) occupancy type. Remember that a "water closet" is a toilet and a "lavatory" is a sink without food waste going down the drain. This can be confusing because in common language, sometimes a bathroom is called a water closet, or a bathroom is called a lavatory. For mixed-use buildings, calculate the number required for each occupancy classification (E, A, S, etc.) and then add them together. Include the occupancy load for outdoor dining and entertainment spaces (courtyards, beer gardens, terraces)