PROGRAMMING + ANALYSIS

Question 1

Gross floor area

Answer 1

In matters of code, gross floor area is measured from the inside face of exterior walls. In other matters of programming and analysis (programming, pre-design, schematic design, or cost estimating), gross floor area is measured from the outside face of the exterior walls. It is a value used in the denominator of economic efficiency proportion measures like “net-to-gross” (interior area, excluding corridors, lobbies, elevators, bathrooms, and stairs, divided by gross floor area). “Usable area,” is like net area, except that it includes corridors. “Rentable area” is like usable area, except that it includes bathrooms and lobbies. “Grossing factor,” is rentable area, divided by usable area. To make these concepts even more difficult to remember, their specific definition varies somewhat by region and industry, so you might have correctly heard one of these terms used in another way. Argh. Try not to stress and do your best based on these definitions.

Question 2

Catchment areas

Answer 2

In a discussion of stormwater runoff, the catchment area is the region from which rainfall flows into a stream, culvert, catch basin, or roof drain.

The field of building feasibility study reappropriated the phrase “catchment area” from the stormwater people as a useful parallel. It is the region from which residents are expected to visit your building. When siting a school, how many children live in an area bounded by the midway points between your site and other schools? When siting a hospital, what proportion of residents within X miles are over the age of 70 and how many of them have health insurance? For your proposed indoor pool site, it is unlikely that residents will drive past another, more proximate, indoor pool to visit your spot further away. Your proposed corner store will have a catchment area of no more than six blocks because it relies on pedestrian customers. In this way, to judge the feasibility of building here, we’ll map a catchment area based on demographics, commerce, geography, and human habit to describe the area from where your building will draw people

Question 3

Where is the most effective location for an outdoor noise barrier?

Answer 3

If you have a noise source (truck) and a receiver (person with ears on a balcony), the least effective place for an outdoor noise barrier is halfway between them. The most effective location is as near as possible to the noise source or as near as possible to the receiver. The image is from my book, Architectural Acoustics Illustrated (Wiley 2015)

Question 4

What is a population pyramid?

Answer 4

Graphic representation of populations showing both age and gender. helps visualize populations as they grow older and new generations fill in the bottom of the pyramid, with the older generations dying off and allowing for the next generation to be the top.

Question 5

Positively- and negatively- pressurized locations in a building with open windows

Answer 5

positive pressure on windward side and negative pressure on leeward.

Question 6

“Ideal” structural parti for seismic design

Answer 6

Uniform loading of structural elements (stress connections from non-uniform loading– for instance, cantilevers– are weak points in an earthquake)

Low, wide buildings (prevents overturning)

Equal floor heights (means fewer stress connections)

Symmetrical plan shape (minimizes torsion/twisting)

Shear walls or bracing at the perimeter (more efficient at resisting torsion/twisting than shear walls in the core)

Short spans (less stress on members and more columns provide redundancy if some are lost in an earthquake)

Minimize openings in floors and roofs (more efficient diaphragms)

Extend shear walls continuously from roof to foundation

Question 7

Why avoid cantilevers, irregularly-shaped buildings, re-entrant corners (L- or T- shaped plans) when designing in seismic zones?

Answer 7

There are two reasons to avoid re-entrant corners (and other irregularly-shaped buildings) in your parti:

First, like any irregular shape, they produce differential motions between different wings of the building, stressing the re-entrant corner (interior notch)

Second, these shapes create torsion in the building that is difficult to predict

Question 8

The problem with re-entrant corners in earthquakes

Answer 8

Each portion of the building twists out of phase with the other

Question 9

Solutions for the reentrant corner problem in seismic design

Answer 9

Separation, strengthening, or stiff wall elements

Question 10

Irregularly-loaded buildings and seismic failure

Answer 10

Failures in earthquakes from:

Soft story problem (tall first story with slender columns and not much lateral bracing). This issue, top row, is the most common and causes the most death and destruction.

Weight irregularity (More weight in the top floor, shown in red)

Shear wall doesn’t extend full height of the building

Shear wall not continuous over full height of the building

One story weaker than the others

Jutting building elevations:https: //www.nps.gov/tps/images/briefs/41-cover-image.png

Question 11

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

Answer 11

When the shear wall is overly-perforated it fails to bestow the benefit of a shear wall. It no longer protects the building from failure under a lateral load like an earthquake

Question 12

Can foundations bear on loam?

Answer 12

Yes, loam can support a building. It is a combination of sand, silt and clay.

Gravel, clay, shale, sand are okay; rock (bedrock, limestone, sandstone) is great for supporting foundations of heavy buildings.

Organic soil and peat (dark brown or black and easily compressible) are not competent soils.

Question 13

What is the difference between a Phase I and Phase II Environmental Site Assessment (ESA)?

Answer 13

A Phase II ESA is more thorough than a Phase I ESA.

Any property owner, regardless of fault, can be held liable for releases of hazardous materials from their land. However, if you purchased a property and can prove you performed appropriate environmental due diligence, but found no environmental red flags before the purchase, you are granted protections from that liability should toxic sludge be found later to be leaking from your land into the river. The Environmental Site Assessment (ESA) has become an established standard for this type of before-you-purchase-land environmental due diligence, and is used by the buyer and lender to both assess risk and protect from future litigation.

A Phase I ESA includes site inspection by an environmental professional, a historical records review of the property, and interviews with owners, occupants, neighbors, and local government officials. If a Phase I ESA turns up a recognized environmental concern (REC), then the environmental professionals conducting it will recommend a Phase II Environmental Site Assessment (ESA).

Unlike a Phase I ESA, a Phase II ESA is invasive, involving soil testing, groundwater sample testing and testing of building materials.

Question 14

Best location in a warm climate? Best location in a cold climate? (Site A:North of river or Site B South of river)

Answer 14

Site A: cold climate, water provides clearing and solar reflection for solar gains

Site B: warm climate trees to south provide shade in summer.

Question 15

Body of water provides clearning for direct (and reflected) southern solar gains

Answer 15

Site A: best location in a cold climate

Question 16

According to the building code, a courtroom has an occupancy classsification of _______ . (You may use the Amber Book Case Study material or the internet to look this up.)

Assembly (A)
Business (B)
Institutional (I)
Mercantile (M)

Answer 16

Answer: a courtroom is classified as Assembly (A).

See a list of code occupancies here. In the exam, you’ll want to be sure to use the search function to find the appropriate occupancy: in this case you’d search for “courtroom” and find it under occupancy classification A-3. These four classifications—Assembly, Business, Institutional, Mercantile—plus Educational (E), can mislead you if you try to guess instead of search. For instance, a medium-sized university lecture hall is not considered Educational, it is Assembly instead—Educational occupancy is reserved generally for K-12. A bowling alley, funeral parlor, and restaurant seem like they’d be Mercantile, but the code also considers them Assembly spaces—Mercantile is reserved for places where things are sold, like markets or department stores, without the density of a restaurant. You might assume that museums and libraries are Institutional occupancies, but they are also Assembly—Institutional as an occupancy is not about government and civic institutions, but rather for buildings like hospitals and jails where people may not be able to leave on their own in a fire. Generally if your building has a high density of visitors, it may be an Assembly occupancy, even if it doesn’t feel like a theater or banquet hall. Business occupancy includes spaces for lawyers and architects where people work every day (and know their way out if the lights fail and the corridor fills with smoke).

Question 17

According to the building code, a bank has an occupancy classsification of _______ . (You may use the Amber Book Case Study material or the internet to look this up.)

Assembly (A)
Business (B)
Institutional (I)
Mercantile (M)

Answer 17

Answer: a bank is Business (B) occupancy.

Why is a bank, post office, or barber shop considered a Business and has the B classification—while a courtroom is considered an Assembly, and has the A classification? They both have papers in storage and visitors. I suppose some threshold of people per square foot is crossed when you move from bank to courtroom on the density scale. In any event, that is why when faced with this kind of question on the exam, you’ll be sure to search the case study for “bank.” Don’t memorize these; use the search function instead because occupancy questions will almost surely come within a case study, and even if they don’t come in the case study section, you can often still look up the answers later in the case study section.

Question 18

You are designing a health clinic in Zambia on a remote site. A well is not an option here, so water will be delivered to a tank. No pump will be used in the building’s plumbing because the clinic is off-the-grid and only has power through photovoltaic panels on the roof. The pressure at the faucet is not sufficient. This can be best rectified by _______.

Increasing the diameter of the pipe

Increasing the height of the water storage tank

Swapping out for a larger tank with a larger diameter

Utilizing pressure-increasing valves

Answer 18

Answer: Increasing the height of the water storage tank

Question 19

Building foundations should rest on _______.

Shallow soils in temperate climates (less than 2 feet deep)

Peat

Sand

Topsoil

Answer 19

Answer: Sand

Peat and topsoil are organic, so they are unstable. In temperate and cold climates, foundations should rest below the frost line, typically more than two feet deep. Sand may not seem stable, but it is! If you’ve been to the beach, you’ve almost certainly seen hundreds of buildings supported by sandy soil. This house is on friction piles (telephone poles driven into the ground); this one is likely on a spread footer concrete foundation.

Question 20

Can you build on a floodplain?

Answer 20

A 25-year floodplain encompasses the area, usually adjacent to a body of water, that has a one-in-25 chance of flooding this calendar year. This is different than the “It floods every 25 years,” misconception because it may flood here twice in one year and then not flood for 90 years, and that’s normal. Likewise, a spot in a 100-year floodplain has a 1-in-100 chance of flooding this year. Most building and zoning regulations are based on a 100-year-flood event.

The National Flood Insurance Program was created by the federal government and administered by FEMA when it became clear that flood insurance couldn’t be effectively offered by the private sector: too much financial risk in the event of, say, all of Houston flooding in a single hurricane event, or all of Los Angeles in a Tsunami, where the insurance company wouldn’t have enough cash reserves to cover the damage to everyone. FEMA, then has requirements should you choose to build on a floodplain. As you may imagine, the rules are complex, but generally new and substantially-renovated buildings must be built such that your lowest floor sits above base flood elevation (BFE). You can find the BFE of your site by studying FEMA maps, and you can get your lowest floor above BFE on piles, on a crawlspace, or on fill. If you build on a floodplain, the feds may require you to purchase flood insurance.

Provided you get your lowest floor above base flood elevation, most municipalities will allow you to build within the 100-year floodplain, but some disallow construction within the 25-year floodplain.

Question 21

What is the building efficiency ratio of an office building with 100,000 sf, given that 20,000 sf is dedicated to elevators, physical plant equipment, restrooms, hallways, lobby, and the building management office

Answer 21

Answer: 80%

The leasable space, divided by the total space, returns the building efficiency ratio. As you may imagine, this number varies by project, is largely controlled by the architect, and often determines whether a development is profitable.

Question 22

In your own words, what is net present value? Provide an example.

Answer 22

You have a choice between two systems: System A has a lower installation cost, but B has a lower operating cost because it is more energy-efficient. Net present value, a technique in life-cycle cost analysis, allows you to easily compare the total cost of the two choices because the cost of installation, plus operation, of each choice is translated to today’s dollars. It accounts for inflation (saving a dollar in energy bills in five years is worth less than saving a dollar today in construction cost); it accounts for compound interest (if we save a dollar today, we can invest that dollar over the next five years to earn a return); and aside from energy costs it often accounts for maintenance costs and how long each choice is expected to last before a replacement is needed. It is the easiest concept to own in life-cycle cost analysis because the spreadsheet will tell you that, for instance, Curtain wall System A, over the next 20 years, will cost 10 million in today’s dollars and Curtain wall System B will cost 12.5 million, also in today’s dollars. In this example, the less expensive system to install (but the more expensive system to operate) has the lower total cost over time. The savings in energy use is not enough to make up the difference in construction cost.

Question 23

Identify the following standards:

ASTM E 1527

ASTM E 1903

ASHRAE 55

ASHRAE 62

ASHRAE 90.1

To hold unscrupulous people making false claims about building performance accountable, to standardize measurement conditions so that we can accurately compare performance from one building to another, to establish a baseline used for clearing code, LEED, or a similar third-party hurdle, and to facilitate a common language in courtroom proceedings, organizations like ASTM, ANSI and ASHRAE create and maintain standards. If you are exploring environmental performance as it applies to the ARE exam, you’ll want to take a minute to memorize which of these standards measures what.

Answer 23

STM E 1527: Phase I Environmental Site Assessment. Often required in commercial real estate before a bank loans money to develop a site, environmental engineers will attempt to determine if there is asbestos, lead paint, contaminated soil, etc. Phase I is a cursory evaluation, involving a walk-through, interviews with occupants, inspections of adjoining properties, and review of government records pertaining to the site. Was there a dry cleaner or gas station nearby that might have contaminated the soil? Does that pipe insulation look to be of an age that indicates it may have asbestos?

ASTM E 1903: Phase II Environmental Site Assessment. A more in-depth analysis often required if Phase I turns up a red flag. In Phase II, soil samples are taken; pipe insulation sample is taken to a lab.

ASHRAE 55 Thermal Comfort. Cited in LEED, this establishes ranges for temperature, humidity, airspeed, and thermal radiation as it relates to the clothing and activity of the occupants. It’s easier to achieve low energy use if you allow the building to get too warm or too cold, so requiring that it meets ASHRAE 55 keeps the energy modeler honest.

ASHRAE 62: Ventilation and Indoor Air Quality (IAQ). Also cited in LEED. Establishes just how fresh “fresh air” must be, establishes required outside air ventilation rates, etc.

ASHRAE 90.1 Energy and Lighting. Also cited (and cited often) in LEED, this checks greenwashing by owners, architects, and energy consultants. It establishes minimum performance for Energy Use Intensity (EUI), which measures annual kBTUs-used per square foot of floor area. Recently, buildings are publishing their EUI, even in design publications and design awards announcements. Understanding EUI isn’t a big part of these exams, but is becoming important to the profession. For instance, a warehouse has a median EUI of about 25 kBTU/sf (not much lighting or equipment or need for occupant thermal comfort. . . and spread over a large space). An office or school is 50, a mall is 100, a grocery store or hospital is 200 (lots of equipment), and a fast food restaurant is 400 (lots of equipment in a small total floor area). The goal then is to get your building well under those industry averages to drive down societal energy use.

*The standards on this list primarily apply to mid-sized or large buildings.

Question 24

Historic preservation and sustainability: this unfolds generally as common sense would dictate. Form a team with members that have a preservation background and members that have a sustainability background. Identify methods to reduce energy use, but consider the impact on the historic building. Execute what is needed to meet energy performance goals, but start with that which is least likely to denigrate the historic nature of the building. Only engage the disruptive technologies after you’ve engaged the less-disruptive ones.

Answer 24

Begin with the least invasive, most cost-effective, weatherization measures. Address air-tightness before adding insulation. Insulate unfinished spaces (attics, basements, crawl spaces) first, then only if the energy model deems it necessary should you remove historic plaster and trim in finished spaces to insulate there. Weather stipping and caulking windows is acceptable, as is installing storm windows. Don’t, for instance, remove a historic, durable, heart pine floor and replace it with a bamboo floor because the bamboo flooring seems to be sustainable. Use solar only after other less-intrusive options have been exhausted.

Please don’t run a wire like this person did!

When upgrading the heating and cooling systems, use the least invasive strategies first: smart, programmable thermostats and ductless HVAC systems that use refrigerant or water pipes instead of ducts. If you require ducts, route them away from important spaces and better to expose them if concealing them requires ripping out important historic finish materials. Don’t position outdoor HVAC equipment where it can be seen. (Consider a geothermal system, which is efficient and has no visible outdoor equipment.)

Retain the roof’s character if it is visible, typically the case in sloped roofs. . . but if the roof is low-slope (“flat”), feel free to install a green roof, high albedo membrane, or cool roof technology.

Question 25

New exterior addition to a historic building?

Answer 25

Only consider new construction if the existing building’s non-significant interior spaces cannot accommodate the new functions. Your new addition should be compatible with the scale and massing of the historic building, but your addition should be differentiated from the historic building. No saccharine, Disney, modern-day interpretations of what a historic building might look like in the new addition! Design the new addition so that it can be removed in the future without destroying the original historic building. This is a pretty good addition to a historic building.

Question 26

Standards for Preservation

Answer 26

1. Use the property to maximize the retention of distinctive features.
2. Retain the historic character
3. Recognize the property as a physical record of its time
4. Preserve past renovations that have acquired historic significance in their own right
5. Repair historic features so that the new material, color, texture, and design match the old
6. Preserve archaeological resources in place

Question 27

How do you repair masonry walls in historic structures?

Answer 27

Repair and replace only the deteriorated masonry; don’t replace the whole wall.

Match the brick or stone that was removed (this may be difficult to pull off). Replacing (only) damaged materials with matched replacement is a common theme in historic preservation guidelines.

Don’t clean old masonry unless necessary and then only clean it gently; cleaning can damage it. Don’t remove the paint on historically-painted masonry, but don’t paint historically-unpainted masonry.

Repoint mortar joints with evidence of deterioration (disintegrating mortar, mortar joint cracks, or loose bricks). Duplicate historic mortar joints in strength, composition, color, and texture when repointing is necessary. Finding the right mortar is not about using old-fashioned mortar, but rather ensuring that you use a softer mortar because old mortars were the lime-type. You don’t want a repointing mortar that cures harder than the old, soft, brick. Don’t repoint masonry with mortar of high Portland cement content because those cure too hard! Use Type O “high-lime” mortar because it will allow the bricks to expand and contract from thermal changes. High-lime mortar also binds to the old brick better and is self-healing. These soft, historic bricks spalled because of a renovation repoint with Portland cement mortar.

Question 28

Detention ponds, retention ponds, bioswales, and cisterns

Answer 28

Detention ponds: hold stormwater for a while, then slowly drain out. They are dry between storms, control flooding, require large amounts of space, and can breed mosquitoes.

Retention ponds: hold stormwater and are always wet. These look like regular ponds (but uglier, if not designed correctly). They both control flooding and promote higher water quality because the soil below them filters out pollutants from the water. On occasion, they can provide for swimming and recreation, but can breed mosquitos and pose a drowning hazard. To see the difference between dry detention and wet retention ponds, see below.

Question 29

You are employing a cut-and-fill strategy, whereby the earth you are using as compacted fill behind a retaining wall will come from excavation for the building’s foundation. How much compacted soil will be available for the retaining wall?

Given:

230 bank cubic yards of earth will be removed for the foundation

After excavation that becomes 300 cubic yards of loose soil

The swell factor for the soil is 10%

Answer 29

Answer: 253 cubic yards of compacted soil will be available for the retaining wall.

A single cubic yard of soil in place on your site will occupy, perhaps 1.3 cubic yards on the pile after it has been excavated because loose fill obviously takes up more volume than undisturbed soil. Then, after erosion of the pile from wind and rain, losses due to hauling spillage, and especially volume losses from compaction, we may only have 1.1 (or even 0.8!) cubic yards of compacted fill left when used under a roadway on another part of the site months later. Shrink and swell factors vary, depending on the soil type, time elapsed, and all the other variables that storage, transport, and compacting entail. . . and they can account for more than mere rounding errors when calculating cut-and-fill volumes. Waste (too much excavated and now we have to haul it away) and borrow (too little excavated and now we have to purchase fill from elsewhere) can be very expensive. When possible, we design for a balanced site: one where we have neither waste nor borrow, so we need to account for shrinkage and swelling.

Earth in its natural state is calculated as bank-measure, so we might say that we are “Removing 230 bank cubic-yards from that hill for the building foundation excavation.”

Earth in transport is calculated as loose-measure so we may say that we are, “moving that same soil in the amount of 300 loose cubic yards”

Loose soil, once compacted, is calculated as compacted-measure so we may say about that same quantity of earth, “We’ll get 253 compacted cubic yards behind that retaining wall.”

Shrink and swell factor is the decrease or increase in the volume of earth, expressed as a percentage, as compared to the volume of earth in its natural “bank” state (not compared to its transport volume). So, when I gave you “After excavation that becomes 300 cubic feet of loose soil” in this problem, I was giving you extraneous information you didn’t need to solve it.

compacted cubic yards=(100%-shrink %) x bank cubic yards

or

compacted cubic yards=(100% +swell %) x bank cubic yards

So for this problem

compacted cubic yards=(100% +10 %) x 230 cubic yards

compacted cubic yards=253

After excavation, but before compaction, the loose soil or rock always swells in volume relative to the bank measure and we use a (different) swell factor to measure that.

loose cubic yards=(100% + swell %) x bank cubic yards

You weren’t asked to solve it, but in this case the swell factor (bank measure to loose measure)

300 loose cubic yards=(100% + swell %) x 230 bank cubic yards

30%= swell factor

Question 30

You are employing a cut-and-fill strategy, whereby the earth you are using as compacted fill behind a retaining wall will come from excavation for the building’s foundation. How much excavated soil will be needed for the retaining wall?

Given:

230 compacted cubic yards of earth required for the retaining wall

The swell factor for the soil is 10%

Answer 30

Answer: 209 bank cubic yards of excavated soil is required for the retaining wall.

This time we are asked to solve the problem in the reverse order: instead of 230 cubic yards of excavated soil available, we instead require 230 yards of compacted soil.

compacted cubic yards=(100% +swell %) x bank cubic yards

230 compacted cubic yards=(100% +10 %) x bank cubic yards

209= bank cubic yards

*if you are asked on the exam, don’t forget that there are 27 (not 3) cubic feet in a cubic yard.

Because of shrink and swell, to achieve a balanced site, we often need to cut less volume than we fill (and sometimes need to cut more than we fill)

A handy trick: remember that the multiplier (shrink or swell factor) is always multiplied by the undisturbed bank cubic yards.

Question 31

You are employing a cut-and-fill strategy, whereby the earth you are using as compacted fill behind a retaining wall will come from excavation for the building’s foundation. How much compacted soil will be available for the retaining wall?

Given:

230 bank cubic yards of earth will be removed for the foundation

After excavation that becomes 300 cubic yards of loose soil

The shrink factor for the soil is 10%

Answer 31

Answer: 207 cubic yards of compacted soil will be available for the retaining wall.

Loose soil is always more fluffy than bank soil, and compacted soil is always less fluffy than loose soil, but compacted soil may actually be less fluffy than bank soil (or may not be). Read that last sentence again until you own it.

compacted cubic yards=(100%-shrink %) x bank cubic yards

compacted cubic yards=(100%-10%) x 230 cubic yards

compacted cubic yards=207

Question 32

Should I study the building code for the ARE?

Answer 32

I don’t think that studying code is a good use of your time. This test has relatively few code questions, and there’s so much material to study, so I don’t think you’ll earn a good yield (number of extra questions correct, per hour of studying). Plus the code questions almost always are part of a case study with searchable code excerpts. If you do wish to study the IBC, focus on Chapter 3 (use groups), Chapter 5 (how to determine the size/construction type of a building and required separation between occupancies), and Chapter 10 (egress sizing requirements). Do not memorize! Just become familiar with what’s available so you will know what to search or browse for during a harried case study section of the exam.

Question 33

You are going to mount photovoltaic panels (solar panels that produce electricity) flush to this south-facing roof in Little Rock, Arkansas (35 degrees latitude, 92 degrees longitude). What should be the measure of angle A?

Answer 33

Answer: 35 degrees, an angle equal to the latitude value is most efficient for year-round solar collection. Think about it for a second in your head until you own it. . . the sun is lower in the sky for more of the year at higher latitudes (Alaska) and higher in the sky at lower latitudes (Hawaii).

Question 34

You are going to mount photovoltaic panels (solar panels that produce electricity) flush to this south-facing roof in Little Rock, Arkansas (35 degrees latitude, 92 degrees longitude). What should be the measure of angle B?

Answer 34

Answer: 90-35=55 degrees. Angle A is equal to the latitude value for year-round solar collection.

A+B+C=180 degrees. . . and because C=90 degrees, A+B=90 degrees

Question 35

You are going to mount photovoltaic panels (solar panels that produce electricity) flush to this south-facing roof in Little Rock, Arkansas (35 degrees latitude, 92 degrees longitude) and you wish to optimize for summer performance. What should be the measure of angle A?

Answer 35

Answer: 35-15=20 degrees. The latitude value is optimal for year-round solar collection but if you wish to prioritize summer collection on a south-facing slope, subtract 15 from that value. It makes sense if you think about it. . . the sun is more overhead in the summer.

Why would you wish to optimize for only summer? Perhaps this is an off-the-grid summer camp and summer is the only time we wish to charge the batteries; perhaps Little Rock is cloudy in winter so optimizing for summer collection makes more sense; perhaps electricity rates fluctuate and are higher in summer when demand peaks because of air conditioning loads.

Question 36

You are going to mount photovoltaic panels (solar panels that produce electricity) flush to this south-facing roof in Little Rock, Arkansas (35 degrees latitude, 92 degrees longitude) and you wish to optimize for winter performance. What should be the measure of angle B?

Answer 36

Answer: 40 degrees.

A=35+15=50 degrees

B=90-50=40 degrees

The latitude value is optimal for year-round solar collection but if you wish to prioritize winter collection on a south-facing slope, add 15 to that value to solve for Angle A. It makes sense if you think about it. . . the sun is lower in the sky in the winter. To derive Angle B, subtract Angle A from 90 degrees.

Question 37

Which is a better choice for a rural site with a geothermal heat pump, trenches or wells?

Answer 37

Answer: trenches

In summer, geothermal heat pumps couple the hot condenser with water that has been cooled by pumping it through the ground—creating a more efficient system than a normative air-cooled condenser. The compressor (pump) doesn’t have to work as hard because the hot side doesn’t have to cool itself in 100-degree air. In the winter, the system reverses and the cold side doesn’t have to heat itself in 0-degree air, and can instead access 50-degree water heated underground.

Digging the earth for these loops of water is, from an architect or owner’s point of view, the dominant factor when considering the geothermal option. The pipes, which are actually more like continuous flexible tubing, can snake and loop through horizontal “trenches,” about three feet below the surface, or snake through vertical “wells,” that extend hundreds of feet downward. Both options prove expensive and disruptive to the land, especially if it’s difficult to get large equipment access to the site, if it’s been raining lately and the earth is soft, or if the soil is rocky/stiff and unlikely to make good contact with the tube.

As you might imagine, horizontal trenches, which look like this and this, are a better option if land is available to house them. Vertical wells are more expensive, but the only option in, for instance, a tight urban infill site. They look like this and this (you can see why this is an expensive option–look at all those rigs).

The systems I described above are “closed loop” systems where the same water (perhaps with a little antifreeze mixed in if wintertime is cold on this site) is recirculated between the indoor equipment and the ground in perpetuity. If there happens to be an underground aquifer or a pond on the site, an open-loop system may prove the best option, whereby temperate water is drawn up through a pipe from the pond or aquifer, used to cool (or, in wintertime, heat) the refrigerant, and then dumped back into the body of water while new water from the pond or aquifer is siphoned up to replace it. An open loop tied to an aquifer looks like this; an open loop tied to an on-site pond looks like this.

Question 38

If the Zoning code limits the building to no more than three stories, and the building code limits it to no more than five stories, how many stories is the building limited to?

Answer 38

Answer: Three stories. Whichever is more restrictive controls.

Question 39

Zoning code limits building heights. What other restrictions is it likely to place?

Answer 39

Answer:

Floor-area-ratio (FAR)

Lot building set-back distances (how close you can build to your front, back, and side lot lines)

Parking space number minimums (and thankfully, more recently, parking space maximums)

What type of occupancy or program is allowed (no gun shop next to elementary schools)

How you must deal with your site’s water runoff (maximum gallon per hour allowed into the sewer)

Building sign restrictions for businesses (height, size, number, type)

Question 40

What are form-based codes?

Answer 40

Form-based local zoning codes shift the emphasis from regulating building use (residential-only allowed here, commercial goes over there on the other side of the city) to an emphasis on regulating urban form. It might include mandates for street trees, sidewalks, front porches, back alleys and public space. It might also limit front-facing parking lots, dumpster visibility, and the type of building materials available to the architect. The principle of form-based codes, most often associated with the New Urbanism movement, is to encourage walkability and allow a bakery or dentist office to open near the homes that they serve.

Question 41

What is the difference between a covenant and an easement?

Answer 41

Both covenants and easements are contractual obligations that “ride” with the deed from today’s property owner to the next property owner. Neither is mandated by the municipality, but rather agreed upon by interested parties.

Easements often give someone else the right to use your property. For instance, I may pay you $30,000 for the right to share a portion of your driveway because I can’t access the roadway from my landlocked property without driving through yours. Or the utility company may have an easement on your property so that they can run power lines on poles and send utility workers to service them without fear of prosecution for trespassing. The next owner is then obligated to share the driveway with me and refrain from shooting utility workers on their land because I would never give you $30,000 for the right to use your driveway if you might sell the land next week and I’d have to negotiate and pay the next owner too.

Covenants often restrict what future owners can do on the property. If you plan on moving but promise your neighbors that no one will ever put a fence higher than five feet around the property, you can add that in a covenant and it rides as a sidecar to your deed. Planned communities that prize uniformity may have hundreds of covenants governing such design decisions as the slope of the roof, the color of the walls, and the depth of the porch.

An easement is typically affirmative, giving someone else the right to use your property, and a covenant is usually negative, restricting future owners from doing something with the property. Each may be in-perpetuity or may sunset after some number of years. Sometimes these two concepts overlap. If you wish to set aside some of your land in perpetuity as an undeveloped tract for wildlife habitat, that is usually called a “conservation easement” because it gives the birds and turtles access to the land. But it is also sometimes called a “conservation covenant” because it limits future owners from paving that portion of the land for a parking lot.

Question 42

What is the floor-area-ratio (FAR) of a five-story building, each story with footprint of 1,000 sf, sited on a 10,000 sf lot

Answer 42

Answer: 5×1,000/10,000=0.5

Zoning codes set maximum FARs

Each municipality has different rules for counting basements, attics, porches, the areas under balconies, etc..

Question 43

What is the authority having jurisdiction (AHJ)?

Answer 43

The authority having jurisdiction (AHJ) is the person, office, or organization responsible for enforcing the code. The AHJ may be a federal, regional, state, county, city, or town official. In practice, this may be the electrical inspector requiring a GFI receptacle, the labor board requiring a minimum number of nursing stations, the regional water management authority limiting the depth of your well, the health board limiting the distance between the commercial kitchen and farthest dining table, the insurance representative insisting on a sprinkler system, or an elevator inspector disputing the oil pressure in the elevator machinery . . . but most commonly, when we refer to the AHJ we are referring to the life safety (fire) code and the authority having jurisdiction will be the state fire marshal.

Question 44

The National Fire Protection Association (NFPA) code (commonly referred to as the “fire code” or “life safety code”) doe not require that a fume hood be fire-rated, but the fire inspector insists that the fume hood you install must be one that is UL tested and fire rated. What do you do?

Answer 44

Answer: the fire inspector is the authority having jurisdiction (ASJ), and if she says it has to be fire-rated. . . it has to be fire-rated. AHJs enjoy broad powers of interpretation and wield considerable weight.

Question 45

The elevator inspector, electrical inspector, fire inspector, and your interpretation of the building code are each requiring a different minimum level of fire protection for an elevator shaft. Which of these entities governs?

Answer 45

Answer: you must meet the most stringent requirement of any of these authorities having jurisdiction (AHJs)

Question 46

Single-loaded corridors vs double-loaded corridors

Answer 46

You likely already know the difference between single-loaded corridors and double-loaded corridors, but if you don’t, you can see the difference here. The corridor interferes with cross-ventilation and limits the direction of daylight in dorms, hospitals, apartment buildings and office buildings.

Single loaded corridors offer the opportunity for daylight in the circulation space, and may make it easier to provide cross-ventilation in the rooms, provided the corridor has operable windows and the occupants don’t mind leaving their hallway doors open (or have louvers that can connect their rooms to the hallway air). Double-loaded corridors allow for larger floor plates and more efficiency, as measured in hotel rooms/sf, because rooms can sit on either side of the hallway.

Question 47

Horizontal vs vertical louvers

Answer 47

Design horizontal louvers for south-facing apertures where the sun is high in the sky, and vertical louvers for east- and west-facing apertures where the sun may be low in the sky at sunrise or sunset. North-facing apertures almost never need shading because the sun doesn’t hang out much on the north face of the building.

Question 48

Overhangs vs louvers

Answer 48

Louvers are almost always less impactful on the architecture and structure.

Question 49

What do we use climate zones for?

Answer 49

Climate zones are useful for energy and thermal comfort rules-of-thumb, for instance

How much insulation should we use under our foundation in Climate Zone 5?

Are Low-e windows really that helpful in Climate Zone 3?

Do we need a vapor barrier in Climate Zone 2?

In what climate zone is a Trombe Wall appropriate?

Is a heat pump efficient for heating in Climate Zone 6?

How much heating load in BTU/sf*yr should we expect for a commercial building in Climate Zone 4?

Question 50

Should the open field/lake/clearing be on the north or south side of your building?

Answer 50

Answer: it depends on the climate

Locate buildings so they have less shade (E,W,S) in cold climates and more shade (E,W,S) in hot climates. If there is a clearing, open field, or water feature, treat those as access to sun, and drop your building to the north of the clearing, open field, or water feature (cold climate) . . . or the south side of the clearing, open field, or water feature (hot climate).

Question 51

How should you locate and orient your buildings relative so wind on the site?

Answer 51

In a cold climate you want to block the wind, so shelter your building in the “wind shadow” of other obstructions such as out-buildings, other existing nearby structures, patches of trees, or landscape walls. Use unheated rooms (i.e. an attached garage) to buffer your buildings from winds.
In a hot-humid climate, locate your building to be free of any wind shadow. Orient buildings with the long axis perpendicular to wind in hot-humid climates to give rooms access to breezes. For instance, if the wind comes from the west, locate the long axis of the building north-to-south. But doesn’t that contradict good solar-gain orientation where we’d want to locate a building with its long axis aligned east-west? YES, it does . . . you probably read the question incorrectly if you find such a contradiction. Unfortunately, the exams don’t typically force you to make hard choices where one thermal priority contradicts another. Only answer the question with the information given. If the question asks about breezes, focus on cross-ventilation, not environmental noise from a nearby train track. If it asks about noise, focus on the train track and not on solar access. Right-click to rotate buildings when you drag-and-drop them in a site. Right-click on a digital white board item like a shape or text box to rotate it, copy it, etc.

Question 52

Where do you locate your building on a hill? At the bottom? Partway up? At the crest?

Answer 52

If you are building in the mountains, know that the valley will pool sinking cold air on still nights (good for hot-arid) and the top will have the most wind (good for hot humid). So locate your buildings on the following elevations based on climate: Bottom-Hot Arid 1/3-Cold; 2/3-Temperate; Top-Warm Humid

Question 53

What climate benefits from air movement (breezes)? What climate benefits from evaporation?

Answer 53

Buildings in hot-humid climates benefit from breezes, but buildings in hot-arid climates do not.

Buildings in hot-arid climates benefit from evaporation (evaporative cool tower, swamp cooler, water feature, spraying water), but buildings in hot-humid climates do not.

Question 54

Express this slope:

as a fraction

as a ratio

as a percentage

as an angle

H-25’ L-100’

Answer 54

as a fraction. . . 1/4

as a ratio. . . 1:4

as a percentage . . . 25% (note that if the slope is steeper than 45 degrees, the slope is more than 100%)

as an angle. . . 14 degrees. SOH CAH TOA tells us that Tan=opposite/adjacent so arctan [or inverse-tan or tan^-1] of 25/100 = 14 degrees. Be sure that your calculator is set to “degrees” rather than “radians.”

Question 55

Historical buildings often feature narrow corridors, heavy and narrow doors with decorative hardware, steep terrain, monumental stairs, or other elements difficult to navigate if disabled. How does one balance the sometimes competing priorities of historic preservation and accessibility?

Answer 55

A: Just like you’d guess. . . balance them carefully, with common sense, and clever design.

First, review the property’s historical significance by exploring its nomination file in the National Registry of Historic Places. Use that to prioritize which character-defining feature and spaces to protect from changes. Focus on changes instead to alter secondary spaces and finishes, nonsigniificant spaces, later additions, previously altered areas, and service areas

Second, assess the building’s existing (and required) level of accessibility. Look for inaccessible entrances, floor surface textures that don’t play well with wheelchairs, narrow walkway widths, elevators, toilets, weights & configurations of doorways, and steep grade changes.

Finally, balance the two competing mandates cleverly. “Provide the greatest amount of accessibility without threatening or destroying those materials and features that make a property significant.” Confirm that changes to the historic character can be reversed in the future. Assemble a team of accessibility consultants, historic preservation professionals, building inspectors, persons with disabilities, and the state historic preservation officer (who can allow special accessibility provisions for your project).

Question 56

In a historic preservation setting, list the most important accessibility requirements.

Answer 56

In order of priority:

Main public entrance and primary public spaces accessibility
Restroom accessibility
Secondary space accessibility

Question 57

How to resolve conflicts between historical preservation and the outdoor building site (because cobblestone paths prove difficult to navigate in a wheelchair)?

Answer 57

Short distances between arrival and destination points

Convenient parking

Paths at least 3’ wide and slopes no steeper than 1:20

Stable, firm, slip-resistant outdoor surfaces (may require resetting the paving surfaces)

Question 58

Accessible ramps at entrances to historic buildings

Answer 58

Tricky, because the accessible entrance should be the main public entrance, whenever possible. . . and the main public entrance is often in the center of a significant historic facade and atop monumental stairs! Focus on materials (don’t use unpainted treated wood for the ramp, put your ramp’s railing behind a stone wall, don’t install temporary ramps, etc.)

Wheelchair platform lifts and inclined stair lifts don’t take up a lot of space in plan and can be easily removed in the future (important for historical preservation), but they are usually visually hard-to-hide, aren’t permitted in many states, and should be under a covering, protected from the weather to avoid excessive maintenance requirements. Argh, this is hard.

Can you punch a new main entrance into a historic building to accommodate the accessibility mandate? Yes, but only after exhausting all possibilities of modifying an existing entrance.

Keep the existing historic entrance doors and frames (but you’ll need 32” clear path through them, which is generally only achievable in a 36” wide door). Argh again. Tough calls everywhere we look.

Historic doors often require a lot of pressure to open, but hard-to-open doors don’t meet ADA requirements. Finally . . . an easy win: install automatic door openers. Newer hinges may also reduce the required pressure (and some special hinge types can even get you an extra inch of clear door width).

ADA dictates that door thresholds may not exceed ½”, and many historic thresholds do. If the threshold is deemed historically significant, add a bevel to each side. Otherwise, alter it or replace it altogether.

Question 59

Accessibility and historic interiors

Answer 59

Door knobs don’t meet ADA (arthritis), so new buildings use levers instead. To keep the old knobs on the historic interiors, prop the door open during operating hours.

Restrooms with historic fixtures or marble partitions pose a conflict. You may relocate those within the room to create larger stalls. Add grab bars, shift fixture heights, and protect the knees of those in wheelchairs from burns by covering under-sink hot water pipes. You may create a new unisex accessible restroom if reconfiguring the old ones runs counter to preservation mandates.

A new addition to the building–if it maintains the old scale, protects a significant landscape, doesn’t try to “look old,” and touches the old building lightly such that it can be removed in the future–might be a solution to the entrance door, entrance ramp, elevator, and restroom conflicts.

Question 60

What is the difference between

Preservation

Rehabilitation

Restoration

Reconstruction

Answer 60

Preservation: Maintains and repairs existing historic materials

Rehabilitation: Alters or adds to meet today’s needs

Restoration: Depicts a property at a particular period of time, removing evidence of other periods. Colonial Williamsburg, Virginia.

Reconstruction: Recreates non-surviving portions of a property

Question 61

Steepest slope for planted areas

Answer 61

2:1

Question 62

Steepest slope for parking lots

Answer 62

5% maxium

1% minimum for runoff

Question 63

Road hierarchy

Answer 63

From smallest to largest: local, collector, arterial, expressway

Question 64

What is a rough order of magnitude (ROM) cost estimate?

Answer 64

Rough order of magnitude (ROM) cost estimate: Just what you’d think. . . an early-stage very approximate cost estimate focused on feasibility that can be considered accurate to something like +/- 50%.

Question 65

Identify common development patterns. In what type of cities can you find each of these?

Answer 65

Each of these describes the streets layout. . .

Grid/rectangular/chessboard: like Midtown New York

Radial/star: Major roads fan out from a central point, like Washington DC or Paris

Radial-ring: Concentric circles of bypass roads established to divert traffic around the dense center each time the city grows in girth, like Houston

Contour-forming: In steep terrain, roads follow lines of elevation, like rural mountain roads

Irregular/field: Roads every which way, most associated with organic (not centrally-planned) city growth, like Boston

Satellite: Smaller cities linked to a central megacity, like Shanghai

*Most development happens as s mixture of these

Question 66

You have a high water table on the site you plan to build on. . . now what?

Answer 66

Foundation footings and basement slabs should sit above the water table (soil depth where wet all year).

With a high water table, we may need to use a shallow footing (but of course, below frost depth). . . or mound up the earth below the building. . . . or use piles, pilings, piers, or caissons, which can be drilled or driven below the water table.

Question 67

What is the occupancy classification of a 250sf cardboard box storage room. You can use this reference to approximate the case study documents you’d be provided on an exam.

Answer 67

Answer: Group S-1 Moderate Hazard Storage. You’ll be afforded the use of a search function in the case study portion of the exam, so search smart. Search that site I provided you for “cardboard”

Because the storage room is more than 100sf, declaring it an “accessory space” (and not having to classify it as a separate occupancy from the rest of the building) is not an option for you here.

Question 68

What is the occupancy classification of a 250sf chipboard storage room. You can use this reference to approximate the case study documents you’d be provided on an exam.

Answer 68

Answer: Again, this is S-1 Moderate Hazard Storage. Obviously, not every possible room use could possibly be explicitly included on the occupancy classification list in the code. Because chipboard is “cardboard-adjacent” we can assume that the two sit in the same occupancy classification.

Note that S-1 Moderate Hazard Storage includes flammable (but not gasoline-like flammable): lumber, furniture, baskets

. . . and S-2 Low Hazard Storage includes markedly less-flammable items (though sometimes with thin flammable wrappers): cement in bags, meat, glass, washers/dryers.

Question 69

Can you build in a riparian zone?

Answer 69

A: Not usually, but it depends on local zoning and if the bank will loan your client capital to build where it will likely flood.

Riparian zones: the buffer areas adjacent to a water body. They are sometimes wet (after a rain or at high tide) and sometimes dry; often heavily vegetated; and important for flood and erosion control, wildlife habitat, and water quality. They are especially salient in dry climates where the stream banks are the only places with enough water to support trees, and heavy rains pose a considerable erosion/mudslide threat without the vegetation to shore up the banks.

Clients want to be on the river/wetland/lake for views and recreation, but those areas flood often, damaging buildings.

Old thinking: put the river in a ditch and build right up to it.

New thinking: let the river do it’s thing. . . give it some room on either bank for the sake of everyone.

Question 70

An architect is developing a 115-acre site with a goal for the entire site of 16 units per acre. He’s developed 75 acres of the site so far at 14 units per acre. What should the density be, in units per acre, for the remaining not-yet-developed portion?

Answer 70

A: 19.75

115-acre site with a goal for the entire site of 16 units per acre.

75 acres of the site developed so far at 14 units per acre.

What should the density be, in units per acre, for the remaining not-yet-developed 40-acre portion?

14(75/115) + x(40/115) = 16

Need more problems like this? Click here to watch an Amber Book : 40 Minutes of Competence video with extra questions. If you do, be sure to hit pause and make your own earnest attempt at solving the calculation; listening to me solve it without attempting it yourself does you less good.

Question 71

How far up a hill should you locate a small building in a cold climate

Answer 71

A: Approximately a quarter of the way up the hill.

Question 72

What are catch basins?

Answer 72

Catch basin: the box below an outdoor drain. It looks like this.

This catch basin, because it’s adjacent to a construction site, has a device to limit topsoil erosion. Water moves through. . . but soil stays on site.

Question 73

Why the reflector “hat”? For transfer through conduction, convention, or radiation?

Answer 73

A: Radiation

This is kind of similar to how Low-E windows work, at least for half the low-E process. They reflect the sun’s heat, like this reflector redirects the flame’s heat, but unlike this reflector, low-E windows let (most of) the light through. That concept will probably never be intuitive to you, but own it none-the-less. Electromagnetic energy (radiation) can be blocked (shaded), allowed through (transmitted), or bounced back (reflected). . . and with the right film on a window, some of the frequencies (heat) can be reflected while other frequencies (light) are transmitted.

Question 74

You are stumped on a test item in PA. Your answer choices are:

Schematic Design (SD)

Design Development (DD)

Construction Documents (CD)

Construction Administration (CA)

. . . . which one do you guess as the answer?

Answer 74

Answer: Schematic Design (SD)

If not sure, always guess the design phase that corresponds with the exam division you are taking!

PA =Schematic Design (SD)

PPD = Design Development (DD)

PDD = Construction Documents (CD)

CE = Construction Administration (CA)

Question 75

What is the minimum slope for swales to prevent standing water?

Answer 75

1%: the minimum slope for swales to prevent standing water (1/100)

2%: maximum cross slope for ADA walkways (1/50)

5%: maximum slope before accessible ramps are required (1/20)

Question 76

Required land slopes

Answer 76

-1:100-1%-.5deg: min for storm water run off(parking lot)
-1:50-2%-1deg: Max ADA cross-slope
-1:20-5%-3deg:max before ADA ramp is req., max of parking lot.
1:12-8%-5deg:Max ADA ramp slope (not including 5’landings at top/bottom of every 30’ segment)
1:10-10%-6deg:Max before Step footing req.
1:4-25%-45deg:Max for driveway
1:1-100%-45deg: Max for a green roof
very steep site: post-and-beam/pole foundation required

Question 77

What to do if your land is too flat to drain?

Answer 77

If your vegitated land is sloped at less than 1%, or your parking lot is sloped at less than 0.4%, water will pool causing basement flooding, parking lot damage, mosquitos, etc. . . . to prevent that, create local low-points and install storm drains (then to catch basins, then to underground storm sewer pipes, then to daylight or to underground cisterns that slowly drain)

This drain on an occupiable flat roof plaza, over a sub-grade building, feeds stormwater pipes in the ceiling of the space below. During the Covid pandemic, weeds began growing in these local low-points, perhaps because they supported less foot traffic that otherwise tamped down plant life, or perhaps because landscaping maintenance schedules were disrupted by the pandemic.

If, on the other hand, you have more slope than those minimums, and therefore enough for gravity to pull water to one part of the site, use curbs to redirect water to retention/detention ponds or swales.

Question 78

Name the causes, and solutions, of the urban heat island effect

Answer 78

Urban heat island effect: the local urban microclimate is warmer than surrounding hinterlands, especially after sunset on sunny, still-air days when the thermal mass of the city slowly releases the solar energy it absorbed all day

Causes: reduced natural landscapes, fewer trees, absence of vegetation, fewer bodies of water (evaporation and transpiration cool the microclimate), more hardscapes, more roofs, dark-colored pavements and roofs, building and road geometries that block breezes that would have otherwise flushed the hot air from the city

Solutions: just what you’d think. . . plant urban trees and reduee asphalt paving! Also disturb less greenfield, design light-colored pavements and light-colored or green roofs, wide boulevards to allow uninterrupted summer breezes to flush cities of built-up heat

Question 79

What is universal design?

Answer 79

Universal design: The theoretical framework behind ADA. . . The idea that buildings should be able to be used by all people, regardless of disability, age, or size—that accessibility it is not a design constraint for the benefit of a small minority, but rather that universal design is good design.

Question 80

What causes light pollution?

Answer 80

Threee things cause light pollution:

(1) Uplights. Click here to see what they look like.
(2) Unshielded lights without cut-offs (cut-offs are blinders or baffles that prevent “leaked” light from moving toward the night sky). Click here.
(3) Well-lit light-colored ground surfaces that reflect downward-facing light back up to the night sky. It can be seen in the University of Arizona campus nighttime helicopter photo below: the large light spots are reflections from light-colored concrete lighted parking lots.

Question 81

Which one of these building forms is more efficient in a cold climate, assuming that they each have equal volume

multi story or single story

Answer 81

The multi-story cubic building has less surface area (for the same volume) and therefore less skin heat-loss (and less skin heat gain, and a smaller roof for less radiant summertime gains)

Question 82

From a programming point of view, what else makes a building more efficient?

Answer 82

A: Daylight availability (so electric light isn’t needed), summertime shading, central mechanical systems are more efficient than in room-systems (one fan and one compressor for multiple zones), sharing heat from core to perimeter (variable refrigerant systems), on-demand hot water heating (so that hot water needn’t be stored for later use), radiant hydronic heating and cooling systems, small openings in cold and hot-arid climates, large openings in hot-humid climates, and southern glass and thermal mass (cold sunny climates).

Question 83

Venturi effect

Answer 83

Wind flows fast through breezeways and narrow openings. See here.

Question 84

What is the most efficient parking lot layout?

One-way or two-way traffic?

Perpendicular, parallel, or angled?

Answer 84

One-way traffic angled parking offers the most parking spaces on a given site. See here.

Question 85

How many accessible entrances are required?

Answer 85

50% of public entrances must be accessible.

For most small buildings, fire code requires two means of public egress, so, in that case, one must be accessible (the main entrance).

Larger buildings have more entrances, and 50% of those must be accessible.

Question 86

How many nighttime hours on March 21 and September 21 at 22 degrees north latitude?

Answer 86

A: 12

Question 87

How many nighttime hours on March 21 and September 21 at 42 degrees north latitude?

Answer 87

A: again, 12 hours of daylight and 12 hours of darkness during the equinox, regardless of latitude. . . . that’s why we call it the equinox.

It’s the midpoint in the season when long nights turn to long days at the middle latitudes, and extremely long nights turn to extremely long days at the higher latitudes.