Site Work DD Flashcards

1
Q

How exactly is “runoff” defined?

A

The amount of stormwater that accumulates on the site beyond what can be absorbed by the soil.

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2
Q

What elements are included in “above-ground drainage”?

A
  • pervious paving
  • sheet flow (sloped surfaces)
  • gutters / ditches
  • groundwater swales
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3
Q

What are the general minimum slopes for sheet flow?

A

Minimum:

  1. 5% for very smooth, carefully constructed surfaces
  2. 5% for most types of surfaces
  3. 3% for underground piping
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4
Q

What are “drain inlets” and “catch basins”?

A

Drain inlets are the grated opening into which surface runoff is collected.

Catch basins are vessels (usually underground) where water is temporarily collected before flowing out again, allowing sediment to settle to the bottom (essentially a sump).

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5
Q

What are the genera placement criteria for stormwater manholes?

A

For manholes serving the stormwater sewer:

Wherever the SW sewer changes direction or minimum every 500ft.

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6
Q

What are the general applications of the “n-year storm” criteria?

A

100-year storm = 1% chance per year

25-year storm = 4% chance per year

ETC…

Most systems are designed for a 25-year storm; 10-year is also common.

Size of system is: [runoff-coefficient] * [size-of-drainage-area] * [n-year-water-amount]
(the runoff coefficient is fraction of water not absorbed)

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7
Q

How are “holding ponds” used?

A

Used if the amount of expected runoff exceeds the amount that the municiple SW system can receive.

They hold SW temporarily and allow it to drain into the municiple SW system at a controlled rate.

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8
Q

What are the general slope minimums for SW and sanitary sewer lines?

A

Slope minimums are between 0.5% and 2.0% (1/16” to ~3 3/4” per foot)

Minimum slope depends on pipe size, with smaller pipes needing more slope.

2 1/2” pipe …> min. 1/4” per foot (~2.0%)
3 - 6” pipe ….> min. 1/8” per foot (~1.0%)
8” + pipe ……> min. 1/16” per food (~0.5%)

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9
Q

In what case is a SW or sanitary sewer not able to run directly from the building to the sewer main?

A

When the highest point of sewer at the building with the slope does not allow it to meet the sewer main ABOVE. It must then travel farther to join the main at a point where it is lower.

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10
Q

What are some general road widths and radii for on-site drives?

A
  • Min width for one-way traffic: 12’
  • Min width for two-way traffic: 24’
  • Min radius for roundabouts, cul de sacs, and other loops: 40’
  • Min width for parking lane: 8’
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11
Q

What are some general slope guidelines for on-site drives?

A
  • Absolute maximum slope fo 15%
  • Perferred maximum slope of 10%
  • Transitions to 10% or higher slopes should have a slope of half the higher slope
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12
Q

What are the general cross slope guidelines for on-site drives?

A

Should slope away from the centerline of the drive, called the “crown”. Should slope are 1/4” per food minimum.

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13
Q

Where should entry drives to a site be located with respect to main road intersections?

A

Either as far from the intersection as possible (to avoid confusion and congestion) or right at an intersection (if appropriate).

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14
Q

What are some general guidelines for site walk stairs?

A
  • 14” tread depth
  • 6” riser height
  • Slope treads 1/4” per foot for drainage in the direction of travel
  • Min. 3, max. 10 risers continuously
  • Handrail 34-38” A.F.F.
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15
Q

What are some general guidelines for on-site drives for service vehicles?

A

For moderate-size, straight-body trucks:

  • Min. 45’ outside of turns
  • Min. 35-50’ straightaway after a turn (from inside)
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16
Q

What are the standard parking spaces sizes?

A

Typical: 9’ by 19’

Compact: 7’ 6” by 15’

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17
Q

What is the comparison between 90-degree and angled parking?

A

90-degree parking is the most efficient (more parking spots per land area).

Angled parking is easier to use and, since it can accomodate one-way aisles, has less total width

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18
Q

About how much space is needed per parking space?

A

In aggregate (including drives, landscaping, ETC), about 400 ft2 per parking space.

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19
Q

What are some recommended slopes for parking areas?

A

For drainage of parking areas:

Minimum 1.5%

Maximum 5.0%

Typically 2.0 - 3.0%

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20
Q

What are the possible aesthetic and functional uses of landscapeing?

A

Aesthetic:

  • aesthetically pleasing plants / lawns
  • frame views
  • block unwanted views

Functional:

  • assist w/ energy conservation
  • mitigate noise
  • create privacy
  • provide shade
  • retard errosion
  • manage stormwater absorbsion
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21
Q

What are the general guidelines for using trees to mitigate wind?

A
  • Reduce wind most effectively at 0-5 times the tree height. Beyond 20 times the tree height, the wind reduction is negligible.
  • Can reduce wind from 30-40% within this effective range.
  • Evergreen trees are more effective at reducing wind.
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22
Q

How is a “sunpath chart” arranged for a the four different types of projections?

A

Rectilinear

Azimuth (E or W of south declination of the sun) is plotted along the bottom axis.

Altitude (height above horizon of the sun) is plotted on the vertical axis.

Bell-shaped curves show the position of the sun throughout the day on a given day. Vertical curves cross those looped curves giving the location of the sun at various times.

Equidistant Horizontal

Same as Rectilinear, except the Altitude is plotted as a circle and the Azimuth is plotted as rays from the center.

Gnomic

Looks like a fish-eye projection of the chart. Less useful; can be used to predict shadows on the site. Traditionally, uses a peg placed at the base of the chart to project a shadow onto the shart lines.

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23
Q

How is “passive solar” defined?

A

Alternate energy from solar without the use of mechanical equipment.

Uses direct sunline on thermal mass, often through a window hitting floors or walls with thermal mass.

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24
Q

What are the general design techniques for materials in passive solar?

A
  • Thermal mass elements should have good heat storage (concrete, stone, tile, masonry, ETC)
  • Other thermal mass materials include water and phase-changing substancs such as eutectic salts.
  • Thermal mass elements should be dark in color
  • Thermal mass elements should be free of carpets, hangings, and other insulating coverings
  • Glass that allows sunlight should be highly insulating (low-e coating, U-factor of less than 0.35
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25
Q

What are the three basic types of Direct Gain passive solar systems?

A

Direct Gain Space
Sunlight passes through glass and then directly strikes thermal mass walls and floors.

Thermal Storage Wall
Also called a “Trombe Wall”. Sunlights passes through a window that is directly in front of a thermal mass wall. Air is circulated in front of the wall to move the heat.

Greenhouse
Silimar to a Thermal Storage Wall, except the space in front of the wall is a greenhouse enclosure and the rock bed of the greenhouse also stores heat. Air is passed in to and out of greenhouse to heat the inhabited space.

26
Q

What is an Indirect Solar Gain passive solar system?

A

Thermal mass elements are not in direct sunlight.

Instead, they are heated by reflected sunlight or by warm are from direct gain areas.

About 1/4 as effective as Direct Gain systems.

27
Q

What is an Active Solar system?

A

Uses mechanical systems (pumps, fans, ducts, pipes, ETC) to more effectively collect and store heat.

28
Q

In solar heating, what is a “passive system with active assist”?

A

A primarily Passive Solar system which uses some Active Solar conveyance to augment its storage and distribution capacity.

29
Q

What is the difference between an open-loop and closed-loop active solar system?

A

Open-Loop: The substance being circulated is the one that is directly used (such as hot water that is directly circulated in the collecort and then used by inhabitants).

Closed-Loop: The substance being circulated is a special mixture (water w/ antifreeze, ETC) that collects heat more efficiently and then indirectly transfers that heat to the substance being used.

30
Q

What is the best tilt angle for photovoltaic panels for energy production year-round and in winter?

A

Year-round: equal to the global latitude of the site

Winter: 10-50-degrees greater than the latitude of the site

31
Q

What is are the general best orientation guidelines for a build?

A

With the long side facing roughly 15-degrees east of south.

East of south for various climates:

  • Cool ………… 12º
  • Temperate … 17.5º
  • Hot-arid ……. 25º
  • Hot-humid … 5º
32
Q

What is the difference between an Internal and External Load Dominated building?

A

Internal Load Dominated

  • heating and cooling load is primarily driven by the occupants and internal equipment.
  • generally buildings with more dense occupants, heavier equipment, and larger volume
  • generally: offices, institutional, retail, laboritories, and some types of industrial

External Load Dominated

  • heating and cooling load is primarily driven by the loss or gain through the envelope
  • generally buildings with less dense occupants and smaller volume
  • generally: residential and storage
33
Q

What are the general design principles, with respect to building shape, for Internal and External Load Dominated buildings?

A
  • Building shape has less of an impact on Internal Load Dominated buildings
  • The use of Passive H/C techniques increases the effect of building shape

Most efficient shape for different climate regions:

Climate External L.D. Interanl L.D.
Cool cube square footprint multi-story
Temperate rectangle rectangular footprint multi-story
Hot-arid square w/ courtyard rectangular footprint multi-story
Hot-humid enlongated rectangle elongated rectangular footpint mulit-story

34
Q

What is the best type of shading for facades that face different directions?

A

South-facing: deep horizontal overhangs

East- or west-facing: multiple shallow vertical louvers

35
Q

What type of insulation guidelines are provided in the IRC?

A

Prescriptive values for all types of assemblies (floor, wall, perimeter slabs, ETC) within different climate zones and for different number of heating degree days.

36
Q

What is “superinsulation”?

A

A design where there are absolutely no thermal breaks. All surfaces are sealed and insulated to a minimum level.

37
Q

What is the Stack Effect?

A

A difference in temperature between the top and bottom of a tall building, where hot air percolates to the upper part of the building, driving air leakage.

38
Q

What is an Air Barrier? What are the different types?

A

Air Barrier
Prevents the movement of air into and out of the building.

Vapor-Impermeable
Also acts as a Vapor Retarder, IE, it blocks the movements of water vapor.

Vapor-Permeable

  • Allows the movements of water vapor while still preventing the movements of air. At least 5 perms.*
  • “house wrap” (spunbonded polyofin)
  • polyethylene
  • liquid- or spray-applied coatings
  • self-adhering membranes
  • special sheathing + taping products
39
Q

What is the standard measure of permeance?

A

The “perm”

One grain of moisture per hour, per square-foot inch-mercury difference in pressure

1 gr / ft2-hr-in Hg

40
Q

What are the ANSI / ASHRAE 90.1 standards for permeance of an Air Barrier of a commercial building?

A

** 0.3 in wg at 68ºF is the standards testing conditions

Either:

1 - 0.004 cfm / ft2 at standard conditions for an Air Barrier material

2 - 0.04 cfm / ft2 at standard conditions for an Air Barrier assembly (EI677)

3 - 0.4 cfm / ft2 at standard conditions for an entire building (test E779)

41
Q

What is the best design practice when the Air Barrier and Vapor Retarder are separate layers in an assembly?

A

The Air Barrier should be 10 to 20 times MORE PERMEABLE to water than the Vapor Retarder.

This prevent moisture from being trapped between the two layers.

42
Q

What considerations must be made for earth-sheltered buildings?

A
  • Should be within a natural slope, to minimize the amount of excavation
  • Soil should be gravel, sand, or sandy loam. Clays and silts do not drain well and can expand when moist.
  • Site should be tested for excess radon
  • The groundwater must be below the building
  • Portions below the ground must be well water-proofed and drained
  • Must have adequate ventilation to control humidity
  • Insulation must be placed carefully to prevent build-up of condensation
43
Q

What is the difference between Intensive and Extensive Green Roofs?

A

Intensive
Thicker (12”+) soil capable of sustaining complex and varied vegetation.I

Extensive
Thinner (~6”) soil for sustaining grasses, sedums, herbs, and perennial flowers.

44
Q

What are the assembly layers for a green roof?

A

For concrete decks:

  • Structural deck (12-300psf, depending on type of vegetation, ETC)
  • Roofing membrane
  • Roof barrier (if the roofing membrane is not also roof-resistant)
  • Rigid insulation (to prevent water in the growth medium from stealing heat from the building)
  • Drainage layer (minimum 1.5% slope
  • Filter fabric (to prevent growth medium from erroding away)
  • Growth medium (soil with a nutrient mix and thickness appropriate to the vegetation)

For metal decks:

  • Metal deck
  • Sheathing
  • Rigid insulation
  • Roofing membrane
  • *same as above*
45
Q

What is a Cool Roof? When is it appropriate to be used?

A
  • Also called a “reflective roof”
  • A roof that reflects more sunlight energy than is absorbs
  • But have an initial reflectivity of at least 0.65 and a 3-year reflectivity of at least 0.50

Appriate uses:

  • in warm climates (with more cooling degree days than heating degree days)
  • sometimes in cool climaets in Internal Load Dominant buildings
46
Q

What is SHGC of a window?

A
  • “Solar Heat Gain Coefficient”
  • The amount of solar radiation that is transmitted through the entire window assembly
  • Decimal between 0.0 and 1.0
47
Q

What is the SC of a window?

A
  • “Shading Coefficient”
  • Largely obsolete (in the US), replaced by SHGC
  • Amount of solar radiation that passes through just the glass
  • Is scaled against a theoretical control, which is a clear, unshaded, double-strength 1/8” piece of glass
  • Decimal from 0.0 to 1.0
48
Q

What is the Daylighting Factor?

A

Often abreviated “DF”

The ration of illuminance on a horizontal surface at the interior of a building to the illuminance on a horizaontal surface on the exterior of the building, during at an overcast moment.

It is expressed as a percentage.

49
Q

What are the ranges of desirable Daylighting Factors?

A

~ 1.5% DF for most tasks

~ 4.0% DF for difficult or intensive tasks

Above 5.0% is not recommended, as glare and excessive heat gain can occur.

50
Q

What factors go into the “effective aperture” of a daylighting window?

A

Product of two figures:

Visible Light Transmittance
The percentage of light that passes through the glazing material.

Window-to-Wall Ration
NET glazing area in the room divided by the GROSS area of the exterior wall

An A.E. of 0.20 to 0.30 is considered good.

51
Q

How can the conflicting interests of daylighting and other issues, such as glare and heat gain/loss?

A
  • Use glass with a low U-value
  • Use glass with a low SHGC
  • Use glass that has “spectrally selective” properties (low SHGC but high VLT)
  • Use a type of shading appropriate to the orientation and climate which optimizes daylight
  • Combine shading with light shelves
52
Q

What interior room adjustments can help optimize daylighting?

A
  • Use reflective materials
  • 80% for ceilings
  • 50-70% for walls
  • 20-40% for floors
  • Place lower furniture / equipment closer to the window than higher ones
  • Locate activities that need more light closer to the windows
53
Q

What is the Maekawa equation and how does it work?

A

It determines the decibel noise reduction of a sound that is blocked by a wall. “N” in that formula is determined using a simple calculation, in which the height of the sound that is blocked increases the noise reduction.

f : frequency of sound

A + B : shortest path distance from sound to receiver

d : straight-line distance between sound and receiver

54
Q

What are some basic rules of thumb about placing noise reduction barriers for side noise?

A
  • Noise reduction for linear sounds are about 20-25% less than for point sounds
  • Solid barriers are better at blocking high-frequency sound than low-frequency sound
  • Barriers are more effective as they get closer to the source or the receiver
  • For point noises, the width of a barrier should about four times longer than the distance from barrier to source or receiver, whichever is shorter
55
Q
A
56
Q

What are some general design strategies for reducing site noise (other than barriers)?

A
  • Reduce hard surfaces near the source of noise
  • Parallel hard surfaces will intensify sound (reduce how much it attenuates over distance)
  • Promote masking sounds that are desirable (running water, ETC)

-

57
Q

What are some lesser-known techniques for providing site security?

A
  • “Sally port” : essentially an airlock for cars …. two gates in series only allow one vehicle in at a time and hold them while their authorization is being checked
  • Hardening innocuous site elements (tables and seating, bike racks, kiosks, ETC) so that they provide a barrier to vehicle attacks / entry.
58
Q

What is the definition of “analemma”?

A

The apparent position of the sun in the sky at the same time of day throughout the year. It forms a figure-eight shape.

59
Q

What is the definition of “daylight autonomy”?

A

The percentage of a building’s area that means certain minimum daylighting standards. These are usually a minimum illuminence for an arbitraty fraction of the operating hours of the building. This is a measure used by the LEED system to award points for daylighting.

60
Q

What is the definition of “net metering”?

A

The concept that utilities will pay equal rates for receiving electric power onto the grid, regardless of which direction the power is coming from. This is the basis for buildings to be able to sell PV power back to the grid.