Environmental Conditions & Context Flashcards
Aboveground drainage systems
Pervious paving, sheet flow, gutters in roadways and parking areas, ground swales in landscaping, channels
Underground drainage systems
Perforated drains and enclosed storm sewers to carry runoff away from the site to a municipal storm sewer or natural outlet like a river
Minimum slope for very smooth surfaces
.5%
Minimum slope for most paved surfaces, accounting for roughness and variations
1.5%
Minimum slope for underground pipes
.3%
Drain inlet
An opening in the ground that allows stormwater to run directly into the storm sewer; the opening is covered with a metal grate for safety and to keep out debris
Catch basin
Underground reservoir with a built-in sump pump; debris settles into the sump instead of flowing down the sewer and potentially clogging the pipes; sump needs to be cleaned out on occasion
Where should storm sewer manholes be located?
Wherever the sewer changes direction or a maximum of 500’
Storm sewers are always kept separate from
Sanitary sewer system
Runoff coefficient
The fraction of water not absorbed
What is the capacity of a drainage system based off?
The size of the area to be drained, the runoff coefficient, and the amount of water to be drained during the most severe storm anticipated by the design (N-year, most often 25- or 10-year storms)
Which utilities usually take precedence when locating a building?
Sanitary sewers and storm sewers, because they depend on gravity
Size and sloe of sewer piping depends on:
Capacity needed to service the building
Where is the actual connection of the building sewer and the main line
At an elevation above the invert of the main line at any given point in order to not interfere with the free flow of the main line
Minimum slope for building sewer
.5% to 2% depending on the size of the pipe; greater slope for smaller pipes:
2.5” pipe at 1/4 in/ft
3-6” pipe at 1/8 in/ft
8” or more pipe at 1/16 in/ft
Maximum slope for a road
15% for short distances, but 10% or less is preferred
Before crossing a sidewalk, the road must do what?
Become level after a ramp
Crowns and gutters should be used for what?
To slope water; crowns are 1/4 in/ft minimum and gutters are 6” high
Collector walks
Should be located next to parking areas
Should be a min of 6’ wide, especially is car bumpers overhang it
Provide seating, lights, and trash collection
1/4 in/ft slope across the walk
Exterior ramp requirements
36” minimum width
1:12 max slope
5’ minimum length landing at top and bottom
30’ maximum run between landings
30” maximum rise between landings
34-38” height from surface of ramp to center of handrail
Handrail required on both sides is rise is greater than 6”
Extend handrail 12” beyond top and bottom of ramp
Curb cuts are 1:10 max slope at the edges
Exterior stair requirements
Rise 6” maximum, 4” minimum
Tread 14” for 6” in rise
Slope tread 1/4 in/ft from riser to nosing for drainage
Minimum 3 risers
Maximum 10 risers between landings
34-38” height from surface of ramp to center of handrail
Provide handrail over 4 risers or where icy conditions exist
Extend handrail 12” beyond top and bottom of stairs
Parking capacity is determined by
The requirements of the zoning ordinance or by the building program
Parking space standard size
9’W x 19’L
Parking space compact size
7’-6”W x 15’L; zoning ordinances may allow for a percentage of parking space to be compact
Most efficient parking in terms of land use
90 degree
Angled parking
Easier to use, uses 1 way circulation, requires less total width
Parking area used for prelim evaluation
400 SF per car; includes parking spaces, drives, and minimal landscaping
Parking lot drainage
1.5-5%; 2% can be used for convenience
Water to drain towards edges
Curbs must have curb cutouts or drains
Landscaped planting strips
7’W between paved areas and in parking lots; 4’W for grasses and ground covers
Contours of the land cannot be changed where?
Within the drip-line of a tree
Azimuth
Compass orientation of the sun, usually degrees east or west of south
Altitude
The height of the sun measured at an angle from the horizon; horizon is 0, directly overhead is 90
Rectilinear Projections
A type of chart where the solar azimuth is plotted along the horizontal axis, and the solar altitude is found along the vertical axis
Equidistant Horizontal Projections
Plots the path of the sun at various times of the year on a circular chart; the spokes represent the solar azimuth; the curved lines overlaid are the path of the sun on different dates based on the latitude; intersecting lines are the time of day
Gnomonic Projection or Sunpeg Chart
Derived from the sundial projection, useful for shadow studies
Passive Solar Design
Direct gain systems
Indirect gain systems
Thermal storage wall
Phase change materials
Greenhouse design
Roof pond
Convective loop systems
Active solar design requires 3 components
A collector (flat plate or a focusing collector), storage device, and distribution system
Flat plate collector
A network of pipes located on an absorptive black surface with low emissivity, placed below a covering of glass or plastic; the pipe carries the heat transfer medium, usually water with antifreeze
Focusing collector
Parabolic reflectors that focus the incoming radiation to a single pipe that carried the heat-transfer medium; operates at a much higher temp than flat-plate collectors
Active solar design storage devices
Water for water systems
Rock beds for air systems
Phase-change materials can be used but are costly
Active solar design distribution systems
Ducts for air
Pipes for water
Associated fans, pumps, registers, and control devices
When solar energy is used for water the system may be
Open loop systems of closed loop systems
Open loop systems
Water is heated directly in the solar collector
Closed loop systems
Antifreeze or another transfer medium is heated in the collector and circulated to a heat exchanger, where the domestic water is heated by the transfer medium
When solar energy is used for space heating…
Either air or water can be used as the heat transfer medium
Geothermal
Uses ground-source heat pumps; electrically powered systems that work like air-source heat pumps but extract heat form the ground of give excess heat back into the ground; initial costs are high but long term costs are lower
Photovoltaics
The direct conversion of sunlight into electricity
Ideal angle of the sun
Varies slightly but approximately 15 degrees east of south
External load dominated building
Aka skin-load dominated building
Energy use is determined mainly by the amount of heat loss or gain through its exterior envelope
Generally have fewer people
Houses, apartments, condos, and warehouses
Building shape more important
Internal-load dominated building
Energy is driven by high heat gain from occupants, lighting, and equipment
Office buildings, hospitals, retail stores, schools, and labs
Building shape for cool/cold regions
Cubic shape
2 story house better than 1 story
Building shape for temperate regions
Shape has less of an effect
Elongated east to west has some advantages
Building shape for hot/arid regions
Squarer is better
External load should have courtyards
Internal load should be a solid multistory arrangement
Building shape for hot/humid regions
Elongated east/west orientation to allow breezes
Courtyards and broad overhangs
Insulation R-values
Prescribed in building codes or energy codes
Insulation
Usually must be installed with a vapor barrier to be effective
HCFCs should not be used
CFCs already phased out
Superinsulation
the technique of providing higher levels of insulation than normally used, tightly sealing all joints and cracks, and preventing any thermal bridges between inside and outside; electrical outlets are usually placed on inside walls or inside the insulation
Transparent Insulation
has a thick layer of polycarbonate honeycomb material, acrylic foam, or fiberglass sandwiched between layers of glazing; admits light while providing high degree of insulation; not used for a view
Movable Insulation
usually used on windows that provide passive sola heating; removed during sunlight hours and replaced at night or on cloudy days to prevent heat loss; manually, power or automated operation; roll-down shutter, insulated shades or curtains, swinging panels of insulation, and expanded polystyrene beans blown between panes of glass
Stack effect (chimney effect)
a difference in pressure between the top and bottom of a building due to a temp difference; most pronounced in a high-rise
Permeance
a measure of hour readily a material or membrane allows vapor to pass through it; the unit is perm which is one grain of moisture per hour per square foot per inch of mercury difference in vapor pressure
Air barrier should generally be located where
behind the exterior cladding and outside the sheathing; if both air and vapor barrier, place outside the structure and sheathing but within the building envelope