Environmental Conditions and Context Flashcards
Architect’s task during project planning and design =
select and prioritize which site-specific constraints and opportunities identified in programming and analysis are to be integrated into the final site planning and building form
4 elements that form the basis for building design and site development:
- site-specific constraints and opportunities identified in programming and analysis
- Programmatic requirements
- Adjacencies
- Planning concepts
What are 12 factors to consider when locating a building in a site? Which is often the most important?
- Topography = often the most important factor if there is significant change in elevation
- Views
- Solar orientation
- Geology
- Wind patterns
- Transportation
- Drainage
- Sustainability concepts
- Utilities
- Neighboring context
- Existing planting
- Site acoustics
What is “runoff”?
Runoff = stormwater that accumulates on the site in excess of what can be absorbed by the ground
What is “sheet flow”?
Sheet flow = water that drains across a sloping surface
What is a catch basin?
Catch basin = underground reservoir that has a sump built into it so that debris settles in the sump instead of flowing into the sewer and clogging pipes
What is a holding pond?
Holding pond = also known as a detention pond, it collects site runoff and releases it into the sewer systems at a controlled rate to prevent excess water from flooding to other areas.
What is the difference between a retention pond and a detention pond?
Both are types of storm water ponds, but a retention pond is designed to hold water all the time, where a detention pond is designed to be dry some of the time. Both hold excess water until it can be released into the storm sewer.
What is a swale?
A swale is a natural or human-created low tract of land that is designed to manage stormwater runoff and provide a place to filter pollutants or trap particulates, allowing water to slowly seep into the ground. A swale can be designed to be covered with grass or other types of marshy plants. When constructed like a natural wetland, a swale is often called a stormwater wetland. However; unlike a natural wetland, it is human-created, as direct discharge of stormwater to natural wetlands is prohibited by law.
What is a stormwater pond?
A stormwater pond is a basin that has a permanent pool of water. It differs from a swale or stormwater wetland in that it has a greater average depth and is covered with water all the time. However, like a stormwater wetland, it is designed to collect, detain, and release stormwater runoff at a controlled rate and to help settle solids and particulate pollutants.
What are the 2 types of drainage systems?
2 types of drainage systems:
- Aboveground = pervious paving, sheet flow, gutters, ground swales, channels
- Belowground = perforated drains, enclosed storm sewers
What are the dimensions of: A standard parking space? A compact parking space? An ADA parking space? An ADA van space?
9x19’
7.5x15’
8’x19’ with a 5’ access aisle
11x19’ with a 5’ access aisle (or 8’ wide with an 8’ access aisle)
What is the general rule of thumb for initial parking space estimations?
400 sf per car
What is the typical radius of a cul de sac turnaround?
40’
How many ADA parking space are required? ADA van parking space?
1 for every 50 parking spaces required, unless total is <25, in which case 0 ADA parking spaces is required
1 per every 6 required accessible parking spaces
What are 3 ways to drain a parking lot?
- drainage perpendicular to the length of the lot (slope down across the lot)
- drainage parallel to length (slope down on each side of central ridge)
- drainage across lot (diagonally)
What is the optimum building location angle for each of the primary climate types?
Hot-arid = 25 deg east of south Temperate = 17.5 deg east of south Cool = 12 deg east of south Hot-humid = 5 deg east of south
Where should the entrance be located in:
cool climate?
temperate climate?
hot-humid climate?
cool = avoid winter winds temperate = south for solar gain hot-humid = take advantage of cooling breezes
What is the difference between an external-load dominated building and an internal-load dominated building?
External-load dominated building = skin-load dominated building = energy use is determined by amount of heat loss or gain through its exterior envelope
Examples = houses, apartments, condominiums, warehouses
Internal-load dominated building = energy use is driven by high heat gain from occupants, lighting, and equipment.
Examples: office buildings, hospitals, retail stores, schools, laboratories
What is the ideal building shape for an external-load dominated building in a cool/cold climate? For an internal-load dominated building?
External-load dominated building (aka houses and small buildings): square or cube
Internal-load dominated building (aka larger commercial/industrial buildings): square multistory
What is the ideal building shape for an external-load dominated building in a temperate climate? For an internal-load dominated building?
External-load dominated building (aka houses and small buildings): elongated east/west with a footprint proportion of 1:2
Internal-load dominated building (aka larger commercial/industrial buildings): elongated east/west
What is the ideal building shape for an external-load dominated building in a hot-arid climate? For an internal-load dominated building?
External-load dominated building (aka houses and small buildings): courtyards
Internal-load dominated building (aka larger commercial/industrial buildings): elongated east/west
What is the ideal building shape for an external-load dominated building in a hot-humid climate? For an internal-load dominated building?
External-load dominated building (aka houses and small buildings): elongated east/west with a footprint proportion of 1:3 or 1:4
Internal-load dominated building (aka larger commercial/industrial buildings): elongated east/west
What is super insulation?
A technique of providing higher levels of insulation than normally used, tightly sealing joints and cracks and preventing any thermal bridges between the inside and outside.
What is transparent insulation?
A relatively thick layer of polycarbonate honeycomb material, acrylic foam, or fiberglass sandwiched between layers of glazing.
- Used to transmit light while providing a high degree of insulation
- Can be used over another thermal mass material to trap solar heat then slow the loss of stored heat back into atmosphere
Moveable insulation
Typically used on windows that provide passive solar heating. Insulation is removed during sunlight hours and replaced at night or in cloudy weather to prevent heat loss.
Ex. roll-down shutters, insulated shades/curtains, etc.
What is the air barrier? Where should it be located?
The part of the building envelope system that controls infiltration and exfiltration, reduces energy consumption, and keeps out pollutants and excess moisture.
Should be located behind the exterior cladding and outside the sheathing.
What is permeance?
a measure of how readily a material or membrane allows water vapor to pass through it.
What are 6 condition an air barrier system must meet in order for it to function properly?
- Permeance: The air barrier, assemblies, and whole building must meet the minimum permeance ratings as prescribed by local building code.
- Continuity: The air barrier must be continuous around the conditioned spaces, including walls, roofs, foundation walls, and slabs on grade.
- Attachment: The air barrier must be securely attached to the structure to prevent billowing, tearing, or breaking away from attachments and other building components.
- Movement joints: At movements joints, the air barrier must be capable of moving with the joint without breaking or tearing.
- Durability: The air barrier must be durable and last the life of the building.
- Vapor retarder: If both vapor retarder and air barrier are used and are separate membranes, the air barrier should be 10 to 20 times more permeable to water vapor diffusion than the vapor retarder to prevent trapping of moisture between the two layers.
What are 3 types of earth sheltering?
- Built above grade and fill earth is bermed against the walls on 1+ sides
- Built into the excavated side of a hill
- Completely buried below grade with a central courtyard for access, daylight, and ventilation
What are 6 considerations to take into account when earth sheltering?
- natural slope (want to minimize earthmoving)
- granularity of soil (want gravel, sand, and sand loam. No clay)
- radon concentrations (need to test the site)
- groundwater level (must be below the building)
- drainage (need positive drainage away from building)
- waterproofing (extra care to waterproof underground portions adequately)
What are 9 advantages to green roofs?
- conserves energy by reducing cooling and heating loads
- reduces storm runoff
- reduces ambient air temperatures
- absorbs carbon dioxide
- filters the air and binding dust particles
- reduces the heat island effect
- protects the roofing membranes from ultraviolet light degradation, temperature extremes, wind, and hail
- adds acoustical insulation
- adds aesthetic appeal to the roof
What are two types of green roofs?
- extensive green roofs
2. intensive green roofs
What is an extensive green roof? What type of planting
can it support?
soil < 6” deep
can support meadow grasses, sedums, herbs, and perennials
What is an intensive green roof?
soil > 12” deep
- can support complex landscapes, including shrubs and small trees
- may feature ponds and fountains
- may be used as occupiable garden
What 3 characteristics must a green roof have to be successful?
- subsurface irrigation (to help plants establish themselves and then for supplemental watering as needed)
- continuous layer of growth medium (a material with property nutritive and drainage characteristics for the proposed plants
- constructed over a structural deck strong enough to hold weight of assembly
What are the 7 assembly layers of a green roof on concrete deck, from bottom to top?
- Structural deck (with a slope 1.5% > 3%)
- Waterproof membrane (PVC, TPO, or EPDM)
- Root barrier (if necessary, depending on type of waterproofing membrane selected)
- Rigid insulation (helps prevent water from extracting heat from building’s interior during the winter)
- Drainage layer (allows water not absorbed by plants to flow to drains/scuppers)
- Filter fabric (prevents fine soil particles from entering/clogging the drainage layer. May be made from polypropylene mats, polyethylene mats, and water-resistant polyester fiber mats.)
- Growth medium (2”-12+”)
What are the 7 assembly layers of a green roof on metal deck, from bottom to top?
- Metal deck (with a slope 1.5% > 3%)
- Thermal barrier (often 1/2” gypsum sheathing)
- Rigid insulation (helps prevent water from extracting heat from building’s interior during the winter)
- Waterproofing membrane (PVC, TPO, or EPDM)
- Root barrier (if necessary, depending on type of waterproofing membrane selected)
- Drainage layer (allows water not absorbed by plants to flow to drains/scuppers)
- Growth medium (2”-12”+)
What is a flood test?
A way to verify watertightness in which the area is flooded with 2” of water for 48 hours and the building interior is inspected for leaks.
What is a cool roof?
What are its advantages? Disadvantage?
In which 2 scenarios is it appropriate to use?
An alternative to a green roof, also known as reflective cooling, in which the roof is covered with a light-colored material that reflects more of the sun’s heat than it absorbs. (min reflectivity = 0.64 when new; 0.50 after 3 years).
Advantages:
1. Reduces energy use by lowering the building’s cooling needs.
2. Reduces the heat island effect in urban areas.
Disadvantage:
Possible glare for adjacent buildings
Use in:
- climates where cooling degree days exceed heating degree days
- internal-load dominated buildings in cool climates
What is an air lock system?
What are its advantages?
In which 2 climates is it desirable?
Vestibule entry system
- Cold and temperate climates
- Hot climates where a building is mechanically cooled
Advantages:
- prevents cold drafts from entering when an exterior door is opened
- minimizes heat loss when people/enter leave
2 common ways of expressing how well a window/glass reduces solar radiation:
- Solar Heat Gain Coefficient
2. Shading Coefficient
What is SHGC?
Solar heat gain coefficient (SHGC) = the amount of solar radiation that is transmitted through the entire window assembly, expressed as a fraction of the total amount that strikes it
Applies to the entire window assembly
A decimal between 0 and 1
What is shading coefficient?
Shading coefficient = ratio of the amount of solar radiation that passes through a piece of glass to the amount that would pass through a similar piece of unshaded, clear, double-strength glass ⅛” thick under the same conditions
Applies just to a piece of glass
A decimal between 0 and 1
What is insulated glass? Also known as double-pane or triple-pane glazing.
2 or 3 panes of glass are separated by sealed air spaces or partially evacuated spaces that act as insulators
What is a way to increase the efficiency of double or triple pane glass?
Fill space between panes with gas
- argon
- krypton (~200x as expensive as argon)
What is the U-value of a double pane 1/4” glass?
Of a double pane 1/4” glass with argon?
- 57
0. 52
What is low-e glass?
Low-E glass (low-emissivity glass) = double glazing that includes a thin film or coating placed somewhere in the glazing cavity, which allows both visible and near-infrared radiation to be transmitted but prevents the loss of heat gained by reflecting it back into the room
What is the U-value of a double-glazed window with argon gas and low-e coating 1/4”?
U-value of a double-glazed window with argon gas and low-e coating 1/2”?
- 36
0. 28
What is spectrally selective glazing?
What is the u-value of a double-glazed spectrally selective glazing with low-e coating?
For what buildings is this a good option?
Spectrally selective glazing = transmits a high proportion of the visible solar spectrum while block up to 80% of near-infrared radiation
0.25
Good for buildings that have a long cooling season and need high interior light levels
What are super windows?
U-value?
Super windows = combine low-e coatings with gas-filled cavities between 3 layers of glass
U-value = 0.15
Can gain more thermal energy than they lose in 24 hours in winter
What is switchable glazing?
Switchable glazing = chromogenic window products that change their characteristics based on particular environmental conditions or human intervention. (Think: transition lense glasses)
What are 4 types of switchable glazing?
- Electrochromic
- Photochromic
- Thermochromic
- Transition-metal hydride electrochromic
What is electrochromic glazing?
Electrochromic glazing = a multilayered thin film, applied to glass, that can change between opaque/clear or change colors when a burst of low-voltage electrical current has applied
Allows variable transmittance in the visible portion of the spectrum while reflecting in the infrared spectrum, thereby reducing solar heat gain
What is photochromic glazing?
Photochromic glazing = darkens under direct action of sunlight (think: transition lens glasses) such that as light intensity increases, the window becomes darker
Con = automatic; does not offer control
What is thermochromic glazing?
Thermochromic glazing = changes darkness in response to temperature, becoming translucent when reaching a certain temperature
Con = automatic; does not offer control
What is transition-metal hydride electrochromics ?
Transition-metal hydride electrochromics = makes it possible to have a glazing material that changes from transparent to reflective.
What is a double envelope system?
Double envelope system = the outer skin of the building consists of 2 glazed layers separated by ~2-3 ft. A type of sun control (louvers, blinds, or shades) and a passive or active ventilation system is incorporated with the space.
What are the primary 2 elements of a double cavity system?
- The outer shell = moderates the effects of the environment
- The cavity = passively heated. Can exhaust excessive heat back to exterior in hot months, and use direct heat gain to warm incoming air in cold months
What is a dynamic buffer zone?
A new outer layer of glazing is built around an existing building
- Prevents and controls condensation resulting from remodeling and upgrading the existing building’s HVAC system for higher humidity levels
- Space between existing building and new facade is ventilated with dry, preheated air in cold months
What are 3 conditions for feasible and cost effective daylighting:
- There must be enough view of the sky → may not be practice for dense urban or forest conditions
- Glazing must transmit sufficient light → may be a problem in renovating historic buildings
- Daylighting design must be coordinated with artificial lighting control and mechanical systems design