2. Site and Environment - NM Flashcards
What does LEED stand for? Who developed the rating system?
Leadership in Energy and Environmental Design;
U.S. Green Building Counsil
LEED rating system (6 concepts)
- Sustainable Sites
- Water Efficiency
- Energy & Atmosphere
- Materials & Resources
- Indoor Environmental Quality
- Innovation & Design Process
How to do a Site Analysis (6 steps)?
- Zoning : property line, setbacks, easements, right-of-way
- Topography & Water: slopes, soil conditions, existing drainage patterns, water table elevation, areas susceptible to flooding / erosion
- Plants: existing trees, water features (wetlands, streams)
- Climate: path of sun, winds, rainfall
- Services: public roads, trains, water mains, sanitary & storm sewers, gas & elec lines
- Existing context: views, noise, history, neighbourhood
Soil profile
Vertical section of soil showing horizons (layers)
Subsurface investigation
Done by geotechnical engineer;
Test pits up to 10’ deep;
Structure of soil, shear resistance & compressive strength, water content, permeability, expected consolidation under loading
Allowable bearing capacity of soil
Maximum unit of pressure a foundation is permitted to impose vertically or laterally on soil
How do we measure soil density?
Standard Penetration Test (number of blows required to hammer soil sampler)
Which types of soil are stable and which are unstable and why?
Coarse grained = stable = low % of void spaces between
Clays = unstable = shrink / expand with changes to moisture content
Shearing strength of soil
Its ability to resist displacement when external forces are applied. Cohesive soils (clay) retain their strength when sloped = angle of repose is steep Granular soils require confinement = angle of repose is shallow
Water table
The level at which the soil is saturated with water
What ground slopes are suitable / not suitable to build on?
25% = erosion, difficult to build on 10% = challenging, more expensive to build on 5-10% = suitable, can be build on 5% = easy to build on
What is a good ecological way to develop a site?
Minimize disturbance
- Do not disrupt drainage patterns
- Include provisions for drainage of surface & ground water
- Attempt to equalize cut and fill on site
- Avoid building on steep slopes - erosion
- Protect wetlands, wildlife habitats
- Avoid floodplains
Effect of : large bodies of water
Heat reservoirs, evaporative cooling effect
Effect of : plant materials
Provide shade, Windbreak, Define space, Screen views, Attenuate Sound, Improve Air Quality, Stabilize Soil
Effect of : grass
Reduce air temperature, stabilize soil, increase permeability of soil
Cool Regions
- Minimize surface area of building - cube shape
- Maximize solar radiation - orient east of south - large south windows, small windows EW, no windows N
- Reduce heat loss - use interior materials high thermal mass
- Provide wind protection
- Dark / medium color materials
Temperate Regions
- Minimize east-west exposure - rectangular shape - orient east of south
- Balance heat gain with shade protection - seasons (heat in winter, cool in summer) - large windows S
- Air movement in hot weather but protect from wind in cold weather
- Medium color materials.
Hot-Arid Regions
- Reduce solar heat gain - cube shape - orient east of south
- Cooling - water features, plantings
- Solar shading for small windows
- Courtyards
- Light color materials - large thermal mass
Hot-Humid Regions
- Minimize east-west exposure - rectangular shape - orient almost full south
- Reduce solar heat fain
- Use wind - evaporative cooling - large openings, high ceilings, cross ventilation
- Solar shading on all openings
- Light color materials - small thermal mass
Different types of passive solar design
- Direct Gain - wdws & thermal floor mass
- Indirect gain: thrombe wall (cocnrete) or drumwall (water pipes)
- Sunspace: solarium
- Roof pond
- Isolated fain : collect & store away from the space
Where should we put windows?
East - west : sources of overheating, difficult to shade
South : can be shaded with horizontal shading devices
North: exposed to winter in cool climates
What is the angle of repose of most soils?
33 degrees
What can make a retaining wall fail?
Overturning, horizontal sliding, or excessive settling
Architectural elements to design of retaining wall?
Drainage - relieves built up water pressure - gravel & weep holes 2”@4’-6’ OR perforated drain pipe
Vertical control joints @ 25’ AND vertical expansion joints every 4th control joint
Batter - backward sloping surface of the retaining wall so it doesn’t appear to be leaning forward
Footing to extend to frostline or 2’ below grade (greater of)
What does the foundation wall do?
- Transfers dead & live loads to the soil.
- Prevents wind-induced sliding, overturning, uplift
- Withstands sudden ground movements of earthquake
- Resists pressure from soil & water
- Counters thrust from tensile structures.
Settlement. What is it and which soils are most susceptible?
Gradual subsiding of a structure as the soil consolidates under loading.
Moist, cohesive clay with large % of voids can consolidate most and occurs slow, over long periods of time
Differential settlement.
Uneven consolidation of the soil.
What type of soil for shallow foundations?
Stable soil of adequate bearing capacity
What type of soil for deep foundations?
Unstable or inadequate bearing capacity
Types of excavation support systems?
Sheet piling
Tiebacks
Slurry wall
Dewatering
Bottom of footing to be at …. of frost line?
12”
What is the most often used foundation wall type?
Strip footings
Catchment Area
the area from which a city, service or institution attracts a population that uses its services.
Proctor Compaction Test
a laboratory method of experimentally determining the optimal moisture content at which a given soil type will become most dense and achieve its maximum dry density.
Baseline Survey
In the United States Public Land Survey System, a baseline is the principal east-west line (i.e., a parallel) upon which all rectangular surveys in a defined area are based. The baseline meets its corresponding principal meridian at the point of origin, or initial point, for the land survey
Aboveground Drainage
sheet flow, gutters built into roadways and parking area, ground swales as par t of the landscaping, and channels.
Underground drainage
perforated drains and enclosed storm sewers that carry the runoff from the site to a municipal storm sewer system or to a natural drainage outlet such as a river.
Sheet flow
water that drains across a sloping surface, whether paved, grassy, or landscaped.
Existing Utilities
Sanitary sewers and storm sewers usually take precedence in planning because they depend on gravity flow. The invert, or lowest, elevations of the existing public sewer line should be established, since the effluent must flow from the lowest point where the sewer line leaves the building to the main sewer.
Building sewer
the portion of horizontal piping of the sanitary sewer system between the building and the sewer main. Minimum slope of the building sewer is 0.5% to 2.0% depending on the size of the pipe. (1% is 1/8” / ft.)
Road slope
15% maximum for short distances, 10% or less preferred. If sloped 10% or more, transition slopes of one-half the maximum slope should be provided.
Roads should also have 1/4”/ft 2% slope for drainage from the center of the roadway, called the crown, to the sides, called the gutter.
Sidewalk slope
1/4”/ft 2% for drainage across walk, maximum
4% (1/2”/ft) mas at buildings
6% max preferred elsewhere
8% (1:12) absolute max Accessibility
Exterior Stairs
Minimum 3 risers / Maximum 10 risers between landings
rise 4” min. / 6” max.
run 14” for 6” rise
slope 1/4”/ft. for drainage
provide handrail over four risers or where icy conditions exist
Parking Spaces
8’ x 18’ standard
Parking Lot Layout
1.5% - 5% slope for drainage
(use 2% or 3%)
90 Degree Parking - Most Efficient
Accessible Parking
Van-accessible access aisle 96 inches (8’)
Car-accessible access aisle 60 inches (5’)
2% maximum slope
Maekawa equation
used to evaluate the reduction in noise decibels (NRdb) from a point source
Basic principles for designing outdoor sound barriers
Solid barriers block high-frequency sounds better than low-frequency sounds.
The barrier is best placed as close as possible to either the source of the noise or the receiver.
If the barrier is close to the noise source, it should be at least four times as high as the distance from the source to the barrier.
The greater the effective height (the distance from the acoustic line of sight to the top of the barrier), the greater the attenuation.
For blocking noise from a point source, a short barrier should be at least four times as long as the distance from the barrier to the source or the distance from the barrier to the receiver, whichever is shorter.
A barrier should have a density of at least 5 lbm/sq ft and be solid. However, greater densities than this do not increase sound attenuation significantly.
Soil Types
Gravel: well drained and able to bear loads (2 mm)
Sand: well drained and can serve as foundation when graded (> .05 - 2 mm)
Silt: stable when dry, swells when frozen, do not use when wet (.002 - .05 mm)
Clay: must be removed, too stiff when dry and to plastic when wet (< .002 mm)
Levels of Soil
A = Topsoil B = Minerals C = Partially weathered/fractured rock D = Bedrock
Potential Land Problems
Water within 6’ of land surface: pump out excavation, waterproof basement, resist hydro-static pressure (continuous drain pipe installed at foundation)
Rock at/near surface: use explosive to reduce manual labor
Soil is soft clay, water-bearing sand or silt: construct deeper foundations or drive piles, remove poor soil.
Underground streams: avoid and be cautious of siting of structure
Cut and Fill: balance it. There should not be more taken away than added or vice versa.
List physical factors? (6)
- Climate
- Topography
- Soil geotechnical
- Public Services
- Immediate Environment
- General Services
List physical factors : climate ? (5)
- Dominant winds
- Sun path
- Temperature
- Humidity
- Rain
List physical factors : topography ? (10)
- Legal description(property limits, servitudes, right of passage)
- Topography maps & aerial photos(level curves, slopes, rocks, etc.)
- Physical characteristics studies
- Access & circulation(cars & pedestrian)
- Vegetation
- Streams & lakes
- Water evacuation(rivers, streams, etc.)
- Relative servitudes & ways
- Surface water evacuation
- Unique characteristics
List physical factors: soil & geotechnical ? (5)
- Surface soil composition (sand, silt, clay, roc, gravel, etc.)
- Type of rock & soil (slope, bearing capacity)
- Rock (depth,classification)
- Sysmic
- Environmental risks
List physical factors : public services ? (8)
- Water
- Electricity
- Gas
- Telephone
- TV
- Sewer
- Rain sewer and surface water drainage
- Fire Protection
List physical factors : Immediate Environment ? (5)
- Adjacent Buildings
- Sun & shade
- Street noises, emergency services, airplanes, etc.
- Smells
- Views
List physical factors : general services ? (3)
- Police & fire department
- Waste removal
- Snow removal
List cultural factors ? (3)
- Site history
- Land occupation & property
- Economic value
List cultural factors : Site history ? (2)
- Previous use - Archeologic site
2. Existing constructions history - Historic value - Height - Condition - Use
List cultural factors : Land occupation & property ? (5)
- Zoning of land & neighbours
- Use of neighbour sites & effects on the studied site
- Type of site property
- Type of site use (public, agricultural, etc.)
- Placement, type et size of the permanent collective services (school, church, park, shops, health, transportation, etc.)
List cultural factors : Economic value ? (4)
- Political aspects ; cost of site
- “Territories” accepted
- Future potential
- Dimensions of adjacent lots & approx. price
List regulatory factors ? (4)
- Zoning
- Allotment, urban planning & other local requirements - Lot requirements, public ways, water management, parks, etc.
- Environmental requirements
- Others - Protection of patrimony - CCU - CNB
Design strategies for environmental questions while evaluating site? (6)
- Vegetation
- Sun
- Passive solar heating
- Daylighting
- Winds
- Solar & visual environment
Design strategy for environment: vegetation? (10)
- Aesthetic value
- Conserves energy
- Views
- Offers visual link btw building & its environment
- Reduces ambient temperature, as absorbs sun
- Stabilizes fill.
- Prevents erosion
- Makes soil more permeable to water & air
- Wind barrier
- Improves air quality
Design strategy for environment: sun? (10)
- The placement, form & orientation must maximize the thermal & psychological benefits of the sun.
- Design building for equilibrium between little sun (heat) & too much sun (glare).
- The sun trajectory varies with seasons & latitude of site.
- Hard surfaces increase temperature.
- Pale surfaces reflect sun rays.
- Dark surfaces absorb & Retain sun rays.
Design strategy for environment: passive solar heating? (2 characteristics)
- Heating building without mechanical systems.
- It depends on the transfer of the heat by conduction, convection and radiation to CAPTURE, STORE, DISTRIBUTE & REGULATE solar energy.
Design strategy for environment: passive solar heating? (2 functional elements)
- South facing window to capture solar energy.
2. Thermal mass to capture, store & distribute heat, oriented to maximize sun exposure.
Design strategy for environment: passive solar heating? (3 ways to achieve it)
- Direct
- Indirect
- Isolated (away from building)
Design strategy for environment: passive solar heating? (Direct)
Captures the heat directly within the space.
Design strategy for environment: passive solar heating? (Indirect)
Heat reaches thermal mass (thrombe wall) which is situated between sun & interior. The captured energy circulates inside the wall through conduction, and radiates / concection within the space.
Design strategy for environment: passive solar heating? (Isolated)
Captures & stores the solar heat away from the heated room. Water or air circulate to capture sun, then move it to a storage location within thermal mass until needed.
Design strategy for environment: daylighting? (2)
- Reduces energy consumption for artificial lighting.
2. Daylight offers lighting within a room that has its depth equal to double the height of the window.
Design strategy for environment: daylighting? (adv / disadv of EW windows)
Shading devices required to avoid early morning
/ late afternoon sun.
Design strategy for environment: daylighting? (adv / disadv of S windows)
Excellent daylight sources if a horizontal shading device reduces glare.
Design strategy for environment: winds? (2)
- Wind Direction
2. Wind Speed
Design strategy for environment: winds? (why is it essential to know them 3)
- Ventilation through rooms, exterior spaces in warm weather.
- Heat loss in cold weather.
- Lateral pressures put on building structure.
Design strategy for environment: winds? (2 strategies)
- Ventilation - evacuate humidity & avoid condensation.
- Wind break - Protects building against wind in cold regions to reduce cold air infiltration & heat loss (earth berm, trees)
Design strategy for environment: Solar & visual environment? (7 strategies)
- Place building as far away as possible from noise source.
If impossible :
- Make non-sensitive parts of the building block the noise.
- Materials & assemblies to establish noise transmission in air & structure.
- Openings far away from noise sources.
- Physical barriers (earth berms)
- Closely placed trees
- Protect soil with vegetation cover that absorbs sounds better than hard / reflective surface or pavement.
Topography (2 strategies)
- Modify as little as possible forms of the terrain
2. Take advantage of natural slopes & microclimate
Design strategy for environment : Drainage (3 strategies)
No negative impact on natural drainage streams.
IF it has to be modified:
- Drain surface & subsurface waters
- Avoid strong slopes: erosion & sliding
- Pile structure: preserves slopes & vegetation
What is the biggest energy consumption related to in a building?
Manufacturing, heating, cooling, lighting
Approaches to reduce energy consumption (2)?
- Active approach
2. Passive approach
Describe passive approach to reduce energy consumption?
- Take account of climate, placement & orientation of building during design.
- Reduce energy requirements by passive cooling / heating.
Describe active approach to reduce energy consumption?
Increase building’s ability to capture solar energy & renewable sources.
List renewable energy sources (6)?
- Solar energy
- Wind energy
- Geothermal energy
- Ecological hydroelectric energy
- Biomass
- Biogas
