Site Assessment and Site Work

  1. When analyzing potential sites what are some of the variables that an architect must take into account?
    • That the program will fit on the site
    • Topography, orientation, access, availability of utilities
    • Applicable restrictions imposed by the city, state, and federal regulations
    • That the soils are adequate to support the intended structure
  2. The geographic location of the project is most often determined by the client.
  3. Land forms and ground slopes affect a buildings:
    Foundation, drainage, and microclimate
  4. Site vegetation affects a sites
    microclimate, views, solar radiation, and sound travel
  5. Site orientation affects a buildings
    solar radiation, natural ventilation, views, and ease of access to the site
  6. A regions climate is modified by local conditions which include
    topography, structures, exposure, ground cover, elevation, and water bodies
  7. What is the Comfort Zone?
    It is the narrow range of related conditions in which people are comfortable in regards to temperature, humidity, air movement, and air quality
  8. The typical comfort zone for people is the 65 to 75 degree range at 30 to 60 percent humidity
  9. How is high temperature brought within range of the comfort zone?
    Thru air movement or mechanical cooling
  10. How is low temperature brought within range of the comfort zone?
    By providing heat.
  11. What is the ideal orientation for a structure in the northern hemisphere?
    Slightly east of south
  12. Large glass areas on the west side of a building have an additional problem if the west side faces a highly reflective surface such as a body of water
  13. Northern light has a relatively even intensity.
    It is ideal for artist's studios or similar spaces.
  14. When is the sun highest in the sky?
    During the summer solstice on june 21
  15. When is the sun lowest in the sky?
    During the winter solstice on december 22.
  16. Heat transmission thru walls is more important in the high latitudes since the sun is lowest and hits mostly on the walls.
  17. Heat transmission through roofs is more important in the low latitudes.
  18. In more southerly latitudes the amount of overhang required for sun control is lessened.
    This is because the sun is higher in the sky
  19. The use of sun shields outside of a building is much more effective than trying to reflect or absorb the heat after it contacts a buildings surface.
  20. Proper solar design can help reduce cooling demands by up to
    15 percent or more
  21. Trees help reduce noise, filter air, reduce glare, and provide privacy and protection.
  22. Whatever the design sun shields take, they should always:
    • admit light and views
    • exclude the sun's heat and glare during the warmer months
    • admit solar heat during the winter
  23. Sun shields carry with them some impact on cost because
    They represents a higher additional cost in a building, and will require on going maintenance. Most importantly, shading needs to allow for daylighting to reduce the amount for electric lighting and thereby electric cooling
  24. What is the typical wind intensity throughout the country?
    • per UBC wind map, the average national wind intensity ranges from 70 to 80 miles per hour
    • 13 psf
  25. Wind acting on a surface will exert pressure, what is this amount?
    anywhere from 13-17 pounds per square foot at a height of 30 ft.
  26. Where do the highest wind speeds occur in the US?
    On the gulf coast from texas to florida, and on the atlantic coast.
  27. Wind loads increase with height, while at ground level, wind loads decrease to almost zero.
  28. How is wind pressure expressed?
    • It is expressed in pounds per square foot and varies as the square of the wind velocity in miles per hour.
    • When wind velocity doubles, the wind pressure increases fourfold.
  29. What considerations must be taken in regards to winds and building walls?
    Building walls must be designed to withstand wind loads, as well as prevent wind infiltration.
  30. Wind infiltration mitigation is the single most important consideration in sustainable design. Cold and warm winds can transfer through walls.
  31. As wind intensity in the area and building height increase, the cost for a building structural system will increase.
  32. Winter winds should always be blocked as much as possible.
  33. Cooling summer winds should be admitted and utilized as much as possible.
  34. Wind breaks can be used to block undesirable winds.
  35. When is the use of a wind break most effective?
    In protecting large downwind areas.
  36. What wind conditions will form on tall buildings?
    • Wind will go over the top of tall buildings
    • Wind will also blow down the face of the windward side creating a vortex at the ground level
  37. Ground level opening in tall building structures can result in high wind velocities at the ground level.
  38. What are desirable effects of windows?
    They allow for views, light, air, and solar radiation.
  39. Light and view are vital to psychological well being
  40. Most people prefer operable windows, and this is also a desirable sustainable design approach.
    Even in tall buildings.
  41. Glass can lose heat up to 20 times greater than an insulated wall. For this reason a buildings glazed area is one of the most critical elements as far as heat gain and loss are concerned.
  42. Large areas of glazing, when properly shaded against direct sunlight, can reduce cooling loads in the summer by reducing the need for lighting which in turn reduces cooling loads.
  43. What is daylighting?
    It is a technique in which natural sunlight is combined with dimmed overhead lighting to reduce energy costs and indoor heating loads.
  44. Insulation within a wall helps reduce heat gain and heat loss.
  45. How is the measurement of heat transmission thru a material referenced??
    The measure of heat transmission is referred to as the U-Factor, which is the number of BTU per hour that passes through one square foot of wall or roof when the difference between inside and outside air temperature is 1 degree farenheit.
  46. Low u-values indicate what?
    slow heat loss or gain
  47. High u-values indicate what?
    High U values indicate rapid heat loss or gain of heat.
  48. Insulated brick and plaster walls have low u values. Ordinary glass has a u value of 1.
  49. What is Thermal Inertia?
    It is the ability of a material to store heat.
  50. What kind of materials are desirable in regions with a high diurnal temperature variation?
    Dense, high mass walls such as concrete or masonry are desirable.

    This is because the materials can store more energy throughout the day and release it when temperatures drop.
  51. Wall orientation can determine what levels of insulation are required, thus determining the material types.
    In temperate climates, such as NY, heavy materials should be used on the west to delay the impact of afternoon heat, with adequate insulation on the other walls.
  52. Concrete slabs can also be a source of heat gain or loss, so they should be insulated at the edges.
  53. Climates can also determine which materials are to be used. Why?
    Climatic conditions such as humidity, heat, etc can affect materials in different ways.
  54. Metal corrodes near the ocean, so avoid using it.
    If it is used, it must receive proper ongoing maintenance.
  55. In extremely dry weathers exposed wood will split and check.
  56. In hot and humid areas, wood may be subject to the detrimental effects of mold and fungi.
  57. Solar heating and cooling will become increasingly important if fossil fuels continue to become scarcer and more expensive.
  58. Solar energy can be used for both heating and cooling.
    • Solar hot water heating
    • PV Paneling for electricity
    • Active and Passive solar design for heating and cooling
    • Fuel cells for electricity
    • ice storage systems for off peak cooling.
  59. The majority of heat during the cold months of the year must be provided thru mechanical means.
  60. The cost of heating is related to the difference between the outdoor temperature and the indoor design temperature.
  61. Design temperature vary depending on the building use occupancy.
    Gyms have a lower desirable indoor temperature than a hospital where there little physical activity.
  62. Desirable indoor temperatures vary with the seasons, being higher in the summer than in the winter.
  63. Hot humid areas do not generally require any heating.
    Instead, cooling and dehumidifying the air and reducing heat gain are of prime importance.
  64. Structures requiring both heating and cooling would be located in what climates?
    • Hot arid Regions
    • Temperate Regions
  65. Cooling is more critical in hot and arid regions.
  66. Cool zones have heavy heating demands and minimal cooling requirements.
  67. Mechanical systems are designed to provide an inside design temperature of ?
    75 degrees, when the outside deign temperature is from 90 to 110 degrees.
  68. Land adjacent water is very desirable.
  69. Bodies of water can be protected by preventing or treating polluting runoff prior to entering a body of water.
  70. Bodies of water can also be protected by preventing development around the shoreline, thereby creating attractive open space.
  71. Shapes of bodies of water should be such that the entire shape can not be determined from the shoreline.
  72. Bodies of water have the best aesthetic effect, when they are lower in elevation than any other point in the immediate area.
  73. Free board is the distance between the water level and the level of the land before water floods out.
  74. Bridges across bodies of water are best placed where the body of water is most narrow to minimize structure, where there is good soil in the banks, and where the banks are higher than the expected highest expected floor line.
  75. When bridge are long and require piers be set into the water, the piers should be set so that their long direction is in the direction of water flow to reduce turbulence, and obstruction of flow.
  76. Water fountains are perceived as a cool element, making it a good focus for war dry climates.
  77. What is the Hydrologic/water Cycle?
    It is the concept that all the water on the earth, under the ground, and in the atmosphere is part of one unified system.
  78. There are 4 parts to the water cycle
    • 1. Precipitation 
    • 2. Runoff
    • 3. Infiltration
    • 4. Transpiration
  79. What is precipitation?
    It is when water in clouds reaches a cold temperature and falls to earth as either snow or rain.
  80. What is Runoff?
    After precipitation lands reaches the earth, a small amount of it will run off to streams, rivers, and ultimately into the ocean.
  81. What is Infiltration?
    When precipitation reaches the ground, a small portion of it will soak into the ground.
  82. What is Transpiration?
    Most of the precipitation is evaporated into the atmosphere directly.
  83. Whenever a site is developed, the amount of runoff will increase. What are contributing factors?
    • 1. Removal of vegetation (transpiration)
    • 2. Replacement of pervious land with impervious surfaces (infiltration)
    • 3. A decrease in the other two processes results in a direct increase of runoff.
  84. What is the reasoning behind Detention ponds?
    • Rainwater is held in ponds during the rain, and then released at a controlled rate.
    • The intent of this design approach is that the flow of rain water from the new development will be equal to the runoff from the site prior to development.
  85. There are two ways of dealing with runoff on a developed site.
    • 1. Storm sewer
    • 2. Detention pond
  86. Land development on a large scale can result in flooding.
  87. What is a flood plain?
    It is the relatively flat land within which a stream overflow spills onto.
  88. The floodplain elevation for a ten-year period, will be lower than the floodplain elevation for a 100-year period.
  89. It is desirable for building in a flood plain to have an elevation higher than that of the given flood magnitude, either 10 or 100 year.
  90. The best use for lands in a flood plain are open space uses such as recreation and agriculture.
  91. Soils within a stream or flood plain are generally poor and subject to volumetric changes under dry and wet conditions.
  92. The conventional solution to the problem of potential flooding involves the construction of concrete channels.
  93. The amount of water found below ground exceeds the amount of water that is found in lakes, or streams.
  94. What is the Ground water table?
    It is the area between the zone of Aeration and the Zone of Saturation.
  95. The ground water table usually follows the flow of the land.
  96. What mitigation must occur when there is a high water table?
    • Where the ground water table is high, roughly 6 feet below ground, construction excavation must be braced and kept dry through pumping.
    • Basements must be waterproofed
    • Subsurfaces structures must be designed to resist hydrostatic pressures
    • There is also a need to improve the existing poor soil bearing conditions.
  97. What is an Aquifer?
    It is an underground permeable material such as sand, gravel, or sandstone.
  98. Poor aquifer materials include clay, shale, metamorphic and igneous rocks.
  99. Plantings that are intended to be used for privacy or screening should be evergreen.
  100. Trees act as nature's air conditioning, they:
    • Cool
    • Humidify 
    • Filter the air
  101. Landscape can be used to moderate the climate
  102. Trees and other plantings help to control erosion, destructive runoff, and flooding.
  103. Soils on a site must always be investigated.
    Simply because the soil at the ground seems to be desirable it does not mean that the soil is the same underground.
  104. What are the two simple soil tests?
    • Test Pit
    • Soil Load Test
  105. Test pits allow direct visual inspection of the soil strata
  106. Test pits are costly.
  107. Soil load tests determine the capacity of the soil by building a platform on which soil is loaded onto.
    The total test load is usually double the contemplated design load.
  108. Core borings are the most expensive and most reliable of the soil test methods.
  109. Dry sample borings
    This test samples the soil at 5 inch intervals.
  110. Who determines the number and location of soil boring tests?
    The structural engineer can decide locations based on the building outline.
  111. Settlement of buildings must be carefully considered, except when the structures foundations are on solid bedrock where little to not settlement can occur.
  112. A small amount of Settlement that is uniform across the structure is of little concern.
  113. During construction of a building, constant checking with surveying equipment should be performed to note any settlement.
  114. In all areas subject to frost action, footings must be placed at least one foot below the frost line.
  115. If a structure has some footings closer to the surface with others deeper into the ground, then earth movement becomes a concern
    A Building should have all of its footings on soils which act the same throughout.
  116. The moisture content of clay can be disturbed by adjacent excavations, which can result in slippage.
  117. Building foundations should be located well above the water table.
  118. Subsurface water should always be diverted away from building foundations thru the use of drainage tiles.
  119. Drainage tiles have a minimum diameter of 6 inches and are laid in gravel and at least 6" below the lowest floor slab.
  120. Slab waterstops
    These are place in concrete slabs and footings to prevent water from entering.
  121. Slabs on grade not subject to hydrostatic pressure are often placed over a gravel fill several inches thick to prevent water from being drawn into the slab by capillary action.
  122. Drainage of surface water is achieve by directing water away from structures through the manipulation of site contours.
  123. Gutters, flumes, berms and paved areas are all used to direct water away from a building.
  124. All soil modification methods intended to increase load bearing capacity should be reviewed by the local building department prior to commencing work.
Card Set
Site Assessment and Site Work
Lesson 2