CLIMATIC & SITE FACTORS in DESIGN :

1. CLIMATIC & SITE FACTORS in DESIGN: Sun, rain, wind, heat, and cold shape architecture in many ways. Designing a building to resist them also has its subtle and dominant elements, which may be distilled to three aspects • 1)Designing a building’s exterior to resist the forces of climate. • 2)Quantifying a building’s thermal loads and optimizing the possibility of utilizing solar energy based on local climate patterns and extremes. 3)Maintaining constant comfort inside a building by properly selecting and sizing its climate control system.

2. CLIMATIC & SITE FACTORS in DESIGN: Frank Lloyd Wright said: “I think it far better to go WITH the natural climate than try to fix a special artificial climate of your own.” The natural features and forces around a building into working for you instead of against you. Design for climate begins with analyzing the building’s surrounds for at least 200 ft in every direction if it is two stories tall or less, regardlessof the location of its property lines.

3. CLIMATIC & SITE FACTORS in DESIGN: Warm breezes born in the Pacific or Gulf of Mexico usually arrive from the southwest, while cold fronts originating in the Arctic and northern Canada arrive from the northwest. In temperate and cool climates (average annual temperature is less than about 65˚), a building should generally be exposed to the southwest and sheltered from the northwest

4. CLIMATIC & SITE FACTORS in DESIGN: As prevailing winds glide over trees, roofs, and prominences in terrain, eddies of swirling or stagnant air fill yards, streets, and other open areas below. When these currents sluice though narrow openings or slide down the sides of hills, bluffs, and long buildings, they increase in speed

5. CLIMATIC & SITE FACTORS in DESIGN: Foliage A building shrouded in foliage will experience gentler breezes, more equable temperatures, and more humid air than one in a clearing nearby. In temperate and cool climates, high-branched deciduous trees should rise around the building’s southern half and low-branched evergreens around the north.

6. CLIMATIC & SITE FACTORS in DESIGN: Foliage is beneficial in many ways. Dense arrays mufflesounds from neighboring areas and are excellent at maintaining privacy. Masses of foliage, by generating oxygen, also freshen the breezes flowing above them; and their leaves absorb carbon dioxide, sulphur dioxide, chlorine, nitric oxide, and other noxious gases as well as collect airborne particulate pollutants. How foliage affects microclimate.

7. CLIMATIC & SITE FACTORS in DESIGN: Terrain Wind blows over a landscape much as water flows over the bed of a stream. Where the ground is smooth, currents flow evenly; where it is rough, air flows fast over the high spots and slowly over the low. Light surfaces are cooler and more reflective than dark. All these factors can add up to a big difference in a building’s seasonal heating and cooling loads Warming & cooling features of terrain

8. CLIMATIC & SITE FACTORS in DESIGN: SUN The angle and intensity at which the sun’s rays strike the ground are a function of the site’s local latitude as well as the time of day and time of year. find the sun’s altitude and azimuth Using the formulas with a computer allows one to plot solar trajectories across the sky quickly and accurately. To determine the amount of solar energy, or solar heat gain, that a building may utilize to heat its interior space.

9. CLIMATIC & SITE FACTORS in DESIGN: Angle of Incidence The formula below allows one to compute the angle formed between the sun and a planar surface no matter where the sun is in the skyor in what horizontal or vertical direction the plane is facing. Sun angle on sloping roof

10. CLIMATIC & SITE FACTORS in DESIGN: Overhangs A roof eave or other projection above a predominantly south-facing window, and even east-and west-facing windows, can shield the glazing below from high-angle summer sunrays while letting low-angle winter rays enter indoors. But in the spring and fall this technique is only partly successful, because then the sun’s trajectories are alike the same number of days before and after the winter solstice while the weather is usually not. H cos La = L tan Lv Shaded overhang

11. CLIMATIC & SITE FACTORS in DESIGN: WATER In a building, about the only place where water belongs is inside refrigerators and plumbing systems. Anywhere else, and the building’s life is in mortal danger. Divert the approaching liquid at every outer surface of the building. If waterproofing were simple, designers of buildings would enjoy more pleasant nights of sleep. Unfortunately, water has an insidious way of materializing out of thin air via the laws of condensation, a contradictory way of flowing uphill via the laws of osmosis. to become a welcome mat for rotting, spalling, rust staining, and colonies of carpenter ants and termites.

12. CLIMATIC & SITE FACTORS in DESIGN: WATER An excellent pre­ventive technique is to insert a layer of 90 to 15lb rolled roofing between every contiguous surface of wood-to-metal, wood-to­masonry, or metal-to-masonry, as well as between any two metals that are far apart in the galvanic series. A layer of this material will prevent Water condensation and temperature differentials between the surfaces-in-common. polyethylene vapor barrier slick surface actually collects moisture and within a few years it usually becomes brittle and cracks. .

13. CLIMATIC & SITE FACTORS in DESIGN: WATER An other important moisture preventive is venting, particularly in roofs between insulation and sheathing. In warm humid regions, this space may need to be 8 in. deep and accompanied by wide continuous screened vents at every eave and peak in a building’s roof. .

14. CLIMATIC & SITE FACTORS in DESIGN: Hydrostatic Head The force of water in the earth below an area’s local water table can turn a building’s basement into an empty boat and pop it out of the ground —a phenomenon well-known to swimming pool contractors

15. CLIMATIC & SITE FACTORS in DESIGN: Precipitation Precipitation is the descent from the sky of several kinds of moisture, particularly rain and snow, and its deposit on buildings and terrain. The formulas to keep precipitation away from entering the building: Sizing gutters, leaders, footing drains, and storm drains.

16. CLIMATIC & SITE FACTORS in DESIGN: Gutters 1) never hesitate to oversize this relatively low-costing component. 2) gutter is usually at least 4 in. 4) Every gutter should pitch at least 1/16 in/lf to facilitate drainage. 5) A gutter exceeding 50 ft in length requires an expansion joint.

17. CLIMATIC & SITE FACTORS in DESIGN: Gutters

18. CLIMATIC & SITE FACTORS in DESIGN: Gutters Rainfall Intensity Map

19. CLIMATIC & SITE FACTORS in DESIGN: Leaders Also called downspouts, leaders generally have round or rectangular sections with plain or corrugated profiles. Every gutter should have at least two leaders in case one is clogged. 1) Use as few elbows as possible, 2) Secure each leader to the building with a U-shaped holddown. 3) Install basket strainers at the top of every downspout Roof runoff management doesn’t end at the bottom of the leaders but only when the runoff is well away from the building.

20. CLIMATIC & SITE FACTORS in DESIGN: Footing Drains 1) Every foundation wall below grade should be as waterproof as the hull of a boat. This is done by covering the wall’s outer surface below grade with a layer of thick gooey asphalt laid on with a trowel or a membrane. 2) Then a minimum 4 in. diameter perforated drain should be laid completely around the building with its crown 4 in. below the floor. Periodic inspection of the construction site just before the foundation is backfilled. Otherwise, caveat emptor. Footing drain & outfall design details.

21. CLIMATIC & SITE FACTORS in DESIGN: Footing Drains

22. CLIMATIC & SITE FACTORS in DESIGN: Storm Drains Waterflow collected by storm drains may include direct rainfall, water-flow from paved surfaces that arrived from other areas, overflow from ponds and other bodies of water. These waterflows are quantified in three ways: 1) Runoff. Surface drainage of excess rainfall or snowmelt from a roof or area of terrain. 2) Discharge. Waterflow from such non-rainfall sources as under­ground springs, excavation seeps, AC disc. 3) Fixture unit waste. Drainage from spigots and other plumbing out­lets that do not empty into sewage or septic systems. an open or closed channel is usually sized to carry the flow to safe discharge areas such as stormwater retention basins and terrain depressions.

23. CLIMATIC & SITE FACTORS in DESIGN: Storm Drains An open or closed channel is usually sized to carry the flow to safe discharge areas such as stormwaterretention basins and terrain depressions. It is difficult to predict such storm drainage accurately because (1) the rainfall itself can’t be predicted accurately (2) it is difficult to determine the porosity of the soil (3) the water absorption of any foliage growing on the drainage area varies depending on its biology, season of year, and density of growth (4) in northern latitudes the drainage may include snowmelt during spring thaws (5) normally porous soil may be fully saturated after recent rains.

24. CLIMATIC & SITE FACTORS in DESIGN: Storm Drains Rainfall that is so heavy and can be devastating. It can make the ponds overflow, its erosive power could wash away a spillway, especially if it is small. Thus wise design includes not only ample safety factors, but an orchestration of several soft-path methods that would minimize any damage that could conceivably result if failure did occur.

25. CLIMATIC & SITE FACTORS in DESIGN: Storm Drains Guidelines for designing storm drains: 1) Storm drain design requires analysis of watershed areas, discharge paths, recharge basins, erosion potential, ground cover regeneration. 2) Soil retainabilitymay be increased with landscaping. 3) Storm and sanitary sewers should be designed for 0.8 full capacity 4) The minimum flow velocity in sanitary sewers is 2.0 fps, but 2.5 fps is better; this keeps solids from settling out of the fluid. Even a minor defect in a storm drain’s joinery can fail years later and create a sudden major problem in the community. A compression test should be performed.

26. CLIMATIC & SITE FACTORS in DESIGN: Drywells A drywell is a covered pit with walls of open bricks or concrete blocks laid on their sides through which flows water discharged from roofs, basements, turnarounds, and the like. Drywells should be at least 10 ft from septic tanks and lot lines, 20 ft from buildings, and 100 ft from water supply sources. Their bases must lie above the highest annual level of the local water table; they cannot accept toilet wastes; and they cannot be built in rock, hardpan, dense clay.

27. CLIMATIC & SITE FACTORS in DESIGN: Flood Force The damage that can be caused by even a small stream that has risen to flood stage is staggering. This is primarily because the erosive power of water relates to the fifth power of its speed. Thus if a stream’s speed doubles, its erosive force is 25 = 32 times greater; and if its speed quadruples, its erosive force is more than a thousand times greater. 70 meter section of the flood prevention wall in nearby Dianpu River

28. CLIMATIC & SITE FACTORS in DESIGN: TEMPERATURE Owing to changes in temperature, no part of a building is ever still. Such expansion and contraction not only creates problems in long exterior walls and large roofs, it can also cause trouble in large interior spaces if vacancies, blackouts, or acts of terrorism shut down a building’s climate control system during very hot or cold weather. To avoid damage to a building due to thermal movement, expansion joints are installed in any dimension exceeding about 100 ft.

29. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW A comfortable indoor environment has a year-round temperature between about 67˚ F in winter and 77˚ F in summer. As heat flows through any portion of a building envelope, so does water vapor. Unfortunately, the moisture carries most of the heat. Even worse, as the moisture passes through the envelope’s insulation from its warm side to its cold side, the moisture’s temperature steadily lowers, until it often falls below the air’s dewpoint whereupon its precipitates out of the air and condenses in the insulation, where it instantly reduces its ability to insulate.

30. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW Thus moisture migration must be minimized, especially in warm humid regions. A common way to do this to install aluminum foil facing, polyethylene sheeting, or other water vapor barrier on the warm side of the insulation. In temperate climates, where the average annual temperature is near 65˚ F. Then where does the barrier go? Whether inside or outside, it seems moisture will collect in the insulation during a good part of the year. The answers to this dilemma are few but finite: in temperate climates use insulations that are least affected by water: styrofoam boards instead of batts.

31. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW There are four kinds of heat flow that affect a building’s interior spaces: 1) Conduction of heat through the building envelope. This is heat migrating through the envelope construction and insulation. 2) Convection of heat via air infiltration through seams and openings in the building envelope. (cold air is denser than warm, because the same molecular mass has shrunk.) Thus, according to Boyle’s Law, infiltration air­flow varies directly according to the temperature differential between indoors and outdoors.

32. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW - Convection Infiltration A building’s infiltration air loss is also difficult to quantify due to the following additional variables: 3)The introduction of fresh air into the HVAC system. 4)In an occupancy that has a fireplace or furnace. infiltration heat flow through a building envelope is reduced by sealing all envelope seams, using nonporous construction materials

33. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW - Convection Infiltration infiltration heat flow through a building envelope is reduced by sealing all envelope seams, using nonporous construction materials

34. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW 3) Auxiliary heat gain radiated within the building envelope via occupants’ metabolism and Btus emitted from lights and machines. Installing exhaust fans that remove heat from its source before it spreads to adjacent areas. 4) Solar heat gain arriving through areas of glazing in the building envelope. This heat flow is also desirable in cold weather and undesirable in warm. Constructing overhangs and other sunshields outside An organized way to perform thermal calculations is to begin with a building envelope spreadsheet.

35. CLIMATIC & SITE FACTORS in DESIGN: HEAT FLOW

36. CLIMATIC & SITE FACTORS in DESIGN: Insulation Since any undesired heat loss or gain through a building envelope is an economic loss, architectural materials that impede heat flow are commonly installed in building envelopes. These materials’ selection is based on relative values such as C(thermal conductivity), K(thermal conductance), U(heat flow coefficient), and R(thermal resistance). Perimeter Heat Flow. When many small pieces of insulation are fitted into a network of construction (as within the studs and plates of a wood stud wall),

37. CLIMATIC & SITE FACTORS in DESIGN: Insulation Surface air film. A thin film of insulating air covers the inner and outer exposed surfaces of the building envelope. Moisture. Whenever moisture collects within the building envelope, it must be removed or it will degrade the construction

38. CLIMATIC & SITE FACTORS in DESIGN: Types of Insulation Batts These are fluffy masses of spun glass that are usually fitted snugly into the voids of wood frame construction. + Economical, effective. Small pieces may be stuffed into any size void. - Loses its R value if saturated with moisture Boards rigid foam or fiber attached to walls or roofs or laid under concrete floor slabs. A few popular foams in ascending order of R value (usually at increasing price) are beadboard, styrofoam, urethane, and isocyanurate. +Won’t decompose when placed in contact with earth.

39. CLIMATIC & SITE FACTORS in DESIGN: Types of Insulation Fills Granules poured into small construction voids such as cells in concrete blocks. “The most economical thickness of insulation for a given project is based on the cost of the insulation and the cost of energy.”

40. CLIMATIC & SITE FACTORS in DESIGN: Insulation Superinsulation As a result of the Energy Crisis of the late 1970s, architects found that by increasing the thickness of insulation in a building’s walls from the then-standard 4 inches to 10 inches or more, the building’s life-cycle energy costs would be significantly reduced.

41. CLIMATIC & SITE FACTORS in DESIGN: Conduction & Infiltration Heat Flow Conduction is heat gained or lost through the building envelope’s solid surfaces while infiltration is heat gained or lost through any openings such as pores, cracks, flues, and vents.

42. CLIMATIC & SITE FACTORS in DESIGN: Design Heating Load Insulating Value of Materials

43. CLIMATIC & SITE FACTORS in DESIGN: Design Heating Load Winter design temperature map

44. CLIMATIC & SITE FACTORS in DESIGN: Design Heating Load Summer design temperature map

45. CLIMATIC & SITE FACTORS in DESIGN: Design Heating Load The EnthalpyGraph is used to size a cooling system given the local summer design temperature and humidity, as enthalpy is a thermodynamic measure of the air’s heat content, which is a function of its temperature and humidity.

46. CLIMATIC & SITE FACTORS in DESIGN: Auxiliary Heat Gain This is the heat added to interiors by occupants, lighting, appliances, and other internal heat sources. Although auxiliary heat gain can comprise a significant portion of a building’s heating or cooling load, it is difficult to estimate . Conduction, infiltration, and auxiliary heat gain are often all that is needed to compute a building’s total heating and cooling loads.

47. CLIMATIC & SITE FACTORS in DESIGN: Solar Heat Gain Solar heat gain is the amount of the sun’s energy that enters indoors through glazing in the southerly surfaces of a building envelope during cold weather. Although this heating load is conceptually simple, it has numerous variables. First, the sun’s energy fluctuates according to sun­spots and other hyperactivity occurring on its surface. Second, the amount of solar energy that enters the earth’s atmosphere varies from about 445 Btu/sf·hron Dec. 21 when the sun is closest to the earth to about 415 Btu/sf·hr on Jun. 21 when it is farthest away.

48. CLIMATIC & SITE FACTORS in DESIGN: Solar Heat Gain Third, as this energy enters the earth’s troposphere, some is scattered by the air’s molecules and some is absorbed by the molecules depending on the air’s temperature, chemical composition, and moisture content. Fourth, as a site’s elevation above sea level increases, the sun’s energy increases (at mile-high Denver it is about 7 percent greater than at sea level). Fifth, as the sun descends from directly overhead tow near the horizon, the air its rays travel through becomes thicker, which decreases their intensity.

49. CLIMATIC & SITE FACTORS in DESIGN: Solar Heat Gain Thus, for all practical purposes, the sun’s average intensity as it reaches the earth’s surface at sea level at noon on a clear day when it is at least 15˚ above the horizon is normally taken to be about 300 Btu/sf·hron a surface perpendicular to the arriving rays. This energy is available from about 9:00 A.M. to 3:30 P.M. even in late December almost everywhere in the country. huge amount of free solar energy is potentially available for heating interior spaces in buildings all over America.

50. CLIMATIC & SITE FACTORS in DESIGN: Solar Heat Gain - Solar panels Why did solar flat plate collectors fail? They were too shallow. Imagine trying to collect enough energy in a container a few inch­es deep to heat a container that is 30 feet deep. whenever energy is transferred from one medium to another, some is irretrievably lost.