1. Environmental Controls I/IG
Lecture 8
Microclimate

3. Microclimate
Immediate local conditions for temperature, humidity, solar radiation, and wind.
Mesa Verde: vernacular, passive solar, sun angles, thermal mass

4. Microclimate Affected by: Earth Wind Fire Water
Mesa Verde: vernacular, passive solar, sun angles, thermal mass

5. Earth: Topography
The leeward side of a hill can protect from unwanted winds

6. Elevation Salt Lake City 4200’ 95º F Park City 6800’ ~86º F
Temperature changes about -3.6 ºF with each feet change in altitude
Elevation Temperature
Salt Lake City 4200’ 95º F
Park City 6800’ ~86º F

7. Rain & Snow Shadows
Form when moisture precipitates out as air moves up slopes
L: p.73 Fig. 5.2d

8. Ground Cover – Vegetation
Trees, shrubbery, and grasses provide shade that prevents moisture from evaporating
Permeable surfaces reduce temperatures through evaporative cooling
Reeves House, Lopez Island, WA
Cutler-Anderson, 2002

9. Ground Cover
Impermeable surfaces reduce evaporative cooling opportunities

10. Surface Color Darker surfaces absorb radiant heat
Lighter surfaces reflect radiant heat
Darker surfaces absorb radiant heat

11. Urban heat island
Large concentrations of thermal masses with darker and/or impermeable surfaces create urban heat islands

12. Wind: Topography Warm air rises Cool air drops
Morning and afternoon “diurnal winds” are intensified in canyons and on sloped surfaces and diverted by hills and ridges

13. Convective Air Flow Warm air rises Cool air drops
Recognizing air channels can help reduce discomfort or enhance comfort

14. Wind Direction & Speed Confirm mean (average) speed direction
Consult a wind rose for prevailing direction
L: p. 89 Region 1

15. Wind Roses
January
L: p.81 Fig. 5.6d

16. Wind Roses
July
L: p.83 Fig. 5.6f

17. Sea Breeze Effect
Onshore winds occur when water temperature is lower than adjoining air temperature over land.
Offshore winds are the reverse process.

18. Bernouli Effect
Air flow closer to the ground is slowed by frictional effects of surfaces
L: p.270 Fig. 10.5j

19. Venturi Effect Air follows the path of least resistance
Wind speeds increase as cross sectional area decreases
L: p.318 Fig. 11.8c

20. Wind Breaks/Channeling
Terrain and vegetation can block or channel wind
Plan Views

21. Solar (Fire): Mean Daily Radiation
Confirm how much solar radiation is a available
S: p. 1504, T. C.3

22. Mean Percentage of Possible Sunshine
L: p. 89 Region 1
Confirm how frequently the sun shines

23. Solar Orientation
South facing slopes get significantly more solar radiation than north facing slopes N

24. Water: Thermal Mass Large bodies of water moderate local temperatures
A thermal mass that can act as at thermal buffer/ heat sink

25. Lakes & Oceans Warm temperatures are reduced in summer
Cool temperatures are raised in winter
72ºF
80ºF
35ºF
30ºF
10ºF

26. Groundwater
Groundwater table affects temperature and humidity

27. Rivers & Streams
Moving water generates air movement

28. Perspiration Occurs as body core temperature rises
In low RH conditions evaporation occurs and cools skin
In high RH conditions evaporation is inhibited

29. Insolation
Humidity and cloud cover affect the amount of solar radiation entering or leaving the local environment

30. Evapotranspiration
Trees and shrubbery give off moisture that increases local humidity