Paula_Microclimates.doc

Design with Microclimates

Microclimate is the horizontal topography we design to.

To design microclimatees we need to analyze sectors, develop skills in observation, and experiment to develop our knowledge and understanding. 

To see microclimates we need to observe the landscape:

Checking for temperature differences

Reading plant indicators for hot and wet spots (specific plants prefer different microclimates)

Observing at sensitive times of the year – fall, spring, early morning, late afternoon

The microclimatic factors you can change:

Temperature and temperature range

Humidity and humidity range

Wind speeds and direction

Moisture ranges

Factors affecting Microclimate

Topography

·         Aspect (most important in edge climates, less important in cloudy climates; early morning sun is solar, fast warming, late afternoon is hotter and drier – use for late ripening fruits )

·         Slope (flatten or increase slope by tree size plantings; frost dams behind trees on a slope – to remove the pocket cut the trees)

·         Cold air drainage

·         Winds (winds accelerate in gaps and up slopes)

·         Elevation

Vegetation

·         Forests (trees are thermal sinks and hold off frost effects; also cool air and increase moisture; moisture is concentrated at the roots and dripline)

·         Clearing and thinning

·         Windbreaks (deflect harsh winds and funnel favorable winds; should be perpendicular to the prevailing winds; use multirows of different species with 50% permeability.  Don’t want to create gaps; 1 or 2 rows of evergreens; for household distance of windbreak take height * 10 and windbreaks should be 10* the height apart in rows – if 50’ tree than 500’ apart; multiple rows and crenallated windbreaks to increase edge)

·         Vegetation edge

Soil & Mulch & Pavement

Water (creates heat sinks; moderates temperature and humidity)

Human Structures

·         Walls (rough, smooth, light, dark all effect microclimate)

·         Trellises

·         Glass houses

·         Stones (warm areas – herbal spirals)

·         Plant potatoes in tires; put in mulch, stack hay; add tire and harvest; hay bales are a sun trap.

In the temperate region we tend to employ the following design strategies:

·         Maximize the warming effect of solar radiation in winter months and maximize shade in summer months

Ø      Utilize deciduous trees for shade in summer and sun in winter             

Ø      Orient living spaces to the south for winter warmth

Ø      Design building overhands to shield the high summer sun and expose the area to the lower winter sun

·         Reduce the impact of winter winds but maximize summer breezes

Ø      Steeply pitched roofs on the windward side deflect wind and reduce the roof area effected by winds

Ø      Blank walls, garages or storage uses on the northern exposures

Ø      Protect north entrances with earth mounds, evergreens and walls or fences

Ø      Allow for natural ventilation with prevailing summer breezes             

In permaculture we continually use and create different microclimates to extend the range of plant species.  Most plant species prefer a certain microclimate

Ø      Plants prefer cold – brassicas, apples, stonefruit

Ø      Plants prefer hot – tomatoes, kiwi

Ø      Plants prefer wet – blueberries, celery

Ø      Plants prefer dry – herbs

Permaculture Research Institute – Cold Climate           03/15/2006