Here are my highly personal notes on Chapter Nine: Running on Sunshine in Peter Bane’s The Permaculture Handbook (2012). Any misrepresentations of Bane’s words or work are mine alone and completely unintentional. Notes on each chapter linked here.
“The main thing to remember is that the sun is the source of energy, so you need to know where it will be in the sky and arrange your buildings and landscape to receive its rays at the right time and season.” — Peter Bane
Climate is the interaction of latitude, altitude, local topography, and proximity to ocean coasts — these influence winds, solar gain, air layering.
Microclimate is climate near the ground, influenced by degree of slope, the direction the land faces (aspect), local water bodies, presence of vegetation, the nature of the ground surface (soil, pavement), and human structures. Our goal is to remove or mitigate limits to the growth and health of our crops, which in much of the U.S. and Canada means cold weather, especially freezing temperatures, and too much or too little moisture.
Late afternoon in March or November is a good time to observe microclimate, to notice pockets of cold air (our bodies can detect changes in air temperature of 2F or more). Also, a late winter or early spring snowfall will reveal ground temperatures by speed of melting. A cool night in August or Sept. can reveal frost pockets. Nightshade plants (tomatoes, tobacco, ground cherries, etc) also indicators, as they can’t germinate in cold soil and frost will reliably kill them.
Inventory your land for slope, aspect, vegetation, buildings, prevailing winds, elevation differences, water bodies, pavement and soil surfaces.
Finding the Sun: Sun angles are determined by tilt of Earth, latitude, and season. In the U.S. the sun is always in the southern sky at midday, higher between 21 March and 21 Sept. and lower in fall and winter.
Formula for sun’s angular elevation at midday at different times of the year:
90 degrees – (your latitude) = equinox elevation
Equinox elevation + 23.5 degrees = Summer Solstice elevation
Summer Solstice elevation – 47 degrees = Winter Solstice elevation
[When my group was reading this book in 2014, I noted that our sunrise on 11 Feb. was 6:52 and sunset was 5:13 … At Jekyll Island, GA, a favourite vacation spot, sunrise the same day was about 20 mins later, at 7:09 a.m., but sunset was almost an hour later, at 6:11 p.m., and in total Jekyll Island had 41 more minutes of daylight than we did in NH then.]
[You can also go to suncalc.net for sun angle info for your location]
Bringing the Sun Indoors: Lots of applications to the sun’s angle, most importantly comfort inside the home. People in industrialised countries spend 90% of their lives indoors. All buildings where winter skies aren’t completely overcast should be oriented for solar gain, i.e., the long axis oriented east-west. [There is a publication error from pp. 139-140, with a missing phrase, sentence, or more.]
A house “needs to be as close to the street as can be tolerated, but somewhat central to the land around it, so that all parts of the farm can be reached easily. … The house should be located at least a few feet above the lowest part of the landscape, and preferably at the midpoint of any slope of substantial length, to take advantage of the thermal belt created there. Of course buildings for occupancy should be placed on south-facing ground, though a little southeastly or southwesterly can be serviceable.”
How to capture heat from the sun, in a house, greenhouse, etc.: glazing to admit light; thermal mass with surfaces exposed to light; and a tight, insulated envelope to hold heat.
Sun trap: “An arc of trees facing the south will reflect light and heat toward its focal point. We call this a sun-trap, and if it’s a true parabola, there will actually be a hot spot at the center.”
Surfaces intercept and convert light better if they lay perpendicular to the direction of the sun’s rays. Each 5% of slope tilt toward the sun changes the climate there to be like the climate one zone (300 miles) to the south.
Bane says (p. 144) that “afternoon light through west windows is almost never helpful” — not true at our house, where it’s very helpful. Our sunroom has its long wall and most of its windows facing west and because of this it warms up to 65F or more on afternoons in March/April and October/November, when the outside temps are in the 40sF.
Espalier: Training trees to grow against a south- or west-facing stone wall, where it’s warmer than the area nearby. Can also grow vines and trees on wires (cordon). Pergolas and trellises, porches, awnings can also shape outdoor spaces to create microclimates of sun or shade.
Any body of water exerts a microclimate influence on the air around it to 1/4 of its width from the edge.
Winds: Weather fronts move from West to East across the U.S. on a 7-10-day cycle, especially in winter. Prevailing winds are westerly, aside from local topographical variations.
Hills and valleys — daily updrafts and nightly downdrafts. Anywhere cold air falls from a high ridge can create a frost pocket, especially in narrow valleys.
“After sunshine, wind energies are one of the most important sectors affecting any property. Cooling breezes are one of the few low-cost ways to keep comfortable in hot weather, while cold winter winds stress livestock, increase heating bills, and can harm crops and tender plants.”
[There is a very cool wind website, Windy, that shows the direction and strength of wind for your lat/long coordinates. Thanks, Mary Anne, for this.]
Windbreaks: Banes has a page of suggested trees (50′ and taller, 8-35′) and shrubs (3-8′) to use for windbreaks and hedgerows. You can also use small structures like tires, straw bales, row covers, temporary fencing to protect plants and animals from sun, wind, rain.
Featured image (top image) is the Conservatory Garden in Central Park, NYC, early April 2016, with vine-covered pergola, rows of hedges, brick walkways to trap and hold heat.