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Zones and Sectors – Efficient Energy Planning
The fourth Permaculture Design principle is principle of 'Zones and Sectors’.
The design principle of Zones and Sectors is concerned with efficient energy planning, that is, planning the placement of elements in the design, such as trees and plants, animals, structures and buildings, to make to most efficient use of energy.
Efficient energy planning can be broken down to the following three categories:
A. Zone Planning
B. Sector Planning
C. Slope
We will examine each in turn to see how we can use these concepts to maximise energy efficiency in our Permaculture designs.
A. Zone Planning
Zone planning is a system where the location of an element in a design is determined by:
How often we need to use the element
How often we need to service the element
This is a basic logical principle, whereby the things you use most often, and the things you have to pay the most attention to, are placed closest to the house in the design.
Consequently, the things that are used the least often, or that require little or no attention, are placed furthest away in the design, and things that fall somewhere in between are placed accordingly.
By situating the most often used or serviced elements in a design closest to the home, it makes it easier to access them. This means less energy is expended to access them, making for a more energy efficient design.
As a practical example, a kitchen garden containing the most often used vegetables and herbs would ideally be located in close proximity to the kitchen itself, so when the need for herbs and vegetables arises, it’s only a quick step outside the back door of the house to get the required cooking ingredients. It would be highly inefficient, and extremely wasteful of energy if you had to walk across your whole property, to some remote back corner, to get what you need to prepare a meal, for the following reasons. Firstly, you’d be less likely to go there, and secondly, you would have difficulty maintaining a kitchen garden that is harder to access – as you can’t keep an eye on it, and are less inclined to maintain it if it takes a whole lot of effort and energy to do so simply because it is so far out of the way!
Zones are abstract conceptual boundaries around the home which help us to work with distance to plan efficient energy use.
The areas around a house are divided up into zones numbered 0 to 5, based their accessibility and frequency of use in relation to the location of the house. The lowest number denotes the most frequently accessed areas, while the highest number indicates the areas least accessed.
Here is a conceptual zone diagram, illustrating the various zones around the house.
NOTE: Zones are often misunderstood in Permaculture design. Let me stress the following points before we get into further details:
Zones are not hard boundaries, they are not necessarily delineated by fences or other hard structures.
Zones can blend into each other at their boundaries, this is most often the case in real life designs.
Zones are not circular, they can be any shape, defined by how accessible the areas around the house are.
By defining the different zones around the home, we can then create some guidelines of what we can put in each zone in our designs.
So, let’s see what goes into each zone!
Zone 0
This is the home itself, the centre of activity.
Unless you are creating a Permaculture design for a bare block of land, and have to decide where to locate the house, and the design house itself, then Zone 0 is not normally a concern for most designers.
Where there is a pre-existing house on the land, that normally will be your Zone 0 and the beginning of your zone mapping. If you do have to locate and/or design the house (!) , It goes without saying that the home design should be energy efficient, and provides an environment where the occupants can live and work in a sustainable and harmonious way.
Zone 1
This is the most intensively used zone, and the most managed and controlled.
Zone 1 is the area nearest to the house, and also includes the most frequently accessed areas , such as alongside often used paths.
Keep in mind that this zone is defined by access, so if there is an area near the house that you don’t visit, or is hard to get to, even if it sits next to the house itself, then it is not included in Zone 1.
If you leave your property daily to go go work for example, then the path from the street to your house and the immediate areas alongside it will be included in Zone 1, as you visit these areas twice daily.
The diagram below shows how the area around the house, coloured green, is Zone 1, as is the path from the street. The area to the the side of the shed is not an area that is often accessed , so it is not included in the Zone 1 region, even though it is very close to the house.
Elements that are located in this zone include all the things that you need to access most often, or that need the most frequent attention, such as:
a kitchen garden to provide vegetables and salad greens which have a short growing season (time from planting to harvest) and herbs for teas and culinary use
small trees which provide often used fruit, such as lemons
worm farms for processing kitchen waste
greenhouses, cold frames and propagation areas
workshops or shed s
rainwater tanks, water bores and wells
fuel for heating or fire, such as wood or gas
small animal pens/cages for rabbits or guinea pigs
Zone 1 plantings usually employ complete mulching, using a system such as sheet mulching, and are fully irrigated with irrigation systems such as drip systems, which sit below the mulch on the garden beds.
Remember, Zone 1 is an intensive system, it is a human ecology, that does not exist in Nature, and would fall apart without human attention.
Note:
For many urban properties, where the backyard is quite small, then the whole property will be Zone 0 and Zone 1 only!
Most urban properties can only be divided up into Zones 0, 1 and 2, and the designs for these properties will not need to include any of the other zones.
When starting to map zones on your site design, start with Zone 1 first, and when constructing the site, build and complete Zone 1 first, then work outwards to complete the other zones.
Zone 2
This zone is also used quite intensively , but a bit less than Zone 1, and accommodates some of the larger and slightly less frequently used elements, that still need fairly frequent attention.
Elements that are located in this zone include all the things that you need reasonably often, or that need the fairly frequent attention, such as:
perennials and vegetables which have a long growing season (time from planting to harvest)
fruit trees/orchards
compost bins
bee hives
ponds
chicken/poultry enclosures
enclosures for larger animals that need to be regularly monitored, maintained and attended to
Zone 2 plantings can employ complete mulching using a system such as sheet mulching, but if the area is too large and this is impractical. then spot mulching around the trees may be employed, and tree guards can be used to protect trees while they get established. These plantings are fully irrigated using irrigation systems such as drip systems.
Zone 3
The zone is basically farmland, where the main crops are grown (for personal use and to sell), where orchards of larger trees are located, and where livestock is kept and grazed. Once these areas are established, they only require minimal maintenance and care.
Elements that are located in this zone include all the things that require infrequent attention only, such as:
orchards of larger trees
main farming crops
pastures and rearing areas for large livestock such as cows and sheep
semi-managed bird flocks
large trees for animal forage – oak trees and nut trees
dams for water storage and drinking water for animals
Zone 3 plantings employ green mulching, which is an under-planting of ground cover plants which serve as a 'living mulch’ for the trees. These plantings are unpruned, and not all plants have irrigation to water them.
Zone 4
This zone is a part wild/part managed, and its main use is for collecting wild foods, timber production, as a source of animal forage, and pasture for grazing animals.
The trees in this zone are managed by allowing animals to browse to control new growth, or by thinning (removing) seedlings to select the variety of trees that will be allowed to grow.
Zone 5
This zone is an unmanaged wild natural ecosystem, such as bushland, forest or similar natural area, free of human intervention, interference or control.
Zone 5 is a wilderness conservation area, and space that provides us with the opportunity to step down from our role of controlling Nature, to one where we can just witness Nature in its pure form, where we can simply observe the cycles of Nature and learn from what we see. It the place where we can meditate and reconnect with Nature, and come to understand our place in the world.
The wilderness area does not have to be restricted to the outer perimeters of a property in a design. Zone 5 can extend as a wedge all the way from the outer perimeter right up to the house, to create a wildlife corridor as part of a design that brings natural ecosystem close the the home.
In urban areas, Zone 5 can be a nearby creek, or a neglected area of unused vacant land.
Practical Zone Diagrams
Now that we have discussed some of the guidelines of what we place in each zone, it is appropriate to now revisit our zone diagram, but with a more practical focus.
The reason zones are rarely circular is because ground is rarely flat, and even apparently flat ground will have a measurable gradient. Furthermore, areas of land can be irregularly shaped, so real world zone diagrams can appear very different from our previous conceptual zone diagram.
Here is an example of a zone diagram which is closer to a real-life example, where each zone is shown in a different colour for illustrative purposes.
Here, we can see that the zones can be irregularly shaped, they can overlap rather than form concentric circles and a particular zone can appear more than once.
This should illustrate the flexibility we have in mapping zones in zone diagrams, and how far from the circular conceptual diagram real-life examples can be.
Zone Sizes
One question that often arises for designers is “how big should the zones be”?
The size of a zone is driven by two factors:
the distances that are practical to cover on a human scale, and
the amount of space required to yield produce to support a given number of people.
With these factors in mind, here are some practical design guidelines for the ideal amount of area allocated to each zone.
Zone 1 – is ideally around 1000 sq. m (1/4 acre) in size for a family of four, this size is manageable as an intensive food production system.
(All vegetables required can be grown in an area of 50sq. m per person.)
Zone 2 – is ideally 4000 sq. m (1 acre) in size for a family.
Zone 3 – can range from 4 to 20 acres for a family.
Zone 4 – can be any size
Zone 5 – is a wilderness and is used for hunting and gathering
In conclusion, zones are concerned with the flow and use of energy inside our system, optimising it by the use of distance, and the strategic placement of elements, according to their frequency of use and the attention they require.
Zone planning though, does not account for all the systems of energy interacting with the site we are designing. A site does not exist in isolation, it exists as part of a larger environment, where external energies, the elements of nature, which come from outside our system, also act on it.
To plan for these energy systems, we use a system of energy planning known as Sector Planning, which is discussed in the next section.
B. Sector Planning
Sector planning is concerned with energies external to our site, the elements and forces of Nature, that come from outside our system, and pass through it.
These energies include:
hot summer winds
cold winter winds
winter and summer sun angles
salty or damaging winds
water flow and flood prone areas
unwanted views
fire danger areas
Since these wild energies come into our system from outside, we can strategically place elements in our design to manage or take advantage of these incoming energies.
By placing plants, trees or structures in the appropriate areas, we can:
Block the incoming energy
Channel the incoming energy for our intended use
Open the area to allow the incoming energy in
Let us now examine each of these three approaches.
Blocking incoming energy
Where external incoming energy is detrimental to our system, we can block its flow, preventing disruption to our system.
Wind is an element which often requires steps to manage it in most designs. Hot summer winds, cold winter winds, salty seaside breezes, and damaging dusty winds all need to be restricted in a design through the use of windbreaks. Windbreaks can be constructed using specifically resilient plants and trees, or by building protective structures.
Identifying where the summer sun and winter sun shines is important for managing the harsh midday and afternoon summer sun (north and west sun in southern hemisphere, south and west sun in northern hemisphere). Deciduous trees can be planted around the house to block the sun in summer, keeping the house cool. In winter, when the leaves fall, the low winter sun can warm the house naturally. Man-made structures can also be built around the house which take advantage of the sun’s low winter angle and high summer angle to provide summer shade and winter sun.
Where fire dangers exist, the areas most prone to incoming fire are identified, and firebreaks are placed in this area in our designs. We place elements here that do not burn such as roads, cleared areas, stony ground, concreted areas, stone walls, ponds, marshes and waterways. These areas are planted with fire-resistant tree species and vegetation to create a shelter belt. Trees suitable for this purpose are typically European deciduous trees, such as deciduous fruit and shade trees. A selection of suitable trees includes deciduous fruit trees in general, oaks, elms, willows, poplars, aspens, cottonwoods, figs, carob, mulberries and mirror bush. I have included a wide list of fire resistant trees and plants in the article Permaculture Design Principle 3. Each Important Function is Supported by Many Elements.
Another application of 'blocking incoming energy’ is the screening of unwanted views. Trees, plants and structures can be erected to provide additional privacy, and block out unwanted views, while providing a more aesthetically pleasing alternative.
Channelling incoming energy for our use
Free energy coming into our site from outside can also be utilised for our benefit.
Water flowing into our site, either from directly above as rain, from run-off coming from adjacent properties, or collecting in an area (such as a flood prone area) can be redirected into lakes, dams, ponds, irrigation channels, swales and other water management systems.
Wetter areas can be used specifically to grow very 'thirsty’ plants and trees, which will help manage the excess water, or they can be converted to wetlands or bodies of water, such as ponds, lakes and dams for water storage.
Water can be captured at an elevated point on the site, and being elevated, it is a store of what they call 'potential energy’ in physics. The water can then flow under gravity to perform work, such as irrigation or water supply.
Water flowing across a stream or river can be used to drive a hydroelectric generator to provide electricity, or can have some of the flow diverted for irrigation purposes.
Wind can be captured to drive wind turbines or windmills, providing a source of free energy to the site which we can utilise for our purposes.
Sunlight can be harnessed in the generation of solar power, solar water heating, drying foodstuffs and so forth.
Opening areas to incoming energy
An area of a site can be opened up or cleared to allow a natural energy to come into the system more easily.
Sunlight is one of the elements of nature that we might want to increase in our design. If we have structures or trees blocking the light reaching our Zone 1 kitchen garden for example, rather than relocate the garden, we can clear the area to allow more light in. Where places are too shaded, we can thin out trees or branches to increase productivity from our available space.
Similarly, we can clear an area to create a view of a pleasant outside area. If we have potentially stunning views of mountains, lakes, forests or simply an inspiring piece of Nature from the home, we will want to clear any objects obstructing the view to take advantage of such a positive feature in our site design.
Mapping Sectors
To map out how these wild energies interact with our site, we can use a sector diagram.
Each sector indicates one of the external energies discussed above, and is usually represented as a wedge shape, like a slice of a pie, radiating our from the centre of activity, Zone 0, the home, but it can be any other structure of central focus if necessary.
The diagram below shows a sector diagram for the southern hemisphere, with the sun to the north. The sun paths are shown, as well as other key energies. Note that the Zone 5 wildlife corridor extends into Zone 1 in this example, to show demonstrate the flexibility of zone design.
So, in summary,we can use sector planning in our design to manage the incoming wild energies moving through our site.
By the strategic placement of elements in our design, we can block, channel, or open up access to these natural energies. to optimise the use of energy in our site.
Together, zone planning and sector planning cover the management of energy inside the site and external energies flowing through the site respectively. Once we have completed our zone and sector analysis, we can then consider one more factor in efficient energy planning, that is the concept of Slope. The contour of the land has a considerable bearing on the design of the site, so this topic will be discussed on the following section.
C. Slope
When the site we are designing is on uneven ground, with, slopes, hills and valleys, further design considerations need to be taken into account because the contour of the land has a pronounced effect on the flow of energy in the system.
With any slope, gravity will move things from the highest point to the lowest, and we can take advantage of the work performed by gravitational force to make our system more energy efficient. The main emphasis of designing with slope is efficient energy flow.
Water
Water naturally flows from the highest point to the lower, so slope can be used to move water downhill by gravity.
By situating water storage such as tanks or dams uphill on the higher points of a site, gravity alone can supply a flow of water without needing additional energy to power a pump.
Gravel pits with reeds growing in them as a wastewater treatment system located downhill from the house, waste water (greywater) can flow under gravity into the reed beds, where it is cleaned, and then directed into a pond situated further down the slope.
As an alternative to using a reed bed wastewater treatment system, the wastewater from the kitchen, bathroom and laundry can be directed to an orchard that is located downhill from the house.
Structures that have a large roof areas for rainwater harvesting, such as sheds, workshops and other such buildings that people don’t live in can be located uphill from the house, to capture rainwater, which is collected in water tanks located next to these structures, and fed via gravity to the house.
Materials
The movement of resources and materials from the high areas to the lower ones uses less energy than moving them across level ground, and considerable less energy than moving uphill.
By locating access roads uphill of the house, less energy is expended delivering any materials to the site.
Growing timber for firewood or plants for mulch uphill from the house makes it easier to bring the material back to where it will be used because the load is carried downhill.
Heat
Heat behaves in an opposite manner to water, as heat rises upwards, as does warm air. Conversely, cold air, being more dense, sinks and flows downward.
Dams and bodies of water situated downslope can reflect heat, as well as act as a thermal mass, heating up during the day, and releasing the heat at night. Since heat rises, the heat emanated will rise upwards and warm the upslope area.
Similarly, we can place plantings of tall trees on a slope to retain heat, to warm the incoming cold night air that flows down the slope. When the warm air moves through the forested area, it will have warmed up as much as it can, and on reaching a plateau at the end of the forest, all the warm air will begin to rise, creating a thermal belt, which will be warmer than the surrounding area. If we place a house in this thermal belt, it will be warmed naturally.
The keypoint referred to in the diagram below is the flat area or plateau that lies between the convex slope above it and the concave slope below it.
We can also take advantage of the fact that hot air or water rises to set up the collection point downhill and use the energy above the collection point. If we set up a solar water heater downhill, the hot water will naturally rise upwards by convection, and the hot water can be accesses from an elevated tank. This is the principle by which thermosiphons work.
A solar hot water heater is basically a thermosiphon, a passive heat exchanger that works by convection to circulate water without a pump.
The water starts to move when the water inside the collector is heated by the sun. It expands, becomes less dense, and therefore lighter, and rises to float above the cooler, denser, heavier cold water.
As the convection moves the hot water upwards, out of the collector, cold water flows by gravity into the collector where it in turn is warmed up.
Erosion Control
Forested steep slopes not only warm the cool night air to create a thermal belt as described previously, but they also help control soil erosion. When water runs downhill, it will carve its own watercourses and gullies, washing away the soil in the process. Trees, vegetation and ground covers absorb the flow of the water, and by creating a buffer between the flowing water and the soil, they control the problem of soil erosion.
Water flows the fastest straight down a slope, and the effects of erosion will be most pronounced when water has the most direct path down a slope. Additionally, when water flows fast down a slope, very little of it is absorbed into the soil.
By digging trenches on the contours of the slope (contour trenches or swales), the flow of water can be slowed down, and diverted sideways on its downhill journey, to allow it to soak into the soil. Swales are discussed in further detail in the article on Permaculture Design Principle No. 3. Each Important Function is Supported by Many Elements.
Likewise, when constructing paths, tracks and fences, it is best to have then run along the contours of the site, and not downhill, as downhill running paths will create significant soil erosion, because there are no ground cover plants protecting the soil on a cleared path. Fences holding livestock will become tracks as livestock walk the fence-line day after day, so we also avoid running these straight downhill if possible.
Fire Control
In areas where the ground is not flat, and the house is located on a slope, the biggest danger is from fires running from the downhill area up the slope. These are called upslope fires.
The steeper the slope. the higher the risk. The speed and intensity of the fires doubles for every 10 degree increase in the slope angle. This happens for two reasons:
The angle of the slope allows the fire to dry the material uphill, making it more flammable when the fire reaches it, and
The updraught effect – when a fire burns, the heat creates an 'updraught’, hot air rises fast, and the fire pulls in more oxygen-rich air from lower downhill to feed it. The more air that feeds in, the hotter it gets, and the fiercer it burns.
As a consequence, the worst places to site a house is on sharp ridgetops or hilltops. The house is exposed from all sides to the threat of fire, and fire will race quickly up the slope to reach the house.
Another risky spot is the lee side of a hill, that is, the side of the hill sheltered from the wind. As the wind blows over the crest or top of the hill, it creates a low pressure area on the lee side, which creates a lot of air movement. During a fire, this powerful air movement can drive a fire cyclone, which will be burning directly over the house!
To reduce the risk of fire, houses need to be sited:
Away from the tops of hills or ridges
Preferably on downslope plateaus (level areas)
If the house is located on a slope of a hillside, excavate a shelf, a flat area, and locate the house on the shelf, well back from the edge to protect it from radiant heat coming from the downhill area.
If excavating a shelf, build a pond as a firebreak or an earthbank to protect the house from radiant heat.
Fire control is discussed in further detail in the article on Permaculture Design Principle No. 3. Each Important Function is Supported by Many Elements.
Aspect
The aspect of a slope is simply the orientation of the slope, the direction it faces.
A sun facing slope (facing north in the southern hemisphere, facing south in the northern hemisphere) is the ideal we aim for.
When the slope faces the sun. the site is able to receive the maximum amount of sunlight possible, which means the house, trees and gardens can make the best use of available light, and there will be less issues with the damaging effects of frost.
Conclusion
When creating a site design, if we:
determine the zones within the site to optimise the distances where elements are located,
analyse our sectors carefully to account for all the 'wild energies’ moving through our site, and locate design elements to harness or reduce them as necessary, and
assess the sun angle and slope to gain maximum benefit from them,
then we will have a fairly sound and potentially successful design in terms of making the most efficient use of energy for our site.
It is a fairly simple and straightforward exercise to systematically step through each of the areas covered under Zone, Sector and Slope, and attend to each part of the design as a separate task. By breaking up even the largest site into smaller sections, it’s much easier to design. Dividing up the site into zones does this for us, sector planning involves observation of Nature to see where the elements of nature come into our site design, and slope is a really a creative exercise where we see how much free energy you can grab from what nature offers!
Happy designing!