The 12 principles published here are explained in detail in the book Permaculture: Principles and Pathways Beyond Sustainability, by David Holmgren.
In 1978, Australian ecologists David Holmgren and Bill Mollison coined for the first time the concept of permaculture as a systematic method. For Mollison, "permaculture is the philosophy of working with and not against nature, after a long and thoughtful observation."  Meanwhile, Holmgren defines the term as "those consciously designed landscapes which simulate or mimic the patterns and relationships observed in natural ecosystems." 
In 2002, Holmgren published the book Permaculture: Principles and Pathways Beyond Sustainability, defining 12 design principles that can be used as a guide when generating sustainable systems. These principles can be applied to all daily processes in order to humanize those processes, increase efficiency, and in the long term ensure the survival of mankind.
What if we apply them to the design process of an architectural project?
Principle 01: OBSERVE AND INTERACT
"By taking the time to engage with nature we can design solutions that suit our particular situation." - David Holmgren
According to Holmgren, the first principle is focused on the observation of nature, in order to understand the elements of the system in which we are working, before acting on it. Attempts to understand and really engage with the situation we face should naturally lead to a deep reflection that allows us to deliver an appropriate response.
In architecture, before sitting down to design, you need to ask yourself: What is the real need of the user of the project I'm designing? What is the context that surrounds it? How can I respond to this need in the most efficient and appropriate way possible?
Connecting with the user and interacting with the context of the project will facilitate our conscious process when engaging with the commission. We will have fewer opportunities to make erroneous assumptions and will be obliged to respect the users' pre-existing conditions and specific circumstances. A good architecture project will result if we are attentive to the clues that we are receiving.
Principle 02: CATCH AND STORE ENERGY
"By developing systems that collect resources when they are abundant, we can use them in times of need." - David Holmgren
The "green fever" that overtook architecture a few years ago relies on a rather passive sustainability, with the aim of achieving real efficiency in every possible way. However, beyond the "sustainable techniques" that can be applied, an appropriate question in regards to this principle might be: how do we deliver the best possible architecture using only the available resources, or even less?
Although architecture itself can function as a system to capture, store and use available resources such as the wind, sunlight, and rainwater, our responsibility as architects should not be narrowed down to these methods.
We must be aware that each line that we draw on our plan has an associated cost, a footprint. It makes no sense to raise large skyscrapers full of solar panels if your single construction generates a huge waste of resources and a series of negative externalities in other areas.
Principle 03: OBTAIN A YIELD
"Ensure that you are getting truly useful rewards as part of the work that you are doing." - David Holmgren
For this principle, Holmgren says that "you can't work on an empty stomach," ensuring that we get immediate rewards to sustain ourselves. He adds that the designed systems should ensure the survival of the community without compromising their future and that productivity should be measured in terms of the real products from the effort that was invested.
Beyond the fair and necessary monetary payment we receive for our work, our performance and productivity as architects should be measurable in relation to all the positive externalities that our projects are generating.
An architecture project has the ability to greatly influence the context in which it operates, and we can't lose the opportunity to identify and develop its potential benefits to the greatest extent possible. A project can't be considered sustainable if it only fills our pockets but does not "surrender" positively in other ways, or worse, if it harms its environment.
Principle 04: APPLY SELF-REGULATION & ACCEPT FEEDBACK
"We need to discourage inappropriate activity to ensure that systems can continue to function well." - David Holmgren
This principle is represented by the planet Earth, with the idea of showing the most visible "example of a self-regulating ‘organism’ which is subject to feedback controls, like global warming." The proverb used to describe it suggests that this negative feedback usually takes time to emerge, and the impact of our actions are not immediately visible.
In the case of architecture, we are generally prepared to plan our designs for the present, but not to think too much about what will happen with them in the future. It makes sense to do it that way, because our work needs to fit a user and a context in particular, with needs and requirements that are relevant today. How can we rid ourselves of an unpredictable and unfavorable future?
The key is just to "self-regulate" what we propose, in order to discourage, prevent or rethink the design answers (and/or related activities) that at least today, we can identify as inappropriate.
Principle 05: USE AND VALUE RENEWABLE RESOURCES & SERVICES
"Make the best use of nature’s abundance to reduce our consumptive behavior and dependence on non-renewable resources." - David Holmgren
For this point, the call is to "let nature take its course," to the greatest extent possible, and Holmgren gives us a somewhat extreme but clear example to understand its depth. The building of the Argentine Permaculture Institute was designed and built with straw and earth, materials that if not maintained - to allow life inside the building - will slowly return again back to earth. Its impact is minimal and its service life is directly associated with its use.
This is a difficult principle to apply because we are used to - and we were trained to - use materials, systems and services based on (nonrenewable) fossil fuel processes, but it challenges us to incorporate as many resources as possible which can be restored at a rate higher than their consumption.
Solar, wind, hydro and geothermal energy, or biomass and biofuels, can be effective options to explore which allow the operation of our "off-grid" projects; while some renewable materials like adobe, cork, straw and bamboo can provide good alternatives if properly applied. Woods produced through sustainable forestry techniques can also be added to this list.
Principle 06: PRODUCE NO WASTE
"By valuing and making use of all the resources that are available to us, nothing goes to waste." - David Holmgren
This principle is simply based on using all the resources we have available, avoiding waste of material. It's easy to waste when we have abundance, but what would we do if there were no warehouses filled with construction materials to build our projects?
We grew up in a profligate world, and as architects, from our first months at university we begin to spend more than necessary. Every week we make models and print meters of sheets of paper; expensive materials in many cases quickly end up in the trash. In professional life, the plotter is continuously hard at work and our old models are amplified to the scale 1:1.
Why not always design from the standard dimensions of materials to avoid waste? Why not consider whether it is really necessary that our housing project measures 6500 square feet, or whether that cantilever or that curved wall that force us to spend increasingly scarce resources are justified?
Principle 07: DESIGN DETAILS FROM PATTERNS
"By stepping back, we can observe patterns in nature and society. These can form the backbone of our designs, with the details filled in as we go." - David Holmgren
To explain this principle, Holmgren gives the example of the spider's web: each is unique, however, the geometric pattern of spiral rings is universal.
Many times we are told in architecture school that it's not necessary to "re-invent the wheel" every time we undertake a new project. There are many operations, dimensions and spatial configurations that are obvious and effective for architecture because they arise directly from previous experience and the behavior of human beings.
If we follow these proven patterns using common sense, we will be working on a solid and unquestionable basis, which can then lead to a project's full potential through its development. The details, as part of our particular contribution, move away from mere ornament to emerge as an added value, that supports and gives identity and specificity to the response.
Principle 08: INTEGRATE RATHER THAN SEGREGATE
"By putting the right things in the right place, relationships develop between them and they support each other." - David Holmgren
This principle is clear and we all have seen it at university or in our working life: "many hands make light work." It is likely that working together will allow us to reach a better result, because we can share strategies, compare views, and question our ideas with each other, in addition to speeding up a process that individually could take longer and be less effective, or even wrong. But we can go further:
Our designs can be really integrated if all the elements that constitute them are adequately working together, forming a cohesive whole, where nothing is lacking and nothing is superfluous.
Moreover, the possibility is in our hands to define the way the designed space will be inhabited in the future, and in that sense it's possible to incorporate subtle operations that encourage integration among users, creating spaces of friction and meeting that come into balance with those essential private spaces for individual development.
Principle 09: USE SMALL AND SLOW SOLUTIONS
"Small and slow systems are easier to maintain than big ones, making better use of local resources that produce more sustainable outcomes." - David Holmgren
At this point, the "maintenance" concept arises as a subject that is far more important than it seems, because the larger a building is, the more resources and processes are required to preserve it and prevent its decay.
If we as architects are really committed to a project and its future, we will try to make our design minimize and facilitate maintenance requirements, from its materials to the size and the configuration of spaces.
A good building should require minimal attention from its users, allowing them to realize their activities without constantly concerning themselves over malfunctioning systems or materials that show excessive wear.
If a project's dimensions are adjusted to the real needs of the customer, it is more efficient in its construction because it uses fewer hands and fewer resources. In turn, it becomes easier to achieve thermal comfort, facilitating the heating and cooling of interiors, and even improves other everyday issues such as simplifying cleaning.
Principle 10: USE AND VALUE DIVERSITY
"Diversity reduces vulnerability to a variety of threats and takes advantage of the unique nature of the environment in which it resides." - David Holmgren
In this tenth principle, Holmgren says "don't put all your eggs in one basket," stating that diversity "offers insurance against the variations of our environment."
If we take notice, a city has different types of buildings, with different sizes, configurations, and orientations. Each was intended to respond to the specific conditions of each site and particular user. If instead, we find neighborhoods where absolutely all houses are the same, something is wrong. Why should a house located on the main street be equal to one that is located in a quiet side street with little movement? Why should a home that receives plenty of light from the north be equal to one that is oriented more towards the south? It makes no sense.
Diversity reflects a certain specificity in the responses that each architect has delivered, allowing each project to be designed in accordance with the circumstances surrounding it.
Principle 11: USE EDGES AND VALUE THE MARGINAL
"The interface between things is where the most interesting events take place. These are often the most valuable, diverse and productive elements in the system." - David Holmgren
"Don't think you're on the right path just because everyone else used it." Holmgren is clear to say that the most popular technique does not always match with the best approach.
This principle tells us to seize and to value all the opportunities that at first glance don't seem relevant, and to analyze the commission received with open eyes, allowing us to see beyond the obvious.
If our project seems to be moving in the wrong direction, it may be good to turn it around completely. If there aren't variables contained within the site that help us to design, it might be good to look beyond the walls surrounding it.
On the edges, just by being outside the "norm" (or a centralized look), it could be that a series of spontaneous situations can happen which in most cases are correct because they arise naturally, without pressure or stereotypes. Our designs should arise in the same way; avoiding preconceived ideas and fashions that restrict us to working within certain margins, because we can easily ignore the "key point" of the project.
Principle 12: CREATIVELY USE AND RESPOND TO CHANGE
"We can have a positive impact on inevitable change by carefully observing, and then intervening at the right time." - David Holmgren
Finally, Holmgren said that "the vision is not seeing things as they are but as they will be" and that "understanding change is much more than a linear projection."
Although it is a difficult task, as architects we must be able to imagine the future. The buildings we are raising today make up the context for other architects in the following decades and somehow, we are determining what will continue to be used or not.
Our responsibility is to anticipate appropriately what is to come and the best way to do this is by making sure that each of our projects helps us orient ourselves, as human beings, to the best possible future.
Perhaps if we follow these 12 principles we would be closer to leaving a good legacy. It's just common sense.