Introduction to Appropriate Energy

Energy is a challenging concept to define. Attempts often start by listing specific energy sources: electricity, natural gas, propane, etc.  These sources of energy have the potential to do work: they move things, whether those things are people, electrons, water, heat, etc. Thus, energy is the ability to do work.

An (Extremely) Brief History of Humanity’s Relationship with Energy

The potential work that we are able to do with our human bodies comes from the embodied energy contained within them at any given time. That energy is converted from the embodied energy in the food that we eat, which was originally created through photosynthesis of the sun’s energy into plant matter. There are limits on the amount of energy (in the form of food) that we can consume and convert, and for most of history, the physical work that humans had the ability to do was simply based upon the amount of embodied energy remaining  after fulfilling essential metabolic processes.  Energy, in the context of animals and food, is often spoken of in calorie units.

At some point, humans learned how to release the sun’s energy stored in dried plant matter in the form of fire, warming themselves beyond what their bodies were capable of on their own. Sometime much later, humans learned to domesticate animals (also fed by the sun’s energy) and leverage their energy to do specific work, and developed tools to increase the efficiency of the work that they and the animals did – further increasing humans’ ability to do work beyond what their bodies were capable of. 

RIGHT: Casey enjoying the warmth provided by the release of the stored sunlight energy contained in wood – with the added yield of biochar from this 5 gallon TLUD pyrolizer!

This was the extent of humanity’s ability to do work until the advent of hydraulics (utilizing the potential energy in moving water, which ultimately occurs because of the hydrological cycle driven by the sun’s energy) first saw development as early as 6,000 B.C. in the form of irrigation canals, aqueducts, and water wheels. This was followed not long after by wind power (also fueled by – you guessed it – sunlight) in the form of sailboats and windmill-driven water pumps.

It turns out, nearly all of the stored energy available on earth originates with the sun, with the exceptions of geothermal energy and nuclear energy, both of which originated with the forming of the Earth. Humanity has survived and expanded on an annual solar budget for most of its existence, utilizing the stored energy of the sun in the forms of food, wood, water, and wind to get work done. This all changed with the discovery of fossil fuels and the enormous amounts of stored sun energy present in them – fossil fuels like coal, crude oil, and natural gas.  

It has been estimated that one barrel (45 gallons) of crude oil yields the same amount of energy as roughly 25,000 hours of an average human’s physical labor, or 12.5 years at 40 hours per week. Even if that number is not entirely accurate (as human energy is a tricky thing to accurately quantify for many reasons) , one thing that cannot be argued is that fossil fuels are an incredibly dense energy source.. These fuels, along with nuclear, have allowed humans to do levels of work that would have been unfathomable prior to their discovery, and are responsible for our culture’s rapid ascent into the modern industrial age, including the development of modern “renewable energy” technologies like solar photovoltaic systems.

In 2019, the U.S. consumed an estimated 100.166 quadrillion British Thermal Units (BTUs – the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit) of energy. Using the previously cited energy density estimates of a barrel of oil, this total U.S. consumption is an estimated 635 times the energy that the entire U.S. population could produce doing hard physical labor 40 hours per week every single week of the entire year.  This energy usage is broken down by economic sectors in the image below..

Source Data:

Our discoveries and advances in leveraging the energy of the sun and Earth to help us achieve more work than we could do with our own bodies is truly amazing. 

We also know that the methods and rate of our current energy consumption are unsustainable. We have been discharging the stored energy reserves of our planet far, FAR quicker than they can recharge, and the repercussions of that – on our economy and environment – are becoming very clear. The time is now for a new energy paradigm, one that will bring us back towards balance with the planet and living well within an annual solar budget.

Since our primary focus at 7th Generation Design is residences and the food-growing systems that support the people in those residences, the remainder of this article will focus on the residential slice of the energy pie. Specifically, how we can design energy systems that help us to accomplish the most important things needed for a high quality of life with a much smaller energy footprint.

How We Use Energy in Our Residences

Below is a breakout of the total energy consumption by end-use in U.S. residences in 1978 and 2015 according to the U.S. Energy Information Administration’s Residential Energy Consumption Surveys (2015 was the most recent one available).  For both time periods, space heating consumed the majority of our energy use, with the “Other” category (which mostly comprises appliances and electronic devices – including refrigerators and freezers) taking second. Space cooling is the end-use that we use the least energy to provide.

Source Data:

In comparing the total energy usage between the two years, total energy use in 2015 had dropped by 14% since 1978, which certainly is a hopeful trend – except, most of the appliances and end-use items that we had in our homes in 2015 (and now) are at least 50% more efficient than they were in 1978. 

Why has our energy usage not dropped by 50% or more? 

A lot of that increase can be attributed to increases in residence size (1,755 sq.ft. in 1978 to 2,687 sq.ft. in 2015, despite average household size dropping from 2.81 persons/home to 2.55 persons/home, respectively), as larger homes obviously need more heating and cooling, and the rest of it can be attributed to the increased quantity and use of electronic devices and gadgets.

The ‘Old Way’ Of Designing Energy Solutions

The ‘old’ approach to selecting energy solutions is to look at how it’s always been done at similar sites, and emulate that. 

  • Urban residence?
    • Gas-fired furnace for heating: check. 
    • 240V split system for cooling: check. 
    • 120V refrigerator: check. 
  • Rural house?
    • Solar system, batteries, inverter, and backup propane generator: check. 
  • New farm? 
    • Diesel tractor and side-by-side ATV: check! 

Commonplace solutions for getting specific tasks done in different contexts are commonplace usually because they work well. Looking at what other people are doing who are in similar situations to you is certainly agood place to begin – but we can’t stop there! Just because a specific solution is commonly used, doesn’t necessarily mean it is the most appropriate.

We have to think and design more deeply, especially if we want to maximize efficiency, redundancy and resilience.

How our modern built-environments are designed and constructed exerts enormous influence on how energy-intensive they are to inhabit and maintain. Cheap, mass-produced, cookie cutter appliances were the perfect complement to the cheap, mass-produced, cookie cutter homes prevalent in America in the 1900s – homes that were placed in whatever orientation was most convenient to maximize housing density in a neighborhood. There is a resurgence in interest now though for unique, well-built, energy-efficient, and climate-appropriate housing, ranging from well-insulated wood-framed homes to extremely well-insulated (and nearly fire-proof) strawbale and cob houses – all of which can be oriented and designed in ways to reduce energy needs.

Our energy sources are also changing. Cheap, mass-produced alternating current (AC) electricity (produced by coal-, nuclear-, and hydro-fueled power plants) that could not easily be stored was the primary form of electricity at the same time that the mass production of appliances and homes was happening, and thus everything was designed to integrate with one another on this “macro-grid”.  Gasoline was also cheap, and thus gasoline-fueled vehicles were produced en masse. Now, however, our electricity production is becoming decentralized, even hyper-local (on your roof, in the case of solar PV), and store-able (in batteries). In the case of solar PV, it is even being produced as direct current (DC) electricity, which should be ideal for our recently developed, primarily DC-powered computing and high-efficiency LED lighting – except for the fact that most homes (and the major appliances still used in them) are still designed for the AC-fueled macro-grid. This mismatch in design necessitates a conversion between electricity types (AC and DC) at a significant financial and environmental cost.

For these reasons and more, we need to begin taking a more whole-systems, process-driven approach to designing energy solutions for our residences and homesteads.

Designing Energy Solutions For Our Residences And Homesteads

How do we design for accomplishing the typical work needs at a site in an appropriate and efficient way? 

1. Identify Your Essential Energy Requirements

Square one is to ask and answer for ourselves  ‘What work do we ACTUALLY need to do?’

We’re not going to all go back to huddling around a fire dressed in buckskin with a speared animal roasting away over the coals (although that would definitely reduce our global energy footprint in a drastic way!). On a societal level, we are so unlikely to give up our modern comforts of indoor climate moderation, pressurized hot and cold water, automatic clothes washing, etc. that we can effectively say the chance of that happening is zero.

We can, however, make significant changes in our energy consumption by taking an introspective look at how we currently use (and abuse) our current abundance of energy.

  • Do we really need to have our homes between 68 and 74 degrees at all times? 
  • Do we really need to have every room in the house be as bright as a hospital?
  • Do we even need a house with so many rooms?? 

By methodically examining our current use patterns and comparing them with our true needs to live healthy, happy lives, we begin to weed out the unnecessary from the necessary energy expenditures.

Once we have narrowed down our energy needs to those essentials, it is time to begin designing the systems that will meet those needs. Three useful and complementary steps to designing energy systems are outlined by Toby Hemenway in his book The Permaculture City.

  • The first, on the end-use side of the energy design coin, is to identify what jobs the energy needs to do – what functions it needs to perform.
  • The second, on the production side of the energy design coin, is to examine energy as a sector – an influence coming from off the design site – similarly to how road noise and winds are defined as energy sectors.  There are three ways to interact with sectors: we can 1) harvest, collect, or store them, 2) deflect or block them, or 3) let them pass by unaltered. 
  • The third step is to appropriately match energy source to end-use with the fewest conversion steps.

Step #1: Identify The Necessary Functions that Energy Must Perform In Your Context

There are three jobs that energy typically performs: moving heat, moving things, and moving electrons.

  • Moving Heat – typically done in two ways: first, releasing and concentrating heat in furnaces, heaters, and stoves so that it can be delivered to living spaces, for household water, or for cooking food, and second, removing heat via cooling equipment such as air conditioners and refrigerators. This work can be done with a wide array of fuels and forces, including burning liquid and gas fuels, wood, or coal; by electricity; by expansion and compression of gas; via friction; by solar-driven temperature gradients to move air and water; and by sunlight itself interacting with various materials. 
  • Moving Things – typically includes spinning fans and motor parts, compressing gases in refrigerators, pumping water, and raising and lowering objects. This is most often achieved by making a shaft spin in a motor or pump, and then translating that rotational energy into linear force or a pressure change. Electricity is the most common power source for this, but fluids (liquid and gaseous) such as water, compressed air, or wind will also do the job. Internal combustion engines, steam, and other turbines are also commonly used to move things, as well as human and animal muscles.
  • Moving Electrons – electricity is the primary energy form here, and it’s doing tasks that are almost impossible to do in other ways, such as computing and communicating over long distances.

Armed with this, let’s take a more detailed look at the 2015 end-use energy breakout of a typical U.S. residence:

Source Data:

We can clearly see from the breakout that the majority of energy used in a residence (74.8%) is performing the work of moving heat (space heating, space cooling, and refrigeration). Some of that equipment also has moving things (the motor spinning the fan in the heater and AC unit, the motor running the compressor in the refrigerator). The “Other” category, which is significant at 25.3% of total energy use, includes cooking equipment, which also works to move heat.  The remaining energy use in the “Other” category is mostly comprised of lighting (now most often CFL or LED, both of which perform the work of moving electrons to create light), appliances like washing machines and clothes dryers which move things (clothes dryers also move heat), and electronics – which move electrons.

Step #2: Examine Energy As A Sector

Examining energy as a sector – an influence coming from or passing through the design site – provides the opportunity to identify the ways in which the energies already present on-site can be harvested and stored, deflected, or left to pass by in order to meet or support an energy function like heating.

Below is an energy sector analysis for one of our client properties in Central California. Here, solar energy is a particularly abundant energy resource for most of the year.  The property is also located near live near forests, so stored solar energy in the form of wood is also a fairly abundant resource. Wind (typically cold during the winter, spring, and summer, warm during the fall) also has a strong presence at this site. There is no year round running water source, nor any sources of fossil fuels in the forms of coal, natural gas or crude oil.

The sector analysis from our Whole-Site Design for Lonely Palm Ranch in central California.

How do we use this information? 

First, let’s look at a need like house heating.

Examining the available energy sectors at our site for those that provide heat, we can do our best to match energy source to function with the fewest conversion steps (discussed further in the next section). Looking at the energy sectors in the image above we see that the sun’s energy provides heat. The wood from the forests also can be converted to heat in a single step. Wind, on the other hand, provides convective cooling during the months that we would likely want heating, and thus should be deflected. So, it makes sense to harvest as much of the sun’s energy as possible and deflect as much of the cold winter winds first, and then supplement with wood-fired heat, before considering using imported energy like gas. During the summer, however, when we want cooling, we likely want to deflect the solar energy hitting the home, and harvest the wind for convective cooling.

This analysis leads us to pursue options for first passively heating and cooling the home through structure design and orientation and the placement of shade trees and wind screens, rather than simply installing the conventional gas-fired heater and electricity-powered split system.  Additional solutions could involve placing a thermal mass in an area in the home that is exposed to the sun during the wintertime, and can be further heated with wood, but is shielded from the sun during the summer, when it can act as a heat sink, transferring heat from the surrounding air into its mass.


Using the sector approach helps us to utilize the free (or nearly free) resources on hand at our sites, (and deflect or let pass by the undesirable ones) first to meet our needs before moving onto other imported sources.

Step #3: Match Energy Source To Function With The Fewest Conversion Steps

Now that we’ve identified the functions that we need energy to provide, and identified the energy sources that are already present or close to our site, the last piece in designing an appropriate energy solution is to match the energy source with the function. Ideally this is done directly (as in using a heat source to move heat – like a thermal chimney to move warm air out of a living space and draw cool air in) or, if conversion is necessary, to perform the conversion in the fewest steps possible.

Let’s look at an example.  A friend of ours who lives in a yurt in a forested area that gets particularly sunny and warm recently told us that she’s looking for a new solution for cooking her beans and grains (a nearly daily staple of her household).  She currently has a pot on her propane stove cooking long hours, which during the hot days makes her yurt even more hot and uncomfortable.  She was considering getting an electric induction cooktop or electric crockpot to minimize the discomfort. 

While this certainly would reduce the amount of heat transferred to the environment over a propane stove (though the pot itself is still radiating heat into the space, even without the open flame), these devices require very high-quality energy in the form of electricity.  To produce the electricity needed for a device like an induction cooktop or crockpot, she would need (in her off-grid location) an additional set of solar panels, battery charge controller, batteries, and a larger inverter (plus all of the fuses and breakers etc). This would take the sun’s radiation, convert it at the solar panel to DC electricity to then charge the batteries, and then invert it to AC to power the device, where it will be converted to heat.  That’s a lot of steps…

How can we match an energy source to a function here? Well, the yurt is typically hot on the days that she’s looking for an alternative, cooler cooking solution for one reason: the sun.  Clearly, we have a source of heat available.  And she is looking to move heat into a cooking surface to warm food to fairly high temperatures.  So, we need something that can utilize the heat from the sun to heat food to fairly high temperatures, ideally in one step…

This solar slow cooker utilizes readily available resource (the sun’s radiant energy) to cook food – with no cost, and no unwanted heating of the home during the warm season.

To take things a step further, she could utilize the abundance of energy-dense wood around her home to cook her food on the cooler days – with added benefits of clearing potential wildfire fuel from the ground surrounding her home, and tending the forest towards greater health.  Using wood for cooking certainly takes a little more time and planning, but many find that once they switch to wood and have acquired the skills, they enjoy the process and ritual so much more than just turning a knob to heat food.  And with recent developments in wood-burning cooking technology that allow for a much higher burn efficiency (greater heat extraction for the same amount of wood input), a cord of wood (or even sticks) can go much further.  A few examples of some of the recent upgrades in wood burning cooking technology are the Walker Stoves and the Rocket Oven.

The Walker Brick Cookstove, which provides a similar cooking experience to a typical indoor gas- or electric-fired cooktop and oven but runs off of wood!
A rocket oven fueled by small-diameter sticks that can bake bread, pizzas, pies, and anything else you’d bake in a typical oven ! Source:

Designing Towards A Future of Energy Abundance

To summarize, the steps to designing truly efficient, redundant, and resilient energy solutions are:

  1. Identify essential energy end-use requirements and categorize them by the functions performed.
  2. Look at energy like a sector to determine available energy resources.
  3. Match energy source with end-uses in the fewest conversion steps.

Utilizing the design approach outlined above, and implementing the resulting energy systems, can easily shift 75-100% of our home energy use from heavily-extractive and polluting fossil fuels and questionably-safe nuclear energy, to locally available sources, all while sacrificing little to none of our comforts. Not only will this reduce the money we are spending on energy, restore our environment towards better health, and increase the safety of our homes and properties, it will also ensure that future generations are able to enjoy a life of appropriate energy abundance.

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