Design of a Self-Sufficient Home

Although sustainable awareness is increasingly present in our society, it has not yet fully taken hold in the world of architecture.

Our team follows many modern architecture magazines via social media and blogs, and the truth is that although architects are evolving and innovating in their designs, there is still no trace of efficiency or health considerations.

Natural and ecological materials? Zero consumption? Passive houses? Self-sufficient off-grid homes?

No trace in any of the main modern architecture media outlets.

Even so, at Slow Studio we are extremely optimistic because although the sector does not promote it, the reality is that we continue to receive calls and emails from clients seeking more than modern architecture—committed clients who prefer to reduce some square meters of their home if it means achieving the design of a self-sufficient off-grid home, clients who request eco-friendly materials and passive houses and who tell us how difficult it has been to find a conscious team that strives for homes that truly work.

We are committed to this: to the design of passive houses that use bioclimatic architecture resources, ultimately committed to the design of a self-sufficient home for each new client, and this is what we want to discuss today.

In today’s article, we thoroughly address the design of a self-sufficient home and what this type of dwelling entails.

Let us begin by clarifying the main question: Is the design of a self-sufficient home more expensive?

The answer is: it depends.

It depends on how demanding you are, because a self-sufficient home can be designed with conventional materials such as polystyrene insulation (a petroleum derivative) and achieve self-sufficiency at a relatively low cost. However, if we go a step further and require the design of a self-sufficient home to use natural, ecological, and breathable materials, then the cost per m² is relatively higher.

In our studio, we have all types of cases, and the reality is that although we are idealistic and committed environmentalists, there are clients with limited budgets who must forgo 100% eco-friendly solutions, but with whom we always strive to achieve near-zero consumption.

Once this is understood, we will develop different points to consider in this post to achieve the design of a self-sufficient home.

First, we must examine the different strategies we can employ to reduce our own consumption. The less we consume, the less energy we need to supply.

Next, how to use the natural resources available to us—from the earth, water, or sun—in favor of our project.
There are many options available, but it is always advisable to consult these possibilities to select those that will work best in each particular case.

Reducing Consumption

While it may seem obvious that the key to building a self-sufficient home is reducing one’s own consumption before generating energy, this is actually the most difficult part.

The trick lies in changing one’s mindset. Instead of thinking about being cold or bundling up more inside the house to reduce heating costs, we can consider heating interior spaces through passive bioclimatic architecture systems, such as capturing solar radiation, storing it in building materials, and insulating the house to prevent heat loss.

Once the house is warm, it is easier and more economical to generate the small amount of energy needed to run the heating on the coldest days.
Conversely, in summer, it will be necessary to protect ourselves from the sun to avoid heat gain, and the small amount of heat that enters the interior must be dissipated through cross-ventilation during the cooler hours at night.

The secret lies in knowing how to maximize the resources offered by our surrounding environment to reduce consumption and therefore require less energy input.

New mindset: Less consumption = less energy production = more self-sufficient home.

Utilization of Natural Resources

Well, once consumption has been reduced, we can now consider how to utilize the natural resources available to us to ensure maximum comfort without the need for external supplies.

The first question we must ask ourselves is What resources are available on our land?

These could be expanded to include vegetation or organic waste, from which we could obtain firewood or biomass, but establishing as a baseline a standard plot of between 500 and 1,000 m², we must consider that we will not have sufficient wood in the long term to be self-sufficient.

So, how do we utilize these resources to build an ecological and self-sufficient home?

1. Earth as a Resource

The earth, in addition to serving as a foundation for our home, stores and offers us a large amount of thermal energy that we can utilize to achieve comfort with a good design of a self-sufficient home.

It is known that by descending just a couple of meters below the surface, the temperature remains stable at around 20 degrees.

Historically, this was already utilized by ancient tribes in warm regions such as Tunisia or Turkey, where underground houses were traditionally built to protect against heat in summer and cold in winter.

But today and in our climate, we can ask ourselves: how can we utilize this earth energy today? What are the most suitable systems?

Geothermal Energy for Heating Water

First, we have the option of geothermal energy. This is a renewable energy obtained by harnessing the internal heat of the earth.

To obtain this type of energy, we use what is called the thermal gradient—that is, the temperature difference that exists between the interior of the earth and its surface.

To harness the greatest possible energy, we should opt for low-temperature energy for heating, burying conduits at shallow depth to minimize installation costs.

In practice, geothermal energy for a dwelling is amortized over a very long term and is not usually the most cost-effective system; however, there are other systems that harness the earth’s heat that are cost-effective. Let us examine them.

Systems for Heating Ventilation Air

Another alternative for utilizing the earth as an energy source would be to use its temperature to heat ambient air.

The best system for this is earth tubes (Canadian wells)—pipes that run underground to temper the air that we subsequently supply to the interior rooms of our home.

To reduce installation costs, we can consider utilizing the foundation phases to excavate trenches for the pipes. That is, if we have a deep foundation or retaining walls, we can take advantage of the excavation to run the pipes.

Earth as a Building Material or System

Earth can also be utilized as a building material.

Historically, it was already used in traditional construction in the form of adobe or in plasters for stone walls—a technique that offered good watertightness, thermal mass, and therefore excellent thermal performance.

Although it is a minority system today, there are still many examples of earth construction, such as architect Martin Rauch’s adobe house or actor Will Smith and his wife Jaden Smith’s house—a large mansion built with rammed earth walls.

For them to function properly, the design of a self-sufficient earth home must have walls of considerable thickness and relatively few openings. It is also important to protect it from the direct action of rainwater.

Earth for Cultivation

Finally, an aspect that is often overlooked is that the earth is the perfect place to grow one’s own food.

Having one’s own vegetable garden at home requires having space for it and considerable attention and dedication during most of the year, but the physical and nutritional benefits of eating self-grown food compensate for this personal investment.

Today, the foods we purchase in supermarkets, if they are not organic, contain large amounts of pesticides and chemicals. It is always advisable to buy organic foods without contaminants that reach our bodies, and growing one’s own food is a way to ensure that we eat without the risk of ingesting toxins of any kind.

2. Water Utilization Systems

In the design of a self-sufficient home, it is vital to consider the water that the site offers, and it will be important to think about it when building our home.

What alternatives and systems are available to maximize this natural resource?

Water Collection Systems

Collecting and storing as much rainwater as possible should be an objective not only for those concerned with the design of a self-sufficient home, but also for the rest of society.

In a home, rainwater collection is carried out through the roof, directing it toward a tank where we can then treat it.
The tank size must have adequate capacity to store water throughout the year, since we may encounter dry seasons and water scarcity.

The advantage of these tanks is that, even if they are large, they are usually buried in a part of the land with just enough width for us to descend if necessary. In the design of a self-sufficient home, it is advisable to plan for the installation of two separate tanks: one for potable water—for personal consumption—and another for recycled water that we can filter for appliances or irrigation.

Although less common, we can also collect water from the subsoil if it is available. The method for obtaining this water is through a well, which provides access to a natural underground water reservoir. This is very useful especially when rainwater is insufficient to meet our needs.

Water for Human Consumption:

Once we have collected rainwater, it may remain stored for a long time before we consume it. Therefore, it is important to treat it to prevent the formation of bacteria or other organisms.

In the case of water obtained from the subsoil, it must be treated and filtered before being stored, since we do not know its origin, and today water can be highly contaminated if it has passed through agricultural or industrial areas. In these cases, it is recommended to commission quality studies to determine the extent to which filtration is necessary before consumption.

If the water ultimately comes from the municipal network, we recommend installing reverse osmosis filters because, although it comes treated, it may have accumulated contaminants from the pipes that transport it.

A reverse osmosis filter is a filter that, through semipermeable membranes, manages to eliminate those components and macroparticles harmful to human health from the water.

In the design of a self-sufficient home, the installation of these filters would allow us to obtain cleaner and safer water, free from contaminants such as asbestos, metals, toxic residues, or pesticides.

Water for Personal Hygiene:

We can also use rainwater for showering, for the washing machine, and for the dishwasher, always in a rational manner. In these three cases, the water does not need to be potable, although it must have passed through filters that eliminate impurities and toxic particles.

Irrigation Water:

We have previously mentioned the possibility of utilizing the land to create one’s own vegetable garden. Well, logically, these lands must be irrigated and cared for.

3. Air

Air in the design of a self-sufficient home is normally used to renew the interior oxygen of the dwelling, refresh the environment, and sometimes generate energy.

Natural Ventilation of Interior Rooms – Cross-Ventilation

Ventilation of interior spaces helps us renew rooms with fresh air.

Today, Spanish regulations themselves require some air renewal system, since through ventilation we can eliminate CO₂ and other contaminants and have fresh, clean air at home.

Studies recommend a minimum of one complete air renewal per 30 m² per person per hour, an aspect that is still far from the ventilation habits of our homes.

Slow Studio, our firm, always works to achieve cross-ventilation in all the projects we undertake. By simply placing windows on opposite facades of rooms or using courtyards to generate air currents, effective and rapid ventilation is enabled, so as not to excessively cool spaces in winter.

Wind Turbines – Obtaining Wind Energy

As we have mentioned, air can also serve to generate electricity through turbines or wind generators.

Recently, increasingly smaller mills have come onto the market that can be installed in a dwelling to generate electricity. These are wind turbines—structures installed like chimneys on the roof of the house and connected to the installation in a manner similar to a solar panel.

These turbines harness the force and power of the wind to generate and subsequently store in suitable batteries all the energy produced.

4. How to Harness Solar Radiation

Finally, it will also be very important in the design of a self-sufficient home to harness the sun, either directly or indirectly.

Light – Natural Lighting

Logically, our home should maximize sunlight through courtyard and window systems. It is recommended that all rooms receive natural light during the day, and it will be important to orient the different rooms according to their use.

Direct Heat

In addition to light, the sun provides us with heat. If we know how to harness it well, it will allow us to reduce heating consumption, although especially in temperate climates, we must be careful because in summer it can be excessive, so we will need to compensate for this overheating with ventilation systems.

In this section, the design of a self-sufficient home will aim to capture as much solar radiation as possible. Good orientation and a good proportion of openings relative to the facade will be key for our dwelling.

Through south-facing windows, we can capture much energy and subsequently store it in building elements that have high thermal mass and good insulation.

Another alternative would be to use systems such as photovoltaic panels to capture energy indirectly.

These panels are those that allow us to obtain electrical energy thanks to the movement of photons that are activated by sunlight. The electricity is stored in batteries that will allow us to use it later with complete peace of mind, whether on a sunny or cloudy day or even at night.

Finally, we also have solar thermal panels or thermodynamic plates available on the market, whose main function is to heat water both for heating and for daily use in bathrooms and kitchens.