Design Process
Building an eco-friendly and self-sufficient home
Building an eco-friendly and self-sufficient home should nowadays be a given before planning a house build; however, self-sufficient construction is still considered a costly and unattainable investment.
While building an eco-friendly and self-sufficient home is initially more expensive than building a conventional house, the reality is that the initial investment pays for itself within 5 to 10 years, as the savings achieved in a home disconnected from all utilities make the additional construction cost extremely quick to amortize.
The secret to building an eco-friendly and self-sufficient home
The secret to building an eco-friendly and self-sufficient home is to reduce consumption before generating energy.
This seems very obvious, but it’s the most difficult part. For example, if we want to reduce heating consumption, it’s not about being cold, but about heating the house through bioclimatic architectural design that captures solar light and stores heat indoors.
Once the house is warm, it’s very easy to generate the small amount of energy still needed to run the heating on the coldest days.
As we can see, the secret lies in making the most of the resources offered by our environment.
So, what resources do we have on our land?
Okay! This might seem more like a primary school lesson than an article for people who want to build their home, but sometimes simplifying things to their origin can help us clarify ideas and understand how a self-sufficient home relates to the land and climate.
Thus, in any location we find ourselves, we have:
1 Earth
2 Water (rainwater or, if we’re lucky, from an underground well)
3 Air or wind
4 Sun
We could also have trees from which to obtain firewood or biomass. But if we base this on a standard plot of 500 to 1000 m², we must consider that we won’t have enough 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 Utilizing the land itself
While the land is where an eco-friendly and self-sufficient home is built, the reality is that underground, our planet stores an enormous amount of energy in the form of heat.
In fact, just a couple of meters below the surface, the temperature remains stable at around 20 degrees Celsius.
This was well known by inhabitants of warm regions like Tunisia or Turkey, where traditional buried houses protected from heat in summer and cold in winter.
Well, how do we harness the earth’s subterranean energy today?
Geothermal energy
Geothermal energy is a renewable energy obtained by harnessing the earth’s internal heat.
This type of energy is obtained thanks to what is called the thermal gradient, that is, the temperature difference that exists between the earth’s interior and its surface. Every 100 meters, there is a difference of between 2 and 4 ºC, and at 15 meters deep, we already reach a stable temperature throughout the year.
The best strategy, however, will be to utilize low-temperature geothermal energy for heating, allowing us to bury the conduits at shallow depths to reduce costs.
Underfloor heating is surely the best type of heating we could install if we use geothermal energy. This is because geothermal energy allows us to heat or cool water to a more comfortable temperature than the outside.
Heating ventilation air
Just as we use the earth to heat water, we can also use it to heat air.
The system that allows this is Canadian wells (earth-to-air heat exchangers), which are pipes that circulate underground to temper the air that we must necessarily draw from outside to ventilate our home.
These wells, like geothermal systems, will be installed when it’s worthwhile. If deep foundations or retaining walls are needed, we can take advantage of the excavation to lay the pipes.
Growing your own food
Logically, the earth is where we can grow our own food.
It’s true that having your own home garden requires dedication for most of the year, but those who have done it highlight the incredible satisfaction of eating home-grown food.
With the amount of pesticides and chemicals found in the food we eat today, it is always advisable to buy organic, contaminant-free food, and growing your own food is a way to eat toxic-free.
Earth as a Building Material
Before finishing with earth, it’s important to note that earth has been and still is a building material. In fact, in our country, traditional houses have been built with stone and earth, and earth has excellent climatic performance.
Today, there are examples of modern earth construction, such as architect Martin Rauch’s house in Australia. It is a house built with adobe.
Another example of earth house construction is the house of actor Will Smith and his wife, Jada Pinkett Smith, a large mansion built with compacted earth walls.
Building an earth house requires thick walls and relatively few openings, and it’s also important to protect it from direct rainwater. On the other hand, it is a material with excellent thermal inertia that also acts as insulation.
2 Collecting rainwater or through a well
Water is also an element that the location offers us, and it will be important to consider it when building an eco-friendly and self-sufficient home.
Let’s look at the alternatives we have for obtaining water from the land itself.
Collecting rainwater
Our goal regarding water is, of course, to collect as much as we can.
The primary strategy for obtaining water is to collect rainwater.
Rainwater collection is done via the house roof, directing the water to a tank where it can then be treated.
We must ensure we have a large enough tank to accumulate water throughout the year, as we may encounter seasons with months of no rain.
A large tank doesn’t mean it has to take up space in our home or garden, as rainwater tanks for private homes are usually built deep underground in a part of the plot, with just enough width to allow access if needed.
Although less common, we can also collect subsurface water if available. This water is obtained through a well, which provides access to a natural underground water reservoir. It is very useful, especially when rainwater is insufficient to meet our needs.
How do we use the water we collect?
Okay! We obtain water naturally. But how do we use it?
When building an eco-friendly and self-sufficient home, we will plan for two distinct tanks. One will be for potable water for our own consumption or cooking, and the other for filtered but non-potable water for appliances or simply for irrigation.
Collecting water for drinking
While rainwater can be drunk directly without filtering, the reality is that from collection to consumption, days or even months can pass during which it remains stored in the tank. For this reason, it will be necessary to treat it to prevent bacteria or other organisms from populating it.
Water filtering for drinking will be especially important when collecting groundwater, as we don’t know the path that water has taken to reach our well. Nowadays, water can be highly contaminated if it has passed through agricultural areas where, for example, it may have been contaminated with slurry – pig excrement. In this case, it will be advisable to commission water quality studies to determine the extent to which pre-consumption filtering is necessary.
On the other hand, if drinking tap water from the municipal network, this is perhaps the most complex case, because even though it is treated, it may have accumulated contaminants from the pipes that transport it. Until a few years ago, asbestos pipes were permitted, and water, through friction as it passes, picks up asbestos fibers, which are carcinogenic.
Thus, depending on the origin of the water we drink, in addition to treatment to prevent spoilage during the time it remains stagnant, it is important to consider installing an osmosis filter (especially for tap water from the municipal network).
Osmosis systems, through semi-permeable membranes, remove these harmful components from the water. When building an eco-friendly and self-sufficient home, this would help us achieve cleaner, safer water free of contaminants such as asbestos, metals, or toxic residues and pesticides.
Collecting water for personal hygiene
We mention personal hygiene, but we could also say personal showering, as we must understand that if we want to be self-sufficient with rainwater, unless we live in a tropical area, we cannot take a daily bath since we would not have enough water to cover the entire year.
Thus, the rainwater we collect can be used for showering, for the washing machine, and for the dishwasher. In these cases, the water does not need to be potable, although it should pass through filters to remove any impurities.
Collecting water for garden irrigation
The garden is also something that can benefit from water, either directly or indirectly.
On the one hand, we can irrigate the garden with the rainwater we collect; in fact, rainwater for irrigation requires less treatment than water for consumption.
Furthermore, we can always reuse greywater from showers or sinks, and after a biological filtering process in the garden itself, which removes organic residues and soap, reuse it for irrigation. This is very suitable when there is little rainfall in our area.
Collecting water for toilets
A conventional toilet needs between 3 and 6 liters of water per flush.
If we calculate with our climate’s rainfall and the water we need each time we flush, we will see that the numbers don’t add up if we want to be self-sufficient.
In this case, we could consider a dry toilet. This is a toilet that does not use water but relies on gravity to direct waste to a tank for composting.
This way, we wouldn’t use water for the toilet and could rely solely on what we collect naturally.
3 Harnessing fresh air and wind
Air can also help us make our home eco-friendly and self-sufficient.
Fresh air renewal
The first and simplest way to harness it is through ventilation itself.
Aside from Spanish regulations requiring some air renewal system, ventilation is important for getting rid of CO2 and other pollutants and having fresh, clean air at home.
In fact, it is estimated that we need a complete air change for every 30 m2 per person per hour, and this is far from the ventilation habits in our homes.
In our office, we always work to achieve cross-ventilation in all projects, including windows on both facades or courtyards that allow for effective and rapid ventilation so as not to cool spaces in winter.
This, besides providing less stale air, helps us dissipate heat in summer.
Wind turbines
Of course, air can also be used to generate electricity through turbines or wind generators.
In recent years, increasingly smaller wind turbines have appeared on the market that can be installed in a home to generate electricity. These are structures installed like a chimney on the house roof and connected to the electrical system similarly to a solar panel.
An example of this type of system is the Graeme Attey Wind Turbine, a small-scale wind power turbine that aims to revolutionize domestic electrical self-sufficiency.
Generating water from air
It is also possible to obtain water from the air.
There are water generators capable of condensing air to obtain water, just as dew appears on a cold night.
At Eole Water, for example, they market equipment that operates exclusively with solar and wind energy, condensing water that is stored in a tank.
4 Harnessing the sun
Finally, to build an eco-friendly and self-sufficient home, it will also be very important to harness the sun, either directly or indirectly.
Light
Light is a source of life that the sun provides us directly, and we must make the most of it.
It is important for our home to maximize sunlight through courtyards and windows; all rooms should receive natural light during the day, and it will be important to orient the different rooms according to their use.
Energy generation
Additionally, the sun provides us with heat that allows us to reduce heating consumption. In this regard, in our climate, we must be careful that this sun, which warms us in summer, is not excessive and requires ventilation.
Reducing consumption in climate control systems will largely depend on how we design the architecture in relation to solar capture. Good orientation and a good proportion of openings relative to the facade will be key for our home.
Working on direct energy capture through windows, which is stored in building elements with thermal inertia and good insulation, will help us maintain the generated heat.
On the other hand, indirectly, we can obtain energy through photovoltaic panels.
Photovoltaic panels are those that allow us to obtain electrical energy thanks to the movement of photons activated by sunlight.
In this case, it will be necessary to store all the energy we obtain from the sun in electricity storage batteries to have it available during hours with less sun or at night.
On the other hand, there are also solar thermal panels that heat water; the hot water obtained can be used for heating or as domestic hot water, i.e., for bathrooms or the kitchen.