Energy
Building an Off-Grid House
Every week we receive inquiries at the studio from people who want to build an off-grid house, and the idea that once we have built our house we will live without paying bills of any kind is very attractive, but it also comes at a cost.
Most clients find it difficult to accept that achieving zero consumption requires investing somewhat more during the construction process, and to do so we may need to sacrifice some square meters of living space.
So it’s not all good news, because although we have the knowledge and the means, building an off-grid house is more expensive, yes! and the payback is not immediate—it may take around 10 years to recover the investment.
Having clarified this point, let us examine what it entails and what the viability is of building an off-grid house.
If we opt for a sustainable lifestyle, the design, materials, systems, and construction of our home must constantly seek a balance in terms of energy consumption and use of natural resources.
A self-sufficient house is one that supplies itself, being capable of producing the energy it consumes, and the result of its consumption is zero.
Building an off-grid house should today be more integrated into our society, more considered especially in the steps prior to the actual construction of the dwelling; however, self-sufficient construction is still considered an expensive and unattainable investment.
It is true that a higher initial investment is required than in the case of conventional houses. But this investment is amortized in a relatively short period (around 10 years), since the savings achieved in a house disconnected from any supply are such that the construction cost premium is amortized extremely quickly.
We will divide the strategies into two groups. The first are passive strategies, that is, those that take advantage of natural resources (soil, topography, sun, temperature and humidity, winds, etc.) offered by the climate and location where they are situated. Secondly, active strategies, which use the installation of mechanical systems to help meet the energy and comfort demands of the dwelling.
These strategies are not universally applicable and must be adapted to each particular condition and site where we wish to build our zero-consumption house.
Passive Strategies for Building an Off-Grid House
Orientation and Siting
One of the most important strategies when building an off-grid house is orientation. It will determine the arrangement and composition of openings, the design of walls, and the distribution of interior spaces.
This orientation is decided in the design phase and must take into account the path of the sun during daylight hours as well as its inclination in each season of the year.
It is vital, to achieve zero consumption in the dwelling, that we maximize solar radiation, and this will be achieved if we orient and site our house properly. In temperate climates like ours, we must not forget that, although in winter the intention is to capture as much radiation as possible, in summer things change and this demand decreases, so we must protect ourselves from the sun.
To do this, strategies usually come directly from the design of openings, providing them with operable filters that we can adapt according to the season and time of day.
Another resource is vegetation. With a good selection of flora surrounding the dwelling—provided this is possible—we can use foliation cycles to protect and cool the house in summer without losing radiation in winter.
Finally, and also depending on the design of the dwelling, we can create transitional spaces between the exterior and interior of the house in the form of porches that can be opened or closed according to requirements, functioning as a greenhouse that captures sun and transfers it to the interior.
Daytime rooms can be located on facades that will receive light during sunlight hours. Service areas as well as bedrooms can be placed in the cooler part, away from radiation.
Regarding siting on the land, we must take advantage of the plot conditions to favor the dwelling’s conditions. For example, taking advantage of sloped terrain to settle the building into the land itself. With this, part of the dwelling is semi-buried and therefore better insulated.
The first step we must take is to select those walls that will serve as heat collectors and those that will simply insulate us from the exterior.
On the other hand, considering the thickness of enclosures as well as the insulation we will use can contribute to not wasting the captured energy, using thermal mass systems and avoiding losses to the exterior with good insulation.
Building with local materials is always more coherent and sustainable. If building in wood, we can opt to contact local sawmills that build with smaller sections, solid wood, and light frame structures. If using brick, there are good local ecological alternatives.
As for prefabricated panels, we must avoid non-ecological ones, that is, those that use plastic materials, chemical agents difficult to recycle, and sometimes even harmful to health.
Water Utilization
Regarding water supply, this can be obtained with two systems depending on whether or not we have water on our land.
(a) Rainwater collection with subsequent filtration (ultraviolet light system).
Whether we have groundwater or not, harvesting and storing rainwater is always a good option.
The system is simple and its installation not complicated. Water is collected through the roof of our house and carried through downspouts to a tank usually located underground. This location is due both to its large dimensions (it can have a capacity of around 10,000 liters) and to maintain stable water temperature.
It is necessary to bear in mind that although the theory of water collection is very simple, the amount of water to be collected must be assessed according to the rainfall of our location, and in any case it will be necessary to make rational use of water. In our latitude it usually rains large amounts on few days, and for this reason tanks must be larger than in rainier climates.
In any case, it will be irrelevant whether the design of our roof is pitched or flat, but in each case we must ensure that water collection begins once the dust and recent dirt from the roof and downspouts has been cleaned.
(b) Private underground wells.
We will only excavate an underground well if we know of the existence of water in the subsoil of our land.
To determine its presence or absence, we must contact an expert or water diviner, whose profession is based on detecting underground currents and water wells using metal or wooden rods or pendulums.
The construction process of the well begins with excavation to the water table (where the water is located) and subsequently an extraction pump and the relevant piping are installed.
We must not forget the possibility that our well may dry up or run out of water if consumption is high or if, for any reason, water stops reaching it.
Water Use and Consumption
Once we have built the water collection mechanisms, we must establish the guidelines and systems for its consumption.
Building an off-grid house implies obtaining water naturally. We completely cut off external supply, but to do so we must become aware and commit to not abusing its consumption. If we do not, we run the risk of running out of water. It is extremely important to reduce and optimize water consumption in the dwelling to the maximum.
As an aid, we have water reuse systems, with which we can use, for example, water that passes through the sink or shower in the toilet after a simple filtration process. However, we can avoid this last consumption in the toilet by installing a dry toilet, which does not require water for its operation and whose waste is transformed into compost that is poured into the garden soil.
Water for personal consumption (drinking water) comes from that water stored in the tank of our house. Prior filtration is necessary since the slightest dust or organic residue can generate the growth of microorganisms.
Water filtration from collection to final consumption passes through different filters:
– an initial filter that separates larger particles by gravity.
– a second biological treatment that decomposes dirt particles.
– sterilization using an ultraviolet filter that eliminates microorganisms and bacteria.
Natural Ventilation and Hot Air Supply
Although in our self-sufficient house we must insulate ourselves as much as possible from the exterior, it is important to ventilate and provide some fresh air to the interior.
The incorporation in the dwelling design of interior courtyards and openings on opposite facades are very useful strategies when ventilating and regenerating stale air in rooms. In addition to offering light and visual connection with the outdoor environment.
If this were insufficient, there are mechanical systems that ensure air regeneration without losing the comfort conditions of interior spaces.
What is done is to conduct interior air through a mechanism that recovers the heat and transfers it to the new incoming air. The same system incorporates filters that will guarantee that the supplied air will be of good quality, something very useful in polluted environments.
The supply of hot air to the dwelling can serve both to ventilate and to heat the rooms. A single system can meet two needs.
Semi-exterior spaces can, in winter, be covered with glass that, through the greenhouse effect, will heat the air in the room. This pre-heated air can be conducted to the interior of the dwelling, contributing to the climate comfort of the rooms.
Energy Supply by Photovoltaic Panels
Today, the use of photovoltaic panels is the most widely used system for generating electricity and also the most suitable for building a self-sufficient house.
Photovoltaic panels should not be confused with solar panels! The latter do not generate electricity but hot water.
Photovoltaic panels generate electric current from the solar rays they capture, as their operation is based on the conversion of solar radiation into electrical energy.
Their efficiency will be conditioned by the number of panels installed, their position, and their orientation. Although these elements are controllable, the performance of these panels is still low and we do not yet have a sufficiently good energy storage system.
There are several companies that promise to manufacture low-cost, high-performance domestic batteries such as Tesla, Nissan, and Solar Rocket, but for now the technology remains in its early stages.
In 2015, the Spanish Government approved the “Sun Tax,” which establishes that those dwellings with photovoltaic panels connected to the grid must pay a tax of 9 euros per year per kW of power generated plus a variable amount based on the energy fed into or consumed from the electrical grid, to which we must be connected if we do not have an energy storage system using batteries to cover demand during hours when we do not have sun, that is, during the night.
In any case, in Europe, directives are going in the opposite direction and we hope that this Spanish regulation will be modified as soon as possible.
For more information on this topic, you can consult other articles on our Blog that address the subject in depth, or contact us personally.
Hot Water Supply Using Thermal Panels
For the production of hot water, whether for consumption or for supplying heating systems (radiators, radiant floors, etc.), we can use solar panels.
There are 3 types on the market: photovoltaic solar panels, thermal photovoltaic panels, and thermodynamic solar panels.
The latter are currently the most used both for their greater efficiency and for their smaller size and roof footprint. They are somewhat more expensive but the investment is offset by their efficiency. They do not depend directly on the sun to capture energy but are capable of generating energy through indirect light, so they are able to generate energy even on rainy or cloudy days.
Through passive and active design strategies, we can build a house disconnected from the electricity and water grid; as we have seen, this is possible today if we are able to adapt our lifestyle to the available resources from the sun, water, breeze, or the earth itself, adjusting our needs to their natural availability.
Building an off-grid house may stem from an economic or ecological argument, but in any case it represents a contribution to life on a more conscious planet that respects available resources. An off-grid house is a future value, which requires an additional investment but is amortized quickly and acquires greater value in the market.