Sustainable houses, an energy saving of 75%

One of the problems we face when buying or building a house is its energy consumption. An old house, both due to the deterioration of the materials and the technology used for its construction, usually offers a worse energy performance, which means a higher expense.

However, since 1988, the year of the first publication of the current passivhaus standard, a whole series of techniques have been developed in relation to near-zero consumption houses or sustainable houses.

These techniques can help us to save a large percentage of our electricity bill, in the case of a renovation, or bring energy efficiency to a peak, in the case of new construction.

Sustainable houses are characterised by a very low energy demand. In fact, their objective is to consume the energy that they are capable of generating internally, for example, through renewable energies, water recovery, use of vegetation, etc.

In this post we will talk about energy self-sufficiency, its main characteristics, advantages and disadvantages of this type of energy self-sufficient housing. Let’s go there.

Sustainable houses, designed for saving


One of the concepts directly related to sustainable houses is bioclimatic architecture, that is, the design of buildings taking into account climatic conditions and the use of available resources.

For this type of construction, some factors must be taken into account such as: the path of the sun and the use of natural light, the orientation of the house and its rooms, the vegetation of the area and the wind conditions, etc.

This type of conditioning forms part of the passive management of a sustainable houses. But there is also active management, which is related to the use of mechanical elements and systems to help cover the energy demand of the house.

Let’s look at it in more detail:

Passive management

As we have said, passive management is the use of the natural resources of the place where a self-sufficient home will be installed. For example, a house built on the coast will not be the same type of house or use the same materials as one built inland.

Thermal insulation

As we know, there are certain areas of a house’s envelope where leaks occur. The most common are the doors and windows, so it is advisable to reinforce their insulation.

Another part is the facade, which must be sufficiently well insulated to make the house efficient, i.e. require less active energy.

Just as there are many building materials for cladding a façade, so too are insulation materials, which will help us to keep the temperature inside our self-sufficient home at a pleasant level.

Another option is the ventilated façade, which will create an air chamber on the façade of our home that will help to regulate the interior temperature.

Water harvesting

According to some estimates, of all the water consumed in a home, only 4% is intended for human consumption, i.e. for drinking. This is a very low percentage compared to the almost 40% use of the bathroom between the toilet and the shower.

This leads us to think of ways to reuse the water that reaches our homes but is not going to be used for our direct consumption. We talk, for example, about collecting and filtering rainwater or using a well.

In the case of rainwater collection, it usually runs down the drain of the house to an underground tank. To use it, it should be filtered

On the other hand, a well requires the legalization of the installation and the search for underground water. With the installation of a pump and a motor we will be able to supply water to our home that would otherwise remain unused.

Vegetation as an insulator

Within the passive management of a self-sufficient home we cannot overlook vegetation, which can help us both to protect the house from solar radiation and from wind exposure.

The type of plants that we use must first undergo a study of the soil, its exposure to atmospheric agents, the growth of possible plants, etc., before making a decision about their use.

Some examples of vegetation as natural thermal insulators would be vines, green roofs or vertical gardens.

sustainable houses, vertical garden

Active management

As active management of a self-sufficient home we understand one that makes use of different devices to cover the energy demand of our home, such as solar panels, heat pumps or biomass cookers.

Energy collection with solar panels

When we think of renewable energies for our homes, the first thing that comes to mind are the solar panels, which can help us produce electrical energy or heat a DHW tank.

Let’s take a closer look at the different types of solar panels available on the market:

  • Solar thermal panels: Solar thermal panels allow the use of solar energy to generate heat that is used to heat water (DHW), which is then diverted to heating by means of radiators, underfloor heating, etc.
  • Photovoltaic solar panels: These are responsible for transforming the energy from the sun into electricity. They are made up of photovoltaic cells that can be monocrystalline or polycrystalline, made of silicon, or non-silicon, such as organic, made of carbon.
  • Hybrid solar panels: this is the least known and least used type of panel. It combines thermal and photovoltaic panel technology to produce both hot water and electricity.
sustainable houses solar panels

Biomass boilers

This type of boiler uses, as an energy source, fuels such as pellets, which are produced from forest residues. They are usually installed next to an accumulator that will serve to provide the home with heating and DHW.

Biomass boilers generate waste that is deposited in an internal ashtray that must be emptied.

Whether this is clean energy or not is somewhat controversial, as burning it releases CO2.

Heat pump

The heat pump is another of the active systems for supplying heat and DHW to a home that have become more popular in recent years.

Depending on the system used, either air (aerothermal) or groundwater temperature (geothermal) is used, which is achieved by means of wells.

Heat pumps are responsible for transporting energy from one point to another, reaching the desired temperature with less effort than a traditional boiler, as they take advantage of the stability of, for example, the temperature of the groundwater.

Sustainable houses and rehabilitation


However, if instead of building a house it is a rehabilitation, achieving a self-sufficient home becomes a slightly more complicated task that will ultimately depend on the degree of intervention implemented.

For example, if only renewable energy sources such as solar panels or heat pumps were added to a conventional home, it would achieve annual energy savings of around 18%.

On the other hand, if a house were intervened to improve its insulation by modifying its floor, envelope, windows and doors, the savings would shoot up to 64% per year

Finally, if the two interventions are combined, i.e. a total reform, the average annual savings could be increased to 75%, by modifying the envelope and adding renewable energy sources.

As you have seen, the fact that a house has almost no consumption is a matter of a few key details and a lot of study.

Even if what you are looking for is simply to save on your electricity bill without disconnecting completely from the grid, you can apply only some of the techniques we have just learned.