Building a bioclimatic home

The 5 basic principles for building a bioclimatic home

Pre-existing Conditions and Solar Orientation

The first factor to consider when building a bioclimatic home is its surroundings and orientation. If we analyse the existing conditions, we will find many clues as to how the home should be designed to best adapt to the site.

In this regard, it is important to pay attention to the slope of the plot, as we can use it to increase thermal mass by partially burying part of the home, and to the presence of vegetation, which will help us create shaded, cool spaces in summer.

As for orientation, a bioclimatic home is characterised by making the most of solar energy—capturing and storing it to heat the rooms—and protecting itself from it in summer through deciduous vegetation or south-facing overhangs.

Energy capture and storage

Bioclimatic homes stand out because their design incorporates energy-efficiency criteria and passive climate control. This makes it possible to keep the home at optimal temperature and humidity conditions while minimising energy consumption.

Given that energy can be light, heat, or electricity, we should first distinguish between passive and active capture strategies, understanding passive capture as that which is part of the home’s design itself and does not generate additional maintenance costs.

Passive capture would be, for example, large south-facing windows that collect the sun’s heat. Active capture would be, for example, through solar panels or underground geothermal energy.

Once we capture solar energy, we need to find a way to store it. Here again there are active storage methods, such as a battery, and passive ones, such as underfloor heating that, once switched off, remains warm for hours.

Each site, each family, and each budget require a different type of strategy, which is why at Slow Studio we always say that an eco-friendly home should be custom-designed.

Thermal insulation

Thermal insulation is also a key factor in building a bioclimatic home and is, again, closely linked to the concept of thermal mass. If we have a wall with significant thickness, we will have the capacity to store energy in the form of heat, whereas a wall with high insulation will prevent interior heat from escaping but will not allow us to store energy within it.

So, once again, we must adapt our bioclimatic strategy to our needs and decide whether the home will achieve energy efficiency through high insulation or through wall thickness.

For example, at the studio we are designing a home that the clients will use only on weekends. In this case, we will work with very well-insulated walls, so deciding what type and thickness of insulation we need is the key point.

In the case of building a timber home, since wood is a more porous and insulating material, we will seek indoor comfort by preventing outside heat and cold from entering the home. We will do this through good insulation which, together with wood’s insulating properties, will help us design a well-protected home.

In this case, we must be very careful with thermal bridges, ensuring continuity of thermal insulation throughout the entire building envelope at all times.

If, on the other hand, we choose to work with thermal mass, it will be more interesting to select materials with greater mass and water content, such as brick or earth, using a strategy that is the reverse of the previous one.

In this case, we will capture external solar energy, store it, and use it to our advantage to passively condition the home.

Ventilation

Natural ventilation in a home is a very simple bioclimatic architecture principle to apply, and it will ensure good indoor humidity conditions.

To achieve it, it is necessary to plan openings on different sides of the home and introduce elements such as interior courtyards that help us increase the ventilated surface area, especially when the plot is between party walls or has limited exposure to the outside.

Water

Finally, there are water capture systems and reuse options that allow us to reduce consumption and use this precious resource in a coherent and conscious way.

On the one hand, there are capture systems. Water can be captured directly from rainwater, which we can collect and reuse for irrigating landscaped areas or for the home’s domestic water, with prior filtration; or through well water, if we are fortunate enough to have it on our land. In both cases, it is necessary to bear in mind that, depending on its source, water accumulates more or fewer minerals and toxins. Thus, rainwater is similar in composition to distilled water from an iron, and well water is not always suitable because, along its path, it may have collected contaminants that are difficult to filter.

As for recycling and reuse systems, the flagship solution is greywater recovery: greywater from the washing machine, dishwasher, bath, or shower can be reused for toilet flushing.

Lastly, there are essential systems to reduce consumption. In this case, one solution is to install a dry toilet, the type of toilet that was used for centuries before running water reached our homes.

As its name suggests, a dry toilet does not need water to work; instead, it accumulates waste for months until it turns into compost for the soil. It is a highly recommended option and, contrary to what is often thought, it does not generate odours and requires minimal maintenance—around once or twice a year.

Dry toilets can be installed inside the home or outside so that they are connected directly to the ground. The important thing is to have good mechanical or natural ventilation and keep humidity to a minimum.