THE RENAISSANCE OF NATURAL MATERIALS

Green buildings are now a "global trend" and saving energy is the first priority of people all over the planet. Customer demands, combined with environmental laws for healthier buildings will see this trend grow in the coming years. It is a fact, as far as the US is concerned, that construction companies targeting the buildings they construct to be green increased from 16% in 2016 to 32% in 2018. Analysts estimate that this percentage will exceed 45% by 2021. The greater demand for green buildings has led to investments in innovative, new, "green" materials to meet the needs of this rapidly growing building sector.

Editor: George Igglezakis & Dimitris Koudounakis Zeropixel Architects

WHAT IS PHYSICAL STRUCTURE?

Natural building means sustainable building in its greenest form.

Natural building uses minimally processed, non-toxic materials and systems used appropriate for the climate, site and intended use. It incorporates primarily natural materials rather than high embodied energy, processed commercial materials, with an emphasis on sourcing these natural materials as locally as possible - ideally, from the construction site itself.

NATURAL MATERIALS

Natural materials used in green buildings can be wood, straw, hemp, soil, lime and others.

Some of these are found in abundance, such as soil, and others come from recycling. Others can be reproduced as they come from renewable sources. Some of them like straw, hemp and similar materials, absorbed carbon dioxide as they grew and then when used as insulating materials, they store it. This significantly reduces the carbon footprint of a building.

Many of the methods of building with natural materials are accessible to unskilled workers. For example, building with straw, hemp and wood, are methods that can be learned quite easily and quickly.

WHY NATURAL MATERIALS?

Environmental sensitivity

Think about what will happen at the end of a building's life. Try to choose materials and techniques that will make it easy to reuse or recycle. Many common building materials will eventually end up in a landfill or incinerator because they cannot be reused or recycled. The construction industry is responsible for 40% of the waste we produce, 40% of the energy we consume and almost 20% of the clean water we use.

Health reasons

Another important factor is the creation of healthy buildings. It's not just about indoor air quality, it's about breathing a building. The use of materials that do not emit harmful particles, regulate the humidity of our internal environment and do not trap it are ideal for avoiding problems related to it.

BUILDING WITH SOIL

Soil is the central building material of natural construction. It has a very low carbon footprint because very little energy is required to extract, transport and process it. It's not an insulating material, but it's a great way to provide "thermal mass" that helps regulate the temperature of our spaces. This makes it a good alternative to cement blocks or bricks for interior walls.

There are different ways of using soil in building and most of them have a very long history. The main ones are:

• Plates

• Rammed Earth

• Light Clay

• Straw bales

• Cob

CONSTRUCTIONS THAT BREATHE

In general, the breathability of a material is its ability to regulate moisture - to absorb and release it. Most natural building materials breathe and we should make sure we don't seal them behind finishes that will trap moisture.

An example is the use of lime mortar. Unlike cement, lime breathes and is thus an ideal finish or binder for natural materials. Lime works well with soil because it is also a soft and porous material.

Soil and lime expand and contract at the same rate, so the lime finish will remain stable and cohesive. We can even remove, soak, mix and reuse old mortars or plasters. Lime coatings gradually harden by absorbing back the amount of carbon dioxide that was released to produce it.