Why Is Hempcrete Perfect for India’s Climatic Diversity?

As the climate conditions continue to change around the world, experts are looking for sustainable solutions that can help us survive. And hempcrete offers a number of benefits towards this goal. Its eco-friendliness, low carbon footprint, thermal regulation, and moisture-absorbing properties tout it as an ecologically and financially sensible solution, especially in a climatically diverse country like India.

India’s hemp industry is growing at a steady pace. And Hempcrete is a popular, much-talked-about hemp product. In fact, many have lauded the Uttrakhand couple who built an “all-green” house using hempcrete.

But what exactly is it about this bio-aggregate concrete that can contribute to our fight against climate change?

 

What is Hempcrete?


Hempcrete is a bio-composite material obtained by mixing hemp hurds and lime used as a material for construction and insulation. Experts believe hempcrete to be a splendid building material owing to its many desirable thermal, structural, and moisture-handling properties.

It can be used to build, renovate, and/or restore all types of buildings—from houses and apartments to public sector buildings. What truly makes hempcrete versatile is the fact that it can be made by mixing lime and hemp hurds in proportions adapted to the work to be done.

 

Constructional Advantages of Hempcrete


Sustainability enthusiasts around the world have been using hempcrete for its many constructional advantages. 

  • Hempcrete is eco-friendly and energy-efficient. The hemp plant is typically grown for either fiber or seed. In either case, the hurd is considered to be a by-product. Large-scale hemp production can therefore generate tons of hurd for the construction and insulation markets.
  • It is quite a benign material given how, after it is placed in the walls (whether as a layer or as a wall itself) and completely dry, it does not release any toxins into the indoor environment.
  • Hempcrete’s unique ability to store energy and release it at a slow rate to stabilize temperature fluctuations makes it the ideal building material for all weather conditions.
  • Hemp is a carbon-negative crop. But what’s interesting about hemp hurds is that they store carbon in their cellulose structure and do not release it back into the atmosphere.
  • Hempcrete is a renewable building material. The hemp plant takes only 12-14 weeks to mature.
  • It has a high moisture-handling and resistance capability. This unique plant-fiber insulation material can absorb up to 3.6 gallons per square meter of water.

 

How Can India Benefit From These Constructional Advantages?


Hemp hurds are able to store considerable amounts of moisture because of their porous structure. This moisture gets absorbed into the large internal surface area of the plant fibers and moves to the cellular structure. This storage capacity allows Hempcrete to absorb moisture when it exists and release it when conditions allow.

On the other hand, the presence of lime, which is an inherently antimicrobial and antifungal compound, proves to be useful by creating a surface that resists mold in high temperature and humidity conditions. This resilience gives hempcrete an edge over other insulation materials, making it a desirable choice in both hot and cold climates as well as anywhere where humidity levels are high.

These properties prove to be highly beneficial for a country like India which experiences an average annual rainfall of 118cm, providing natural and long-term relief from fungus-related health problems that often originate from excessive moisture being absorbed into concrete walls. In addition to this, India is one of the most climatically diverse countries in the world, hosting six major climatic subtypes based on the Köppen Climate Classification.

This climatic diversity is often manifested in varying temperature conditions across the country—from arid deserts and alpine glaciers to wet and humid rainforests. But this variation makes India the perfect base to test the versatility of hempcrete.

Since hempcrete is openly lauded for its temperature-regulating properties—staying cool in the summers and warm in the winters. In the Indian climatic context, this property can be used to ease living conditions and combat global climate change.

Let’s talk about the latter first. In a tropical country like India, air conditioners are heavily used to beat the heat and humidity. But a hempcrete building will dehumidify and cool down quickly without the need for an AC to stay on.

A study done in France found that 1 cubic meter (35.3 ft3 of hempcrete can store up to 596 kilograms of water vapor, accounting for sufficient storage capacity for elevated relative humidity of 93% without overpowering the capacity of the material to absorb moisture.

India’s average humidity levels go as high as 70% in the north, 81% in the east, 79% in the south, and 76% in the west.

Hempcrete will use its hygroscopic nature to stabilize the relative humidity for long periods without the need for an air conditioner. To think of the energy this can save when adopted on a larger scale!

Hygroscopy refers to the phenomenon of attracting and holding water molecules through the process of absorption or adsorption from the surrounding environment.

Not to forget that the good carbon sequestration ability of hempcrete will give carbon-free structures.

Cost-efficient

Hempcrete also turns out to be highly cost-efficient for homeowners in the longer run.

  1. Hempcrete is lighter than cement and decreases the construction cost.
  2. Its thermal regulating properties significantly reduce the need for air conditioning, saving money and energy.
  3. Hempcrete is naturally resistant to mold and termites which contributes to low maintenance costs.

Healthier

Even if you’re not too keen on the sustainability issue, hempcrete can still be useful to you because it contributes to a healthy indoor living environment.

Because it is naturally resistant to fire, mold, and termites, builders don’t need to throw chemicals all over the materials. This decreases the density of toxins thereby reducing the risk of health problems in workers and residents.

An Example

Building homes with hempcrete is not as far-fetched as it may seem. As a matter of fact, the state of Himachal Pradesh proudly hosts the country’s first wattle and daub hemp hut

The building has been constructed using a wattle i.e. a wooden strip lattice with a combination of straw, animal dung, clay, sand, wet soil etc. The team innovated on this 6,000-year-old method by adding hemp to create what they proudly call the Hemp Slap Hut.

It has been almost a year since its construction and the hut stands tall after having weathered the monsoons and winters of the mountains. Those who have inhabited the hut at different times testify to its thermal-regulating properties, supporting the benefits of hempcrete for different weathers.

 

So, where’s the challenge?


Hempcrete seems to be perfect for India’s climatic diversity. And yet, we are far from adopting it. Why?

Different Construction Methodology

Modern hempcrete has been envisioned to be used as a thermal insulation material for temperate climates. For instance, in Europe, it is developed to be compatible with timber frame structures and is used as in-fill in timber-stud walls.

However, both weather and construction conditions in India are different. The weather throughout the country can vary from extreme hot to extreme cold with perhaps the certainty of extreme rainfall in between.

While in theory, hempcrete should adapt to the changing weather conditions, it is yet to be tested. Not to forget that timber structures are not a common practice in India. This calls for analytical work to formulate hempcrete that fits well with our construction methodology and fluctuating temperatures.

Invalidated and Unrecognized

Though hempcrete has been the focus of a number of studies in Europe, USA, and Canada, no scientific investigations prove its readiness for adoption by Indian consumers.

How hempcrete will behave when produced with locally available materials in India is still unknown.

Moreover, India is yet to define thorough standard practices relating to the manufacturing of different hemp products. While hemp seeds, oil, and powder have received guidelines from FSSAI, rules on fiber products are yet to be established.

This lack of standardization is bound to contribute to inconsistent material behaviour, making it difficult to generalize hempcrete’s behavior in domestic settings.

Calls for a Different Skill Set

Simple as it may seem to mix hemp hurds with lime, the production of hempcrete calls for an intricate skill-set. It requires lime and plant particles followed by air curing—materials and processes that local engineers and construction workers in India are not familiar with.

 

What can be done?


Establishing hempcrete as a reliable and widely-used construction material in India calls for the collective efforts of the authorities, construction crew, and homeowners.

Authorities should lead the way by first recognizing hempcrete as a construction material followed by framing standardizations that define formulation procedure and methods as well as the scope of use.

Official bodies, ideally formed by collaborations between the governments and construction companies, dedicated to educating and training construction crew, at all levels, about these new methodologies seems to be the logical second step.

Committees that go out and educate homeowners about the benefits of hempcrete will also be important for widespread adoption. At the same time, homeowners need to keep an open mind and ready inquisitiveness for building a house that is healthier—for them and for the planet.

The road is long but isn’t the journey, and the destination, worth it?

Apurva Sheel
Apurva Sheel
Apurva Sheel is a communications consultant with 3 years of experience in the Indian cannabis industry. Her thoughts and opinions find expression in writing.

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