Acoustic Value of Hempcrete [Explained]
Thin walls w/ Loud Tenants and Construction Noise
Ever since we started working from home it has been harder to find peace and quiet to get some work done. While many office spaces are designed to keep out city noise, our home is not exactly designed the same way.
Made from the inner part of the hemp plant, hemp hurd is has excellent sound dampening properties. These sound dampening properties are most commonly utilized through hempcrete construction.
People that live in Hempcrete Homes have reported great acoustical properties from the building material.
What is a Hempcrete Wall?
A hempcrete wall is made up of hemp hurds, binder and water. Hempcrete is non structural and used only for the wall with the structural support of a standard wood frame.
To learn more about this method look into this article below.
What does Sound Absorption mean?
Sound absorption is the measure of the amount of energy removed from the sound wave as the wave passes through a given thickness of material.
We will cover two basic options when it comes to using hemp as a sound absorbing material: Hemp Lime Concrete or Hemp Panels
Hempcrete for Sound Absorption
What is it?
Hemp Lime Concrete, also known as Hempcrete is a unique building material, being a composite of a bio-fibre (hemp hurd or shiv) and a mineral binder (lime). These ingredients are blended together with water, and the moistened binder coats all the particles of hemp shiv.
How does it work?
While hempcrete is not structural, it does have many benefits, one of which is it’s extraordinary ability to provide acoustic comfort.
Acoustic Value:
The hempcrete walls in this study 300mm thick with a size of 1m²
“Unrendered hemp concretes exhibit significant acoustic absorption, with average sound absorption of 40–50% of the normal incident signal, across the tested range of frequencies.” — Acoustic absorption of hemp-lime construction
As per International Standard EN ISO 11654, this product falls into the range of Class C which is sufficient for most rooms, even classrooms.
Points to Note:
- The density level of the hempcrete can change it’s acoustic performance.
- Higher density hempcrete provide higher acoustic performance.
- Higher acoustic performance could mean less thermal insulation performance.
- The use of lime-pozzolan binders exhibit superior sound absorption.
- Non-toxic, mold resistant, humidity regulating, carbon capturing and environmentally friendly.
Hemp Panels for Sound Absorption
Acoustic panels have become quite popular in recent years and all the mainstream acoustic panels are made of polyurethane foam. These foams are good at providing acoustic comfort but they are made from fossil fuels, utilize toxic isocyanates, and are very flammable.
Let’s look at hemp acoustic panels as a possible alternative.
How does it work?
If you live in a home that is built with mainstream materials, chances are that you most likely does not have much acoustic comfort in your space therefore you are looking to add to the interior wall.
An acoustic panel that looks like a decorative picture frame can be quite ideal for such a purpose.
Acoustic Value:
Focusing specifically on this Hemp Soundproofing Panel (show in image above) from the 2022 Green Products Award Austria.
Thickness of this product is 45mm with a size of approximately 0.39 m².
As per International Standard EN ISO 11654, this product falls into the range of Class C which is sufficient for most rooms, even classrooms.
Points to Note:
- More expensive compared to regular polyurethane foam acoustic panels.
- Less availability in the market place.
- Can be made at home with basic tools, wood and hemp straw.
- Lightweight, long Lasting, non-toxic, mold resistant, humidity regulating, carbon capturing, environmentally friendly and biodegradable.
Conclusion
Both hempcrete and hemp acoustic panels fall into the Class C range as per International Standard EN ISO 11654. This means they are sufficient for most rooms.
Some of the most popular reasons for using hemp include the fact that it’s non toxic, breathable, moisture regulating, carbon capturing and environmentally friendly.
