A hemp-lime wall that dries unevenly cracks. Sometimes one inconsistent batch of hemp shiv does it: the lime sets at one speed in one stretch of wall and at another speed in the next, and the flaw is locked in. H0ME's life-cycle assessment puts the savings at 71.7 tonnes of CO₂ for a typical 150 m² home, transport included, against standard brick-and-concrete construction. That number depends on who grows and processes the hemp, and on how far it has to travel. Let the material drift from bag to bag, and the savings start shrinking before the crew finishes the first wall.
H0ME is the general contractor bringing the HES building system to Italy. Vetting hemp shiv suppliers is a technical step on the way to every first H0ME home built with this technology.
What hemp shiv has to clear before it reaches the site
HES's technical spec sets hard limits. The shiv has to show up dust-free and clear of excess loose fiber, because long fiber holds water differently than the woody core of the plant, and that throws off how fast the lime-hemp mix sets. One inconsistent batch, and the same wall dries at two speeds.
Then there's particle size, how coarse or fine the shiv is ground. Grind it too fine and it traps less air, and air is what insulates the wall. Grind it too coarse and the pour comes out with voids and weak spots. So a supplier gets qualified batch by batch, not once at the start of the relationship.
None of this is a preference H0ME invented. It comes from how the HES mix works: lime and hemp shiv bond only when the aggregate has the shape and cleanliness the spec calls for. H0ME has held the Italian license since 2019, and those parameters arrive already written, thresholds and all.
The check that happens before anyone signs off
Before a producer gets approved, H0ME asks for a sample from the batch and the technical data sheet for that specific delivery, not the generic catalogue version. The sample gets measured against the parameters of the HES mix. Fail, and the batch is rejected or sent back for reprocessing. And the check runs on every delivery, because no hemp harvest comes out the same as the one before it.
Distance counts too. The environmental case for a hemp-lime home rests on the materials and on the miles those materials covered to reach the site. A supplier who's excellent but far away eats into the CO₂ savings on transport alone. The delivery radius matters as much as the quality of the raw material.
What it means for the people who live there
The payoff shows up inside the house. Hemp shiv that's consistent and graded right lets the lime hydrate evenly across the whole wall, with no patches curing ahead of others. Even hydration is what makes a wall genuinely breathable: it regulates the moisture in the indoor air instead of trapping it or dumping it all at once. For the people living there, that means steadier comfort, less mold, and a dehumidifier that stays off more of the time.
Why this discipline pays off from day one
Checking every batch can feel like overkill when you trust your supplier. But on a build aiming for energy class A4 and the numbers on the HES spec sheet, λ of 0.048 W/(m·K) and 18 hours of thermal lag at 320 mm, trust comes after the testing. The HES system H0ME brought to Italy sits on top of a European network that has already measured these effects in the field, from the "G. Rodari" school in Rossano Veneto to the Fortuny Museum in Venice. An Italian general contractor's job is to carry that same discipline into every delivery.
FAQ
Is hemp shiv for natural building an agricultural byproduct, or an engineered material?
It's an engineered material: dust-free, stripped of excess loose fiber, ground to a precise particle size.
How much does the producer's location affect the home's environmental footprint?
A fair amount. The life-cycle assessment counts transport, so a closer supplier keeps more of the CO₂ savings.
How do you hold technical consistency from one delivery to the next?
Every batch comes with its own sample and data sheet, checked against the parameters of the mix before it's cleared for the pour.
The Technology page (/tecnologia/) walks through how these checks feed into the HES mix and how the system works as a whole. The previous piece in this series covered thermal bridging (/il-ponte-termico-dove-la-casa-perde-il-fiato/).
Article produced with the support of artificial intelligence and reviewed by the H.0.ME. editorial team.