Some houses heat up by day and stay hot even at night. The HES system, which H0ME is bringing to Italy, delays heat by 18 hours with a 320 mm wall, according to the HES technical data sheet. Under reference conditions, the heat of 2 p.m. reaches the interior around 8 the next morning.
For the first H0ME house with HES technology, we've drafted five technology lines: what goes in, how it's installed, what performance is required. No amounts: finishes shape most of a house's price, so every project gets its own tailored quote after a site visit, and the first consultation is free.
Last time, in Hygroscopicity, Explained with a Glass of Water, we saw how the wall absorbs and releases moisture. Here it becomes spec lines.
The Physics on Site: 5 Lines
1. Hemp shiv. The woody core of the hemp stalk, chopped into granules. Particle size decides how well the wall insulates and how porous it stays; see hemp shiv particle size. The specification must state the required grade: "hemp shiv" alone isn't enough.
2. Lime as binder. It holds the shiv together without sealing it, keeping the pores open. Everything else follows, as in the hemp-lime mix.
3. Timber frame. The load-bearing wooden skeleton into which the hemp-lime mix is cast. The specification sets section sizes and spacing, and the frame fixes the final thickness. At 320 mm, you're back to the 18-hour delay.
4. Skilled installation. Here labor counts. The wall is tamped by hand, in layers, with a precise technique: poor workmanship wastes the performance, however good the materials.
5. Breathable finishes. The final plaster must let vapor through as freely as the rest of the wall; one that is too impermeable can reduce its exchange capacity. More in the wall that breathes.
Who Has Already Used It
The HES network has used this system in Europe for years: by 31 December 2014 it had built 27,653 m² (source: HES Group). According to HES documentation, at the "G. Rodari" school in Rossano Veneto (VI) in 2016, a comparison of two identical classrooms measured 27% lower CO₂ concentration in the air of the one built with the HES system (air quality, not climate). Also per HES documentation, at the Fortuny Museum in Venice a FLIR thermographic survey two years after installation showed no detachment or deterioration. These are HES network data, not H0ME projects: they show the system used and monitored in real buildings.
What It Means at Home
Besides the time delay, the HES data sheet gives a thermal conductivity of λ = 0.048 W/(m·K). HES data indicate up to energy class A4 with the 35 cm build-up in climate zone D, to be verified on each project. The material has a manufacturer's declaration of conformity (LVS EN ISO 17050-1) for non-load-bearing use.
Hemp captures CO₂ as it grows, and that plant-derived carbon stays in the walls as long as the house is in use. That's about 150 kg of CO₂ per m³ of biocomposite as contained carbon (estimate: 94 kg of dry hemp shiv per m³ × 1.6 kg CO₂ per kg), not a climate balance for the house. The figure depends on density and installation.
H0ME has been a General Contractor in Avellino since 2019 and, since 2019, holds the Italian license for patent US 10.266.451 B2 (PCT/CH2015/000085), on which the HES system is based. The first HES site signed by H0ME is in preparation: here we describe the draft specification that precedes it, not a finished building.
Want to talk about your project? The first consultation is free: request a site visit, and the quote is tailored to you.
FAQ
Does a specification with these 5 lines apply to any HES house?
These technology lines are the structural ones of the HES system. Quantities and sections are adapted to each project.
Why are there no prices?
Because finishes shape most of a house's price: every project gets its own tailored quote after a site visit, and the first consultation is free.
Is skilled installation a materials line or a labor line?
Labor. It is a separate line because the tamping technique weighs on final performance as much as the materials.
Want to talk about your project? The first consultation is free: request a site visit, and the quote is tailored to you. The system's full technical data sheet is at /tecnologia/. The previous installment is Hygroscopicity, Explained with a Glass of Water. The next one is in preparation.
Article produced with the support of artificial intelligence and reviewed by the H.0.ME. editorial team.