On this page we keep apart three things that are often mixed up: the data declared by the developer of the building system, the tests carried out by independent laboratories, and the tests that we do not yet have on our own mix. We update it whenever a new result comes in.
1. What the system developer declares
We use the Hemp Eco Systems building system, as its Italian licensee. Hemp Eco Systems declares a thermal conductivity of 0.048 W/(m·K) in its technical data sheet, which describes itself as «indicative», and 0.056 W/(m·K) at about 240 kg/m³ in its 2016 brochure. These are manufacturer data, not our measurements.
2. What independent laboratories have measured
We hold two test reports on the system:
- Vilnius Gediminas Technical University (VGTU), report no. 1434 of 27/03/2014, accredited laboratory, sample at 319 kg/m³: 0.0633 W/(m·K) on the dry sample and 0.0981 W/(m·K) on the sample conditioned at 23 °C and 50% relative humidity.
- University of Bath (BRE Centre), 2013: between 0.058 and 0.064 W/(m·K) on oven-dried samples, between 0.068 and 0.087 W/(m·K) on samples conditioned at 60% relative humidity.
Density, moisture, composition and test method can all affect the result, and the Vilnius sample was denser than the 240 kg/m³ reference. These figures do not transfer to our own mix without checking that the test conditions are comparable, and we do not have a test at the reference density.
3. What we are missing
On our own mix, at our density and with our way of casting, we do not yet have accredited tests: conductivity in service conditions, vapour resistance, mechanical strength, reaction to fire. We intend to carry them out with laboratories and universities. Until then, the designer chooses and documents the value used in calculations according to technical standards and the available tests; we give them every document we have.
4. What we do not say
We do not say that our houses «absorb more CO₂ than they emit»: there is no verified life-cycle assessment yet. We do not speak of «certification» where there is a manufacturer's self-declaration. We do not present results obtained elsewhere by the system's network as our own: the Hemp Eco Systems network had already built more than 27,000 m² in Europe by 2014, but we did not build those buildings.
5. How we keep you updated
Every new test will be published here with laboratory, date, report number and conditions. If you are a designer and want the full documents, write to us and we will send them.