Summer means the air conditioning running non-stop and a bill that makes you wince. Winter means cold coming through the walls, however high the heating goes. Anyone drawn to a house that breathes eventually asks: what does it cost?

Here's the number: €1,800–2,200 per square metre, turnkey, for high-quality natural building — with hemp-lime toward the upper end of that range (source: ANAB industry estimates). That's the price of a house built properly, with natural materials and measured performance.

One clarification: that range is the build cost, full stop. Land, groundworks and foundations, planning charges and permits sit outside it. Anyone quoting an "all-in" price at that figure is selling something else. Our last piece broke the bill of quantities down line by line (read the full breakdown): that's what's inside the number.

Why a range? Two houses of the same size can cost very differently, depending on storeys, floor plan, finishes and systems. The figure helps you get your bearings; a real quote comes only after the design.

The physics of hemp-lime

Most people picture hemp-lime as plaster. It's a building system: a timber frame filled with hemp and lime, in substantial thicknesses. The HES system that H0ME brings to Italy has a thermal conductivity of λ = 0.048 W/(m·K) — a wall that insulates hard without being enormous. At 320mm, the thermal lag is 18 hours: the heat of an August afternoon arrives indoors in the dead of night, once it has cooled off. At 35cm thick, in climate zone D, that's energy class A4 (source: HES technical datasheet, tests by Vilnius Gediminas University and the University of Bath's BRE).

Then there's something that never shows up on a bill: the wall lets vapour through and keeps humidity in check. We covered that in the wall that breathes.

Skilled labour, natural materials, walls thicker than a conventional build all add to site costs. Which is why hemp-lime sits toward the top of the natural-building price scale.

What it changes for the people living there

An 18-hour thermal lag means less air conditioning in summer and less heating in winter. That's materials physics, backed by years of HES building and monitoring in Europe: by 31 December 2014, the HES network had completed 27,653 m² with this method across the continent (source: HES Group). At the "G. Rodari" school in Rossano Veneto, near Vicenza, a comparison of two identical classrooms measured 27% lower indoor CO₂ with this system (source: HES network) — the air children breathe in class, before you even reach the energy bill. At the Fortuny Museum in Venice, a FLIR thermal scan after two years found no delamination and no signs of deterioration (source: HES network).

That last figure touches your wallet too, but read it for what it is. Two years doesn't say how the wall will hold up in fifty. It says nothing came loose in the first two — a good early sign, and one less repair to budget for now.

These figures come from the HES network across Europe, not from projects H0ME has built itself. H0ME has operated as a General Contractor in Avellino since 2019 and holds the Italian licence for patent US 10,266,451 B2 (PCT/CH2015/000085); our first build is now in preparation.

Then there's the environmental ledger. According to H0ME's own life-cycle assessment, a typical 150 m² house built this way saves 71.7 tonnes of CO₂ against standard brick-and-concrete, transport included — on top of what you save on bills.

How these materials come together inside the wall: how HES-mix works and hemp shiv particle size and insulation.

DATA_BOX: €1,800–2,200/m², turnkey — the industry estimate for high-quality natural building in 2026, excluding land, groundworks and planning charges. Hemp-lime sits toward the upper end of that range (source: ANAB estimates).

FAQ

Does the per-square-metre price include the land?
No. The €1,800–2,200/m² range covers construction only, turnkey. Land, groundworks and foundations, charges and permits are separate.

Why does hemp-lime cost more than other natural building methods?
Thicker walls, natural materials and skilled labour add to the build cost — hence the upper end of the range.

Does this price apply to a house built with HES technology?
Yes — it's the same system. The cost reflects the conductivity and thermal lag described above.

See how the building system works on our Technology page. Next time, we continue the journey toward H0ME's first house.

Article produced with the support of artificial intelligence and reviewed by the H.0.ME. editorial team.