Build · 2015-2019 · Lasson, Normandy
A passive, energy-positive house,
end to end.
The short answer: yes, a motivated individual can lead a passive build from A to Z. We found the land, I taught myself Revit to design the house, assembled the building-permit file myself (no architect, below the legal threshold), coordinated some twenty trade lots, and the regulatory energy study concluded: primary energy consumption of −12 kWh/m²/year. The minus sign is not a typo: the house produces more than it consumes.
This page tells the four years between a property listing and a completion-of-works declaration, with the real figures from the file.
Measured airtightness (Q4), against 0.6 required: twelve times better.
kWh/m²/year of primary energy consumption. Yes, negative.
m² of heated living space, drawn in Revit, learned for the occasion.
kVA of electrical supply. Studio-apartment sized.
The land · Lasson, near Caen
1,792 m² facing south
Listing spotted in April, offer in early May, sale agreement signed on 29 May. A 1,792 m² plot in a Normandy hamlet, a few kilometres from Caen, with the one thing you cannot negotiate: full south orientation. The geotechnical soil study was ordered right away, before drawing anything.
The design · Revit, learned for the occasion
The architect's project dropped, mine approved
A first project, drawn by a professional, did not feel like us: we dropped it in April 2016. Meanwhile I had learned Revit in the evenings, tutorials and keyboard-shortcut sheets in hand, and modelled the entire house in BIM. The new permit file, generated from my model, was filed on 11 April and granted by the town hall on 25 May: six weeks, without an architect, the project sitting under the legal threshold of the time (170 m²; it is 150 m² today in France).
The build · Direct project ownership
Twenty trade lots, no turnkey builder
Works officially opened on 12 September 2016. No turnkey construction contract: every lot was tendered, chosen and coordinated directly, from earthworks to painting, with a local carpenter for the timber frame. Cellulose-insulated timber walls (295 mm in total), 440 mm blown into the roof, triple glazing, heat-recovery ventilation, solar hot water, a grey-water heat recovery unit, and home-brewed KNX home automation.
The proof · Final airtightness test
Q4 = 0.05: the blower door finds nothing
On 22 March 2018, the final infiltrometry test measured an air permeability Q4 of 0.05 m³/(h·m²), where the regulation demands at most 0.6. Twelve times better than required: passive-construction territory. It is the figure I am proudest of, because it cannot be claimed, only measured.
The delivery · And the verdict
Works complete, positive balance
Move-in during 2018, completion-of-works declaration in early 2019. The final regulatory energy study concluded with a BBIO of 18.3 (62.2 allowed) and a primary energy consumption of −12 kWh/m²/year, with 34 roof-integrated photovoltaic panels. The document states it verbatim: "the house is energy-positive".
Real life · The one-year balance
The surplus goes to the grid
After one year with five people in the house: photovoltaic surplus sold back to the grid, a 6 kVA electrical subscription, and a wood stove for pleasure more than need. And yes, there is plenty of sunshine in Normandy.
The technical sheet, for the curious
| Item | Choice | Figure |
|---|---|---|
| Structure | Timber frame, painted cladding, slate roof | 166.4 m² heated living space |
| Insulation | Cellulose (walls and blown roof) | 295 mm walls · 440 mm roof |
| Windows | Triple glazing | Ug 0.6 W/m²K |
| Airtightness | Final infiltrometry test | Q4 = 0.05 (requirement: 0.6) |
| Ventilation | High-efficiency heat-recovery unit | 2.1 kW backup heating on supply air |
| Production | 34 roof-integrated PV panels + solar hot water | Primary energy: −12 kWh/m²/yr |
| Design | Revit BIM model + Twinmotion and Lumion renders | Permit granted in 6 weeks |
| Management | Direct project ownership, KNX automation | Some twenty lots coordinated |
Can you really file a building permit yourself?
In France, yes, as long as the floor area stays under the threshold that makes an architect mandatory (150 m² for an individual today; 170 m² when we filed). The file is not rocket science in principle: a standard form and a set of normalised drawings, plans, sections, landscape insertions. What is demanding is precision: the local planning code reads like a specification, and every document must stay consistent with all the others. It is engineering work before it is drawing work, which is exactly why I felt at home.
Is learning Revit on your own feasible?
It is, and I recommend it to any technical mind who builds. Revit is not a drawing tool: it is a database that happens to look like a house. Once that mental switch happens, everything flows: the model produces the permit drawings, the sections for the carpenter (exported as DXF), the quantities, and the 3D renders that let you make decisions before pouring concrete. My survival tip: learn the keyboard shortcuts early, and model cleanly from day one, the way you would name your variables cleanly.
What a house taught me about software
Everything, honestly. A construction site is a distributed system whose nodes have schedules, egos and trucks. Ambiguous specs are paid for in rework, the interfaces between lots are where bugs are born, and tests (the blower door) are worth more than any promise. Nothing made me grow as an engineer like coordinating craftspeople. And the golden rule is the same as in computing: what is not measured does not exist.
Frequently asked questions
Does a passive house work in Normandy?
Ours does: a compact design facing due south, and a negative primary-energy balance validated by the regulatory study. Normandy sunshine is an underestimated partner.
What exactly is an "energy-positive" house?
A house whose annual primary-energy balance is negative in regulatory terms: production (here, 34 photovoltaic panels and solar hot water) exceeds the conventional consumption. For ours: −12 kWh/m²/year, when the regulation allowed up to 50.
Would you do it all the same way again?
Almost. I would redo the self-taught Revit and the direct project ownership without hesitation: that is where quality and pride are won. I underestimated the coordination time between lots, though. A building site, like a software project, moves at the speed of its slowest interface.