Project · Deep renovation
A 1965 house renovated to Passive House level in Limburg, Netherlands
A detached house of about 160 m², built around 1965, went from energy label F and about 3,000 m³ of gas a year to a heating demand of about 10 kWh/(m²·a), calculated in PHPP. It now produces more energy than it uses.
- Building
- Detached house, c. 1965
- Heated area
- c. 160 m²
- Location
- Limburg, Netherlands
- Role
- PHPP, HVAC, site checks, build
Results
Before and after
Annual figures, rounded.
| Measure | Before | After |
|---|---|---|
| Energy label | F | A+ (the best Dutch label at the time) |
| Energy for heating | c. 3,000 m³ gas/year (c. 26,000 kWh) | c. 1,300 kWh/year for heating and cooling |
| Heating demand (PHPP) | — | c. 10 kWh/(m²·a) |
| Energy produced / used | — | 12,000 / 6,500 kWh/year |
Gas converted at about 8.8 kWh/m³. For comparison: the Passive House standard allows at most 15 kWh/(m²·a) for new buildings, and EnerPHit (the retrofit standard) at most 25 kWh/(m²·a) in a cool-temperate climate.
Works
What was done
The house was treated as a whole: the envelope first, then the building services, sized for the new, much lower demand.
- Insulation of the walls, roof and floor.
- New high-performance windows.
- Mechanical ventilation with heat recovery and dehumidification.
- Fresh air drawn through an earth-to-air heat exchanger, which pre-warms it in winter and cools it in summer.
- A heat pump for heating and cooling.
- Solar panels producing about 12,000 kWh a year.
Role
What Dezideriu Florian Pana did
- 1
PHPP energy model
The energy balance of the house and the choice of insulation, windows and systems, down to about 10 kWh/(m²·a).
- 2
HVAC design
Heat-recovery ventilation with dehumidification, the earth-to-air heat exchanger and the heat pump, sized on the calculated demand.
- 3
Site checks
The details that decide the result: continuous insulation, airtightness, and how the windows and ducts are fitted.
- 4
Build and project lead
Builder and project lead, from the start of works to handover.
For Romania
What this means for a house in Romania
- Houses from the 1960s to the 1980s have the same problems as this one: uninsulated walls, thermal bridges, poor windows and air leaking in where it should not.
- The right order (envelope, airtightness, ventilation, then the heat source) allows a small heat pump and very low bills.
- A PHPP calculation before the works shows what each measure brings, so you do not pay for what never shows up on the bill.
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Published 24 October 2026.