Why are prefabricated houses energy-efficient? Technology that lowers bills
Heating bills are one of the biggest home running costs – in traditional construction it can be PLN 500–1,000 per month during heating season. Treevia prefabricated houses achieve heating costs of PLN 150–250/month for a 120 m² house. How is this possible? The answer lies in combining precise manufacturing, thoughtful construction and modern installations.
Airtightness – the foundation of energy efficiency
The biggest "enemy" of a building's energy efficiency isn't thin insulation, but uncontrolled air leaks. Every gap, every imprecise wall joint, every seam through which air penetrates – that's heat loss no amount of insulation can compensate for.
In prefabrication, wall panels are produced as complete elements in the hall – with structural layer, insulation, vapour barrier and wind protection. Connections between panels are designed and executed with millimetre precision.
Every Treevia house undergoes a Blower Door test – our houses achieve results of n50 < 1.5 1/h, meaning airtightness significantly better than required by standards (standard for energy-efficient buildings: n50 < 3.0 1/h).
Multi-layer thermal insulation
Treevia walls are not simply "timber with insulation." It's a thoughtful, multi-layer construction:
From inside to outside:
- Plasterboard – interior finish
- Installation space – layer for electrics and plumbing without breaching the vapour barrier
- Vapour barrier membrane – prevents moisture penetration from interior to structure
- Timber structure with insulation – mineral wool or cellulose, 15–20 cm thick
- Wood-based board (e.g., OSB) – stiffening layer
- Wind protection – protects insulation from wind and external moisture
- Ventilated facade – timber, render or facade panel with ventilated air gap
Treevia wall thermal transmittance: U < 0.15 W/m²K – significantly better than current standards (0.20 W/m²K for external walls).
Heat pump – heating from air
In Treevia houses, the heating distribution system uses underfloor heating – the client chooses their own heat source. Modern heat pumps achieve COP 3.5–5.0, meaning from 1 kWh of electricity they produce 3.5–5 kWh of heat.
Combined with a well-insulated house and underfloor heating, this gives heating costs of:
- 70 m² house – PLN 80–150/month (annual average)
- 120 m² house – PLN 150–250/month
- 220 m² house – PLN 200–350/month
Heat recovery ventilation
A recuperator recovers 85–95% of heat from exhaust air and transfers it to supply air. Result: fresh, filtered air in the house – without opening windows and without heat loss.
Additional benefits:
- Air filtration – HEPA filters remove pollen, dust and smog. Ideal for allergy sufferers
- Constant humidity – no "steamed up windows" problem
- Quiet – no need to open windows in a noisy environment
How much does heating a prefabricated house really cost?
Simple comparison for a 120 m² house in central Poland:
Traditional brick house (gas, radiators):
- Annual gas consumption: approx. 1,500–2,000 m³
- Annual cost: PLN 6,000–10,000
Treevia prefabricated house (e.g. with heat pump, underfloor heating, recuperation):
- Annual electricity for heating: approx. 3,000–4,500 kWh
- Annual cost: PLN 2,000–3,000
Difference: PLN 3,500–7,000 per year. Over 30 years: PLN 100,000–210,000 in savings.
Summary – energy efficiency is not a luxury, it's a standard
At Treevia, energy efficiency is not an add-on or premium option – it's a fundamental feature of every house. Airtight construction, multi-layer insulation, recuperation and underfloor heating create a system where living comfort goes hand in hand with low running costs.