Key takeaways
- About 70% of Polish residential buildings were built before 1993 — without modern energy standards. They use 2–5 times more energy to heat than thermally modernised homes (Statistics Poland, building energy efficiency, 2023).
- The Clean Air programme offers up to PLN 135,000 in grants for a comprehensive thermal modernisation of a single-family home, depending on income (NFOŚiGW, 2025).
- The thermal-modernisation relief lets you deduct up to PLN 53,000 from the taxable base — it can be combined with the Clean Air grant.
- A full thermal modernisation of a 120 m² home costs PLN 80,000–150,000 gross, but with funding the real out-of-pocket falls to PLN 30,000–70,000. Payback without grants: 12–20 years. With funding: 5–10 years.
How do you know your home needs thermal modernisation?
The signals are usually visible — and felt in the bills. According to Statistics Poland, about 70% of Polish residential buildings were built before 1993, when energy standards were noticeably weaker than today (Statistics Poland, building energy efficiency, 2023). Such homes lose heat through walls, roof, windows and foundations — and you have to make that up across the whole winter.
The first signs it's time to act:
- Heating bills rising year on year even though you haven't changed your habits. Gas price growth explains part of the difference but not all of it.
- Internal walls feel cold to the touch even with the heating on — that means thermal bridges and poor insulation.
- Condensation and damp around windows — old box or single-glazed windows are a major route for heat loss.
- Loft or basement uninsulated — an uninsulated ceiling above the ground floor is another large thermal hole.
- The boiler runs at full power for most of the season — a well-insulated home doesn't require such intensive boiler operation.
If you see three or more of these — thermal modernisation is no longer a "whether" question but a "when and in what order".
In conversations with homeowners while designing Homeward one theme repeated: people knew that "the home is cold and expensive", but didn't know where to start, or whether it was worth investing at all. The key takeaway: thermal modernisation without an energy audit is a bit like treatment without a diagnosis. Start with an audit. And then keep the whole project in one thread: decisions, documents, costs and service after the works are done.
How much does thermal modernisation cost and how much can you save?
There's no single number — the scope of works varies too much. But ranges can be given that let you assess the order of magnitude.
Indicative costs by work item (Poland, 2025–2026):
| Work item | Indicative cost |
|---|---|
| External wall insulation (styrofoam + render) | PLN 100–200/m² of wall |
| Roof or ceiling insulation | PLN 80–160/m² |
| Window replacement (per window) | PLN 800–2,500 |
| External door replacement | PLN 2,000–5,000 |
| Air-source heat pump (complete install) | PLN 15,000–35,000 |
| Ground-source heat pump (complete install) | PLN 30,000–60,000 |
| 6 kWp solar PV | PLN 25,000–35,000 |
| Full thermal modernisation of 120 m² home | PLN 80,000–150,000 |
Source: indicative contractor rates, Murator.pl, 2025
How much can you save? A home built in the 70s–80s without insulation typically uses 150–250 kWh/m²/year for heating. After a comprehensive thermal modernisation: 40–70 kWh/m²/year. That's 50–70% savings on heating bills (NFOŚiGW, Clean Air — programme results, 2024).
For a 150 m² home and gas at ~PLN 0.35/kWh (including distribution): the old home costs ~PLN 8,000 a year to heat. After thermal modernisation: ~PLN 2,600. That's PLN 5,400 in annual savings.
A comprehensive thermal modernisation of a 120–150 m² single-family home cuts heating energy use by 50–70%. At current gas prices that translates to PLN 4,000–7,000 in annual savings on heating bills — and that result is confirmed by Clean Air programme data from over a million completed investments (NFOŚiGW, 2024).
Where to start? The right order of works
A mistake is starting with replacing the boiler. The most common trap: buying a heat pump for a home without insulation — and the pump runs flat out all winter, with the electricity bill eating the savings. Order matters.
The correct order of thermal modernisation:
- Energy audit — the starting point. The auditor will show where the home loses heat, in what order it pays to act, and what insulation parameters your building needs. Cost: PLN 800–2,000. Payback: fast, because without an audit you can miss the priorities.
- Building envelope insulation — walls, roof/ceiling, foundations. The biggest energy effect. Without this, any other heating unit has to work at higher loads.
- Window and door replacement — once envelope insulation is done, window replacement makes sense. Earlier you can end up with condensation on new windows because of thermal bridges in the walls.
- Ventilation — an insulated home is airtight. Without mechanical ventilation with heat recovery (recuperator) you'll start growing mould. This is a step often skipped, yet crucial for health and air quality.
- New heat source — only now does it make sense to replace the boiler or install a heat pump. An insulated and sealed home has a different heating demand than the pre-renovation building.
- Solar PV — the last step. Once you have a heat pump or other electric units, PV really starts to pay.
Worth knowing that the order of works also has a financial dimension at grant time. Clean Air requires the heat source to be replaced or thoroughly modernised — an insulation investment without replacing the old coal boiler often doesn't qualify for the higher grant level. The energy audit before submitting the application isn't a formality — it's a condition for an optimal grant.
What funding is available for thermal modernisation?
This is the most important part of the article from a financial point of view. Thermal modernisation without funding is many times more expensive than it has to be.
Clean Air programme (NFOŚiGW)
The main support programme for single-family home owners in Poland. Three levels of funding based on income (NFOŚiGW, Clean Air, 2025):
| Level | Income criterion | Max grant |
|---|---|---|
| Basic | Up to PLN 135,000/year of income | Up to PLN 30,000 |
| Raised | Up to PLN 2,250/month per person (multi-person household) | Up to PLN 60,000 |
| Highest | Up to PLN 1,090/month per person or benefit-eligible | Up to PLN 135,000 |
Source: NFOŚiGW, as of 2025. Programme conditions may be updated — check the current version at czystepowietrze.gov.pl
The grant covers: wall and roof insulation, window and door replacement, heat pump, condensing boiler, mechanical ventilation, micro-installation PV.
My Electricity programme (NFOŚiGW)
For micro-installation PV. Current edition: up to PLN 7,000 of grant for PV + additional support for an energy storage (up to PLN 16,000), DHW heat pump (up to PLN 5,000) and EV charger (NFOŚiGW, Mój Prąd, 2025). Check the current edition at mojprad.gov.pl — conditions and amounts change between editions.
Thermal-modernisation relief (PIT)
A single-family home owner can deduct up to PLN 53,000 of thermal-modernisation expenses from the taxable base. The relief works independently of the Clean Air grant — both can be used at the same time (on expenses not covered by the grant) (Article 26h of the PIT Act, 2021). This is a key point: grant + relief = double support.
BGK thermal-modernisation bonus
For those financing the investment with a loan. Bank Gospodarstwa Krajowego pays off 16–26% of the thermal-modernisation loan value as a non-refundable bonus if the energy audit confirms achievement of the assumed energy savings (BGK, thermal-modernisation bonus, 2025).
How do you apply for Clean Air?
The procedure is simple but takes several steps:
- Check your funding level — based on income from your most recent PIT or the prior-year PIT.
- Order or do an energy audit — for grants above PLN 25,000 the audit is required. Below — recommended, because it lets you plan scope and order.
- Find a contractor and get preliminary quotes — useful for calculating the application amount.
- Submit the application online — via the gov.pl/czystepowietrze portal or at a WFOŚiGW branch (Provincial Environmental Protection Fund). Some municipalities have consultation points.
- Wait for the decision (typically 1–4 months) and sign the grant agreement.
- Carry out the works and collect VAT invoices — this is the basis for settlement. Without invoices in your name — the grant is lost.
- Settle the application — send documentation to WFOŚiGW and receive the payment.
Important: under Clean Air you can receive part of the funds before completion (pre-financing) or after (refund). The pre-financing option is better if you don't have starting funds.
Thermal-modernisation documentation — what to keep
Thermal modernisation is a project that runs for months and involves many contractors. Material invoices, energy audit reports, contractor contracts, inspection confirmations — all of it matters not just during execution, but for years after completion. We cover the home document storage system separately.
Why keep thermal-modernisation documentation?
- Settling the Clean Air grant (mandatory — without VAT invoices the grant won't be paid)
- Thermal-modernisation relief in PIT — invoices as the deduction basis for years to come
- Warranties on the heat pump, windows, insulation materials — require invoices and installation reports
- Property history — at sale, the buyer and surveyor will ask about modernisation documentation
- Service of heat pumps, recuperators — the technician needs the installation history
A folder on disk doesn't remember that the heat pump warranty expires in three years' time. It won't remind you that at sale the buyer will ask about the energy audit report and material invoices. Homeward designs the Home Passport for exactly this kind of documentation: invoices, audit, acceptance reports, warranty terms and later service form one investment history that you return to at grant settlement, equipment service or a conversation with a notary. Homeward is in pre-launch — you can join the waitlist for free.
Thermal-modernisation documentation has value over the building's entire operating life: it's the basis for the thermal-modernisation relief, the condition for settling the Clean Air grant, and an argument at property sale. Without complete VAT invoices and acceptance reports you lose access to tax deductions and may lose the warranties on installed equipment.
Frequently asked questions about thermal modernisation
Where do you start a home thermal modernisation?
With an energy audit. The auditor assesses where the home loses heat, which works will deliver the biggest savings and in what order to carry them out. Without an audit you can hit the wrong order: e.g. buying a heat pump for an uninsulated home, which won't deliver the expected savings. Audit cost: PLN 800–2,000. It's also required for higher Clean Air grants. After completing the investment, remember annual checks on new heating equipment — a condition for keeping the warranty. If you're not ready for a big project all at once, start with a smaller tidy-up and observation, e.g. through a summer home reset, which helps gather the first technical and cost signals.
How much is the Clean Air grant?
Depending on income: from PLN 30,000 (basic level) to PLN 135,000 (highest level, for benefit-eligible). The grant covers insulation, windows and doors, heat pump, condensing boiler, ventilation and PV. It can be combined with the thermal-modernisation relief (up to PLN 53,000 PIT deduction) on part of the costs not refunded by the grant (NFOŚiGW, 2025).
Can you combine Clean Air with the thermal-modernisation relief?
Yes. The Clean Air grant and the thermal-modernisation relief can be used at the same time, but on different bases. The relief covers expenses that were not refunded by the grant — i.e. on the amount after subtracting the refund. On a PLN 80,000 investment with a PLN 30,000 grant — the relief applies to PLN 50,000 (within the PLN 53,000 cap).
How long does the investment in thermal modernisation pay back?
Without funding: 12–20 years for a full thermal modernisation, shorter (5–8 years) for wall insulation and window replacement alone. With Clean Air funding: 5–10 years. As energy prices rise the trend shortens — an investment today pays back faster than the same one 5 years ago (NFOŚiGW, 2024).
Is thermal modernisation worthwhile in a block of flats?
For a flat owner the scope is limited — external walls and roof are part of the commons managed by the cooperative or community. Individually you can replace windows (within community rules), install a DHW heat pump or upgrade heating inside the flat. Insulating the whole block requires a community resolution and is financed inter alia from the BGK thermal-modernisation bonus.
Checklist: what to do step by step
- [ ] Check heating bills from the last 3 years — are they rising faster than inflation?
- [ ] Order an energy audit (PLN 800–2,000, required for higher grants)
- [ ] Check your Clean Air funding level (czystepowietrze.gov.pl)
- [ ] Set the order of works: insulation → windows/doors → ventilation → heat source → PV
- [ ] Gather a minimum of 3 quotes from contractors for each work item
- [ ] Submit the Clean Air application before starting works (or after — depending on the mode)
- [ ] Collect VAT invoices in your name for every material and service
- [ ] Document acceptance reports and warranty terms for every installed unit
- [ ] Settle the thermal-modernisation relief in PIT (on expenses not refunded by the grant)
- [ ] Keep all documentation — it's needed for years after completion
