Passive House modular home maintenance: annual guide and real costs

Direct answer: an Ecoimport T3 Passive House modular home costs €250 to €500 per year in real maintenance, against €800-1,500 for a traditional equivalent. Most tasks are done by the owner in 2-4 hours per quarter (MVHR filters, visual checks, sanitary ware), and multi-year interventions (exterior varnish 5-8 years, blower door 5 years) are planned in advance. This guide gives you the month-by-month schedule, item-by-item costs and when to bring in professionals.

One of the promises of modular Passive House construction is "low maintenance by design". It is true — but only insofar as minimum maintenance is carried out. This article compiles what to do, when, and what it really costs over the year.

Passive House philosophy: fewer parts, fewer failures

The Ecoimport Passive House has fewer technical systems than a traditional home:

• No wall-hung gas boiler.
• No chimney or drawn-air fireplace.
• No radiators with individual thermostats.
• No conventional hot-water cylinder.
• No central air conditioning with ducted returns.

Instead: a compact air-to-water heat pump for DHW, continuous MVHR ventilation, and an airtight envelope that eliminates active heating 90% of the year. Fewer moving parts mean fewer failures, fewer interventions and lower costs.

Monthly / annual schedule

January — starting the year

• Check MVHR filters. If last replaced more than 6 months ago or looking dirty, replace them (€40-80 the pair).
• Clean bathroom and kitchen traps (pour 1 L of hot water with detergent).
• Check shower and tap flow (a drop in pressure may indicate a blocked filter in the water column).
• Inspect the exterior of the house after winter rain: stains, streaks, obstructions in gutters.

March — arrival of spring

• Garden maintenance: first lawn cut of the year, mowing, aeration.
• Check the automatic irrigation system (after winter it may have burst nozzles).
• Clean solar thermal or photovoltaic collectors (soft cloth, warm water, avoid abrasive products).
• Inspect exterior windows and doors: weather-seals, ironmongery, latch adjustment.

June — preparing for summer

• Check the split cooling unit (occasional use in a Passive House): clean interior filters, check the outdoor unit.
• Adjust awnings and exterior shading (blinds, shutters, pergolas).
• Test exterior lighting (LED signage, garden).
• Check outdoor taps and irrigation system for peak-heat conditions.

September — pre-autumn

• Replace MVHR filters (six-monthly change).
• Inspect gutters and downpipes, remove leaves and debris before the rains.
• Check exterior door seals.
• Visually inspect the roof (from the outside, without climbing): tiles, membrane, flashings.

December — airtightness check

• Check heat-pump operation (correct winter-mode function).
• Visually inspect cold spots on walls/ceilings: condensation would signal compromised airtightness.
• Check MVHR air flow (should remain stable).
• Inspect skirting boards and window reveals from inside: humidity or abnormal condensation.

Detailed annual items

MVHR filters — €40 to €160/year

The mechanical ventilation with heat recovery system has F7 (supply air) and G4 (extract air) filters. Replaced every 6 months or annually depending on:

• Coastal zone (Ferragudo, Albufeira, Vilamoura): 6 months (salt aerosol, high pollen).
• Inland zone (Alte, Salir, rural Loulé): 8-12 months.
• Homes with pets: 4-6 months.
• Homes with smokers: not recommended, but if so: 3-4 months.

Cost per F7+G4 pair depending on manufacturer: €40 (Genvex, Aldes) to €80 (Zehnder, Vallox). Change takes 5-10 minutes, no tools needed.

Exterior timber varnish or oil — €800 to €1,500 every 5-8 years

If the house has exterior cladding in thermally treated or natural timber (larch, cedar, treated ash), apply UV-protection varnish or penetrating oil every 5-8 years. Professional service (surface cleaning, light sanding, 2-3 coats) for a T3 home with 60-90 m² of treated surface: €800-1,500. Materials alone: €200-350 (if DIY).

Alternative claddings require less maintenance: fibre cement (Cedral) and lacquered steel practically 0 maintenance; HPL panel 15 years without intervention; exterior PVC 10-15 years.

Solar thermal or photovoltaic panels — €100 to €250/year

Annual cleaning (optional but recommended, especially in dusty areas or near pine forests): €60-120 via external service or DIY with a cloth and soft water. Solar thermal temperature sensor check: professional every 2-3 years, €100-180. Photovoltaic electrical inspection: professional every 5 years, €150-250. Replacement of anti-corrosion fluid in the solar-thermal loop: every 5-7 years, €200-350.

Sanitary ware and traps — €20 to €60/year

Monthly self-cleaning with hot water + detergent resolves 90% of odour problems. Anti-odour seal replacement every 3-5 years: €15 per trap. Toilet gaskets every 6-8 years: €20-40 with external service.

Insulation and envelope — biennial inspection

The insulation is not touched (it is encapsulated). What you do is check visually and by feel:

• Cold spots on walls/ceilings (indicate thermal bridges or a defect).
• Condensation on internal glass in winter (indicates high indoor humidity or an under-sized MVHR).
• Draughts near windows or doors (dried-out seals).
• Stains or infiltrations on skirting boards, ceilings or corner points.

Blower door at 5 years — €350 to €500 (optional)

Envelope airtightness test. Not mandatory, but useful to confirm that the house maintains the project's n50 value (≤0.6 h⁻¹ at 50 Pa). A blower door test at 5 years allows early detection of degradation (settled joints, opened ironmongery). Done by a Passive House certified technician.

DHW heat pump — €80 to €150/year

Annual check: intake filters, pressures, backup element, temperature sensor. A maintenance contract with the manufacturer typically costs €100-160/year with parts included. Typical service life: 15-20 years.

Table of total annual costs

Spread out: DIY 2-4 hours/quarter, real cost €200-400/year; full external service €800-1,500/year. Most Ecoimport clients opt for a mixed model — DIY on quarterly routines + an annual contract for the heat pump and solar check (€250-400/year of contracts).

Multi-year costs (spread over 5-10 years)

Amortised multi-year total: €725 to €1,360/year equivalent. Adding to current annual costs: €850-1,615/year DIY, €1,305-2,575/year with full external service. The latter figure is still below the typical maintenance cost of a 1970s-1990s traditional house in the Algarve (€1,500-2,500/year in current services alone, excluding multi-year items).

Comparison with a traditional house

Cumulative difference over 20 years: a Passive House spends €40,000-70,000 less on operation and maintenance than an equivalent traditional house. It is like cutting the mortgage by €200-350/month.

Ecoimport maintenance plan (optional)

We offer an annual maintenance plan for Ecoimport clients with three tiers:

• Basic tier (€185/year VAT included): annual check of MVHR, solar panels, heat pump, sanitary ware and envelope. 3-4 technician hours. Suitable for a home lived in by an attentive owner.
• Plus tier (€345/year): Basic + filter changes included + solar collector cleaning + 2 routine visits + priority on corrective interventions.
• Premium tier (€595/year): Plus + garden care + biennial airtightness check + blower door every 5 years + 24/7 direct line.

Short-term rental clients frequently opt for Premium to offload operations to us.

"Regular maintenance is not an expense — it is what keeps the Passive House performing on day-one terms 20 years later."

Mistakes to avoid

1. Leaving MVHR filters unchanged: flow rates drop, indoor air deteriorates, and in the long run fans can be damaged. It is not worth saving €60 a year on filters.
2. Covering MVHR grilles with furniture or curtains: obstructs air flow, creates humidity points. Keep them clear.
3. Letting traps dry out in seldom-used bathrooms. The water evaporates, letting odours in from the network. Pour 1 L of water monthly.
4. Applying unrecommended paints or varnishes on exterior timber. Some products seal the wood and create internal humidity. Always use microporous oils or varnishes recommended by the manufacturer.
5. Ignoring visual signs (stains, condensation, noises). Early intervention costs 5-10x less than late correction.

Conclusion

An Ecoimport Passive House modular home has real annual maintenance of €250 to €500 (smart DIY) or €800-1,500 (full external service), against €1,500-2,500 for a traditional equivalent. With simple quarterly routines, planned multi-year interventions (timber varnish at 5-8 years, blower door at 5 years) and an Ecoimport maintenance plan if desired, day-one performance is preserved across decades. The Passive House is not complex machinery — it is good engineering with few points of failure.

Figures and frequencies are 2026 estimates and vary with use, zone (coastal vs interior), equipment manufacturers and choice of finishes. Contact us for a tailored plan.

→ Ask us for an Ecoimport maintenance plan for your case or see the construction system page.