🏡 Part L & Part F 2026: What the Big Changes Mean for Your Projects
The UK is gearing up for one of the biggest building regulation updates in years. With the Future Homes Standard arriving in 2026, both Part L (Energy Efficiency) and Part F (Ventilation) are getting major upgrades.
If you’re a developer, designer, or contractor, these changes will shape how you plan, build, and sign off homes from 2026 onwards. Here’s the simple version of what’s coming and how it affects you.
⚡ Part L 2026: Energy Efficiency Gets Serious
🔥 No More Gas Boilers
From 2026, new homes will be designed around low‑carbon heating. That means:
- Heat pumps become the default
- Solar PV is built into the notional dwelling
- Waste Water Heat Recovery (WWHRS) is assumed
- Airtightness targets tighten to around 4 m³/m²/hr @ 50 Pa
Gas boilers aren’t banned outright, but the compliance route makes them practically impossible to justify.
📉 Lower Carbon, Lower Energy Use
Part L keeps the familiar metrics:
- DER – Dwelling Emission Rate
- DPER – Primary Energy
- DFEE – Fabric Energy Efficiency
These will be calculated using SAP 10.3, a transitional version until the new Home Energy Model fully takes over.
🧱 Fabric First, Always
Expect improved minimum standards for:
- Walls
- Floors
- Roofs
- Windows & doors
Better fabric = better heat pump performance = easier compliance.
🌬️ Part F 2026: Ventilation Re‑Designed
💨 Ventilation as a Whole System
The old “trickle vents + intermittent fans” approach is being phased out. The new guidance pushes for:
- Continuous ventilation systems (dMEV or MVHR)
- Balanced airflow strategies
- Ventilation designed alongside airtightness
Good ventilation is now a core part of energy performance, not an afterthought.
🏠 Healthier Indoor Air
With homes becoming more airtight, Part F strengthens requirements around:
- Moisture control
- Pollutant removal
- Overheating risk management
Part F 2026 now has more robust commentary on the importance of:
- Proper design, with more conscious thought of ductwork, internal noise and air quality.
- Proper commissioning and verifiable airflow testing.
This supports the Building Safety Regulator’s wider focus on occupant health.
📅 When Does It All Happen?
2026: New Approved Documents L & F published
March 2027: Regulations take effect for most new building work
September 2027: Additional rules apply to higher‑risk buildings
🔧 What This Means for Your Projects
📝 Design Early, Design Smart
Heat pumps, PV, airtightness and ventilation must be planned from RIBA Stage 2. Late‑stage fixes won’t cut it.
📊 More Testing, More Evidence
Expect tighter scrutiny on:
- Airtightness
- Ventilation commissioning
- SAP modelling
- Low‑carbon system performance
👷 Skills & Supply Chain Shift
The government is investing heavily in low‑carbon training. The industry is moving fast — and so should your team.
🤝 How Building Compliance Testing Can Help
We support developers, architects and contractors through every stage of the new standards:
- SAP 10.3 modelling & Part L testing
- Ventilation testing & commissioning (Part F)
- Airtightness testing to 2026 expectations
- Low‑carbon system verification
We make compliance simple, predictable, and stress‑free.
Have a project in mind? Let’s get to work.
Need help with your retrofit renovation project or PAS-2035 compliance advice? Get in touch with our team today.