The Architect’s Guide to Part F, L & O: Design-Led Compliance

Stop Ruining Your Elevations To Tick A Box.

The era of the “Slimline Window” is ending. The trickle vent is growing. Here is how to achieve 2025 compliance without compromising your design.

The “Drill and Grill” approach is dead.

You didn’t spend weeks detailing a minimalist façade just to have it scarred by 5,000mm² of plastic.

Yet, the collision of Part L (Energy), Part F (Ventilation), and Part O (Overheating) has created a “Compliance Trap.” As you push for the airtightness required by the Future Homes Standard, the regulations demand larger holes in your envelope.

If you get the balance wrong, you risk more than just ugly windows. You risk summer overheating, condensation lawsuits, and retrofits that are obsolete before they are built.

There is a better way.

VENTI’s “Insider” CPD series helps architects navigate the aesthetic and technical minefield of modern ventilation. We don’t just quote the Approved Documents; we show you the strategic workarounds that save your design.

Choose your CPD briefing. All sessions are hosted on Teams.

AESTHETICS VS. AIRFLOW (The Anti-Trickle Vent Masterclass)

Official Title: Approved Document F Uplift: Why Architects Need to Re-Think Background Ventilation.

The 2022 uplift was a stealth killer for window design. With background ventilator sizes jumping to 5,000mm², the “invisible” vent is a myth.

The Conflict: Why regulations are phasing out trickle vents in compliant scenarios.
The Fix: How to justify Whole-House Mechanical Strategies to clients who balk at the cost, securing your aesthetic vision.
Time: 1 Hour

THE ENVELOPE-VENTILATION-OVERHEATING TRIAD

Official Title: Part O’s Hidden Pressure on Part F.

High fabric efficiency + airtightness = a summer greenhouse. Architects must now balance solar gain, external noise, and security against the need for night-time cooling.

The Conflict: The drive for Part L efficiency is actively fighting Part O cooling.
The Fix: “Integrated Compliance”—how to design the envelope and ventilation as one system, not two.
Time: 1 Hour

NAVIGATING THE UNKNOWN: THE FHS PARADOX

Official Title: The ‘Zero-Carbon Ready’ Paradox: The Final Specification Uncertainty.

The Future Homes Standard (FHS) is looming for Autumn 2025, but the final “compliance wrapper” is still undefined. This uncertainty is a major risk for current designs.

The Conflict: Designing for today’s Part L might leave your project non-compliant by the time ground is broken.
The Fix: How to “hedge” your design risks now and mitigate strict transitional arrangements for refurbishments and extensions.
Time: 1 Hour

THE STRATEGIC COMPARISON

Official Title: Domestic Ventilation Approaches Compared.

Stop defaulting to System 1 (Intermittent Fans) out of habit. We provide a ruthless comparison of PI, MEV, and MVHR performance against modern fabric standards.

Time: 1 Hour

VENTILATION FUNDAMENTALS REVISITED

Official Title: Understanding Part F and Its Impact on Residential Ventilation Design.

A foundational update on the 2022 changes. We cover the shift in minimum whole-dwelling rates and the new mandatory checklists that are catching architects out on site.

Time: 1.5 Hours

2 DECEMBER 2025 13:00 – 14:30

15 DECEMBER 2025 10:00 – 11:30

27 JANUARY 2026 10:00 – 11:30

9 FEBRUARY 2026 10:00 – 11:30

We believe ventilation is an architectural issue, not just a plumbing one.

We help architects bridge the gap between Beautiful Design and Healthy Air. Our approaches are used by practices that refuse to let regulations dictate their aesthetics.

“Finally, a ventilation CPD that understands the pressure architects are under to deliver clean elevations.”

Get in touch

Don’t let the regulations design your building for you.

Secure your place on the next “Insider” briefing.

What Architects Are Saying (Post-CPD Feedback)

To give you confidence that this session is directly relevant to your practice, here is a summary of the confidential feedback provided by recent attendees from architectural firms and design practices.

Relevance to Architectural Practice

Clarity of Regulatory Updates

Likelihood to Recommend

On Solving Retrofit & Product Pain Points

“It was interesting to hear the industries move away from horrible trickle vents! This session gave us a viable solution.”
— Architect, Bristol (Rated 10/10)

“The local MVHR units, all self contained, offer a good solution for projects where whole-house ducting simply isn’t feasible.”
— Architectural Technologist, London (Rated 9/10)

“Per room ventilation is a viable strategy even in comparison with whole-house MVHR. This reframes our initial design approach for older properties.”
— Senior Designer, Manchester (Rated 10/10)

On Compliance and Clarity

“Having clarity on the different ventilation strategies and systems based on various scenarios was very helpful. No more guessing compliance.”
— Design Manager, Birmingham (Rated 8/10)

“The session reinforced existing theory and knowledge with real-world insights on achieving Part F compliance in challenging retrofit scenarios.”
— Director, Architectural Firm (Rated 10/10)

On Expertise & Trust

“Great presentation. Bradley was great. It clearly demonstrated that proper ventilation is essential for healthy living, not just a regulation tick-box.”
— Project Architect, Cornwall (Rated 10/10)