Quick and Cost-Effective Part O Compliance
Part O Simplified Method
The easiest route to Part O compliance. Prescriptive checks for glazing and ventilation. Most standard homes pass.
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Part O Simplified Method
What is the simplified method?
Prescriptive compliance route checking glazing limits and ventilation against Part O tables.
When can I use it?
Standard designs without noise constraints or single-aspect layouts. Try this first.
What are the glazing limits?
Depends on orientation. East/west limited to 13-20% of floor area, south 8-13%.
What ventilation do I need?
Cross-ventilation preferred. Minimum free area varies by room and dwelling type.
How much does it cost?
From £95 for a standard dwelling. Same-day results.
What if simplified fails?
Move to dynamic simulation. The £95 is credited toward TM59 modelling.
Most standard dwellings pass the simplified method. Quick, cheap, and straightforward.
What Is the Part O Simplified Method?
The simplified method is a prescriptive compliance route. If your design meets specific glazing and ventilation limits, you pass Part O without thermal modelling.
Part O provides tables showing maximum glazing percentages by orientation and minimum ventilation requirements. If your design fits within these limits, you demonstrate compliance by completing the checklist - no dynamic simulation needed.
This is the quickest and cheapest way to achieve Part O compliance. We check your design against the tables and provide a compliance report for Building Control.
When Can You Use the Simplified Method?
The simplified method works for most standard dwellings:
Eligible Designs
- ✓ Houses with cross-ventilation possible
- ✓ Flats with dual aspect (two or more external walls)
- ✓ Modest glazing areas
- ✓ No significant noise constraints
Need Dynamic Instead
- ✓ Single-aspect flats (one external wall only)
- ✓ Sites with noise restrictions on ventilation
- ✓ Glazing exceeding simplified limits
- ✓ Complex or unconventional designs
Not sure? Send us your plans and we'll confirm which method applies.
Part O Glazing Limits
The simplified method limits glazing as a percentage of room floor area. Limits vary by orientation:
| Orientation | Cross-Ventilated | Single-Sided Only |
|---|---|---|
| North (±30°) | No limit | No limit |
| East (±30°) | 20% of floor area | 13% of floor area |
| South (±30°) | 13% of floor area | 8% of floor area |
| West (±30°) | 20% of floor area | 13% of floor area |
These limits apply to each room individually, not the whole dwelling. A bedroom with south-facing glazing must keep that glazing under 13% of the bedroom floor area (if cross-ventilated).
Roof lights are treated as horizontal glazing and have their own limits - typically more restrictive than vertical glazing.
Part O Ventilation Requirements
The simplified method requires adequate ventilation for heat removal. Key requirements:
Ventilation Checklist
- Cross-ventilation - Preferred for bedrooms. Openings on opposite walls.
- Minimum free area - Openable windows must provide sufficient ventilation area.
- Bedrooms - Cross-ventilation required where possible. Single-sided ventilation has stricter glazing limits.
- Living areas - Can use single-sided ventilation but limits apply.
If security or noise concerns prevent adequate ventilation, the simplified method may not work and dynamic modelling will be needed.
Simplified Method Pricing
Quick and affordable compliance check.
Simplified Check
From £95
Single dwelling checked against Part O tables. Same-day results.
With SAP
From £220
SAP + Part O simplified together. Most efficient for new builds.
How the Simplified Check Works
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1
Send us your drawings
Floor plans showing room dimensions, elevations showing glazing, site plan showing orientation.
-
2
We check against Part O tables
We calculate glazing percentages by room and orientation, check ventilation strategy, and confirm if simplified method applies.
-
3
Receive your report
Pass result with compliance certificate, or recommendation for dynamic modelling if simplified doesn't work.
What If the Simplified Method Doesn't Work?
If your design exceeds simplified limits, dynamic modelling is the next step. The simplified fee is credited toward this.
Simplified Method FAQ
How long does the simplified check take?
What if I'm slightly over the glazing limits?
Can I reduce glazing to pass simplified?
Do I need the simplified check before dynamic?
Is the simplified method accepted by all Building Control?
Ready to check your design?
Same-day results for most projects. From £95.