SAP Calculations for Extensions
SAP Calculations are often required when extending an existing property, ensuring the new thermal elements meet the energy‑efficiency standards set out in Part L of the Building Regulations. These assessments demonstrate that your proposed extension including its walls, floors, roofs, and glazing, achieves the necessary performance levels without increasing the overall emissions of the home.
Justifying Glazing, Securing Compliance
At Stanley Sustainability, we provide SAP calculations specifically for extensions where the proposed glazing exceeds 25% of the floor area. By modelling energy performance with precision, we help you demonstrate compliance with Part L of the Building Regulations, justify design intent, and avoid costly redesigns.
Our service is ideal for homeowners, architects, and developers seeking approval for extensions with large areas of glass.
What We Deliver
🧮 Targeted SAP Modelling – Assessments tailored to extensions with high glazing ratios
📊 Compliance Evidence – Reports that justify glazing areas above 25% for Building Control approval
🔧 Design Optimisation – Advice on insulation, heating, and renewable options to balance performance
📄 Planner‑Ready Documentation – Clear, referenced outputs that anticipate Building Control queries
Why It Matters
Extensions with significant glazing can trigger compliance challenges. Robust SAP calculations allow you to:
✅ Justify designs with glazing over 25% of floor area
✅ Avoid costly redesigns or reductions in glazing
✅ Demonstrate compliance with Part L and secure Building Control approval
✅ Balance aesthetics, daylight, and energy performance
Why Stanley Sustainability?
We combine technical rigour with practical insight. Our SAP service for extensions helps you:
🪟 Protect your design intent while meeting regulatory requirements
💰 Reduce costs by targeting the most effective fabric and system upgrades
📈 Strengthen compliance strategy with clear, project‑specific evidence
🤝 Gain peace of mind with responsive support and planner‑friendly reports
Let’s make your extension compliant — without compromising the glass you envisioned