Energy Services

Simplifying Energy Standards, Maximising Building Performance

SAP Calculations - Extensions

Maximising natural light and creating a strong visual connection with the outdoors is a common design goal—and often achieved through extensive use of glass in walls and roofs. However, when glazing in an extension exceeds 25% of the floor area, Building Control requires evidence that the project still meets Part L of the Building Regulations, due to the lower thermal efficiency of glass compared to other building materials.

At Ashwood, we provide comprehensive SAP Calculations to demonstrate compliance and keep your project on track. We’ll assess your design and, if needed, recommend improvements to the existing home or the new extension’s fabric to ensure it meets energy standards.

From U-values to DER/TER CO₂ emissions, we handle all the technical aspects—so you can focus on the design, while we take care of the compliance.

SAP Calculations - New builds & Conversions

Design Stage
Once we receive your construction drawings and specification, Ashwood will prepare all the necessary SAP documentation required for submission to Building Control as part of your Building Regulations application. This ensures your design is energy compliant from the outset.

As-Built Stage
After construction is complete and the final build details are confirmed, we’ll produce your Energy Performance Certificate (EPC). This is a legal requirement and must be submitted to receive your completion certificate.

Excessive Glazing Calculations

Modern design often aims to blur the boundary between indoor and outdoor spaces—typically achieved through large areas of glazing in walls and roofs. While visually stunning, extensive glazing can impact your project’s energy performance. If the glazed area in your extension exceeds 25% of the floor area, Building Control will require energy calculations to confirm compliance with Part L of the Building Regulations, due to the lower thermal efficiency of glass.

At Ashwood Energy, we provide the SAP Calculations needed to meet these requirements. We’ll also advise on practical improvements to the existing building or the new extension to help balance design with performance.

From U-values to DER/TER CO₂ emissions, we manage all the technical details—ensuring your project stays compliant, efficient, and on schedule.

BREL Report (New Build Only) & Energy Performance Certificates

Design Stage
Once we receive your construction drawings and specification, we’ll prepare all the SAP documentation required for submission to Building Control as part of your Building Regulations application.

If you're working on a new build, you'll also need Part G (Water Efficiency) and Part O (Overheating Mitigation) calculations. We can provide these as part of a complete compliance package.

As-Built Stage
After construction is complete and the final specification is confirmed, we’ll issue your Energy Performance Certificate (EPC)—a mandatory requirement for obtaining your completion certificate.

Energy Statements for Planning Applications

New planning policies S6, S7, and S8 require developers to submit an Energy Statement as part of their application. This document outlines how your development addresses energy efficiency targets and highlights any challenges in meeting those requirements.

The Energy Statement should demonstrate how energy performance has been considered at every stage—from the early design phase through to application submission. It can also incorporate responses to related policies, including:

S9 – Decentralised Energy Networks
S10 – Circular Economy
S11 – Embodied Carbon
S20 – Resilient Design

Key design decisions—such as site layout, orientation, and form—have a significant impact on a building’s energy performance, so it’s essential to begin this process early.

At Ashwood Energy, we work with you from the outset to prepare a comprehensive Energy Statement that supports your planning application and aligns with all relevant policies.

Overheating Calculations

Part O of the Building Regulations applies to all residential building types, including:

Dwellings (homes)
Residential (institutional)
Residential (other)

The goal of Requirement O1 is to safeguard the health and wellbeing of occupants by minimising the risk of high indoor temperatures during warmer months.

To comply with Requirement O1, buildings must be designed and constructed to:

Limit unwanted solar gains in summer, and
Provide effective means of removing excess indoor heat

There are two approved methods for demonstrating compliance:

Simplified Method (for low-risk designs)
Dynamic Thermal Modelling (for more complex or higher-risk developments)

It’s crucial that this assessment is completed before construction begins to avoid costly design changes or mitigation measures later in the process.

At Ashwood Energy, we offer expert guidance and full compliance reports to ensure your project meets Part O requirements efficiently and effectively.