SAP CalculationsSAP Assessments & EPCs

Find out how Vision Energy can take care of all your compliance needs for your new Build Project

Find out more about SAP Calculations

Conversion SAP CalculationsSAP Assessments & EPCs

Vision Energy can take care of your energy assessments for your conversion project, find out more today

Find out more about Conversion SAP Calculations

Extension SAP CalculationsSAP Assessments & EPCs

All Extensions with 25% or more glazing compared to the floor area require SAP & EPC assessment and calculations, find out more

Find out more about Extension SAP Calculations

Case Study: SAP Calculations for a Low-Energy Residential Infill Development

Case Study: SAP Calculations for a Low-Energy Residential Infill Development

Project Overview

This project involves the construction of four new-build, three-storey terraced homes designed to meet modern space, amenity, and energy performance standards. Located on a constrained urban site, the development carefully balances internal floor areas, external amenity space, and energy efficiency targets. Vision Energy was appointed to deliver full SAP Calculations to support Building Regulations compliance under Part L 2021.


Design & Layout

Each dwelling accommodates a 5-bedroom, 8-person household, spread over ground, first, and second floors. Internal floor areas range from 179 m² to 194 m². The site layout includes private rear gardens, cycle and bin storage, and EV-ready parking. All homes exceed required private amenity space standards, each offering over 100 m² of outdoor space.


Energy Performance Strategy

A fabric-first approach was adopted across all four dwellings, with a focus on minimising heat loss and reducing operational carbon through efficient materials and systems. Key specification highlights include:

  • Walls: 0.18 W/m²K

  • Roof: 0.13 W/m²K

  • Floor: 0.15 W/m²K

  • Glazing: 1.2 W/m²K, low G-value for solar gain control

  • Air permeability target: 5 m³/h·m² at 50Pa

  • MVHR systems specified to reduce heating demand and support internal air quality


SAP Calculations – Results Snapshot (Typical Unit)

Metric Result
SAP Rating 86 B
DER (Dwelling Emission Rate) 11.14 kgCO₂/m²/year
TER (Target Emission Rate) 12.53 kgCO₂/m²/year
CO₂ Reduction vs TER 34.4%
DFEE (Fabric Energy Efficiency) 42.1 kWh/m²/year
DPER (Primary Energy Rate) 73.2 kWh/m²/year

Low Carbon & Renewable Features

  • Each home integrates a roof-mounted solar PV system (~1.3 kWp), contributing to on-site energy generation and offsetting regulated emissions.

  • No gas connection is proposed – space and water heating are provided by efficient electric systems.

  • Design meets the 31% CO₂ reduction target in line with Part L 2021 requirements for new dwellings.


Additional Site Features

  • High-spec thermal envelope and airtightness contribute to reduced energy demand.

  • Secure cycle storage, bin stores, and soft landscaping integrated into the overall layout.

  • Orientation and glazing design mitigate summer overheating risk while maximising daylight.


Outcome

Through detailed SAP Calculations and a coordinated design approach, this development demonstrates how compact infill sites can deliver high-performing, policy-compliant family homes. Vision Energy’s input ensured that all regulatory performance criteria were met while supporting a low-carbon, future-ready design.

Sustainability & Building Compliance

Vision Energy are a leading Sustainability & Energy consultancy working nationwide. We specialise in calculations & reports covering Building Regulations, Planning Permission and all other sustainability or energy needs within the construction sector. With a vast amount of knowledge and experience having worked on thousands of projects across the UK one of our engineers would be more than happy to assist you on your project. SAP Calculations | SBEM Calculations | Energy Statements | BREEAM Pre-Assessments | M&E Design | EPC's | Water Efficiency | Air Permeability

Talk to Our Technical Team

Get a Quick Quote