Rear Perspective

Self Build House, Buckinghamshire

This project consisted of a new self-build house in a rural location within Buckinghamshire.
The development brief was for a 400m2 2 storey house with flexible living.
The scheme was to incorporate a number of sustainable features.

Planning & Design stage

Low Carbon Box provided the SAP Calculations (energy assessments) at planning stage to predict current carbon emissions and the performance of the proposed house. Using this process, the project team was able to confirm the design and specification to achieve significant reductions in annual carbon emissions when compared to Part L1A 2013 of the Building Regulations.

  • Some of the key features included are:
  • 172mm SIPs (Structural Insulated Panels) to achieve 0.18 W.m2.K U value
  • Warm roof construction to achieve 0.15 W/m2.K
  • Ground floor U value of 0.10 W/m2.K
  • Mechanical Ventilation with heat recovery (MVHR)
  • Air Source Heat Pump
  • 7.8 kWp Photovoltaic Panels to the roof

Using the above key enhancements, the project team implemented the specification. Low Carbon Box carried out the design stage SAP calculations based on the updated working drawings for issue to Building Control for Part L1A 2013.

As-Built Stage

Low Carbon Box monitored changes throughout the project and upon completion, were instructed to carry out the air tightness test.

The target was 7m3/hr/m2. Low Carbon Box completed the air tightness test and the target was met. Our air tightness tester also talked the client through areas to improve to help optimise the MVHR performance.

The as-built specification was updated with any changes and Low Carbon Box lodges and issued the air tightness test and final As-Built SAP calculation and Energy Performance Certificate (EPC)


  • Key performance data from the project is outlined below:
  • 78% reduction in annual carbon emissions
  • 18% reduction in Fabric Energy Efficiency standard
  • Air tightness test = 4.33 m3/hr/m2
  • EPC rating of 95 ‘A’

Low Carbon Box Services Provided

  • Eco Build
  • SAP Calculations & EPC
  • Air Tightness Testing
  • Water Calculations

Download the right specification for your project

Do you have a project in mind, configure your specification here.

Learn More