Energy Statement for South Oxfordshire District Council Planning Policy DES10

From the 1st of April 2021, planning applications to South Oxfordshire District Council must be supported by a Planning Sustainability Statement to demonstrate how the proposed development complied with Planning Policy DES10 for Carbon Reduction. 

The target to comply with Planning Policy DES10 is to achieve a 40% reduction in carbon emissions. This is calculated using SAP Calculations and should be carried out by an accredited On-Construction Domestic Energy Assessor.

If the project is non-domestic, then the calculations are undertaken using SBEM for non-domestic energy assessments, preferably by an accredited Non-Domestic Energy Assessor.

Advice on the policy can be found on the South Oxfordshire District Council website.

Pulling out some of the key points, the approach can be a combination of the following:

  • Fabric First Approach
  • Energy efficient building services
  • Renewable energy

Achieving a 40% reduction in carbon emissions to satisfy Planning Policy DES10 can be achieved with the combination of these 3 key elements.

Low Carbon Box have completed several Planning Sustainability Statements to demonstrate how proposed developments meet this requirement.

We are going to use a single dwelling as an example of how this policy was met.

The proposed scheme is for as 3 bedroom detached dwelling based in Cholsey and designed by DP Architects, illustrated below:

As the proposed dwelling was within a tight site, cavity widths were restricted. The basic outline specification was as follows:


  • External walls = 0.26 W/m2.K with 300mm cavity wall construction
  • Roof = 0.14 W/m2.K with warm roof to sloping and flat roofs
  • Ground floor = 0.11 W/m2.K using 150mm PIR insulation in a beam & block floor
  • Windows and doors = 1.40 W/m2.K using double glazed windows
  • Air test of 5m3/hr/m2
  • Thermal bridging details following the Concrete Block Association (

The fabric first approach provides between 13-56% improvements of insulation levels when compared to maximum U values under Part L1A 2013 of the Building Regulations. This reduces the space heating demand.


  • Continuous running extract ventilation using low energy fans which also provide a constant, low velocity change of air to improve indoor air quality
  • Waste water heat recovery using Showersave system. This recovers heat from waste water from the shower and pre-heats the incoming water that feeds the hot water system, lowering energy demand and carbon emissions.
  • Time & Temperature zone control – This allow upstairs and downstairs to have independent heating zones so they can be on separate thermostat and programmers.

These system help reduce carbon emissions further by reducing the energy associated with ventilation and hot water demand.


  • For this project, it was decided to use an air source heat pump to provide renewable energy. The system select is a NIBE system with a winter efficiency of 358% (for every kW energy going into the heat pump, it delivers 3.58 kW heat). Please note the summer efficiency drops.

The combination of these elements resulted in a combined reduction in carbon emissions of 42% which meets and exceeds the target of 40% under the South Oxfordshire District Council Planning Policy DES10.

Alternative approaches that Low Carbon Box have undertaken for this policy include the use of gas boilers and photovoltaic panels combined with improved building insulation levels.


If you want to see more on our planning energy statement services, please click HERE.


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