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PHPP energy balance retrofit results

Retrofit Plan

The retrofit plan will describe how the whole building is to be upgraded given all of the relevant constraints. It should aim for approx 70% energy efficiency improvements. It is important that all of the upgrades are considered side by side in order to avoid unintended consequences. It might be that the plan will be carried out as one project or as a series of phases, in which case the plan should consider how to phase the works. 

Retrofit Assessment

Every retrofit project should begin with an assessment of the existing building, which will comprise an energy assessment using PHPP or SAP software and an inspection of the property. This sets the scene for how the building currently performs and allows a targeted approach to be taken to ensure that the retrofit plan can be tailored to the individual building. 

PHPP and simple payback for retrofit measures

Retrofit Principles

  • Ready for Retrofit – Any building defects should be rectified as part of the retrofit plan.

  • Whole Dwelling - Retrofit plans should be considered for the whole dwelling and not as separate individual measures in order to avoid unintended consequences such as a reduction in ventilation provision due to the installation of wall insulation. 

  • Phased installation of measures – Whole dwelling plans do not preclude phased installations of some of the plan but the phasing should be assessed in regard to all the other principles of retrofit. 

  • Fabric First - Retrofit projects should follow a fabric first approach which prioritises retaining heat / energy within the building before looking at heating systems or renewables etc. 

  • Continuity of Insulation – The dwelling should be fully wrapped with insulation without any gaps to avoid cold spots that can cause drafts, condensation, and mould to form.  

  • Consistency of Insulation – Consistent levels of insulation should be specified to all constructions, or any areas of reduced insulation assessed to avoid cold areas that can cause drafts, condensation, and mould to form.  

  • No Insulation without Ventilation – No insulation works should be carried out without a ventilation assessment and subsequent improvements if needed. Any new insulation works could improve air tightness and negatively affect the existing ventilation causing issues with condensation and air quality. 

  • Airtight construction – Reducing uncontrolled infiltration / leakage to a minimum is a key part of a retrofit strategy, however this needs to not be at the expense of proper ventilation. Airtightness less than 5m3/m2h or 5 Ach requires continuous mechanical ventilation or MVHR. An airtightness test should be carried out to confirm the level of infiltration.

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