The solution that we have developed reduces the risk of retrofitting domestic properties and failing to achieve the desired outcome in respect of reduced carbon emissions and cost of comfort for the resident.

Energy use from domestic properties accounts for 20% of UK greenhouse gas emissions. Reductions in emissions from this sector will be achieved largely by retrofitting most of the existing 30 million homes in the UK. The average cost of property refit is £30k and requires in excess of 40 labour days to make the necessary improvements. Some requirements have already been announced, but for net zero to be delivered more are set to come which will require enormous investment over the next 28 years.

Retrofitting holds high risk for property owners and residents. The cost of inadequate work can include damp and overheated homes and increased fuel costs for those in fuel poverty.

The current standard for assessing retrofits is the weak PAS 2035\. It is based on visual inspection of installations unsupported by empirical data gathering and analysis. It fails to identify issues that would only appear over a longer period of time such as damp and overheating. There is widespread confusion and concern in the retrofit sector about the ability of a retrofit coordinator to assess if a property has been retrofitted correctly by visual inspection at a single point in time and considering a limited amount of utility bills.

Our proposed approach is significantly more accurate, robust and cost effective than that prescribed by PAS 2035\. It is a data led evaluation of the efficacy of retrofit on an individual dwelling using property monitoring combined with AI analysis. By measuring and analysing parameters such as temperature, humidity, CO2 levels and energy use the energy efficiency and retrofit performance can be better determined and the landlord can be confident as to whether the required outcome has been delivered including:

* actual reduction in carbon emissions
* cost of comfort for the resident and live energy consumption
* occurrence of underheat and overheat
* risk of damp
* residents 'ease of use' of their low carbon home

In order to use such a monitoring approach there needs to be a standardised framework for the sensors, methods, data exchange and certification so that the evaluations are robust, meaningful and comparable. This proposal is to specify such a standardised framework for the evaluation of domestic building retrofit using monitoring data.