Bristol Energy Assessors provide full EPC sampling and cloning consultancy services for Social Housing Providers (SHP) across the South of England and Midlands.
SAMPLING & CLONING DEFINED
Sampling constitutes carrying out EPC surveys on a representative group of properties within a larger collection, which can be shown to accurately reflect the energy efficiency of the whole collection within acceptable limits or tolerances.
Providing the properties sampled fall within the specified tolerance limits, an EPC can be cloned for all properties in the greater collection which were not directly surveyed.
PROCESS
According to government guidance documentation, it is the responsibility of the social housing provider to analyse their stock of housing and divide it into 'coherent groups' which would then be supplied to the DEAs as spreadsheets or a database. This would mean that the DEAs receiving the information would expect the housing stock to have been strictly grouped into common or shared ‘properties’ according to location, built form, age, number of rooms, room heating systems & fuel type, water heating systems & fuel type and common levels of loft and wall insulation. The DEA's assigned to the sample would then select a sample group from the supplied dataset and then carry out an initial visual inspection of the group to confirm their suitability for sampling. If a coherent sample group is observed, each property in the sample group will then be individually surveyed and given an EPC. Once all the sample properties have been surveyed, the results are then analysed to confirm they fall within the specified tolerance limits. If the sample is acceptable, the EPC for the Median property is taken and then cloned for the rest of the properties in the wider group. If the sample does not fall within accepted limits, the group must either be re-defined by the SHP or the sample group can be increased by 30% and tolerance analysis re-applied.
PROBLEMATICS
The levels of tolerance within the sample groupings are narrow and require 'coherence' under very strict limits. This applies rules of tolerance to the SAP rating, Environmental Impact Rating, Floor Areas and any upgrade recommendations, which state that set percentages of the sampled group must fall within specified limits of the Median property identified within the group.
SAP Tolerance 90% of sample within +- 4 points, 95% within +- 6 points of median
EI Tolerance 90% of sample within +- 4 points, 95% within +- 7 points of median
Floor area tolerance 90% of sample within +- 5%, 95% within +- 7.5% of median
Recommendations - 95% of sample must share identical recommendations set
HOW CAN WE HELP?
Acting as consultants our DEAs can assist the SHP in determining the appropriate breakdown of their housing stock in order to produce the most coherent groups of properties for EPC sampling and cloning. Closely involving the DEAs who will inevitably produce the EPCs for this requirement, saves time and increases accuracy - in that the initial batches of properties are strictly selected according to the requirements of the RDSAP (Reduced Data Standard Assessment Procedure).
SAMPLE SIZE & COSTING CALCULATOR
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