Refurbishments, Conversions and Extensions

The Requirements

Building Regulations Part L1B specify the energy efficiency standards that a domestic property subject to change of use (e.g. conversion of a commercial property to domestic use, or a change in the number of dwellings), refurbishment, material alteration, or extension in England and Wales must achieve. There are slightly different standards applicable to Scotland and Northern Ireland.

Like Part L1A for new builds, Part L1B defines minimum standards of thermal efficiency for Thermal Elements (exterior walls, roofs, and floors), Controlled Fittings (windows, doors and roof lights) and Controlled Services (heating, lighting, ventilation and renewable energy generation).

Unlike Part L1A, Part L1B standards differ according to whether a Thermal Element, Controlled Fitting or Controlled Service is Provided (new, as in an extension), Retained (from the existing property), Replaced, or Renovated (repaired or refurbished).

The thermal efficiency of Thermal Elements and Controlled Fittings is measured in terms of their U-values. The U value measures the heat energy lost per second per square metre per degree inside-outside temperate difference. The lower the U Value the better the thermal efficiency. The efficiency of Controlled Services is measured by the percentage of input energy which is converted to usable energy (e.g. in the case of a gas heating boiler taking account of heat loss to the outside in hot flue gases).

What ESIW Provides

The local authority Building Control Officer will require documentary evidence that :

  1. A proposed development is expected to meet the applicable standards.
  2. The completed development actually meets the applicable standards.

Energy Services Isle of Wight is qualified to generate the necessary reports from the SAP model to Building Control. These include :

  1. Calculations to show that the energy efficiency of the property following the development will equal or better that of a notional building where all applicable Thermal Elements, Controlled Fittings and Controlled Services meet minimum individual energy efficiency standards.
  2. Energy Performance Certificate (EPC) showing the actual Energy Efficiency Rating (EER) and Environmental Impact Rating (EIR) for the completed development.
  3. Part L1B checklist showing that all individual requirements of Building Regulations Part L1B will be / have been met.

 

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