A guide to Part L and Part F of the Building Regulations

Part L and Part F are the two parts of the Building Regulations that most impact heating and hot water.

Approved document L1 of the Building Regulations places requirements for energy conservation upon domestic buildings. This is split into two distinct primary documents:

  • Part L1a Conservation of Fuel and Power in New Dwellings
  • Part L1b Conservation of Fuel and Power in Existing Dwellings

These statutory documents give top level detail on English Government requirements, a further second tier document, the Domestic Building Services Compliance Guide, gives detailed guidance for services including specific efficiency requirements for space and water heating. Devolved administrations in Scotland, Wales and Northern Ireland have region specific documents and requirements.

In order to demonstrate compliance an emissions compliance calculation must be carried out using Standard Assessment Procedure (SAP). To comply, the Dwelling Emission Rating (DER) must be equal to or less than the Target Emission Rating (TER), with DER taking into account regulated carbon emissions including space and water heating. Given the relatively challenging overall building compliance targets set in the current 2013 version of Part L the efficiency of heating and hot water equipment is a key specification point which can have a marked impact on the overall DER.

In the case of retrofit and replacement projects, compliance is simpler; however, boiler efficiency has a part to play here as Energy Performance Certificates (EPCs) for dwellings can be improved by using more efficient products.

You can find out more about Part L of the building regulations here.

Part F of the Building Regulations sets requirements for building ventilation.  The key statement  in it is:  'there shall be adequate means of ventilation provided for people in the building'.

Appropriate ventilation helps to dilute and remove air pollutants as well as reduce humidity and reduce the potential for condensation. In short, ventilation provides fresh, clean air - reducing health risks to people and protecting the building fabric from damage.

Types of ventilation systems within Part F

Under Part F, a number of variables are used to calculate the background ventilation required for a building based on its design and occupancy.

There are four ventilation systems within Part F:

  • Intermittent extract fans and background ventilators
  • Passive stack ventilation and background ventilators
  • Continuous mechanical extract and background ventilators
  • Continuous mechanical supply & extract with heat recovery

You can find out more about Part F of the Building Regulations here.

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