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Addressing the energy demand and associated CO2 emissions from lighting is a key element in complying with Part L of the Building Regulations (2010). Good lighting design is fundamental to cost-effectively meeting the standards. Furthermore, there are added benefits of a good lighting design in terms of occupant comfort and potentially lower running costs.

Good lighting design will meet CIBSE’s recommended values for maintained illuminance, glare and colour rendering for each area/task type. To be energy efficient, it is important that the installed lighting does not substantially exceed the requirements of each room or task. Our experience is that lighting in many rooms is often overspecified, in some cases unnecessarily putting compliance with Part L 2010 at risk.

Lighting design tools such as Relux or Dialux can help ensure that lighting is correctly specified. Example calculation outputs are shown below:

Relux output calculations


Relux output model

A simple example is a corridor in a residential block of flats. These have traditionally been fitted with compact fluorescent lights to an energy intensity of ~12W/m2. Analysis of these installations has shown that the achieved illuminance can be double the 100lux that is recommended by CIBSE. A reduced number of compact fluorescent lights would therefore be able to meet the CIBSE requirements with an energy intensity of 6W/m2.

The benefits of a full lighting design are therefore: –

  • Lower energy demand, thus facilitating compliance with Part L 2010
  • Fewer lights required therefore lower capital costs
  • Lower operational energy costs

Posted on June 26th, 2012