Conservation of fuel and power: Approved Document L, Volume 2 — Buildings other than dwellings

O N L I N E V E R S I O N B Appendix B: Lighting Energy Numeric Indicator (LENI) B1 The Lighting Energy Numeric Indicator (LENI) method is an alternative approach for complying with the standards for lighting given in Section 6 of this approved document. B2 The LENI should not exceed the lighting energy limit specified in Table B1 for a given illuminance and number of hours run. Step 1: Determine the lighting energy limit from Table B1. If display lighting is used, the lighting energy limit may be increased by the value given for normal display lighting for the area of the room where display lighting is used. Step 2: Calculate the parasitic energy use (E ). If the parasitic energy use is unknown, an allowance p of 0.3W/m2 should be made for any control system. If no lighting control system is used, then E = 0. p Step 3: Determine the total power of lighting (P). l Step 4: Determine the occupancy factor (F ). If no automatic control is used, then F = 1. If controls o o turn off the lights within 20 minutes of the room being empty, then F = 0.8. o Step 5: Determine the factor for daylight (F ). If no daylight-linked dimming system is used, then F d d = 1. If the electric lighting dims in response to daylight being available, then in areas with adequate daylight F = 0.8. This may be taken as all areas within 6m of a window wall or in areas where 10% d or more of the roof is translucent or made up of rooflights. Step 6: Determine the constant illuminance factor (F ). Systems that control the lighting in this c way have F = 0.9, and those that do not have F = 1. c c Step 7: Calculate the daytime energy use (E ). d The daytime energy use is: P× F × F × F × T E (%) = l o d c d d 1000 Step 8: Calculate the night-time energy use (E ). n The night-time energy use is: P× F × F × T E (%) = l o c n n 1000 91 Building Regulations 2010 Approved Document L Volume 2, 2021 edition O N L I N E V E R S I O N