EN 15193, which is the standard relating to the Energy Performance of Buildings energy requirements for lighting, describes a harmonised method of calculation for how to determine energy usage for lighting inside different buildings. Called the Lighting Energy Numeric Indicator (LENI), this is the methodology used to provide a far more effective and flexible approach to building regulations – such as Part L. Voltimum explains LENI here, with the help of the calculation methodology by Thorn Lighting:
LENI is a big step forward for the lighting industry because it promotes the intuitive use of controls and best practice in the use of lighting to minimise energy consumption. This new calculation methodology also reflects much more accurately how a space will be used and lit, based on kWh/m2/year.
The methodology uses a ‘notional building’ that has the same size and shape, and activities, as the real building, but with systems according to Part L2 of the Building Regulations. In effect, this means that two calculations have to be made – the first on the real building; the second on the notional building.
The result is a LENI number, which is for the entire building concerned, and which can be used to compare the energy consumed for lighting. A very useful feature is that comparisons can be made between different buildings having the same or similar functions, but of different design and size.
To read the full article, with its calculations shown, please use the link at the bottom of this page (PDF doc - 167kB file size).
To learn more about the constant illuminace factor, please use the second link at the bottom of this web page (PDF - 57kB file size).
