LENI –
Lighting Energy Numerical Indicator
May 2015
T Bowes
Lighting Applications Manager
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• Contents
• Introduction
• The LENI Calculation
• Whitecroft LENI Calculation Tool
• Conclusion
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• Introduction
• What is LENI?
• Lighting Energy Numerical Indicator
• Calculation of ‘Actual’ Usage – power density
(kWh/m2)
• Detailed calculation
• Provides some limiting values (Annex F)
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• Introduction
• Where are the Power Density targets set?
• SBEM Model - Kg/CO2/m2 per annum
TER (Target Emissions Rate)
v
BER (Building Emissions Rate)
• Part L 2A 2013 – Non-Domestic Building Services
Compliance Guide
• Simplified Method
• Alternative to luminaire efficacy
• Defines some target values
• PSBP
• FOS requires calculation
• Building energy target benchmarked against this value
Whitecroft Lighting
Part L2A & Lighting
• Introduction
• luminaire performance & energy performance
• Luminaire Efficacy
• Table 42 advises new lighting level targets
Area
2010
April 2014
Office, Industrial &
Storage Spaces
55 luminaire
lumens/circuit watt
60 luminaire
lumens/circuit watt
Other type of
spaces
55 lamp lumens/circuit
watt
60 lamp lumens/circuit
watt
Display Lighting
22 lamp lumens/circuit
watt
22 lamp lumens/circuit
watt
Control Factors
1 – 0.85
1 – 0.75
• These values are average over the whole building
• Minimum requirement – does not mean the building
energy model criteria are met
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• The LENI Calculation?
• Made up of 3 separate calculations
E kWh/m2 = Ed + En + Ep
A
• Daytime Use (Ed)
Ed = Pl x Fo x Fd x Fc x Td
1000
• Night-time Use (En)
En = Pl x Fo x Fc x Tn
1000
• Parasitic Loading (Ep) – Controls & Emergency
Ep = (Ppi x Tpi) + (Pei x Tei) + (Ppc x Tpc)
1000
E = Total Power Density
A= Area
P = Installed Load
T = Time
F = Control Factor
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• The LENI Calculation?
• A – Area (m2)
• Room by Room calculation
E = Total Power Density
A= Area
P = Installed Load
T = Time
F = Control Factor
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
E = Total Power Density
• The LENI Calculation?
A= Area
• P –Total installed load
P = Installed Load
• Luminaires
T = Time
• Maximising luminaire lumens/circuit watt value
• LED technology allows for significant reduction in the
F = Control Factor
overall power density of a project:
Units of Measure
49%
Energy
saving
36%
energy
saving
22%
Energy
saving
Watts
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
E = Total Power Density
• The LENI Calculation?
A= Area
• P –Total installed load
P = Installed Load
T = Time
• Parasitic Loads
F = Control Factor
Emergency
Pack
DALI Ballasts
Control Device
Units of Measure
• Default values are used in some instances
Watts
W/m2
kWh/(m2/annum)
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
E = Total Power Density
• The LENI Calculation?
A= Area
• T – Total burning hours
• EN15193:2007 provides indicative burning hours
Building
Type
Daytime
Nightime
Total
Offices
2,250
250
2,500
Education
1,800
200
2,000
Hospitals
3,000
2,000
5,000
Factories
2,500
1,500
4,000
Retail
3,000
2,000
5,000
• Parasitic Load – can be 24/7
P = Installed Load
T = Time
F = Control Factor
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• The LENI Calculation?
• F - Control Factors:
• Appreciation of energy benefits of a lighting control
E = Total Power Density
A= Area
P = Installed Load
system
T = Time
• 3 Factors:
F = Control Factor
• Occupancy (Fo)
• Daylight (Fd)
• Constant Illuminance (Fc)
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
E = Total Power Density
• The LENI Calculation?
A= Area
• F - Control Factors:
P = Installed Load
• Occupancy (Fo)
T = Time
Control Factor
1
Type of Space
Method of Control
Manual ON/ Manual OFF
0.8
High Usage:
Offices/Healthcare
Medium Usage:
Corridors
Auto ON/Auto OFF
Manual On/Auto OFF
F = Control Factor
0.2
Low Usage:
Store Rooms
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• The LENI Calculation?
• F - Control Factors:
• Daylight Factor (Fd)
• Maximising benefit from daylight
E = Total Power Density
A= Area
P = Installed Load
T = Time
F = Control Factor
• Understand amount of daylight penetration
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• The LENI Calculation?
• F - Control Factors:
• Constant Illuminance Factor (Fc)
• Providing the required maintained illuminance from day
one
• Typically only applicable to Dimmable Luminaires
• Reduced Power & Energy Consumption
E = Total Power Density
A= Area
P = Installed Load
T = Time
F = Control Factor
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• Whitecroft LENI Calculation Tool
• Based around Part L2A method of calculation:
• Simplified Control Factors & Parasitic Loading
Control Factors:
Fo – 1 or 0.8
Fd – 1 or 0.8
Fc – 1 or 0.9
E kWh/m2 = Ed + En + Ep
A
Ed = Pl x Fo x Fd x Fc x Td
1000
Parasitic – 0.3w/m2
En = Pl x Fo x Fc x Tn
1000
• Target power density values based on time & light level
Ep = 0.3 x m2 x Tp
1000
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• Example Room
LENI
30.95
kWh/m²
• Results Summary
E kWh/m2 = Ed + En + Ep
A
Office
500Lux
3700hrs
Lighting Compliance
37.9
Conventional Source
No Controls
29%
Conventional Source
Occupancy
Fo
Conventional Source
2 rows daylight
Fd
Conventional Source
Constant Illuminance
Fc
LED Source
No Controls
27.0
LED Source
Constant Illuminance
19.0
26%
28.1
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
• Conclusion
• Method for calculating actual energy usage
in a property – kWh/m2
• Sets Kg/CO2/m2 per annum building targets
• Light source and controls will both assist
with delivering the best possible LENI
number
Whitecroft Lighting
LENI – Lighting Energy Numerical Indicator
Any Questions