On the face of it Self Contained Emergency Lighting can appear as a cost effective option, when directly compared to a Central Battery System. However not many people are aware of their running costs, which needs to be considered for compliance with the Building Regulations; Part L2A & B, “providing and commissioning energy efficient fixed building services with effective controls”.
Let’s have a look at the energy costs you can save by opting for a Central Battery System!
Example based on a design using a 10 kVA Static Inverter and the number of selfcontained
luminaries required to achieve the equivalent emergency lighting levels.
Option A – Self Contained Emergency Luminaries
Energy consumption per luminaire approx: 7 VA @ 0.9pF = 6.3 watts
(excluding maintained lamps)
250 x 6.3 watts x 24 hours = 37.8 kW hours per day
x 365 days = 13,800 kW hours of energy per annum @ 10p per kW/hr = £1,380 per annum
Option B – IT based UPS
(not suitable for this application but could be offered as a prime cost saving)
Battery charging and circuit losses =1250 watts
1250 watts x 24 hours = 30 kW hours per day
x 365 days = 10,950 kW hours of energy per annum @ 10p per kW/hr = £1,095 per annum
Option C – 10 kVA Passive Standby Static Inverter
Battery charging = 250 watts
250 watts x 24 hours = 6 kW hours per day
x 365 days = 2,190 kW hours of energy per annum @ 10p per kW/hr = £219 per annum
An energy saving of £1,161 per annum, when you use an AC Central Battery System.
The larger the system, the greater the cost saving!
