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Report in "Energy In Buildings & Industry" November 2006.



Effective Lighting Controls Generate Energy Savings of Up To 50% In Multi Storey Car Parks


Simon Cooksey, Technical Director of Oxford Automotive Technologies believes that effective control of lighting in Multi-storey and Underground Car Parks can reduce carbon emissions by up to 50% saving tens of thousands of pounds per year and reducing much maligned light pollution.

Visit any town or city in the UK at night and you can virtually guarantee that they are ablaze with light. This comes from shops, pubs, nightclubs and, significantly Car Parks, be they Multi-Storey, or open plan type. Car parks are generally lit 24/7 and 365 days per year, providing a safe, secure environment to leave a vehicle whilst going around your business.

One has to ask oneself if it is really necessary to leave these lights on all of the time, especially when the buildings are unoccupied, and whether it is more cost effective and kinder to the environment to install a control system to operate the lights only as required.


On average, a reasonable town or city in the UK can service between 5 and 25 multi-storey car parks, the obvious exception being London which is home to hundreds.

In perspective, a large multi-storey car park when lit 24/7 can use up to 950,000 Kw/H/year. This is a very significant amount of electricity and, depending on tariff rates can equate to yearly running costs of up to 90K. Not only that, but the associated Carbon Emissions will be around 400,000 Kg/CO2.

Multiply this by the number of Car Park structures in the UK estimated at 2,000 in England and Wales and the figures are quite astounding.


It has long been a feature of new office developments and commercial developments that lighting is only operated when a building or even a room is occupied. This can be achieved in a number of ways from simple time switches, BMS systems and also proximity detection by use of discreet PIR (Passive Infra Red) detectors.

There is no reason why this type of system cannot be applied to a Car Park, as long as the system is robust and reliable, such that car park lighting is only energised when a particular floor or zone is occupied, be that by a moving vehicle or a pedestrian.





















Historically, however there have been issues with installing this type of system, not least the capital expenditure of wiring to PIRs on floors and modification of control circuitry. This costs money, and also necessitates a closure of the car park whilst the work is being undertaken causing disruption and loss of revenue.


Experiments have been carried out using wireless technology for PIR detectors but until now this has proven to be unreliable. This is due to the inherently hostile nature of a car park environment to radio signals that transmit occupancy data to a controller. Wireless technology has recently undergone somewhat of a renaissance, however and the technology is now available to provide highly reliable radio systems that actually do operate in this hostile environment.


The Control System developed uses a highly robust PIR available in a number of variations for detecting vehicles and pedestrians. These have a powerful microprocessor built in that uses a combination of fuzzy logic and look up tables to determine an operation. When an operation is validated, the signal is sent via an onboard radio transmitter to a receiver located next to the Car Park distribution board. Each PIR is encoded so that the receiver can determine exactly which unit has been triggered.

Upon receipt of an activation signal, the receiver sends a volt free control signal to a dedicated controller that, via a software algorithm selects which lights to operate and provides a relay signal to operate the relevant contactors in the distribution board. The software is fully configurable from a laptop computer or PDA and the ‘ON’ time for the lights to operate can be set from 5 to 30 minutes. Once the set time has elapsed, then the lights will extinguish, unless a sensor has been triggered again. This system is specifically designed for use with high frequency ballasts that due to their inherent design traits, are capable of a number of switch starts per day and also have very short time periods between the off and on cycles.


The beauty of a wireless system is the simplicity and flexibility of installation. Sensors can be fitted to the car park ramps and pedestrian exits without disruption of the car park. The main receivers and controllers are similarly fitted adjacent to the mains distribution boards and wired without disruption. When connecting to existing contactors, only those zones that are being worked on are isolated, leaving the majority of the car park fully lit. This means no loss of revenue and the car park is fully in use during installation. Systems can operate for up to two years using standard ‘D’ type batteries available from most outlets.

This technology has been fitted to a number of car parks in the UK and tests show that savings of up to 50% are achievable, depending on the occupancy characteristics of the car park. The system has undergone extensive scrutiny by the Energy Institute and as a result all of the products and the entire installation is eligible for Enhanced Capital Allowances, being classed as energy saving lighting controls. Installation is swift, taking approximately 1 week for an average car park and due to the energy savings that can be attained, payback periods are typically between 1 and 2 years.

Wireless Car Park Lighting Control Systems are now a proven method of reducing energy consumption leading to lower fuel bills and a corresponding reduction in Carbon Emissions. With the Government emphasis on Energy and Carbon Emissions reduction, coupled with spiralling fuel costs, this technology can no longer be ignored.

O.A.T Ltd * Unit 3 * 10 Great Central Way * Woodford Halse * Daventry * Northants * Tel: 01327 263707 * Fax: 01327 263718