Education, Feature, Healthcare, Lighting Controls, Office

What if all the UK’s offices, schools and doctor’s surgeries upgraded their lights?

We could easily cut the energy used to light the UK's offices by two thirds, says Dave Tilley

Install lighting controls in all the offices

What if we installed lighting controls in all the UK’s 19 million square metres of office space? A conservative estimate suggests a saving of half a billion kilowatt-hours, with an associated CO2 emission reduction of 277,000 tonnes.

The calculations for the savings are based on the average space required by an office worker and the number of 4 x 18W recessed modules needed to achieve an estimated 400 lx average.

Let’s consider an area using a dozen 4 x 18W recessed modules. If we were to replace them with an equal number of LED panels, we could save 1,800kWh – about 53 per cent of the energy bill. Add daylight linking, and you’d save a further 480kWh a year, bringing energy consumption down to just 1,120kWh, just a third of the original figure.

The calculations are based on 3,300 operating hours a year – about nine hours a day, seven days a week, or 13 hours a day, five days a week. I have assumed the luminaires will be switched off at night, or they will operate in the evening because of the daylight sensors.

If we assume that 70 per cent of the 19 million square metres of office space would have the lighting controlled, then the number of controlled luminaires can be estimated as six million.

Introducing lighting controls to existing installations requires careful management because older luminaires and lighting systems will have limited functionality.


Install LED lighting in all the doctor’s surgeries

What if the UK’s 10,000+ doctor’s surgeries all went LED? The NHS would save 85,011,700kWh together with reductions in associated CO2 emissions of 47,100 tonnes.

These figures are based on the below assumptions together with a number of random visits to GP practices.

The calculations are based on 3,300 annual operating hours. I have assumed a range of light source, 2D, T8 fluorescent tubes, halogen and incandescent.

Visiting a GP is not usually something done out of choice. A pleasant relaxing environment can be of benefit to what can be a difficult experience. 


Upgrade all the school classrooms to LED

What if the UK’s 233,000 school classrooms were upgraded to LED? An estimated saving of 213.9 million kWh together with the associated reduction in CO2 emissions of 118,500 tonnes would be achieved.

The estimated number of classrooms has been calculated using the government average class size, 30, and the number of children aged 5 – 16 in the UK.

The calculations are based on 2,000 annual operating hours.

The quality of light in the education sector, is particularly important as good lighting is critical to the learning process. The installation of new luminaires will deliver efficiency but it must not be undertaken at any cost. For example, if LED panels are specified the glare ratio must be below 19. In the majority of cases manufacturers, of LED panels, do not publish glare ratio figures, let alone have the test data available.

For the purpose of the calculation I have been quite conservative, however the savings are still significant.

You have to wonder if the government or government agencies and consultants are reviewing and analysing ‘what if’ scenarios such as the ones here, in respect of lighting.


  • Lux is hosting a special webinar on Wednesday 27 April at 1pm (BST).
    ‘Best practice: Lighting for Schools’ will look at latest research on lighting in the learning  environment and is free to everyone associated with lighting for education. 
    To view the details and to register for the webinar, click here.
  • For more information on the Lux Webinar Series, click on the logo.


  • This special Lux conference for Facilities Managers is taking place on Thursday 19 May 2016 at the Cavendish Conference Centre in London. Entry is free to specifiers including facility managers, consulting engineers, estate managers, energy managers and others responsible for the management of lighting installations and their specification. 
  • View the full programme and register for your free place by clicking on the logo