Low-energy lighting

Using energy-efficient lighting in your business

Since we started our campaign, we've noticed how much energy businesses are using through lighting. We also recognise that a shop needs to be well-lit in order to display its goods properly - in fact, without the lights on a shop can look closed. Offices and warehouses need sufficient lighting to meet health and safety requirements. Also, businesses need to have lighting on all day, every day. This means that lighting can make up the majority of overall energy costs and almost all of the onsite electricity consumption. Across UK businesses, lighting is responsible for an average of 25% of electricity use (The Carbon Trust), so it's vital to explore ways of reducing costs.
There is a 'triple-bottom line' benefit to upgrading to low-energy lighting:

 - Environmental benefits (consume up to 80% less electricity and, therefore, less carbon pollution; less waste from longer-life bulbs).

 - Operational benefits (reduced maintenance costs; improved productivity; better working environment; visual demonstration of onsite energy reduction).

 - Financial benefits (
inefficient lighting can make up the majority of onsite electricity costs; predictable return on investment; typical payback of under 1-2 years).

Switch over to energy-efficient lighting
Colour temperature and light bulbs

There are lots to things to consider when upgrading to low-energy lamps. There is a low-energy substitute for almost every lamp, but it may take some research to find it. Some of the key issues are:

 - Fitting: check the exact fitting you need for your lamp (e.g. standard bayonet, small Edison screw, MR16, GU10, PAR)
 - Lumens: light output is measured in lumens, so make sure the replacement bulb you select gives out an equivalent level of light
 - Colour temperature: light from a bulb out in slightly different hues, which means that it is important to check colour temperature (K) broadly matches. 

Upgrading incandescent lamps

If you have any of the traditional, incandescent bulbs in your premises, then you are wasting energy and money by using a 100 year old technology. Compact fluorescent lamps (CFLs) are available in all styles and shapes (e.g. candle, golf-ball, spiral), costing as little as £2 each. They use 80% less electricity than incandescents so they return their investment very quickly. The start up time varies between models, but some bulbs give instant light. The quality of CFLs has improved vastly over the last few years. The spiral bulbs give a more focussed light that more closely resembles that from a conventional incandescent GLS lamp (GLS stands for General Lighting Service). 
 LED replacements for standard fittings are just coming onto the market. A 6W bulb is equivalent to about 60W incandescent saving 90% of the energy. The cheapest we've seen so far is £6. 

Is it better to leave a fluorescent on rather than switching it on and off a lot?

There can be some confusion about whether it's better to leave 
fluorescents on when leaving the room. A small amount of extra energy is used to turn on a fluorescent lamp and starter units have a limited lifespan. Generally, it makes sense to turn the bulb off if you’re planning to leave a room for more than a couple of minutes. The cost of electricity over a bulb's lifetime is far greater than the cost of the lamp itself. 

Worried about mercury in fluorescent lamps?

Fluorescent lamps contain a very small quantity of toxic mercury. A typical CFL will contain around 3-4mg of mercury (enough to fit on the tip of a ballpoint pen) and a 4ft fluorescent tube will contain 10-40mg. In comparison, a old-fashioned mercury thermometer contains around 500-700mg. Mercury cannot escape from an intact tube.

DEFRA advise that the tiny amount of mercury released when a lamp breaks is unlikely to cause harm, but care should be taken when clearing up breakages. The room should be ventilated, gloves must be worn, pieces should put into a plastic container and the area should be woped with a damp cloth (which must then be disposed of in the plastic container).

Mercury is an environmental hazard. However, the environmental benefit from the reduced energy use from low-energy lighting outweighs the environmental damage from the mercury. This is because mercury is emitted from coal-fired power stations, so greater energy use means more atmospheric emissions of mercury. Here is a link to a website that's done a back of the envelope calculation.

Mercury-free options for upgrading conventional bulbs

Even if mercury is still a concern for you, there's no excuse for keeping those energy intensive incandescents. One technology that has been on the market for a while now is a halogen GLS, which will only cost a few pounds per lamp. These use the same technology as halogen spotlights to produce an almost identical light to an incandescent and they use around 20% less energy. They are commonly available, but they are the direct replacement that will give you the smallest percentage saving. A more recent mercury-free option are the LED GLS bulbs. These offer energy savings of 80-90% and they have a much longer lifespan than a conventional bulb. You should expect to pay £6-£12 for a good quality LED lamp bright enough to replace a 40-60W GLS bulb but prices are beginning to fall and we've seen one at about £4. Generally 3-4W is needed depending on your lighting needs. A LED GLS lamp will use around half to one-third less energy than a CFL. 

Upgrading inefficient fluorescent lamps

Most light fixtures in business premises tend to use fluorescent tubes, which come in T5, T8 or T12 sizes (the number means eighths of an inch, so a T8 is one inch in diameter). The smaller diameter lamps use less electricity but give out the same level of light. 

It is relatively straightforward to substitute a T12 tube for a T8. 
You can even get ultra-low energy LED fluorescent strips which fit ordinary fittings with a little starter motor replacement. They use about 70% less energy than T12s and last much longer. The T5 lamps are the next most efficient and their cost is coming down. Modern T5 tubes consume around 20% less electricity than T12 and last for longer. Ultimately, the options for upgrading fluorescents are very much site dependent, but an upgrade of the fittings is necessary in almost all cases. Maclean Electrical in Dingwall and City Electrical Factors in Inverness both offer lighting design services.

Upgrading halogen spotlights

Halogen lighting is inefficient and there are often dozens of lamps in the displays (usually more than necessary). This means that upgrading halogens should be a priority. Halogens are slightly more efficient than incandescents (~10-20
% less electricity for same light output), but they are still energy-guzzlers.Low-energy replacements are becoming more common in shops and offices, including CFLs and LEDs  that are being constantly improved. Unfortunately, good-quality substitutes are expensive: a CFL spotlight costs ~£4 and a LED spotlight costs start at about £4 However, LEDs are a particularly cost-effective solution for lighting display cabinets. Remember to take power factor into account when estimating savings - CFLs and LEDs will be converting 60-90% of energy usage into light and some bulbs will have a lower power factor than others. Beware when a manufacturer claims an LED will replace a 50W halogen bulb - the ones that are as bright are at the higher end of the market. LEDs have the longest life of any lighting technology - operating for 30,000 hours or more. One LED bulb can outlast 30 incandescent lamps or 6 CFLs, which means that even if the LED spotlight is slightly more expensive it is likely to have a lower lifetime cost than a CFL spotlight.

How much money will switching to an energy-efficent lamp actually save?

Although an investment in low-energy lighting has a predictable payback, it’s hard to say exactly how much any single replacement would save. This is because there are many variables involved in the calculation, including cost of the replacement lamp, price of electricity, lamp lifetime and rate of inflation). A key factor is how long the lamp is on for and so we have put together two diagrams to give you an idea of how the savings vary according to how many hours the bulb is used every day. We have assumed an electricity price of 13p/kWh, 0% rate of inflation, lamp lifetimes of over one year and usage of the lamp for 5 days a week, 52 weeks a year.

Upgrading a single 60W incandescent lamp to a 12W CFL of equivalent brightness will save up to £39 a year if used for an average of 24 hours a day. This means that investment in a £2 12W CFL will be paid back in as little as three weeks. Even using the bulb for only four hours a day will return the investment in around three months. A 20W CFL that replaces a 100W would pay back even quicker. Even a lamp in occasional use will return its investment in a few months. It really is important to upgrade all incandescent bulbs to CFLs, even if you have to pay perhaps £5 for a lamp of a more unusual shape. Also, a CFL will last many times longer than an incandescent. Lamp lifetime may be an important factor for you to consider, because having a bulb that lasts for years will mean far fewer replacements will be required. If you have fittings that are hard to reach then a long-life bulb will save you getting out the ladder so often. All in all, you can't help but conclude that incandescents are a waste of money and they need to be upgraded.

The replacements for a halogen are more expensive, but they are still a worthwhile investment. Assuming usage for an average of 24 hours a day, swapping a single 50W halogen spotlight for an 11W CFL will save up to £32 a year (returning the investment in around three months). LEDs are slightly more expensive, so they may have a slightly longer payback. A quick reminder that these savings are for individual bulbs. If you have halogens on for long periods, the savings could be huge. Ten 50W halogens used 24h a day replaced with ten 11W CFLs would save £320 in one year. LEDs would save about twice as much. If you have a high lighting demand, your electricity bill could be slashed through a lighting upgrade.

Dimmable lighting

Dimmable lighting circuits are commonplace, especially in premises where light levels are key to the design. Unfortunately, standard low-energy lamps cannot replace dimmable incandescent bulbs. Special dimmable low-energy bulbs are available, but they are more expensive:

Dimmable GLS CFL = £8-£10    Dimmable GU10 CFL = £11-£13    Dimmable GU10 LED = £14-£16 

Even with the higher upfront cost, an investment in dimmable energy efficient lighting is worthwhile. A dimmable halogen GLS lamp will be a relatively low cost option, but it will only save around 20% of energy. Depending on the layout of your lighting circuits, it may be more cost effective to remove the resistor and install lighting with lower output or zonal controls.

Upgrading lighting systems

When considering installing or replacing a lighting system, try to incorporate zonal lighting (connect the fittings nearest the windows to a separate switch), install occupancy and daylight sensors and add timers.
Another way of reducing demand is to select lighter decor so that the room feels brighter. It may also be possible to install light tubes. They reflect sunlight from a collector through a duct and into the room - giving as much illumination as a bulb.

Maintenance and use

Try to reduce lighting levels in areas that aren't in use (e.g. stock-rooms). Corridoors can often be overlit.
Use blinds to regulate the amount of daylight entering the room and kee
p windows and skylights clean to maximise sunlight. Raise awareness amongst employees in your business by putting stickers next to light switches (e.g. turn off when you leave the room!).

Visit the following websites for more details on low energy lighting - there's lots of great information out there:
 - commercial lighting 
Lyco guide- good guide to lighting
Carbon Trust lots of impartial advice on low-energy lighting
Study of how to use low energy lighting in shop displays 
B&Q's energy efficient lighting site, including a calculator
Earth Org - A review of LED bulbs with some honest views on colour, brightness, etc.
RUH Hospital LED Outside lighting case study

Remember to have a look at our pages on renewablesrefrigerationenergy monitors and low-cost energy efficiency measures.
Peter Elbourne,
5 Jan 2012, 02:45