Lighting has fundamentally changed over the last decade. For the last hundred years or so domestic lighting has been mostly either tungsten filament incandescent light bulbs or fluorescent tubes, but with CFLs and then LED taking over energy efficiency and lifetimes for lighting have vastly improved. We’ve also gained a lot more choice with characteristics like colour temperature, colour quality (CRI) and light distribution. This has given us more power to be creative with lighting design, but also more opportunities to get it wrong.
The standard old fashioned light bulb (incandescent) is not very efficient, with more than 95% of the electricity consumed being emitted as heat rather than light. They work by running electricity through a piece of wire so that it gets hot and glows, with the glass bulb filled with inert gas to prevent the wire burning up.
Fluoro tubes are quite a bit more efficient, but until relatively recently their light quality was very poor, with low quality colour rendering making colours look washed out and people look sickly as well as having considerable amounts of flicker which could bring on migraines in some people. Improvements in fluoro technology reached the market first, with tri-phosphor and quad-phosphor tubes vastly improving colour quality and electronic ballasts eliminating flicker, but the damage was already long done to the reputation of fluoro tubes as a good light source for the home. Compact fluoro lamps (or CFL) were basically a long fluoro tubed coiled up into a bulb-sized shape with the ballast built into the base. They gained more public acceptance and were given a big leg-up with Government support as incentives were introduced to replace inefficient incandescent bulbs with CFLs that used around 80% less energy than an incandescent light bulb to produce the same amount of light.
There were still a few issues with CFLs, including warm-up time, difficulty in dimming, physical size and some poor quality products on the market, but they were overall a vast improvement on the old fashioned light bulbs.
LEDs, or Light Emitting Diodes have now taken over from most other forms of light source. They were first developed around the middle of the 20th century, being discovered when someone noticed an experimental silicon diode glowing in the dark. They have been very common for several decades now as very low-power coloured indicator lights on appliances, starting with red, green and yellow and eventually being developed in a wide range of colours. They are manufactured using similar techniques to computer chips, with very pure materials being ‘doped’ with special impurities to give them different properties, in this case to emit light very efficiently when electricity is run through them.
In the early 2000s ‘white’ LEDs were being experimented with. The problem with LEDs for general lighting is they tend to emit a very pure colour of light, while white light is a blend of all colours. The solution is based on the same technology as fluoro lights, where UV light is changed into visible light using phosphors, special chemical coatings that absorb energy and emit it at different wavelengths. By changing the phosphor blend, you can change the properties of the light emitted. ‘White’ LEDs are most commonly blue or violet LEDs with a phosphor coating, these being the most efficient colours.
At first very expensive, not very bright and with rather poor light quality, white LEDs have evolved very rapidly into a high quality mass-produced product. There are now good LED options to replace almost every type of lighting in almost every situation, and do it with lower energy use and less waste heat. There are also RGB leds, which combine Red, Green and Blue LEDs into a single chip, with each one variable to create a vast range of colours. Not all that useful for normal domestic lighting, but great for parties, art installations, lighting up building exteriors, stage lighting etc etc.
Like any product though, there is a range of quality available, from very high end, expensive, amazing lights through to total rubbish. To a certain extent you get what you pay for, with cheap generic products usually being unreliable and producing poor quality light. The ‘traditional’ quality brands that have always been at the forefront of quality lighting are still relevant, with companies such as Philips and Osram being world leaders in LED technology, along with some newer companies.
Lighting Fittings and Lighting Design
Lighting efficiency isn’t just about the light source though. The type of light fittings and how they distribute the light is critical, as is the layout of the lighting and switches. Every light fitting should have a purpose and the style of fitting and where it is located should distribute the light in a way that fulfils that purpose with minimal wastage of light. The positioning of switches to make switching lights on and off easy ensures that they’re only switched on if required.
What is wrong with downlights?
Downlights, or light fittings recessed to sit flush with the ceiling and aimed downwards at the floor, have become a default standard for domestic lighting in Australia in the last 3 or 4 decades. However, there are many issues with them, making them far from ideal lighting.
For most of this time the light source used has been halogen MR16 lamps, small spotlights with reflectors built in to direct the light downwards. The most common ones used 12V transformers, which increased the light output and lifetime compared to the direct 240V GU10 lamps. They still used a lot of energy though, chewing through 50W per lamp just to light up a couple of square metres of floor. With 4 – 6 in a typical room this meant 200 – 300W to achieve lighting that could often be bettered with a single 100W light bulb in a pendant fitting hanging down from the ceiling.
Because they are an incandescent lamp that worked by getting a wire very hot (2000 degrees+, or over 200 degrees on the back of the lamp!) there’s a serious fire danger from halogen lamps running hot enough to set fire to insulation, timber and debris in your roof cavity. The high heat levels and fire danger also severely compromised the ceiling insulation. Large clearances are required around halogen lights for safety and the heat rising off the lamps would actively draw air through gaps in the light fitting, creating a thermal chimney effect which amplifies the heat losses. A well insulated ceiling must be air tight and with a complete layer of insulation covering it, even small gaps can mean large losses.
Downlighting is also poor lighting design for general domestic use. There are three layers of light to be considered, ambient, task and highlighting. Ambient lighting should be diffused light that fills a room so you can see your way around and feel comfortable. It doesn’t need to be very bright if done well, ideally it should be gentle diffused light washing the ceiling and walls. Downlights are the opposite of this, harsh directional lights pointed at the floor. They are good for task lighting directly over flat surfaces such as a kitchen bench, but this can also be done with surface spots or pendants that don’t compromise the insulation.
What to do about them.
Modern LED lights have solved most of these issues, with much lower operating temperatures (less than 100 degrees, usually more like 60), much higher efficiency (same level of light with typically 80 – 90% less energy use) and the better fittings being fully sealed air tight and able to be safely placed under insulation.
There are a couple of ways of dealing with halogen downlights. The most common way for years was to simply replace the bulb with an LED bulb of similar size, shape and hopefully light output. The benefits of this are lower upfront cost and easy DIY changeover. The downsides are that there are engineering limitations on the brightness of the LED when you’re cramming it into a halogen sized package, there are often compatibility issues with the existing halogen transformer, and regulations say that if it is possible to revert to a halogen lamp in the fitting then it must be treated as a halogen, with the large safety gaps in insulation etc.
There are still many poor quality LEDs on the market though and you do get what you pay for. The ‘free’ government subsidised LEDs are usually very ordinary, often being retrofit bulbs with large ventilation holes, draughtier than having a halogen lamp. Poor quality LEDs, as well as being not so bright, typically have low colour quality and they also tend to have poor consistency between fittings, meaning your ceiling lighting will look uneven and unmatched and your interior design cheap.
A better way these days is to replace the entire fitting with a dedicated LED fitting. You get a better quality, brighter LED with no transformer issues and you can insulate right up to or even over the fitting, depending on it’s rating. The downside is you’re paying a little more for a better light and you need an electrician to swap the fittings over.
The best solution is to remove all of the downlights, patch the holes and repaint and redo your lighting design from scratch. You can achieve a much better overall result for lighting and insulation. If you’re interested in this path give us a call or an email to talk about the possibilities. If you’re capable and willing to do the patching and painting yourself the costs are often similar to replacing with LED downlights, due to less fittings being required overall.