Last week I was invited to talk at the Australian Smart Lighting Summit about Designing Energy Efficient Lighting in Homes... in 20 minutes and with the help of some attractive images, I gave the following presentation to the 260+ attendees - you'll want a comfy chair a bit of time up your sleeve to read this in one session.... however I hope you'll find it interesting and useful in furthering your knowledge of lighting for home.
Before delving into this topic, I would like to draw your attention to the 2 most important words in the title of this session - and they do not start with E… they are Designing Lighting.
By approaching lighting in the home with thought, knowledge and clear design principles you can achieve an energy efficient outcome, without having to resort to counting watts and compromising on light quality.
The basic principle of lighting design is the application of light to provide harmony and useful light for living and completing tasks. Well designed lighting is by its very nature energy efficient.
The quality of any luminaire can be compared by reviewing the manufacturing standards, the efficacy, colour appearance and spectral qualities of the light. One of the best indicators of quality lighting is the ability of the supplier to produce acceptable data which defines the above characteristics in their luminaires. If you head down to the local cheapest LED importers emporium without arming yourself with a little bit of lighting knowledge first, you’re likely to come home with a bunch of light fittings that save energy by failing to produce effective light.
So, for those who haven’t had the opportunity to explore the science of lighting, a quick crash course in the first principles of quality light. After which we’ll have a look at a range of lighting design approaches which make the most of your lighting budget.
There are 3 basic principles that aid us in effectively evaluating light for the home – which is a dramatic change from traditional residential lighting.
All of us grew up with a very easily managed lit environment. $0.60 cents bought you a lamp at the supermarket, you put it in to replace the one that had blown, and moved on.
The light was always the same, and beyond checking you bought the right base and wattage, nothing could go wrong.
With modern lighting however, and by that I mean compact fluorescent “twisty” lamps and LED, getting the wattage and size right does not necessarily guarantee the result you were expecting.
Therefore, you need to understand;
Colour Rendering describes the ability of a light to show colours and people in a room in the right colour tones. We’re all familiar with the experience of buying a coloured shirt in a shop and walking outside to discover that the blue we thought we’d bought was a trick of the light. Colour Rendering describes the rainbow within light. Most commonly, it is listed as a CRI value on data sheets and light boxes. It is measured across 14 standard colours and tells us how well the colours within a space are going to be seen under a given light source. For reference,
Sunlight and traditional incandescent lamps are 100% Fluorescent is either 80% or 90% and LED can range from 50% to 95%. So you can imagine how important this data is when thinking about the quality of the light in your home, and making a selection that will show you and your home in the best light.
Colour temperature describes the appearance of the light. When we first banned the incandescent, many people were horrified at the effect of CFL lamps on their home. In most cases, this was a result of them purchasing cool white lamps, which tint the light blue and can have a very disconcerting effect on a home that has until that point been lit with warm white light. Colour temperature is measured in Kelvin, and is commonly referred to as warm, cool or neutral and cold or daylight. Incandescent is 2800K – very warm and golden, Fluorescent is either 3000K warm, 4000K neutral or 6000K daylight/cold and LED is available from 2800K warm through to 6500K cold. The additional trick with LED lighting is that the colour temperature is not necessarily consistent. Good quality LED lighting will be a set colour temperature, and will also have information available about how much variance there is in the white between one light to the next.
Interestingly, studies have shown that people behave with greater kindness towards each other in warm light – 3000K. So, even if there were no other reasons for selecting warm light in your home, using your lighting to bring more kindness is a wonderful idea.
With the explosion of LED lighting in the domestic market, one of the big issues has been inconsistency of colour temperature. Most people can see the difference in the white in a fitting deviates too dramatically from the light next to it – it will look pink, mauve, green, yellow, blue – and most people find this jarring. Quality LED luminaires now came with an SDCM rating, (Standard Deviation of Colour Matching). What that number tells us is the number of white steps between the chips used in the luminaires. The Just Noticeable Difference – where the majority of people can only just perceive the change in white is an SDCM of less than 3. So, put simply – choose LEDs that have an SDCM of 3 or less for your home.
Calculating the efficacy of a light is key in understanding how much value for money you’re buying. LEDs can be extremely efficient, we all know this. Currently, the best available are up around 110lumens per watt – but this does not mean that every LED is at that level. Understanding efficacy can also help you work out if a particular LED is going to give you enough light – for example, an LED lamp to replace a standard halogen downlight lamp is simply not going to create enough light if it is only consuming 4W of electricity. For a lamp that low in power, it would have to be providing 200lumens per watt – and I can assure you that no downlight lamp is that efficient. Not by a long shot.
So – efficacy is simply – how much electricity in compared to how much light out. How many lumens per watt. Comparing a range of LED lights can seem bewildering – but if you calculate the efficacy of each one, you’ll be in a better position to know how many dollars you are spending on the light you want. It also helps you cut through the nonsense sales brochures that will promise enormous energy savings and like for like lighting effects – putting you in a stronger position when it comes to choosing your home lighting.
2 lights that consume 10W of electricity can produce vastly different amounts of light – and if you’re buying a light – stands to reason you want it to make… LIGHT. So working out how efficient that light is helps you narrow the field. Buying lighting for your home based purely on price and energy – or watts – would be like buying a TV because it’s low energy and cheap – that’s fine if you don’t mind about the picture lag and low definition (let alone the sound) but if you want quality, you need to do your research and understand what you’re comparing.
Quality manufacturers and suppliers will always provide compliant data which will provide colour rendering, colour temperature, lumen output and watts consumed. There are many other factors to be considered – power factors, driver quality, beam angles, quality of manufacture, warranties, price but if you at least check out the 3 points we’ve reviewed, you’ll end up with better results.
The final key with modern lighting that is vital to understand is lumen depreciation. Fluorescent and LED lighting produces progressively less light (for the same energy consumption) over time – as opposed to failing like the incandescent lamp.
Lighting designs are calculated with this in mind.
The “life” quoted by suppliers with regard to LED is usually based on the light fitting producing 70% of its initial light output after X number of operational hours. For a standard home, LEDs are expected to last for many years. However, over that time, they will be subject to lumen Depreciation. Effectively this means that your lights will keep turning on, keep drawing the same power for as long as they work - but will cease to produce producing useful light once they have been in operation for a determined period of time.
Without a failure, there will be no indicator to replace a fitting aside from the fact you can no longer see in your home, even though the lights are on. Compact Fluorescent lamps have the same principle – so if you find that your home is dimmer than you think it should be, and you’ve had your lamps for a few years, it might be worth simply replacing them to bring the light back.
As a result of the variance in the quality of light fittings, especially in LED, learning to make effective comparisons is vital, and understanding these key data give you a great starting point.
SO, how then does all that impact on the lighting design for your home? Put simply – without the maths and science, creating the art of a beautiful lighting design is essentially pot luck. Some people, like some artists, are born with an innate sense of their medium – in this case light – however given the vast array of brushes available in lighting design, being able to clearly know which to select to create an effect is vital.
So, with some of the science under your belt, understanding the process of lighting design will empower you in making smart decisions for the lighting in your home.
We start with architectural plans, and furniture layouts and then ask the most important question – What do you want to see? Once we know where the light is needed, we select the light fittings that will put it there and then work out how to switch them for the most intuitive use of the home. Nothing worse than being faced with 5 light switches and as murphy’s law would have it, having to go through all of them before you find the one you want.
Lighting in the home is regulated by Australian Standards, however, beyond basic safety and essential task lighting, the most important criteria is the ambience in the home – not uniform light levels. We are all familiar with the runway of downlights putting uniform light all over the floor of the home – which is awesome if your floor is the most amazing thing you’ve ever seen, and has been built so perfectly that everyone who ever comes to visit you should arrive and immediately admire it for it’s colour, it’s tones and it’s beauty….
Usually, what you want to see in your home falls within these categories – people, artworks, furniture, work surfaces, stairs and obstacles.
For me, people are the most important thing in a home, so we want to make sure the lighting is kind to faces. Downlights are notoriously bad at lighting people’s faces, creating shadows and highlighting our perceived imperfections. We want to create soft ambient light (professionally known as ambient luminescence) in the areas where people relax and converse, and useful directional light that hits our face evenly and without glare in spaces like bathrooms where we want to be able to see ourselves in detail.
Artworks and personal items on display can be lit by directing light onto walls and using discreet lighting in display areas to highlight the features (think of this as Focal Glow). Furniture will generally be looked after by the ambient light in the room, but where it may present an obstacle, the lighting should provide contrast and highlight the obstacle, without necessarily spotlighting it. Work surfaces in the home, such as the kitchen bench, need higher light levels – but only when they’re being used. Layering your light to allow for high levels and low levels , especially in open plan living areas can enhance the liveability of your home.
Lighting can also be used to define paths of movement through your home, highlighting important areas – such as staircases.
Using contrast in the home creates visual interest, texture and life, and the careful use of colour and varied colour temperature can really add the WOW factor to a home.
The most challenging aspect of domestic lighting for many people comes when it’s time to choose decorative light fittings that are either going to be artworks in their own right, or are needed to provide a bit of spark, and human scale by bringing the light down into the living environment. Choosing decorative fittings really is a matter of taste, but it’s worth keeping in mind that the materials a pendant is made out of have a huge impact on its ability to produce useful light. You need to consider where the light escapes the pendant, is it going to be glary or produce a mean little puddle of light directly beneath it and nowhere else. If you have low ceilings, then a pendant that throws light up as well as down and out can make a huge difference to how a room feels. And finally – you need to think about the lamp you’re putting in it. We can get “replacement” incandescent lamps in both fluorescent and LED technology, but they both behave very differently. CFL is closer to incandescent as it throws light in all directions, while LED replacement lamps throw most of their light directly down. If you have a pendant that needs to be filled with light to look its best, your need CFL, if it is a solid pendant that only throws light down, then LED will likely do the job.
Another point on decorative lighting, we know we can’t use incandescent anymore, because it’s banned and is horribly inefficient. As is the way of things, incandescent lamps were immediately superceeded by carbon filament lamps – also horribly inefficient, but beautiful sources of light and they are a different shape… so that gets us around the import law. Wanting to include this type of lighting in your home is where the real art of design comes into play. Whilst carbon lamps are essentially the deep fried Twinkies of the modern lighting world – having one or 2 strategically placed for effect (assuming they won’t be on all the time because they’ll just keep failing), will not undo all the good work you’ve done using low calorie lighting throughout the home.
Add to all of that a quality control system providing dimming, motion detection, timed lighting and any other control you can imagine and the BCA J6 requirements (which define energy efficient lighting) will be met without you even trying.
A brief word on designer decorative pendants: Pendants can be works of art in and of themselves. They can bring personality to a room and add to the human scale of your home – especially in high voids and double space rooms. As a result of many retailers now selling knock-off pendants as original design, finding a pendant that is both attractive and well-made can be a real challenge. Interestingly, many of these knock off pendants are no cheaper (or at least not much) than original, locally made Australian design light fittings. Locally made can be trickier to locate, but a quick search online will show a dozen or more options in Melbourne, and more than that around Australia. Time spent looking for quality, locally made lighting is well worth the effort - to have lights in your home that are unique to you, and are vastly more energy efficient (think of the transport requirements for large, mostly air, cartons of lights from China or Europe).
The final element of your home lighting is daylight – sky lights and clever glazing can make the difference between an energy efficient home that only needs electric lighting at night and a home that, whilst meeting the BCA J6, is completely inefficient, needing lights on all day and all night to make it habitable. This is especially important in the Winter months, when many people find gloomy houses to be even more oppressive.
So there you have it – designing the lighting in your home to allow you to see the things that are important will give you the energy efficiency you desire, and provide the light you require, with just a little science - colour temperature, colour rendering, efficacy and quality manufacturing and art – ambient luminescence, focal glow and play of the brilliants.
Thank you for reading.