Converting to an Eco-Friendly Home E-Book

Paul Hymers

• Herausgeber: IMM Lifestyle Books
• Kategorie: Lebensstil
• Sprache: Englisch
• Veröffentlichungsjahr: 2019

Seitenzahl: 326

Beschreibung

For a large number of homeowners, the importance of the environment has been highlighted as issues such as global warming becomes big news. With 7 chapters covering elements including Light, Power and Heat, this book covers alterations that anyone can make to their home, from changing to energy-saving lightbulbs and harvesting rainwater to harnessing sunlight through solar panels. Information is given on changes from the very small through to major projects that will male homes healthier and more sustainable. "Converting to an Eco-friendly Home" is a highly informative, easy-access book which provides clear and concise advice on what you can do around the house to help the environment. This book will be an indispensable guide, both for those people who aim to do some of the work themselves, as well as those employing designers and builders to realise their plans for a 'greener', more sustainable home.

Leseprobe

ACKNOWLEDGEMENTS

Thanks to Carl for support and technical advice on all matters electrical. And to all those engaged in eco-friendly improvements who have allowed me to share in their experience and enthusiasm.

DECLARATION

The views expressed in this book are those of the author and do not necessarily reflect those of his employers.

Contents

Introduction

Chapter 1 Light

Chapter 2 Power

Chapter 3 Heat

Chapter 4 Shelter

Chapter 5 Air

Chapter 6 Waste

Chapter 7 Water

Epilogue

Glossary

Useful contacts

Index

Introduction

Climate change, caused by global warming, is a problem that affects us all. Yet the global environment is way too large for us to influence individually. On the other hand, the small part of the world in which we spend over half our lives is entirely under our control. Our home is also our environment; it is both shelter and sanctuary from the elements and the pressures of life. This book is about making small changes to your home, things that you can easily do to reduce the effect you have on the environment – your own carbon footprint – and things that will also create a healthier home in which to live.

One day, no doubt, we won’t have to think about making ‘green’ choices or increasing our environmental awareness, because those choices will have been made already and that awareness will have become second nature. The problem is that ‘one day’ may be some time in the future.

In the meantime, while adapting your lifestyle may not be easy, adapting your home is relatively straightforward. Simple alterations that improve insulation and lighting, cleanse the air, reduce water consumption and increase energy efficiency will soon pay for themselves. More ambitious changes can free you, in part, from the grip of power and fuel companies, setting you on the road to self-sufficiency and saving you money for years to come.

Most importantly, you will not only create a better environment for your home, but also a better home for the environment.

Light

An eco-friendly home is a home blessed with light.

Light brings with it security, serenity and good health. It reacts with chemicals in our skin to create vitamin D, feeding our bodies with calcium, but much more than that it engenders a sense of well-being that feeds our minds, and lifts our hearts and our spirits. It is no coincidence that when homes are judged for fitness under public health laws, the amount of daylight afforded to rooms is measured. A minimum of ten per cent window area to floor area has been considered the minimum for habitable rooms for some time, and if you’ve ever had to spend time in a basement away from daylight, you’ll understand why that is. With advances in glazing, such as Low-e glazing (see diagram, right) we can stretch that ratio to 33 per cent to give us the best possible exposure to natural light.

Improving natural light indoors

Of course the very best form of light is natural light, and to be truly green you would have to live by it alone, but that would be a little restrictive. For the times when natural light is insufficient for our requirements, we have to create light artificially, and it seems we need a lot of artificial light these days. But before we get into that, we can look to see if we are making the best possible use of the daylight that is free to us all.

When the first glazed windows were used in the 16th century, they were formed from tiny panes that were joined together with thick strips of lead. Daylight had a hard job to penetrate them. The Georgians made huge windows to accommodate the fact that small panes of cast glass were still being used between substantial timber bars, and it wasn’t until 1838, when the rolling process of glass manufacture was invented, that windows had more glass than frame. Rolling made it possible to make larger panes. The Victorians gradually increased their size in the styling of their sash windows, which once had contained as many as eight panes in each sash, leading to just two in the Edwardian era. Edwardian homes that haven’t since been modernized with plastic double-glazed units are flooded with daylight because of them.

Low-e glazing

Windows are still large to this day, but by a strange twist of fate, the method of supporting the glazing is still reducing the amount of light they let through. To avoid the chore of repainting window frames, we have switched from wood to plastic, and to improve insulation, double-glazing has become standard. The gap between the panes has grown progressively wider, and now two panes of 4 mm glass are used in most, with a 20 mm cavity between them.

PVC-u replacement windows have been installed at a phenomenal rate since the 1980s, but plastic isn’t as strong as timber, and to compensate for that the framework has to be thicker. The sections are deep and chunky, and on a standard double-casement window measuring 1.2 m wide by 1.05 m high, the glass can be account for less than 75 per cent of the whole area.

It is worse than you think. The single thin sheets of glass used by the Edwardians might have been terrible for keeping in the heat, but they were excellent for letting in daylight. Almost all ultra-violet light can pass through single glazing, but only 75 per cent can pass through a 20 mm double-glazed unit, while a triple-glazed unit offers significantly worse performance. Consequently, larger areas of glass are needed to compensate for that light loss.

To put it simply, we need bigger windows if we are to enjoy the benefit of daylight fully. The problem is that even the best triple glazing can lead to a significant heat loss compared to an insulated wall. At best, it offers an insulation value that is slightly worse than a cavity wall comprising two skins of bricks and no insulation. The best double-glazed windows are comparable to a solid one-brick wall in the rate of heat loss.

Floor plans of two identical terraced homes showing the extent to which daylight can penetrate rooms when different windows are installed

There is some balancing to be done here: as well as sizing windows, their orientation lies at the core of the problem.

In spite of the fact that light travels at a constant and incredible speed, it is easily deflected. Daylight arriving on vertical walls does so at an angle; some of it is reflected, some becomes distorted by double glazing and some makes it into the room just behind the window. High-level windows and windows that are tall rather than wide are much better for lighting a room, although ultimately a combination of both is best. Patio doors are great for letting natural light into a room, but traditional thinking in house design has restricted most homes to one pair, which tend to be stuck in the back somewhere and covered with a conservatory later.

My guess is that in most homes there is at least one window that could be replaced by a pair of glazed doors, without having to widen the opening or disturb the lintel over it. All that’s required is to cut out the wall beneath it, install the doors and make good the reveals. Of course if extra doors will prove to be an unwanted security risk downstairs, full-height glazing can be used instead with openable vents as required. Full-height glazing is in architectural fashion at the moment, and many new-home builders are installing glass that stretches from floor to ceiling. To do this in an existing home requires some structural alteration. Better to stick with your existing window openings and extend beneath them. Upstairs, you can do the same with fixed toughened glass or opening doors and a ‘Juliet’ balcony. If you don’t want to run to the expense of a balcony railing, a pane of 10 mm toughened glass fixed 1100 mm off the floor will keep you safe.

ROOFLIGHTS

Many of us have rooms where we have to switch on the lights during the grey days of winter, particularly in semi-detached and terraced houses where the windows are only at the front and back. There is only so much you can do to bring light into the centre of the home from two end walls, but you can look to the roof for light.

Light from above is better than light from the side. A rooflight, or skylight, that is half the size of a window will provide twice the light. Laid on the slope of your roof, a rooflight is likely to suffer from none of the shading obstructions that can bedevil a wall window, and since the light hits it more squarely, much more passes through.

The manufacturers of roof windows have targeted the loft-conversion market, and in doing so have developed their products for remedial installation rather than new build. For those of us looking to convert to greener homes, this is a happy coincidence. The windows are attractively priced, easy to fit into an existing roof and, to cap it all, have wooden frames rather than plastic. But why draw light into our lofts if we aren’t converting them you may ask. The answer is that while letting daylight into your loft is still a good idea, getting it down into a room is even better, and this is the objective. Creating a light well between the ceiling and the rooflight isn’t difficult in modern homes where the roof often has a shallow pitch.

Penetration of light through rooflights on flat and sloping roofs is enhanced by shaping the light well

Light wells are usually constructed from a timber framework that supports a plasterboard lining, and can also be insulated as necessary from the cold part of the attic. The rooflight and light well can be installed between the rafters and ceiling joists, or these can be cut back and the opening trimmed to allow a larger assembly to be fitted. Usually the trimming timbers are doubled around the opening to support the cut rafters and joists, but since this is a structural alteration, you should take advice from a professional. Building codes and regulations usually apply to structural alterations like this.

The angle of light through skylights

If your roof is made from a series of trusses, under no circumstances should you cut them without obtaining an approved structural design. Trussed rafters comprise a web of thin timbers, joined by metal plates, which work in tension and compression, and they can’t be cut and altered like a conventional ‘cut-and-pitch’ roof structure. Most trusses are set 600 mm apart, and slender rooflights are made to this width, which means that you won’t need to cut through the sloping rafters or the ceiling ties.

Kit form skylights are designed for easy installation

Using 50 mm x 50 mm softwood and 9 mm plasterboard to form the shaft will keep the weight of the structure down to a level that the trusses should easily support, but if necessary bearers can spread the load over several of the ceiling ties.

Pyramidal rooflight

Rooflight structure trimmings around opening

Of course some of the light will be lost as it travels down the shaft, so it pays to keep it as short as you can, installing the roof window lower, rather than higher, on the roof. If the shaft ends up more than 1 m high, you will start to lose much of the light’s brilliance. You can improve matters by painting the shaft white to reflect the daylight and splaying out the base as the ceiling joists allow to create a ‘bell’ shape that is wider at the bottom than the top. More than anything, a south-facing rooflight can bring a little sunshine into a dark part of your home, whether it’s over the stairs or in a bedroom.

Channelling the light down even farther to the ground floor can be done, but it requires either a larger well or a shaft with a highly reflective surface. A larger light well will take up valuable floor space upstairs, so instead pipes made from shiny metal sheeting can be used to create sunshine ducts, or light tubes, that beam the daylight down from the roof. In this case, the rooflight bit is little more than an acrylic dome or pyramid, while the pipes are only 300 mm or so in diameter, but they can be effective. The smaller ones have the benefit of fitting between floor joists and rafters without the need for cutting and trimming if you can get the alignment right, but they do tend to lose their effectiveness over a distance. I’ve planned to install a 300 mm diameter example, south-facing, that is about 3.6 m high from roof to ground-floor ceiling to boost the daylight in my kitchen, but I am aware that this is stretching its capabilities, and it may not prove as effective as I would like.

Conservation style rooflight

Cross-section shows a ventilated roof cavity maintained around skylight

Cross-section shows a thermal break between skylight and roof

INSTALLING A LIGHT TUBE

Light tubes, or sun pipes, are a relatively new invention. They appeared in the early 1990s and have occupied a very tiny space in the market since then, not least because of their cost. Of the hundreds of building projects I become involved in each year, I only get to see a handful of these being installed; mostly they are in school corridors, which is a shame because they have the ability to effectively channel daylight into dark parts of our homes – daylight that keeps us from switching on light bulbs. In schools, where daytime use is predominant, the payback time on light tubes is thought to be as little as six years, but unfortunately in homes, you could look at 20 years as being more likely because they aren’t very cheap to buy.

THE MAKE-UP OF LIGHT TUBES

Light tubes are little more than thin aluminium pipes that are pushed together in short sections to build a tube. The inner surface is highly polished and reflective, having either an anodized finish or a multi-layer polymeric film coating, which allows most of the daylight to bounce down the tube and into your room via a ceiling diffuser. Low technology to say the least, but they are effective. I have seen a 300 mm-diameter example, in bright sunshine, easily light a small internal bathroom. On dull and overcast days, the light level drops off rapidly, but for much of the time a tube of that size can light an area of 10 sq.m to a comfortable level. Some tubes look a bit like an aluminium version of the flexi-hose used for tumble driers and air vents, but although these are easier to install and are much cheaper, they don’t have the reflective qualities necessary to make them worthwhile. When you realize that some reflection of light is knocked back at the roof lens, then again within the tube as it travels down it and finally at the diffuser, you can see that you can lose a good percentage of daylight in the equipment. Hence the shorter the tube and the wider its diameter, the more daylight you will receive. These tubes come in diameters up to 750 mm, but few of us can accommodate such a large duct in our homes. If all you had to run it through was the loft space, it might be possible, but for most lofts, a tube no more than 2 m long would allow a 300 mm-diameter model to be used quite satisfactorily.

Light tubes are assembled from kits, in sections

Assembled light tube

Converting to eco-friendly artificial light

Having done all you can to improve the natural light indoors, it is time to improve the artificial lighting. It is quite possible to save energy here by rethinking the way in which you light your home as well as changing to energy-efficient lamps.

As a rule, we tend to have a poor understanding of our lighting needs and often choose the wrong fittings. As a result, we end up wasting power with needlessly bright lighting and incorrect controls.

CONVERTING YOUR LIGHTING

In terms of conserving power, converting the lighting of your home to more eco-friendly status is the easiest way to achieve results.

Lighting tends to be forgotten until it is too late to reap the full benefits of choice and design, but with any eco-conversion project, it needs pushing to the front of your mind – well ahead of the decorating. Don’t let your efforts stop at fitting a few low-energy light bulbs. You might also look at switching: an internal passive infrared (PIR) switch (see Glossary page 169) or a programmable dimmer switch may be far more efficient than a manual switch that always produces full power and tends to be left on after the room has been vacated. Spaces that we visit temporarily are prone to this. Bathrooms, hallways, stairs and landings that we pass through are all ideal areas for automatic PIR detector switching.

Fitting a PIR that can be adjusted for the time period it stays on after the area has been vacated is essential. I have one that switches on a low-level brick light in my en-suite bathroom. It produces more than enough light from a 10 watt lamp to use the room at night without disturbing anyone and switches off a minute after the room has been left, just enough time to use the reflected light to find my way back to bed.

What matters most about lighting is getting it in the right place and achieving the right effect. Light can be stark and even, bright with contrasting shadow, soft and relaxing, and a variety of hues if not colours. Deciding on what you want for a particular room will mean thinking about how you plan to use that room. In kitchens, adjustable and worktop lights should be employed as task lighting. Bathrooms, bedrooms and dining-rooms benefit from softer light to create a relaxed atmosphere, and lounges may need a variety of lighting options for reading, watching TV and so on. New homes often demonstrate an astounding lack of imagination when it comes to lighting, developers hanging a pendant fitting somewhere near the centre of each ceiling and leaving it at that. That is ambient or general lighting. It is the canvas on which you can create something better, something that is not only more energy-efficient, but also more imaginative and atmospheric. Eco-conversion work can give you the opportunity to install light fittings where you’ve always wanted them, to produce something unique, illuminating your home more effectively and efficiently to save energy in the process.

Energy-efficient lighting relies on three key elements:

•The right position

•The right light source

•The right light fitting

Position

Finding the right position for a light fitting might just be the hardest of the three. The lights in your home may not be in the best positions at present. Ceiling lights can be used for general lighting of a floor by placing them centrally, or as floodlights placed over a chair or sofa to pick out reading areas or work surfaces. Tungstenfilament pendant lights are often overpowered, 100 watts being common on a lounge ceiling, and this is a good place to start. A compact fluorescent lamp replacement of 11 watts will cope with the ambient lighting requirement in most lounges, providing the background (ambient) light source.

Not all of these lamps are pretty to look at, however, so you might consider fitting a shade beneath it to deflect the light up and across the ceiling. If you do, make sure it is highly reflective because you will lose brightness in the reflection. Swirl and decor bulb shapes are available if they will be visible.

In most cases, the right position for a light must ensure that the sharp glare from the lamp itself doesn’t hit us in the eyes. With spots and LEDs (light emitting diodes), if the lamps themselves can’t be seen, just the light from them, then that is good positioning. If you’ve ever had a glass table lamp, you’ll know what I mean. The glare of the bulb fills your retina, even when you aren’t looking at it. In the early 1980s, fluorescent strip lights with their stark illumination were often fitted in kitchens where strong lighting is needed. They do cast a shadowless, even light over everything when mounted to a ceiling, but the fitting might take the older-style tubes known as T12s; T8s are the energy-efficient replacements for these, and apart from being slightly thinner, they appear no different. They are, however, classed in the energy-efficient category.

Reading lights are a form of task light, but it isn’t always easy to direct them. You might prefer the freedom of being able to move furniture like armchairs and study desks around, in which case you won’t want to fix a wall or ceiling light in any position. Portable plug-in lamps are the answer, but they may only use tungsten-halogen bulbs, so make sure they come with dimmer controls. I have a portable standard lamp that combines an uplighter and a smaller reading light on a flexible stalk, both of which are dimmable, but I’d be even happier if the reading light was an LED cluster.

Light source

ENERGY-SAVING LAMPS

Just by changing two filament light bulbs for compact fluorescent ones, you can save the equivalent of 1 tonne of coal from the fire over its lifetime. I’m sure Edison would approve. It was a neat idea of his to heat up a thin wire filament in a glass bulb until it glowed white hot, but really it is time for a change.

Ironically we are going back to gas lights long after Edison got us away from them – compact fluorescent lamps (CFLs) work by using electricity to agitate gas molecules, which then emit light. In this way, the standard CFL bulb burns for 8000 hours, emitting a warm white light with a colour temperature of around the 2700 k mark. This soft light can be misinterpreted as being ‘dim’, even though a 25 watt CFL will produce around 1600 lumens (comparable to the strengh of a 100 watt tungsten filament bulb).

The reason for this is the low temperature of the light. We have developed a taste for a cleaner, whiter light, more akin to daylight. I strongly believe that it has been the light temperature that has put many people off replacing their tungsten-filament bulbs with energy-efficient ones. That combined with a restricted availability of compatible decorative fittings, and the fact that you couldn’t use any controls with them beyond a rocker switch. They haven’t been compatible with dimmers and automatic sensors, but recently some manufacturers have cracked those nuts.

UNITS OF LIGHT

Lumen (lm) – luminous power (or lux)

Luminosity or Luminance – the emission or reflectance of light

Efficacy – measured as lumens per watt (lm/k); theoretical maximum of 683, but should be at least 40 for energy efficiency (eg. 30 lumens from 18 white LEDs of 180mA consumption – 10 mA per bulb)

Candela (cd) – unit of luminous intensity

Lux (lx) – Unit of illumination on a surface (lumen per square metre)

Power – consumption in milliamps (mA)

Watts (W) – power output: approximately 1 watt creates 10 lumens

Daylight-simulation CFLs are now available with a colour temperature between 5000 and 6350 k, similar to daylight with that cooler, bright bluish white light we’ve enjoyed with halogens. If you want to replace some power draining spotlights in the kitchen for example, you can now find floodlight reflectors in the daylight group that are still energy-efficient bulbs of up to 40 watts. At this end, they would be equal to 75 watts in a tungsten-filament floodlight. That is the top end, brightness-wise; you could come down to 20 watt reflectors if they were carefully directed to reduce your power consumption.

LEDs are good for task (reading) lighting when they can be focused close to the subject in a narrow beam (eg. 20–30 degrees).

Different styles for energy efficient lamps

TYPICAL COMPACT FLUORESCENT LAMP PERFORMANCE

CFL

TFL equivalent

Lumens

Life (hrs)

7 watts

30 watts

220

8000

9 watts

40 watts

450

8000

13 watts

60 watts

800

8000

18 watts

75 watts

1100

8000

25 watts

100 watts

1600

10,000

These floodlights aren’t as efficient as standard CFLs, however, as you can see from the accompanying table. You can interpret ‘lumens’ as brightness.

The warm and softer light of 13 watt CFLs can be used in bedrooms and dining-rooms where subdued lighting is agreeable. You can find them in decor globe format or swirled into artistic tubular corkscrews, capable of being fitted to a range of light fittings, although not all. Replacing your bedroom ceiling lamps with CFLs is the ideal place to start. For reading and in bathrooms, where a cooler light might be better, look for those CFLs with a colour temperature of around 4100 k – not quite daylight, but close.

Controls have been the other big stumbling block with these lamps. We need dimmable lights in most of our reception rooms and bedrooms today, allowing us to adjust the lumen output to suit our mood. At long last, some CFLs are now compatible with dimmer controls where the light can be reduced down to around 20 per cent of its full brightness. They aren’t common yet, and you will have to seek them out from specialist suppliers. It is also possible to use them with PIR motion detectors and photoelectric switches that operate at dusk, which means that at last we can have our garden security lights saving energy and money for us rather than burning electricity.

LIGHT EMITTING DIODES (LEDS)

An exciting discovery has been made in recent years with those little red diodes that started life in the 1960s in calculator displays. Somebody found a way of making them white, improving their brightness and clustering them into useful lamps. We’ve had coloured light emitting diodes for decades, but white had long been a problem. This was solved by surrounding a blue LED with a phosphorescent dye that glows white when the blue light hits it. Fluorescent lamps employ a very similar trick by producing ultra-violet light in the tube and using a glass coating to turn it white. The technology is improving all the time.

A GU10 fitting (left) can house a cluster of tiny LEDs (enlarged, right)

LEDs may give a clean white light, but individually it is not very bright. Consequently to light a room with them effectively, they have to be clustered into substantial groups. A cluster might comprise 20 LEDs, all neatly packed into a circular lamp like a GU10 fitting, commonly used for recessed halogen spot lamps. A light fitting like this would normally have housed a low-voltage or mains halogen lamp of 35 or maybe 50 watts. Bright, white and hot – very hot. In this same size fitting, 20 LEDs will glow using just 2 watts altogether, 0.1 watt (100 mW) each. Not only will they do this, but also they will do it without giving off any heat. I have held my hand almost touching one and there was not a suspicion of heat coming off it. The room I was in was a loft-conversion bedroom with a low ceiling, and the halogen lamps that had been installed in every other loft conversion and extension I’d visited would have heated a similar room to an uncomfortable level.

Halogens were designed as spot lamps, and recessing them into ceilings, as so many of us have been doing since the 1990s, meant that they focused bright shafts of light on to the surface below. If that surface was the floor, the ceiling had to have quite a few lamps dotted over it to light the whole room. These lights are ideal for task lighting where you need bright and directed light, but they rarely get used for that. Instead we have peppered our ceilings with them to create ambient light the hard way, and in so doing have wasted a lot of power and created a lot of unwanted heat. In a low ceiling where your head is not far beneath the lights, feeling the scorch of halogen every time you walk beneath one is unpleasant. In one standard sized kitchen, I counted 20 halogen spots in the ceiling, each burning 35 watts – that’s 700 watts at the flick of a switch, and almost enough residual heat to make toast.

LED LIFE

LEDs have a life expectancy of around 30,000 hours, which, according to my pocket calculator, means that you could leave them switched on for 24 hours a day, every day for almost four years before they needed to be replaced. Effectively, in normal use, you can forget about having to change them.

CHANGING LOW-VOLTAGE HALOGENS FOR LEDS

Note that 12 volt (extra-low-voltage) LEDs will not tolerate voltage swings created by wire-wound ballasted transformers. Electronic LED-compatible transformers are required if you’re planning to replace your 12 volt halogen lamps with 12 volt LEDs.

LED light with remote transformer

An average sized double bedroom might have a dozen fittings in the ceiling, each covering 1 sq.m of floor with light. Rooms like bedrooms, dining-rooms and landings, where softer light levels are ideal, are most suited to them. Lounges, kitchens and reception rooms tend to need brighter ambient lights or task lighting, so I would avoid them in such situations.

LED EFFICIENCY

Power consumption runs with brightness, and energy efficiency measures brightness in lumens per circuit watt of power. Typically 18 white LED bulbs in a fitting might produce 30 lumens of light for 180 mA of current, about 1.3 watts of power. This amounts to about 70 mW per bulb. Coloured LEDs offer a lower lumen output – around 20 in the same fitting.

The measure for energy efficiency to kick in has been set at the around the 40 lumens per circuit watt mark. Given this specification, they fall short, but I’m sure their performance will be improved in the near future, so keep an eye on the data. At present, they need using in the right place, and that is where we all could sort out our light energy use. Wasted light is wasted power and money. Directing light where it is needed, in the right levels, is far more important than covering your home in 40 lumens per circuit watt.

In a nutshell, LEDs aren’t much more efficient than tungsten-filament bulbs at present in this context, which is why you can’t afford to use them to illuminate rooms with ambient light and expect to save energy.

CABINET AND WORKTOP LIGHTING WITH LEDS

We tend to go for decorative lighting of cabinets these days, as well as functional under-unit lighting of worktops. Both are ideal tasks for LEDs, which can be installed as clusters in GU10 fittings or slotted individually into tiny drilled holes. The angle of light reflectance is worth noting in these situations. It is as variable with LEDs as it is with other lamps. A 30-degree angle would be defined as narrow, for spotlighting purposes, and a 130-degree angle would be defined as broad for wide-angle light. This is particularly important with LEDs because brightness is proportional to beam angle. A narrow beam will be much brighter than a spread one. For example, seven bulbs focused on a 20-degree spread will achieve the same lumens as 48 spread over a 50-degree beam. Forgetting the science, one cluster of 20 LEDs in a GU10, spaced at 600 mm intervals above a worktop will work brilliantly to light it from beneath wall cupboards or a pelmet.

Flush mounted fittings

ELECTROLUMINESCENT LIGHTING

Don’t get too excited if you haven’t heard of this. It is a new form of cool burning, energy-efficient lighting that, at present, is really only usable in signage and decor. A tiny capacitor is printed on a silkscreen with a phosphorous-based ink on its surface. When a small electrical field passes over the capacitor, it excites the ink’s electrons and illuminates them. These are sometimes referred to as light emitting capacitors (LECs).

LECs are wafer thin and flexible, and can be adhered to almost any surface, but to date you might be most familiar with them in the display of your mobile phone or car dashboard. For safety marker lights on stairs, they could be ideal, but most of the advances in this material seem to be in the glowing, colour splashed world of advertising, where it is being employed with great creativity. I suspect that LECs will become available for installation in our homes to enhance the decor in a room, rather than illuminate it.

Electroluminescent cell structure

THE COLOUR OF LIGHT

Lamps are a long way from being white all the time, but then white is not always the colour you want. Apart from the many coloured lamps available, which tend to provide significantly lower illumination, specific types of lamp have unique hues, determined by their colour temperature.

The varying wavelengths in light’s electromagnetic spectrum are interpreted by our brains as colours – red for the longest wavelengths (700 mn) and lowest frequencies, violet at the shortest wavelengths (400 mn) and highest frequencies. The colours of the rainbow fall between them. Outside of those limits, our eyes can’t see the infra-red before the red kicks in, or the ultra-violet after the violet drops out. We can, however, feel the heat from infra-red light on our skin. The lower the colour temperature, the warmer the light. Take candle light for example. At less than 2000 deg.k, it is edging out of the red and into the orange end of the spectrum. Sunlight on a summer’s day is in the middle of the scale at around 5500 deg.k, but rising up into a blue sky away from sunlight sees the colour temperature increase to 9000 deg.k.

Light fittings

Without the right fitting, your choice of light source and position will have been wasted. The fitting determines how the light is directed around it and reflects the architecture of your home and its interior design. Choosing the right shade will also affect the light level. One fitting you can easily change is the living-room light switch; swapping it for a dimmer switch will give you the chance of altering the ambient (or background) light level.

A COMPARISON OF FIVE LAMP TYPES

TUNGSTEN-FILAMENT

Energy efficiency variable between 1 and 20 lumens per watt, but generally very poor with an average inefficiency of 91 per cent. The traditional standard bulb has a yellowish light of 2000 deg.k. unless in a corrective blue glass bulb as a daylight correction type. This type of lamp should not be used for ambient lighting due to its power consumption and short life expectancy.

TUNGSTEN-HALOGEN

Very popular since the 1990s. White and crisp light, typical as low-voltage or mains-voltage recessed spotlights. Colour temperature of around 3000 deg.k. Small and long lasting, tungsten-halogen lamps produce focused light that works well in uplighters and downlighters. The low-voltage types do have slightly better energy efficiency, but the transformers needed to convert mains-voltage to low-voltage use power inefficiently and thus are a problem. As small spotlights, they should not be used in multiples to provide ambient lighting.

METAL-HALIDE

New for domestic interior use, these lamps offer high efficiency, making them cheap to run. In the form of high-intensity-discharge (HID), they have been used in car headlamps and street lighting as sodium (orange glow) lamps – the most efficient light source known to man. Now also in garden spotlights. For indoor use, the white light halides have five times the efficiency of standard tungsten bulbs. In this form, they provide the most natural light available at between 4200 and 4600 deg.k.

FLUORESCENT

TUBULAR: The light tends to be cold and bluish from standard fluorescents, but the new types (T8s) are far more energy-efficient than the previous T12s. Diffusers help kill the glare, but look cheap and collect flies, making them undesirable.

COMPACT: Daylight versions are ideal for ambient lighting of rooms and as spotlights. Usually they give off a warmer light. They are highly energy-efficient and last eight times longer than tungsten-filament lamps.

LEDS

The energy efficiency of these – 15–20 lumens per watt at present – is considered poor, but is likely to increase with advances in technology. The temperature of white LEDs is very close to daylight, with a slightly blue cast, making them an ideal pure light source for task and accent lighting.

The art of lighting

Now that we have the three ingredients for lighting, how do we use them to best effect? You can split lighting effects into five distinct techniques:

AMBIENT (BACKGROUND)

The general light reflected across a room to provide constant, level illumination that is functional, but featureless and free from shadows, is the ambient light. Outdoors the ambient light would be filtered through clouds on a sunless day to be cast uniformly and evenly on the ground. Indoors the standard ceiling pendant lamp gives ambient light when dressed with a lampshade. Ambient light should always be dimmable.

ACCENT

Because ambient light flattens everything, accent light is needed to highlight shapes and textures. You can pick out architectural features, like an alcove or a fireplace, or objects such as pictures or treasured ornaments. The only exception would be furniture: lighting a chair will draw unwanted attention to a recumbent family member, while on a table or work surface, it becomes task lighting. Accent lighting is valuable in most rooms, but it is particularly beneficial in reception rooms. Spotlights, table lamps and picture lights can all be used as accent lighting, depending on how you want a feature to be displayed. Note that these can amount to a significant energy loss if you employ tungsten-halogen spots! At last, however, we can use something that will generate light that is just as pure and white, but consume a fraction of the power – LEDs. They are the perfect accent lights.

TASK

Task lighting is what you get from lighting a chair or a worktop. It sounds like it should only be employed in the kitchen or in a study, but when you think about it, there are tasks of some kind or another to do in all rooms, and being able to see well to carry out those tasks is important. Task lighting needs to be bright and targeted so that it is restricted to a particular area and doesn’t spill out elsewhere. Reflective shading can be used to achieve this, but it wastes the energy consumed by the light. It is far better if the light is directional. An example of this would be study desk lamps. Being low and shaded, they cast the light down on to the desktop without it spilling around the room or up into your eyes.

DECORATIVE

Lighting for decorative purposes should not to be ignored. Whether it be the sparkle of a glass chandelier or colour from halogen lamps splashed across a wall, decorative lighting is an extension of interior decoration that complements the paint and fabrics.