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L I G H T I N G D E S I G N& A P P L I C A T I O N

Introduction

Energy savings can be achieved by installing energy efficient electrical technology in buildings instead of conventional electrical technology. Installing energy efficient appliances, which comes at a high cost, might seem to be the answer. However, what is the cost effectiveness of so-called energy efficient technology?The primary objective of this study was to analyse the cost effectiveness of implementing energy efficient lighting technology in a new building in Longmeadow for ABB South Africa. The secondary objectives were to investigate the system and operational cost benefit of utilising energy efficient lamp and control gear technology in comparison with conventional lighting technology plus the contribution which lighting management systems make towards energy saving and to investigate the impact which daylight has on energy savings for the interior illumination of buildings.

Literature study

Lighting is one of the world’s largest means of energy consumption and recent technological breakthroughs mean it can make a significant impact on energy saving. Lighting accounts for 19% of all electricity used in the world. Benefits of energy efficiency include:l By using less electricity, energy cost

savings is realised.l Non-renewable resources, like coal,

are preserved.

Energy efficient lighting in a new factory or office building

by G J Hoffman, Light Be

Soaring energy prices and concern about climate change from man-made emissions of carbon dioxide have propelled energy efficiency to the top of the agenda in the boardroom, in public debate and public policy.

l Environmental conservation prevails by reducing emissions and water consumption at power stations.

l Energy efficiency is a key resource for sustainable development on a local, national and global basis.

Evidently, today’s office is more than a place of work. It is a world where people work and live, and a world that is here to stay. It is also where people and their needs are the focus of attention. Communication, motivation, stimulation – those are the requirements of a modern office. Sir Henry Wotton stated the architect’s problem concisely over 300 years ago: “Well, building hath three conditions: commodity, firmness and delight”. What is true for the whole, applies also to the parts, and the modern lighting designer may find it useful to start from this standpoint today. The lighting of a building must clearly have commodity, that is, it must meet the social and physical requirements of the users. It must also have firmness: the technology must be sound. Beyond this and perhaps most of all, the lighting must evoke ‘delight’ and play its part in inducing the desired emotions and creating an appropriate character for the building. Lighting is therefore only one element of many to be considered when designing a building, although an important one. The aim of the architect should be to achieve the ‘delight’ which he or she

wants to evoke, but to do it as energy efficiently as possible.A voluntary energy efficient standard namely SABS 204 part 1-3 has been compiled by Standards South Africa to assist building designers to follow sensible and practical energy saving measures when new buildings are being designed and built.

Lamp technologies

During recent years, compact fluorescent lamps (CFLs) have been playing an intrinsic part of energy efficient campaigns worldwide. Internationally, CFLs are replacing incandescent light bulbs and have become the lighting source of choice as it is extremely energy efficient. Shipments of CFLs to the EU in 2006 went up 6% to 196-million CFLs. These had a total value of US$201-million, 12% higher than the previous year.Light-emitt ing diodes (LEDs) are compound semiconductor devices that convert electricity to light. Invented by General Electric (GE) scientists in the 1960s, LEDs are vastly different from traditional incandescent, fluorescent and neon light sources. LEDs stand out because, unlike lamps that can shatter, LEDs are robust and highly resistant to shock and vibration. Due to the solid-state nature of LEDs, there are no filaments to break, no moving parts to fail and no glass components of any kind.

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Bulk production of the metal halide (MH) lamp family commenced around 1960 and is therefore considered a modern light source. The metal halide lamp (M4) is a very complex lamp covering a wide range of shapes and wattages (35 to 3500 W), applications and light output packages. Apart from the high efficacy, high lumen packages, plus the ability to manufacture different colour temperatures, good to excellent colour rendering is also an inherent feature of MH lamps.

Control gear technologies

Apart from incandescent and halogen lamps, where the resistance of the filament acts as a current limiter, all discharge lamps must have additional circuit components to reduce and control the discharge current. Any discharge lamp from a 5 W CFL to a 2000 W rugby stadium lamp will self-destruct within seconds if connected directly across the mains supply voltage. The series winding will have some power losses depending on the lamp's rating, type of winding, and iron losses. To overcome these wasteful losses, electronic ballasts have reached a high level of sophistication and in Europe and some countries, high loss series chokes have been banned. Due to the differences in performance of electronic ballasts (chokes), a classification system has been developed by the EU and is now accepted as the norm.In the simple form, a wire-wound coil in series with the discharge lamp will limit an arc current within parameters of the coil and the lamp it is controlling. This simple device is called the “choke”. The term choke is taken from the human condition of choking, that is, restricting or reducing air supply. The electrical choke in this instance restricts the flow of current.

Daylight modelling

Daylight modelling takes the mystery and surprise out of predicting the impact of daylight on a building space. The multiple benefits of day lighting are well documented. Through the use of building orientation, transmittance levels, plans, computer aided designs (CAD), files or takeoffs, and target illuminance levels, daylight modelling is often an overlooked design analysis tool to aid in predicting day lighting results .Lighting designers should consider the impact of daylight when calculating the required lighting levels for an interior

room or factory floor. Significant energy savings can be realised over the entire lifespan of the lighting installation by not over-illuminating a room. The contribution which daylight makes through window spaces in offices and factory floors is significant enough to ensure that luminaries with lower energy requirements can be utilised. Artificial lighting in the form of an electric lamp can be controlled, but we have absolutely no control over daylight. It must be accepted in all varying moods, and only in the window and interior design of a building can any limited control of the final light effect be exercised.

Building management systems

One o f the s imp les t ways fo r facility managers, building owners and developers to lower cost is by reducing the energy consumed by their buildings. Approximately 75% of energy consumed by lighting can be reduced, if it is controlled. With lighting control solutions no-one will ever have to think about turning off the lights again, whether it uses occupancy sensors, daylight harvesting, or a complete network solution.The method to automatically and remotely save even larger amounts of energy is by applying sensory control elements. Controllers make use of passive infrared (PIR) sensing to switch lighting installations on and off. Daylight harvesting can be optimised by using controllers powered by daylight sensors.

Empirical study

ABB's new Longmeadow premises have

several energy efficiency features which include the collection of rainwater, reuse of water from employee showers, solar power for hot water, high efficiency motors for air conditioning, an intelligent building automation system and energy efficient lighting.The total lighting cost of an installation is illustrated in Fig. 1 and is a combination of system, operating and maintenance costs. The impact of implementing building management systems for lighting and considering daylight modelling were also simulated and savings were estimated and brought into the calculation.Ensur ing energy ef f ic iency and compliance with the recommend lighting levels in accordance with the Occupational Health and Safety (OHS) Act had to be achieved at all times and could not be jeopardised to achieve energy saving. Anyone can claim to save energy by replacing a 100 W lamp with a 60 W lamp, but this will reduce the amount of lux on the working surface resulting in non conformance with the recommended lux levels prescribed in the OHS Act of 1993.The initial lamp lumen, lamp factor and ballast factor were therefore considered as the influencing factors during the cost effectiveness study of the energy efficient lighting technology used. The lamp lumen produced by each lamp type is indirectly proportional to the wattage consumed by that specific lamp type and was therefore also considered. In order to reach the secondary objectives, data had to be collected pertaining to the following.

Fig. 1: The calculation of the total lighting cost of an installation.

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Data collection

The aim of the research design was to gather data of consumption and performance of conventional lighting technology in comparison to energy efficient lighting technology. The data pertaining to lumen output, lamp life and wattage of each lamp type as well as the wattage losses of conventional and electronic control gear were collected from suppliers’ data sheets and websites.Kevin Crichton of Bergstrom Industries provided the researcher with the maintenance manuals and summary of luminaires installed. 5 405 luminaires were supplied to illuminate the exterior and interior of the Longmeadow building. A total of 44 different types of luminaires were used.

Conclusion and recommendations

The calculated connected load of the energy efficient lamp and control gear technology within the Longmeadow premises came to 562 kW compared to 797 kW for using more conventional lamp and control gear l ight ing technology, resulting in a reduction of

approximately 235 kW on connected lighting loads if energy efficient lighting technology was used.Although the initial cost of installing the energy efficient lighting technology was significantly higher (R4 223 074) than conventional lighting (R1 756 773), it became more economical to run energy efficient technology over a period of time due to the savings in energy and operational costs. The calculated annual energy cost for running the energy efficient lighting technology within the Longmeadow premises was R2 191 569 compared to the cost of R3 096 526 for conventional lighting technology. The cost benefit of installing energy efficient lamp and control gear resulted in an energy saving of 868 148 kWh per annum and a cost saving of R904 957 annually.The total system saving applicable to the Longmeadow premises after five years for using energy efficient lamp and control gear is R 3 469 661. This equates to a system cost saving of 16% over a five-year period. The calculated payback period for this investment is calculated at three-and-a-half years.

Daylight harvesting with the aid of daylight modelling, brings about an estimated 25% saving on energy consumpt ion . Th i s equa tes to 525 606 kWh or R547 892 in annual savings when energy efficient lighting technology was used in combination with daylight.The combined estimated cost benefit for the Longmeadow premises when using energy efficient lighting technology, combined with lighting management systems and introducing daylight modelling is R 1 387 460 annually, which equates to a combined payback period of two years.The study concluded that the initial cost to install energy efficient lighting technologies in combination with lighting management systems, and the use of daylight modelling, can be paid back in as little as two years. It is therefore highly recommended to invest in the above-mentioned technologies. Contact Gert Hoffman, Light Be, Tel 011 762-8933, gert@lightbe.co.za