Lighting Upgrade

Lighting is the largest cost component of a commercial building’s electricity bill and a significant portion of its total energy bill.

Best Ways to Save

• Design light quantity and quality for the task and occupants’ needs
• Maximise lamp and ballast efficiency
• Maximise system efficiency, not just the components.
• Use automatic controls to turn off lights or dim lights in daylit spaces.
• Establish maintenance schedule for group relamping and fixture cleaning.
• Establish responsible disposal practices.

Why is this important?

• Lighting is the largest cost component of a commercial building’s electricity bill and a significant portion of its total energy bill.
• In addition to visible light, all lighting system produce waste heat, often called “heat gain”. By reducing internal heat gain, efficient lighting also reduces your building’s cooling requirements. Consequently, your existing cooling system may be able to serve future added loads.
• Lighting also affects the power quality of your building’s electrical distribution system. Poor quality power is a concern because it wastes energy, reduces electrical capacity, and can harm equipment and the electrical distribution system itself.
• Improved slighting enhances visual comfort, reduces eye fatigue, and improves performance on visual tasks. Well-designed lighting is also likely to improve performance, increase productivity, and reduce absenteeism. Because costs associated with your employees greatly outweigh the other building costs, any lighting changes that improve your occupants’ workspaces are worth investigating.

Maximising Efficiency and Quality

Avoid implementing only the easiest and quickest payback opportunities.  Whilst this may seem appealing, you will forgo quality-enhancing and savings opportunities that result from comprehensive upgrades.  A simplified upgrade may yield faster payback, but you will sacrifice long term energy savings over the life of the system.

Lighting Design

Successful lighting design begins with an assessment of several design issues, such as colour, daylight availability, glare, and light distribution, to meet the occupants’ lighting needs depending on the tasks being performed. Although lighting retrofits are generally limited to the lighting equipment, good design should also evaluate and modify work environments where appropriate. As much as one-third of the energy use of a lighting system depends upon the surrounding interior features, such as the ceiling height, windows, and colour and reflectivity of room surfaces and furnishings.

The Right Quantity of Light

A common misperception contributing to the proliferation of ineffective and inefficient lighting is that more light equals higher quality light. Listed below are some recommended light levels depending on location and task.

Table 1: Recommended Light Levels (footcandles)
Average Reading and Writing	50 fc
Offices with Computer Screens Task Lighting Ambient lighting	25 fc
Hallways	10 fc
Stockroom Storage	30 fc
Loading and Unloading	10 fc
High-Volume Retail	100 fc
Low-Volume Retail	30 fc
Roadway Lighting	.3 – 1.6 fc
Parking Lots	.8 - 3.6 fc
Building Entrance	5 fc
Source: IESNA Lighting Handbook.

It is important to note that these are average maintained target levels for the task and should not necessarily be applied uniformly as the ambient light level for the entire space. Target lighting levels should be the sum of the ambient and task lighting levels. This design approach creates flexibility to accommodate individual tasks or worker requirements, creates visual interest, and can save considerable energy in comparison to a uniform ambient level approach.

Of equal importance to the quantity of light is the quality of light. Special consideration should be given to uniformity of luminance, glare, and colour temperature and colour rendition.

Uniformity of Luminance – The eye does not see absolute levels of luminance. It sees differences in luminance, the amount of light reflected back from the surface. Eyestrain and fatigue are caused when the eye is forced to adapt continually to different luminances. Therefore, it is important not only to provide the right level of light but also to ensure that light is distributed evenly across the task area. Large footcandle variations within a workspace should be avoided.

Glare – There are two types of glare you will encounter – direct glare and reflected glare. Direct glare occurs when the light from a bright object enters your eye directly. Reflected glare is caused by reflected light and commonly occurs on shiny, light-coloured objects and computer screens. Because glare creates discomfort, loss of visual performance, and impaired visibility, it should be minimised wherever possible.

Colour Temperature and Colour Rendition – The ability of a light source to accurately reveal the true colours of objects is measured by its colour rendering index (CRI). Because high CRI lamps improve visual clarity and aesthetics, use the highest CRI lamps economically practical. The colour temperature of lamps refers to their relative warmth or coolness of light colour - the higher the colour temperature, the cooler their light source. Warmer sources (temperature below 3500 K) are generally preferred in lower illuminance environments and cooler sources (temperature above 3500 K) are preferred in higher illuminance environments.

Maximise Source Efficiency

In general, lighting upgrades consider the pairing of lamps with ballasts (lighting fixtures) to find the most efficient combination. However, pursuit of high efficiency alone may lead to compromise in light quality and controllability and higher system maintenance and costs. Lamp and ballast specification should optimise efficiency while maintaining a balance with these other considerations. Table 2 lists a variety of lamps that are available and their characteristics.

Induction Lamps	Appearance	Colour Rendering	Life (hrs)	Run-up time (mins)	Re-strike time (mins)	Best suited for
Induction Lamps	White	> 80	60,000	Instant	Instant	Long hours of operation inaccessible
High pressure Sodium (SON)	Pinkinsh Orange	20 to 35	20,000	3-6	1-3	Long hours of operation
Triphosphor fluorescent	White	> 80	16,000 - 20,000	Short	Short	Long hours of operation
Metal Halide (HPI)	White with bluish tinge	>	9,0000	2	5-20	Long hours of operation
Halogen (HPL)		100	2,000	Instant	Instant	Short hours of operation owing to low efficacy and/or short lamp life. eg suburban sports ground, intermittent operation
Self ballasted mecury (ML)			6,000	Short	Short
Incandescent		100	1,000	Instant	Instant

Fluorescent lamps are the preferred choice in most commercial office and small manufacturing installations where ceiling heights are modest. Fluorescent lights offer the benefits of low cost, high efficiency, good colour rendition, and rapid starting. The three types of fluorescent ballasts are magnetic, electronic, and hybrid ballasts. Electronic ballasts have been developed for almost all fluorescent lighting applications to replace the conventional magnetic ballasts.

Benefits of electronic ballasts over magnetic:

• Generally 30% more efficient
• Less audible noise and virtually no lamp flicker
• Dimming capability with specific ballast models
• Ability to power up to 4 lamps

Hybrid ballasts which combine features of magnetic and electronic ballasts, are also available. These ballasts offer the same efficiency benefits of electronic ballasts but cannot power more than 3 lamps.

High intensity discharge (HID) lamps offer the benefit of high light output from a reasonably compact source. The high light output from these lamps enables the use of fewer fittings. Fewer fittings mean reduced capital cost and maintenance cost. Disadvantages of these lamps include poorer colour rendition and long start and restart times. The lamps are often used in industrial buildings with high ceilings where lights are left on for long periods of time and colour rendition is less important.

Maximise Luminaire (light fixture) Effciency

Generally, the most efficient fixtures have the poorest visual comfort. Conversely, fixtures with excellent glare control are the least efficient. When installing new fixtures, a lighting designer will determine the best compromise between fixture efficiency and visual performance.

Reflectors – Reflectors are inserts designed to reduce the internal light loss in fixtures by using highly reflective surfaces to redirect light out of the fixture. They improve fixture efficiency by up to 17% in new fixtures and more if fixture surfaces are old or deteriorating. Reflector performance is largely determined by design and installation rather than material selection.

Diffusers – Diffusers are semitransparent plastic sheets that hide lamp images and diffuse light evenly across the face of the fixture. Because they spread light in different directions and absorb light, diffusers are inefficient and ineffective at controlling glare. When retrofitting shielding media, evaluate changes in light output, distribution, and fixture appearance using trial installations.

The best type of lighting system for glare control and visual comfort is a direct/indirect pendent mounted system. By providing some up-light against the ceiling and a direct component to the work surface, direct/indirect lighting minimises the extreme brightness between the ceiling surface and the fixture. However, installing pendent mounted systems is usually only cost effective during complete renovations and new construction.

Automatically Control Lighting

Automatic controls switch or dim lighting based on time, occupancy, lighting-level strategies, or a combination of all three. In situations where lighting may be on longer than needed, left on in unoccupied areas, or used when sufficient daylight exists, you should consider installing automatic controls as a supplement or replacement for manual controls.

Time-Based Controls – The most basic controlling strategies involve time-based controls, best suited for spaces where lighting needs are predictable and predetermined. Time-based controls can be used in both indoor and outdoor situations.

Occupancy-Based Controls – Occupancy-based strategies are best suited to spaces that have highly variable and unpredictable occupancy patterns. Occupancy or motion sensors are used to detect occupant motion, lighting the space only when it is occupied.

Lighting Level-Based Controls – Lighting level-based strategies take advantage of any available daylight and supply only the necessary amount of electric light to provide target lighting levels. In addition to saving energy, lighting level controls cane minimise overlighting and glare and help reduce electricity demand charges. The two main strategies for controlling perimeter fixtures in daylighted areas are daylight switching or daylight dimming. Daylight switching involves switching fixtures off when the target lighting levels can be achieved by utilising daylight. Daylight dimming involves continuously varying the electric lighting level to maintain a constant target level of illumination.

Build In an Operation and Maintenance Plan

All lighting systems experience a decrease in light output and efficiency over time from three factors:

 

• Lamp light output decreases
• Dirt accumulates on fixtures.

• Lamps burn out.

Over time, these factors can degrade a system’s efficiency by up to 60%, wasting energy and maintenance costs and compromising safety, productivity, and building aesthetics. A planned maintenance Program of group relamping and fixture cleaning at a scheduled interval minimises this waste and maximises system performance.

Integrating a planned maintenance Program into your lighting upgrade saves money in two ways. First, you will not have to overcompensate with higher initial lighting levels to ensure adequate lighting over time. Second, while replacing lamps as they burn out on a spot basis may seem like a cost-effective practice, it actually wastes valuable labour. Group relamping times the replacement of lamps at their maximum economic value, generally at about 70% of their calendar life. Although it means replacing lamps before they expire, group relamping dramatically reduces the time spent replacing each lamp, which can reduce your overall lighting maintenance budget by more than 25%. In addition, planned maintenance reduces the cost of lamps through bulk-purchase discounts, the storage space needs for replacement lamps, and disruptions in the workplace.

Exterior Lighting

The three main considerations for exterior lighting are energy waste, glare, and light trespass. Energy waste and glare have been discussed previously. Light trespass, or spill light, is light that strays from its intended target and becomes an annoyance or nuisance. Maximising the utilisation of light output where and when it is needed will reduce light trespass.

Strategies for Exterior Lighting

1. Use lighting fixtures with directional control.
2. Direct and control light output to locations where it is needed.
3. Use time controls/dimmers to turn lights on and off and reduce light levels.
4. Design and install lighting to minimise glare.
5. Use the right amount of light for the task.
6. Use energy efficient light sources and fixtures.

Environmental Effects
Exterior lighting can also have effects on the environment; excessive lighting near wildlife areas can adversely impact migrating bird life, nocturnal insects and other species. Disposal A lighting upgrade will most likely require the removal and disposal of lamps and ballasts. Some of this waste may be hazardous. Investigate and budget for disposal costs both as a first cost during the upgrade and as an ongoing operation and maintenance expense.

Disposal

A lighting upgrade will most likely require the removal and disposal of lamps and ballasts. Some of this waste may be hazardous. Investigate and budget for disposal costs both as a first cost during the upgrade and as an ongoing operation and maintenance expense.

Top of Page

Source: US Environmental Protection Authority Energy Star www.energystar.gov