Lighting and Energy Efficiency in PE Power Exam

Amid an ever-changing world where sustainability and climate change are at the forefront of our concerns, exploring every avenue that leads us toward a greener future is essential. While many might overlook it, lighting is pivotal in energy efficiency and significantly impacts our environment.

Lighting is responsible for much of the world’s energy consumption and carbon emissions. Traditional lighting systems, such as incandescent and fluorescent bulbs, are notorious energy hogs contributing to greenhouse gas emissions.

As global leaders gear up for the “Go Green” mantra, energy efficiency has become a center of attention in all industries. Energy-efficient lighting technologies, such as Light Emitting Diodes (LEDs), have revolutionized the Power and Electrical sector. Embracing energy-efficient lighting reduces energy consumption and greenhouse gas emissions and offers substantial cost savings in the long run.

This blog post aims to shed light on the importance of lighting and energy efficiency in the PE Power exam and discuss the subject in the context of sustainability.

Let’s dive deep into the details.

Importance of Lighting and Energy Efficiency in Power Engineering

Importance of Lighting and Energy Efficiency in Power Engineering

The importance of lighting and energy efficiency in Power engineering is evident and reflected in various socioeconomic and commercial aspects. Let’s discuss some key points highlighting the importance of lighting and energy efficiency.

  • Energy Conservation – Lighting consumes significant energy in power engineering applications. Incorporating energy-efficient lighting technologies and practices can help conserve energy and reduce the overall power demand, leading to a more sustainable and efficient power system.
  • Load Management – Efficient lighting systems with advanced control mechanisms enable effective load management in power engineering. By incorporating intelligent lighting controls, such as occupancy sensors and automated dimming systems, power engineers can optimize energy usage and reduce peak demand, contributing to a more stable and reliable power grid.
  • Power Quality Improvement – Lighting equipment, especially traditional lighting systems, can introduce harmonics and other power quality issues into the electrical network. Power engineers can minimize these power quality disturbances by utilizing energy-efficient lighting solutions, ensuring a more stable and efficient power supply.
  • Grid Resilience – Energy-efficient lighting technologies like LED lighting have longer lifespans and improved durability than traditional bulbs. This enhances the power grid’s resilience, as fewer lighting replacements are required, reducing maintenance costs and improving overall system reliability.
  • Integration of Renewable Energy – In pursuing a greener future, power engineering increasingly focuses on integrating renewable energy sources into the grid. Energy-efficient lighting systems align with this objective by reducing the overall energy demand and enabling better integration of intermittent renewable energy sources, such as solar and wind, into the power grid.
  • Sustainability – Adopting energy-efficient lighting in power engineering aligns with the industry’s objective to support the green revolution and meet evolving sustainability goals and new compliance measures.

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Lighting Fundamentals

Lighting Fundamentals

Discussing some critical topics and aspects you can’t afford to skip is necessary to ensure a rich understanding of lighting and Energy Efficiency in the PE Power exam.

Light sources

Light sources

light sources are categorized based on levels of lighting, showcasing different energy efficiencies. The table below shows a categorization of key light sources based on their level of energy efficiency:

Light SourceEnergy EfficiencyLifespanColor Rendering Index (CRI)Environmental Impact
HalogenLow to ModerateModerateHighModerate
FluorescentModerate to HighModerate to LongModerate to HighModerate to High
Compact Fluorescent Lamp (CFL)Moderate to HighModerate to LongModerate to HighModerate to High
Light Emitting Diode (LED)HighLongHighLow

The table showcasing levels of lighting reveals that incandescent and halogen bulbs have lower energy efficiency, shorter lifespans, and lower color rendering capabilities. They also have a higher environmental impact due to higher energy consumption and carbon emissions.

Fluorescent bulbs and compact fluorescent lamps (CFLs) offer moderate to high energy efficiency, longer lifespans, and color rendering capabilities. They have a moderate to high environmental impact, mainly due to mercury in their composition.

LEDs emerge as the most energy-efficient light source with the most extended lifespan, high color rendering capabilities, and a lower environmental impact. LEDs consume significantly less energy, have a longer operational life, and contain fewer hazardous materials, making them the preferred choice for energy-efficient lighting in power engineering applications.

Understanding these differences in energy efficiency among light sources is crucial for power engineers to make informed decisions when designing lighting systems, promoting energy conservation, and contributing to more sustainable power infrastructure.

Lighting Calculations in Power Engineering

Lighting calculations are critical in lighting and energy efficiency in the PE Power exam power engineering to ensure efficient and effective illumination in various applications.

These calculations help determine the appropriate lighting levels, amount of lighting (produced or required), bulb or light placements, and energy requirements. Some key aspects of lighting calculations include:

Luminous Flux (Φ)

Luminous flux measures the total amount of visible light emitted by a light source, expressed in lumens (lm). It indicates the overall brightness of the light source, disregarding the direction of light distribution.

 Illuminance (E)

Illuminance is the amount of lighting falling on a surface area, measured in lux (lx). It represents the light intensity or brightness perceived by the human eye. Illuminance depends on the luminous flux emitted by the light source and the area over which the light is spread.

Lighting Level (L)

Lighting level quantifies the amount of lighting required for a specific task or environment and is measured in lux (lx). It determines the adequacy of lighting in a given space and depends on factors such as the activity performed, visual comfort, and safety requirements.

Reflection and Absorption

Lighting calculations consider the reflection and absorption characteristics of surfaces in a space. Different materials have varying reflective properties, affecting the amount of light reflected in the environment.

Therefore, it is the new norm in modern houses to use white or light themes, paint, and curtains to improve the reflection of artificial and day lightening in the room or hall.

Let’s consider an example to illustrate lighting calculations.

Suppose we want to determine the required illuminance for an office space of 500 square meters based on a 200 – 500 lux lighting level recommendation. We will use energy-efficient LED bulbs with a total luminous flux of 100,000 lumens. (For an idea, a single 9W LED has 800 Lumens replacing 60W bulb or 15W CFL)

The calculation involves dividing the luminous flux by the area to obtain the illuminance:

Illuminance (E) = Luminous Flux (Φ) / Area

We have,

Luminous Flux (Φ) = 10,000 lumens

Area = 500 square meters

We can calculate

E = 100,000 lumens / 500 square meters

E = 200 lux

Therefore, to achieve a lighting level of 500 lux in the office space, we would need approximately 25 LED light bulbs, each with an average luminous flux of 1000 lumens.

Lighting Standards for Homes and Commercial Setups (Recommended Illuminance Levels)

The lighting standards for homes and commercial setups are outlined in the table below.

ApplicationRecommended Illuminance (Lux)
Living Room100-150
Dining Room200-500
Conference Room300-750
Retail Space (General)500-1000

Differentiating Energy and Light Intensity

People often confuse light intensity with energy and use these terms alternatively. But there is a significant difference between them.

Light Intensity

Light intensity, measured in candelas (cd), represents the luminous power emitted by a light source in a specific direction. It provides information about the brightness or perceived intensity of the light. Light intensity is related to the amount of light energy emitted per unit solid angle in a specific direction.


In lighting, energy refers to the amount of electrical power consumed by a light source over a given period, typically measured in watts (W). It represents the input power required to operate the light source and measures the electrical energy converted into light output.

At the same time, the power (P=Ext) is used to calculate the per unit billing of electricity consumption if taken as KWh (Energy in KW and time in hours).

For instance, a commercial building uses fluorescent lighting bulbs in its office spaces. The bulbs consume 40 watts each, with 200 bulbs in total. The facility operates for 10 hours a day, 5 days a week. What will be the annual energy consumption of the fluorescent lighting system?

Let’s solve it step-by-step

Step 1: Calculate the daily energy consumption:

Daily energy consumption per bulb = Power (watts) × Operating hours per day

Daily energy consumption per bulb = 40 watts × 10 hours = 400 watt-hours

Total daily energy consumption = Daily energy consumption per bulb × Number of bulb

Total daily energy consumption = 400 watt-hours × 200 bulbs = 80,000 watt-hours or 80 kilowatt-hours (kWh)

Step 2: Calculate the annual energy consumption:

Annual energy consumption = Total daily energy consumption × Number of operating days per year

Annual energy consumption = 80 kWh/day × 5 days/week × 52 weeks/year = 20,800 kWh/year

Therefore, the annual energy consumption of the fluorescent lighting system in the commercial building is 20,800 kWh/year.

Lighting Design Standards in the USA

The common lighting design standards in the USA from the standpoint of essential topics in Lighting and Energy Efficiency in the PE Power Exam include:

IESNA RP-1Recommended Practice for Daylighting in Buildings. Provides guidelines for integrating daylight into building design.
IESNA RP-8Recommended Practice for Roadway Lighting. Addresses lighting criteria and design guidelines for roadways and streets.
IESNA RP-20Recommended Practice for Lighting Industrial Facilities. Offers guidance on lighting design for industrial and manufacturing settings.
IESNA RP-33Recommended Practice for Lighting for Exterior Environments. Covers lighting design for outdoor spaces and landscapes.
IEEE C2National Electrical Safety Code. Focuses on safety guidelines for electrical installations, including lighting systems.

Energy Efficiency Fundamentals

Energy Efficiency Fundamentals

Let’s move towards another critical area of Lighting and Energy Efficiency in the PE Power Exam. Energy efficiency is the primary intention behind lighting efficiency, as most electric power is generated through fossil fuels.

It becomes crucial to optimize the energy consumption in electrical and power systems due to the inevitable energy crisis and climate change in 2023. Let’s expand the topic vertically and horizontally.

Energy-efficient technologies

Energy-efficient technologies

According to the USAID publication on Overview of Energy-Efficient Technologies, some of the recommended energy-efficient methodologies that help curb the climate and economic impact of energy consumption are divided into the following sections.

Residential Energy Efficiency Applications & Technologies

High-Efficiency Home HVAC Systems – Utilizing advanced heating, ventilation, and air conditioning systems with improved energy efficiency can significantly reduce power consumption in residential buildings. These systems employ advanced technologies and controls to optimize energy usage while maintaining optimal indoor comfort.

Insulation – Proper insulation in residential buildings minimizes heat transfer and reduces energy losses. Effective insulation materials, such as foam or fiberglass, help create a thermal barrier, enhancing the building envelope’s energy efficiency and reducing the need for excessive heating or cooling.

Efficient Appliances – Energy-efficient appliances, including clothes washers, refrigerators, and dishwashers, incorporate advanced technologies that minimize energy consumption without compromising performance. These appliances are designed to meet stringent energy efficiency standards and can significantly reduce electricity usage in residential settings.

Commercial Energy Efficiency Applications & Technologies

Efficient Consumer Electronics – Using energy-efficient consumer electronics, such as computers, monitors, printers, and office equipment, helps reduce power consumption in commercial settings. These devices are designed to optimize energy usage during operation and standby modes, reducing the overall energy footprint of the workplace.

Commercial Refrigeration – Adopting energy-efficient commercial refrigeration systems, such as refrigerators, freezers, and display cases, can lead to substantial energy savings in retail establishments. Advanced technologies, such as LED lighting and efficient compressors, are integrated into these systems to minimize energy usage while maintaining precise temperature control.

LED Lighting with Sensors – Implementing LED lighting systems in commercial spaces offers significant energy-saving benefits. When combined with occupancy sensors and daylight harvesting, LED lighting can automatically adjust illumination levels based on occupancy and natural light availability, optimizing energy usage and enhancing visual comfort in work environments.

Industrial Energy Efficiency Applications & Technologies

Fuel-Efficient Motors – Industrial processes often require motors. Replacing older, less efficient motors with high-efficiency models can save energy. Energy-efficient motors employ advanced design features and materials to reduce energy losses during operation, improving overall system efficiency.

Enhancements to the Building Envelope – Industrial facilities can benefit from implementing energy-efficient improvements to the building envelope, such as upgrading roofs, siding, and windows. These enhancements enhance insulation properties, reduce air leakage, and minimize thermal losses, improving energy efficiency and lowering heating or cooling requirements.

Agricultural Energy Efficiency Applications & Technologies

Efficient Pumps and Motors – Agricultural operations heavily rely on pumps and motors for various tasks such as irrigation and ventilation. Utilizing energy-efficient pumps and motors in agricultural systems can help reduce energy consumption and optimize water usage, resulting in more sustainable and cost-effective operations.

Sample Problem for Energy Saving

A manufacturing facility uses a motor-driven pump system to circulate water. The existing pump has a motor with an efficiency of 80% and operates for 12 hours a day. The facility decides to replace the old pump with a new, more energy-efficient one with an efficiency of 90%.

To calculate the energy savings per year by replacing the pump.

Step 1: Calculate the energy consumption of the existing pump:

Energy consumption per day = Power input × Operating hours per day

Energy consumption per day = (100% / Motor efficiency) × Operating hours per day

Energy consumption per day = (100% / 80%) × 12 hours = 15 kWh

Step 2: Calculate the energy consumption of the new pump:

Energy consumption per day (new pump) = (100% / Motor efficiency) × Operating hours per day

Energy consumption per day (new pump) = (100% / 90%) × 12 hours = 13.33 kWh

Step 3: Calculate the energy savings per day:

Energy savings per day = Energy consumption per day (existing pump) – Energy consumption per day (new pump)

Energy savings per day = 15 kWh – 13.33 kWh = 1.67 kWh

Step 4: Calculate the annual energy savings:

Annual energy savings = Energy savings per day × Number of operating days per year

Annual energy savings = 1.67 kWh/day × 365 days/year = 609.55 kWh/year

Therefore, by replacing the pump with a more energy-efficient model, the facility can save approximately 609.55 kWh of energy per year.

What are Different Types of LED Lighting Available? 

Today, technological advancements have led to many LED lighting options, each catering to specific needs and applications. Here’s a breakdown of some popular types:

  • Surface Mounted Device (SMD) LEDs: These tiny, flat LEDs are commonly used in flat-panel lights and downlights. They offer design flexibility and efficient heat dissipation.
  • Chip-on-Board (COB) LEDs: These powerful LEDs pack multiple LED chips into a single unit, creating a uniform and bright light source. They are ideal for spotlights and task lighting.
  • LED Bulbs: Replacing traditional incandescent bulbs is easy with LED bulbs that come in shapes like A19 (bulbs with a rounded top) and PAR (bulbs with a parabolic reflector). They provide a familiar look with significant energy savings.
  • LED Tubes: Linear LED tubes are perfect substitutes for fluorescent tubes, often used in offices and commercial spaces. They offer superior lifespan and dimming capabilities.
  • Surface Mounted Device (SMD) LEDs: These tiny, flat LEDs are commonly used in flat-panel lights and downlights. They offer design flexibility and efficient heat dissipation, making them ideal for creating a sleek, modern look in residential and commercial settings.
  • Chip-on-Board (COB) LEDs: These powerful LEDs pack multiple LED chips into a single unit, creating a uniform and bright light source. Their high lumen output makes them ideal for spotlights and task lighting in workshops, garages, and industrial settings.
  • LED Bulbs: Replacing traditional incandescent bulbs is easy with LED bulbs that come in various shapes and sizes familiar to consumers. These include A19 bulbs with a rounded top, perfect for table lamps and overhead lighting, and PAR bulbs with a parabolic reflector, ideal for track lighting and recessed fixtures. They provide a familiar look with significant energy savings and longer lifespans.
  • LED Tubes: Linear LED tubes are excellent substitutes for fluorescent tubes, often used in offices and commercial spaces. They offer superior lifespan, dimming capabilities, and improved color rendering, making them ideal for task lighting and general illumination.

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Energy-efficient design principles

We have categorized the following energy-efficient design principles according to the target industries (AEC, Power Engineering, and Electrical Engineering) to help highlight their specific relevance and application areas.

IndustryEnergy Efficient Design PrinciplesDescriptionImportance
Power EngineeringZoning and Efficient Heating/Cooling SystemsUtilizing zoning techniques and energy-efficient heating/cooling systems to optimize comfort and reduce energy consumption.Zoning and efficient HVAC systems allow targeted climate control, reducing energy waste and improving occupant comfort.
Power EngineeringEfficient LightingUtilizing energy-efficient lighting systems, such as LED, reduces electricity consumption and improve lighting quality.Energy-efficient lighting technologies contribute to reduced power demand and enhanced lighting performance.
Power EngineeringEnergy-Efficient AppliancesSelection of appliances with high energy efficiency ratings, minimizing electricity consumption and operational costs.Energy-efficient appliances reduce power demand and promote sustainability by conserving energy resources.
Power EngineeringEnergy-Efficient Hot Water SystemsInstallation of energy-efficient hot water systems, such as heat pumps or solar water heaters, to minimize energy usage for water heating.Energy-efficient hot water systems significantly reduce energy consumption and ensure cost-effective water heating costs.
Power EngineeringSolar PowerIntegration of solar power systems to harness renewable energy and reduce dependence on conventional power sources.Solar power systems offer a clean and sustainable energy solution, reducing carbon emissions and operating costs.
Electrical EngineeringEnergy Audit and AnalysisConducting a comprehensive energy audit to identify areas of energy inefficiency and optimize energy usage in electrical systems.Energy audits help identify opportunities for energy savings, optimize electrical systems, and reduce wastage.
AEC (Architecture, Engineering, and Construction)Block OrientationProperly orienting the building to maximize solar gain or minimize heat gain, depending on the climate.Optimal block orientation can enhance natural lighting and reduce heating/cooling energy needs.
AECBuilding MaterialsSelection of energy-efficient building materials with high insulation properties, low thermal conductivity, and environmental sustainability.Energy-efficient building materials contribute to improved insulation, reduced heat transfer, and reduced environmental impact.
AECDraught ProofingSealing gaps and leaks in the building envelope to prevent air infiltration, improving energy efficiency and indoor comfort.Draught proofing minimizes air leakage, reducing heating/cooling demands and improving energy performance.
AECInsulationImplementing high-quality insulation materials to minimize heat transfer, improving energy efficiency and thermal comfort.Proper insulation reduces heat loss or gain, saving energy and enhancing occupant comfort.
AECVentilationIncorporating efficient ventilation systems to ensure adequate airflow, improve indoor air quality, and reduce cooling needs.Proper ventilation promotes healthy indoor environments, reduces reliance on mechanical cooling, and enhances energy efficiency.
AECWindow Frames, Glazing, and ShadingInstallation of energy-efficient windows with low U-values, appropriate glazing, and shading strategies to minimize heat gain/loss.Energy-efficient windows and shading techniques improve thermal insulation, optimize natural lighting, and reduce energy demands.

By incorporating these principles, professionals in these industries can contribute to sustainable practices, reduce energy consumption, and promote environmentally friendly solutions in their projects.

Energy Efficiency in Lighting

Lighting Retrofits

Lighting retrofits involve upgrading existing lighting systems with more energy-efficient components or technologies. This technique replaces outdated or inefficient light bulbs, lamps, and control systems with modern, energy-saving alternatives.

For example, replacing traditional incandescent bulbs with LED lamps or retrofitting fluorescent bulbs with high-efficiency electronic ballasts and T8/T5 lamps.

Importance and Impact

  • Energy Savings – Lighting retrofits can result in significant energy savings by reducing power consumption and improving system efficiency. Upgrading to more efficient lighting technologies can yield 30% or more energy savings.
  • Operational Cost Reduction – By lowering energy consumption, lighting retrofits can help reduce electricity bills, resulting in long-term cost savings for commercial and industrial facilities.
  • Environmental Benefits – Decreasing energy usage through lighting retrofits helps lower greenhouse gas emissions and reduces the environmental impact of power generation.
  • Enhanced Lighting Quality – Upgrading lighting systems can improve the quality of light, enhancing visibility, color rendering, and visual comfort for occupants.

LED Lighting Technology

LED (Light-Emitting Diode) lighting technology has revolutionized the lighting industry with its high energy efficiency, long lifespan, and versatility. LEDs convert electrical energy directly into light, offering superior efficiency than traditional lighting sources like incandescent or fluorescent lamps.

Importance and Impact

  • Energy Efficiency – LED lighting is highly energy-efficient, consuming significantly less electricity than conventional lighting technologies. LEDs can achieve energy savings of up to 80% compared to incandescent bulbs.
  • Long Lifespan – LED lamps have an exceptionally long lifespan, often exceeding 50,000 hours. This reduces the need for frequent lamp replacements, resulting in lower maintenance costs and less waste.
  • Environmental Friendliness – LEDs are mercury-free and have lower carbon emissions than traditional lamps, contributing to a greener and more sustainable lighting solution.
  • Enhanced Control and Flexibility – LED lighting systems can be easily integrated with advanced controls, allowing for precise dimming, zoning, and color tuning, further optimizing energy usage and creating dynamic lighting environments.


Daylighting refers to utilizing natural daylight to illuminate indoor spaces. It involves strategically placing windows, skylights, light shelves, and light tubes to maximize the entry of natural light while minimizing heat gain and glare.

Importance and Impact

  • Energy Savings –  Incorporating daylighting techniques can significantly reduce the need for artificial lighting during daylight hours, resulting in substantial energy savings.
  • Improved Well-being and Productivity – Natural daylight positively affects human health, well-being, and productivity. Daylit spaces create a visually stimulating and comfortable environment for occupants.
  • Environmental Benefits – By relying on natural light, daylighting reduces reliance on electrical lighting, thereby reducing energy consumption, greenhouse gas emissions, and the carbon footprint of buildings.
  • Design Flexibility –  Daylighting offers architectural design opportunities, allowing for aesthetically pleasing and visually engaging spaces that connect occupants with the outdoor environment.

Lighting Power Density Requirements

Lighting power density (LPD) refers to the amount of electrical power allowed per unit area for lighting in a building. LPD requirements define the maximum allowable power consumption for lighting systems, ensuring efficient energy use in indoor spaces.

Importance and Impact

  • Energy Code Compliance – Lighting power density requirements are included in building energy codes and standards to enforce energy-efficient lighting practices and minimize wasteful energy consumption.
  • Energy Optimization –  By setting maximum limits for lighting power, LPD requirements encourage using energy-efficient lighting technologies and designs, reducing electricity usage and operating costs.
  • Enhanced System Design – LPD requirements drive designers to carefully consider lighting system layouts, bulb types, and controls to meet illumination needs.

Energy Codes and Standards

Energy codes and standards are crucial in promoting energy-efficient lighting. Organizations and governing bodies worldwide have implemented stringent regulations to encourage using energy-efficient lighting solutions.

Understanding these codes and standards is essential for success in the PE Power Exam, as they reflect the industry’s commitment to sustainability.

Energy Code/StandardDescription
ASHRAE Standard 90.1Developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) sets energy efficiency requirements for commercial and high-rise residential buildings.
IECC (International Energy Conservation Code)The IECC model energy code provides minimum requirements for designing and constructing energy-efficient residential and commercial buildings. It is widely adopted across the United States.
Title 24, Part 6 (California Energy Code)This energy code sets the energy efficiency standards for new construction and significant renovations in California, focusing on lighting, HVAC, insulation, and other building systems.
NAECA (National Appliance Energy Conservation Act)NAECA establishes minimum energy efficiency standards for various residential appliances and equipment, including water heaters, refrigerators, and HVAC systems.
ENERGY STARENERGY STAR is a voluntary program run by the U.S. Environmental Protection Agency (EPA) and the Department of Energy (DOE) that certifies energy-efficient products and promotes energy savings across multiple sectors.

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Lighting and energy in the PE Power Exam is an important topic. Making modern electrical and power systems more energy-efficient benefits various industries, corporations, as well as the entire humanity and nature.

They provide cost-effective solutions while addressing climate change and resource scarcity. Globally, governing bodies are increasingly focused on sustainability, making these topics crucial for the exam and your career.

To enhance your prospects in power engineering, visit Study for FE, where our dedicated PE professionals have developed a highly effective PE Power exam preparation course. Don’t miss out on the opportunity to excel academically and professionally.


Licensed Professional Engineer in Texas (PE), Florida (PE) and Ontario (P. Eng) with consulting experience in design, commissioning and plant engineering for clients in Energy, Mining and Infrastructure.