2.7 Energy Performance

[Audio] Hello Everyone!! This is a lecture for JFB32303 Energy Performance And Environmental Assessment.

[Audio] We will continue subtopic 2.7 in the Chapter 2 Carbon Footprint Analysis.

[Audio] In this chapter, we will learn about energy performance in buildings. Energy performance refers to how efficiently a building uses energy to operate systems such as cooling, heating, lighting, and equipment. Evaluating energy performance is important because buildings consume a large amount of electricity and contribute significantly to carbon emissions. By measuring energy performance, engineers and building managers can identify areas where energy is wasted and improve efficiency. Example For example, a poorly designed office building may require excessive air-conditioning, which increases electricity consumption and operational costs..

[Audio] The main learning objective of this chapter is to evaluate building energy efficiency using performance metrics. Energy performance must be analyzed systematically. This means looking at different levels of the building, including: Whole building performance Cooling systems Heating and cooling equipment Comparative analysis with other buildings These steps help us understand where energy is being used and where improvements can be made. Example If a building has very high electricity bills, an energy audit can determine whether the problem comes from inefficient cooling systems or poor insulation..

[Audio] Energy performance can be analyzed at two different levels. Macro Level At the macro level, we examine the entire building. This includes total energy consumption compared to the building size. Micro Level At the micro level, we examine specific equipment, such as HVAC systems or cooling units. Both levels are important for accurate evaluation. Example A building may appear inefficient overall, but the problem could actually come from just one malfunctioning cooling unit..

[Audio] One of the most important indicators of building energy performance is Energy Use Intensity (EUI). EUI measures how much energy a building uses relative to its size. The formula shown in the slide is: EUI = Total Energy Consumed ÷ Total Floor Area EUI is usually measured in kilowatt-hours per square meter per year (kWh/m²/year). This metric allows us to compare the energy performance of different buildings. Example If two buildings consume the same amount of energy but one is smaller, the smaller building will have a higher EUI, indicating lower efficiency..

[Audio] EUI helps us understand how efficient a building is. In the slide example: Building A: 100 kWh/m²/year Building B: 350 kWh/m²/year Building A has a low EUI, meaning it is energy efficient. Building B has a high EUI, which indicates possible energy waste. The slide compares EUI to miles per gallon (MPG) in vehicles. Just like cars with better MPG use fuel more efficiently, buildings with lower EUI use energy more efficiently. Example Green-certified buildings usually have lower EUI values because they use efficient lighting, insulation, and HVAC systems..

[Audio] Another important metric is the Energy Efficiency Ratio (EER). EER measures the performance of cooling systems, such as air conditioners. The formula is: EER = Cooling Output ÷ Electrical Input This means we compare how much cooling the system produces relative to the electricity it uses. A higher EER means the cooling system is more efficient. Example If one air conditioner produces the same cooling but uses less electricity, it has a higher EER and is more efficient..

[Audio] During an energy audit, engineers often evaluate HVAC systems during peak conditions, such as a hot summer day. If the building's EUI is unusually high, the auditor may inspect rooftop cooling units. The key point is that a higher EER value means better cooling efficiency. If the EER is low, it may indicate that the cooling equipment is outdated or malfunctioning. Example Replacing an old air-conditioning unit with a modern high-efficiency system can significantly reduce energy consumption..

[Audio] Another important metric is the Coefficient of Performance (COP). COP measures the efficiency of heating or cooling equipment, especially heat pumps. The formula is: COP = Useful Output ÷ Work Input This means we measure how much heating or cooling energy is produced compared to the energy required to generate it. A higher COP indicates a more efficient system. Example A heat pump with a COP of 4 produces four units of heating energy for every unit of electricity used..

[Audio] The slide shows an example of a heat pump with a COP of 3.0. This means: 1 unit of electricity is used 3 units of heat energy are delivered into the building This shows that heat pumps can be very efficient because they transfer heat rather than generate it directly. Example Modern heat pumps are often used in sustainable buildings because they reduce electricity consumption and carbon emissions..

[Audio] Different metrics are used for different purposes. EER Used for cooling systems Measures cooling efficiency COP Used for heating or cooling equipment Measures overall equipment efficiency Although both compare output to input, they are used for different systems and measurement units. Example An air conditioner may be evaluated using EER, while a heat pump may be evaluated using COP..

[Audio] Benchmarking means comparing a building's energy performance with other similar buildings. This helps determine whether the building is performing well or poorly. Raw numbers alone are not enough. For example, an EUI of 200 may be good or bad depending on the building type. Benchmarking provides context. Example A hospital usually consumes more energy than an office building because it operates 24 hours a day..

[Audio] Benchmarking must compare similar buildings. This means comparing buildings with similar characteristics, such as: Building type Climate zone Operating hours Building size This is often described as comparing "apples to apples." For example, it would not be fair to compare a hospital with a warehouse. Example A university building should be compared with other educational buildings rather than factories..

[Audio] A complete energy audit involves several steps. EUI Analysis Determines the total energy footprint of the building. EER Evaluation Checks the performance of cooling systems. COP Evaluation Measures heating system efficiency. Benchmarking Compares the building with similar buildings. These steps help engineers identify where energy improvements are needed..

[Audio] The slide summarizes the key energy performance indicators. IndicatorFocus AreaDefinitionEUIWhole buildingEnergy use per square meter per yearEERCooling systemsCooling efficiency indicatorCOPHeating/Cooling equipmentEquipment efficiencyBenchmarkingComparative analysisComparing energy performance with similar buildings Together, these indicators help evaluate building energy efficiency..

[Audio] The final slide asks an important question. If a building has excellent COP for heating equipment but a very poor overall EUI, where should the audit begin? This situation suggests that the heating equipment is efficient, but the building still consumes too much energy. Therefore, the problem may come from other sources, such as: Poor insulation Inefficient cooling systems Lighting inefficiency Poor building design Energy performance metrics help identify these problems. Example A building may have efficient heating systems but large glass windows that allow heat to enter, increasing cooling demand..

[Audio] That's all for now. See you in next time!! Have a good day everyone, Bye!.