1.1 What are the current illumination levels in the factory and storage room, assuming that the coefficient of utilisation is 0.6 and the light loss factor is 0.8?

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1.2 How do the illumination levels compare with the minimum standards of illumination required (i.e. 150 lux for factories and 75 lux for storage rooms)? (Max. 30 words)

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Question 2

Maggie has identified two options for replacing the incandescent lamps in the factory:

• Option 1: 14W CFL lamp (800lm), costing R28 with a lifespan of 6,000 hours.
• Option 2: 10W LED lamp (850lm), costing R60 with a lifespan of 14,000 hours.

2.1 How many CFL lamps or LED lamps are needed to achieve the required illumination of 150lux in the factory? Assume that the coefficient of utilisation and the light loss factor remain the same. Show your calculations for both options.

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2.2 If Maggie purchases the required number of lamps, what would the annual electricity cost savings be for each option (CFL and LED)? Assume that each lamp is used for 2,000 hours each year and that electricity costs R1.32 per kWh.

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Question 3

Which lighting option would you recommend to Maggie, based on profitability (NPV) over seven years? Should she switch to CFLs or LEDs? Firstly, remember to factor in lamp purchase costs and the lifespan of each option in your answer and use a discount rate of 8% for net savings. Secondly, remember that the lifespan of CFLs is 6000 hours. Since the project duration is longer than 6000 hours, replacement CFLs will be required. Finally, remember that the phrase "over seven years" means that NPV must be calculated over this period for both CFLs and LEDs. Therefore, replacement CFLs in years four and seven must be included in the project cost. (Max. 60 words for recommendation)

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Question 4

How would changing the incandescent lamps to LED lamps affect the load on the HVAC system in the factory in summer and in winter? By how many watts would the cooling and heating load respectively change? State any assumptions made. (Max. 60 words for explanation)

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Question 5

Maggie has noticed that the performance of the HVAC system in the storage room has deteriorated. She decides to check the system and notices that the condenser and evaporator are covered in dust and debris. She suggests that they hire a contractor to clean these components.

The condenser and evaporator temperatures were measured before and after cleaning.

Before cleaning:

• Condenser: 318.9K
• Evaporator: 276.7K

After cleaning:

• Condenser: 312.8K
• Evaporator: 282.2K

5.1 How has the coefficient of performance (COP) improved after cleaning (i.e. by what percentage)? Assume that actual COP values are 30% of theoretical COP calculated.

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5.2 What are the energy savings and cost savings after cleaning, if the HVAC electrical power consumption (compressor power consumption) before cleaning was 65.6kW and the power consumption after cleaning is 58.2kW? The HVAC system runs for 2,000 hours each year and electricity costs R1.32 per kWh.