ABSTRACT
This paper investigates the pattern and cost of electricity consumption through usage of various electrical appliances in a selected household/home. Furthermore, we propose and describe feasible measures to reduce electricity consumption through these appliances and thus reduce the household’s monthly energy cost. The methodology used for the energy audit is as described in the project hand out; that of constructing daily load profiles for weekdays and weekend days to observe the difference in energy consumption patterns between weekdays and weekend days.
INTRODUCTION
Different levels of energy crisis are being faced in most countries globally, including South Africa, as the demand for energy grows alongside population growth and economical and technological advances. This energy crisis challenge comes as a result of the demand growing much faster than the supply capacity of electrical energy in these countries [1]
To avoid a power crisis there needs to be a healthy balance between the demand and supply of energy which often results in power blackouts, particularly dubbed “load shedding” in South Africa [1]. For more sustainable and desirable methods of creating a balance between consumption and generation of electricity, there either must be a significant increase in power generation or a decrease in energy consumption.
This report will be made up of several sections, starting with the methodology for the energy audit exercise and the load profiles constructed along with the energy and or cost savings design. Following these, will be a discussion of significant and relevant findings from the project and conclusions reached.
METHODOLOGY
We investigate the pattern and cost of power consumption for our selected household via various electrical appliances that we identified.
Based on the power rating of each identified appliance, the time in which it is used (including stand-by mode) and the energy billing utility’s tariff structure for energy cost calculations; daily load profiles for the household were constructed for a week (5 weekdays and a weekend) in the month of May 2017.
From these results, we propose feasible measures to reduce the household’s monthly power consumption and the energy cost.
The following appliances were selected and profiled for weekdays: LCD TV, combined refrigerator, hairdryer, stove, pool pump, iron, dishwasher, computer, geyser and heater. For the weekend, we added the washing machine, gaming appliances and the sound system.
ENERGY SAVING STRATEGY
1. Reduce pool pump operating hours
This household runs their pool pump for unnecessarily long hours. Drop the pool pump operating hours from the recorded 12 hours a day on the daily profile to 6 hours a day in summer and only 4 hours a day during winter. This saves ¾ of the initial running time energy.
Using a pool cover keeps the pool clean and contributes to minimising the amount of time the energy-intensive filter pump has to run.
2. Install a variable speed pump
A variable speed pool pump maximizes pool energy efficiency. Unlike a single speed pool pump, a variable speed model alternates between different speeds to optimise energy use throughout the pool pump’s running and thus reducing pump energy consumption by up to 75%
Energy saved per month = 3 500W*8hours*31 days
= 868kWh
3. Switch off appliances instead of leaving them on stand-by
Our household had their TV on stand-by for 15 hours average on weekdays and 12 hours on weekend days.
The power rating for our TV on standby was 0.072kw
Energy saved per month = 0.072kW*15hours*23days + 0.072kW*12hours*8days
= 31.752kWh
The computer is left on stand-by for an average 0f 20 hours daily.
Energy saved per month = 0.04kW*20hours*31days
= 24.8kWh
The Hi-Fi (sound system) is on stand-by for 8 hours on a weekend day.
Energy saved per month = 0.048kW*8hours*4days
= 1.536kWh
4. Wash full loads of dishes instead of multiple loads in the dishwasher.
Over and above reducing your number of loads; skip the pre-rinse to reduce running time and air dry the dishes instead of using the heat fan in the dishwasher to dry them.
Since the household’s dishwasher goes in one hour washing cycles, we will have single loads per weekday and two loads per day on weekends.
Energy saved per month = 1 200W*1hour*23days + 1 200W*2hours*8days
= 468kWh
5. Opt for a solar powered geyser.
Energy saved per month = 3 000W*8hours*10days + 3 000W*5hours*9days + 3 000W*7hours*4days + 3 000W*14hours*4days + 3 000W*13hours*4days
= 783kWh
MONTHLY ENERGY SAVING
Energy used per month before energy saving strategy was implemented is 2 883,524kWh which amounted to a monthly cost of R4 513,00.
Energy saved per month after the implementation of the energy saving strategy is
868kWh + 31,752kWh + 24,8kWh + 1,536kWh + 468kWh + 783kWh = 2 177,088 kWh
which amounts to a monthly cost of
2 177,088kWh*156.1c/kWh*1/100 = R 3 398,43.
The household’s new monthly energy consumption would be
2 883,524kWh – 2 177,088kWh = 706,436kWh
which would give a monthly cost of
706,436kWh*156,1c/kWh*1/100 = R1 102,75.
The total energy save per month amounts to percentage of
(2 177,088/2 883,524)*100% = 75,5%
DISCUSSION
There’s a significant difference in the amount of energy consumed on weekdays compared to that consumed on weekend days. This is because of factors such as that there are additional appliances profiled for weekend days and more hours of usage for other appliances since the occupants of the house are present at home throughout the day on weekends.
We observe peak consumption between the hours 06h00-06h59 and 17h00-18h59 on weekdays. these are the hours in the day where occupants of the house prepare to go to work and school in the morning and do household chores in the evening. Peak hours on weekend days are between 07h00-10h59 when it’s typically bath time and chores including cooking are done.
Upon implementation of the proposed energy saving strategy, the household would save 75,5% on their monthly energy cost.
The load profiles and energy costs in this project were limited to only the month of May 2017. This means that we could not get enough readings to compare and or make analysis based on factors such as seasonal patterns or variability.
CONCLUSION
This project helps the consumer find ways to reduce the monthly energy consumption and use energy efficiently while they save on monthly costs while the students, via research, learn more on energy consumption.
By implementing different feasible methods to reduce electricity consumption and monthly energy cost, households can save significant amounts of energy and costs monthly. - 6 references