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Business Problem Statement The case study refers to a small 3 storey apartment block in the Johannesburg area, used for social housing. The present boiler is outdated and needs to be replaced. At the same time, energy savings need to be implemented.
Technical Situation Building: | | Storeys: | 3 | Apartments: | 25 | Persons: | 75 |
Analysis of Energy Requirements Water Heating Note that costs are illustrative, based on simple principles. When designing heat pumps, we use simulation models. These show appreciably greater savings than we have presented here.
No of Persons | 75 | | Hot Water Per Person Per Day | 50 | litres | Hot Water Temperature | 55 | deg C | Avg Inlet Temperature Winter | 8 | deg C | Avg Inlet Temperature Summer | 20 | deg C | Boiler Efficiency | 0.8 | | kCal to kWh Conversion | 1.16E-003 | | Operational Hours per Day | 15 | |
| Winter | Summer | | Boiler | Heat Pump | Boiler | Heat Pump | Litres Demand/Day | 3500 | | 3500 | | kCal Demand/Day | 164500 | | 122500 | | kWh per day required | 153 | 69 | 113 | 46.02 | kW Rating | 10.2 | 4.6 | 10.2 | 4.6 | | (Usage in Summer is approx 2/3) | Avg kWh saved daily | 75.49 | | | | Annual kWh saved | 27572.17 | | | |
Solution Any form of direct heating, whether Gas, Oil or Electric has a similar cost structure, and because electricity in South Africa is predominantly coal fired, all have a detrimental effect on the environment. Solar heating is not an option in this case, because of lack of area (3 storeys to support). Heat pumps operate on the principle of moving energy from hot molecules in the air to cold molecules in the water being heated – this is a very much more efficient process than trying to speed up molecules in the water using a heating element. Assessed Benefits of the Proposed Solution Cash Flow - Heating Boiler Cost Alone | R 46 300 | Heat Pump Cos + Boiler Hc | R 80 300 | kWh Saved Annually | 27 572 | R/kWh | 0.63 | Opportunity Cost | R 34 000 | Discount Rate | 0.12 | Escalation rate | 0.15 |
Year | Yield – Loss of Opportunity | Annual Electricity Saving- Rands | Cash Flow | Cumulative | 1 | R 38,080.00 | R 17,370.36 | R-20,709.64 | R 20,709.64 | 2 | R 4,569.60 | R 19,975.91 | R 15,406.31 | R-5,303.33 | 3 | R 5,117.95 | R 22,972.30 | R 17,854.35 | R 33,260.66 | 4 | R 5,732.11 | R 26,418.15 | R 20,686.04 | R 38,540.39 | 5 | R 6,419.96 | R 30,380.87 | R 23,960.91 | R 44,646.95 |
Intangible Benefits Reduction of Carbon Dioxide ( 27 600 kg per annum), Sulphur Dioxide and other pollutants. Products and Services used in the solution
Heat Pump and Boiler used at Thirlestane Results The Client accepted the benefits of installing a Heat Pump to conserve energy and the project is complete. Actual consumption figures will be presented in due course. |
