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Heating - Solar water heater - Swimming pool - Indoor / Canada (Quebec)
Case study assignment
You have been hired by the municipal engineering department of a town in the province of Quebec, Canada, to prepare a preliminary study on their behalf. They would like you to make recommendations for the retrofit of a solar pool heating system. A solar water heater supplier has approached them and proposed using unglazed collectors in a summer-only system.
Site information
The 15 m x 25 m indoor pool, located near Quebec City is heated by electricity. At the beginning of your investigation, you have no information about the temperature maintained by the pool operators: consider standard conditions for the pool (27 °C) and indoor air at 27 °C and 60% relative humidity. The existing filtration pumps are able to feed the solar loop. The roof is flat with an area of more than 2,000 m² available for solar collector installation. There is one floor from the pumping unit to the collector area. The horizontal distance from the pumping unit to the proposed solar collector will be 5 m. Since this is a municipal pool, a relatively high ratio of make-up water (10% per week) is used due to frequent back-washes. The proposed solar system would operate from mid-May to mid-September, when there is no risk of freezing.
Financial information
The municipality can not borrow money for a specific project, and does not pay taxes. The engineering department evaluates projects such as these using a discount rate of 9%. There are no project development costs specifically attributable to the solar installation.
The municipality pays $0.035/kWh for electricity. This is projected to escalate at 3.5% annually, one percentage point higher than the rate of inflation.
The solar water heating system is assumed to last 25 years. Operation & maintenance costs are limited to a half-day inspection in May and a half-day for drainage in September. The system qualifies for a 25% federal government incentive.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
Real project
Results
A solar pool heating system was installed in 1999 at the J.A. Lachance indoor pool, located near Quebec City, Quebec, Canada. It is considered a demonstration project and half of the project funds were provided by the Quebec Minister of Natural Resources. The system operates from mid-May through mid-September, and consists of horizontally-mounted unglazed collectors.
System description
Due to budget limitations, the actual collector size was limited to a total area of 193 m². Pool water is circulated through the collectors by existing filtration pumps.
In this particular case, a feasibility analysis showed that a seasonal system with unglazed collectors was financially preferable to a system with glazed collectors, operating year-round. The municipality received proposals for both types of systems:
Case study assignment
You have been hired by the municipal engineering department of a town in the province of Quebec, Canada, to prepare a preliminary study on their behalf. They would like you to make recommendations for the retrofit of a solar pool heating system. A solar water heater supplier has approached them and proposed using unglazed collectors in a summer-only system.
Site information
The 15 m x 25 m indoor pool, located near Quebec City is heated by electricity. At the beginning of your investigation, you have no information about the temperature maintained by the pool operators: consider standard conditions for the pool (27 °C) and indoor air at 27 °C and 60% relative humidity. The existing filtration pumps are able to feed the solar loop. The roof is flat with an area of more than 2,000 m² available for solar collector installation. There is one floor from the pumping unit to the collector area. The horizontal distance from the pumping unit to the proposed solar collector will be 5 m. Since this is a municipal pool, a relatively high ratio of make-up water (10% per week) is used due to frequent back-washes. The proposed solar system would operate from mid-May to mid-September, when there is no risk of freezing.
Financial information
The municipality can not borrow money for a specific project, and does not pay taxes. The engineering department evaluates projects such as these using a discount rate of 9%. There are no project development costs specifically attributable to the solar installation.
The municipality pays $0.035/kWh for electricity. This is projected to escalate at 3.5% annually, one percentage point higher than the rate of inflation.
The solar water heating system is assumed to last 25 years. Operation & maintenance costs are limited to a half-day inspection in May and a half-day for drainage in September. The system qualifies for a 25% federal government incentive.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
- For this large collector, 3 loops of 51 mm diameter piping would be required by the large water flows. Thus, the costs for solar loop materials and installation have been multiplied by 3. An alternative approach would be to use a single loop of 100 to 150 mm diameter piping.
Real project
Results
A solar pool heating system was installed in 1999 at the J.A. Lachance indoor pool, located near Quebec City, Quebec, Canada. It is considered a demonstration project and half of the project funds were provided by the Quebec Minister of Natural Resources. The system operates from mid-May through mid-September, and consists of horizontally-mounted unglazed collectors.
System description
Due to budget limitations, the actual collector size was limited to a total area of 193 m². Pool water is circulated through the collectors by existing filtration pumps.
In this particular case, a feasibility analysis showed that a seasonal system with unglazed collectors was financially preferable to a system with glazed collectors, operating year-round. The municipality received proposals for both types of systems:
- $20,000 for a 260 m² unglazed seasonal system; and,
- $56,000 for a 160 m² 12-month operating glazed system.
The installed costs for the system were much higher than the initial estimates for a number of reasons:
Lessons learned
The big picture
Indoor solar pool heating is technically feasible, even in cold climates. When solar system reduces the consumption of cheap electricity or cheap gas, however, it will have difficulty attaining financial viability. Pools using more expensive sources of energy, such as heating oil, will have more attractive returns.
Photo
Solar water heater - Swimming pool - Indoor - Solar collector - Unglazed, Quebec, Canada
References
- The municipality would not authorise external piping along the wall of the building between the collector and the filtration pumps, requiring additional roof penetrations costing about $2,500.
- The municipality's procedures for tenders required the involvement of local contractors and suppliers, not necessarily familiar with solar system installation and commissioning. For example, a subcontract was allocated to a separate firm to balance the different loops of the system.
- Commercial grade piping and certified plumbers were used for the installation; this is not generally the case for standard solar systems.
Lessons learned
- The cost of implementing a solar system may be high in the institutional sector due to non-technical considerations.
- A substantial portion of the pool water heating load can be obtained with a solar collector.
The big picture
Indoor solar pool heating is technically feasible, even in cold climates. When solar system reduces the consumption of cheap electricity or cheap gas, however, it will have difficulty attaining financial viability. Pools using more expensive sources of energy, such as heating oil, will have more attractive returns.
Photo
Solar water heater - Swimming pool - Indoor - Solar collector - Unglazed, Quebec, Canada
References
- Hosatte, Pierre, "Personal communication," TN Conseil, 2000.
