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Heating - Solar water heater - Apartment building / France
Case study assignment
A municipality in France has hired you to determine the financial feasibility of installing a solar water heating (SWH) system on an existing residential apartment building.
Site information
The building is located in the town of Bourg-lès-Valence, in the Rhône-Alpes region, at a latitude of 45.7ºN. The nearest available location for weather data is Lyon/Bron. The 4-storey building has 21 apartments with a relatively low occupancy rate of 55%. The required hot water temperature is 60ºC. The existing conventional water heating system is a central natural gas-fired boiler with a seasonal efficiency of 70%.
The client has requested that the project use glazed solar collectors by the French manufacturer Techniques Solaires Appliquées (TSA), type ST3V. These collectors are reported to have a "tau alpha" coefficient of 0.70, a "Fr UL" coefficient of 5.00 (W/m²)/ºC and have an area of 2.31 m² each. For aesthetic reasons, the collectors should be tilted at 45º, facing due south.
For the greenhouse gas analysis assume that "Nuclear" is the base case electricity system.
Financial information
The glazed solar collectors cost €300/m².
The following values should be used for the financial analysis: 5% inflation rate, 3.5% fuel cost escalation rate, 9% discount rate and a project life of 25 years. The price of natural gas is €0.168/m³ and the price of electricity is €0.119/kWh. The project is eligible for a government grant totalling 32% of total initial cost.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from the analysis. If the project's Internal Rate of Return (IRR) is below 10%, determine how much higher the cost of natural gas would have to rise for the project to yield a 10% IRR.
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
In 1996, l'Office départemental de l'habitat, a local public housing agency, installed a solar water heating (SWH) system on an existing 21-unit residential apartment building, the Résidence moulin des prés, in Bourg-lès-Valence, France. The retrofit was implemented as part of the European Union's (EU) SUNERGIE Program and EU grants covered 32% of the total project cost.
System description
The SWH system consists of 15 flat plate collectors of type ST3V manufactured by Techniques Solaires Appliquées (TSA). The total collector area is 34.7 m². The collectors are tilted at an angle of 45º from the horizontal and are connected to a 2,000 L hot water storage tank. Auxiliary water heating is provided by the existing natural gas water heating system.
Lessons learned
The big picture
SWH is a mature, well-developed technology and numerous manufacturers of high quality SWH products exist in many countries. A SWH system can typically displace 30-50% of the domestic water heating energy use in most latitudes, including much of northern Europe. SWH systems are often financially attractive when they displace high-cost energy sources in high load applications. In regions where the price of competing conventional fuels (e.g. natural gas) is low however, environmental concerns and government support programs tend to be the more important drivers for SWH installations.
Throughout the 1990's in France, the installation rate for SWH systems has been low relative to some of the other European countries. By 2001 however, the annual installation rate had increased drastically to about 18,000 m² of collector area. The French government's new Plan soleil aims for 550,000 m² of solar thermal collector installations by 2006. In neighbouring Germany, with longer-standing government incentives, some 900,000 m² of collector area was installed in 2001. The unprecedented growth of the SWH market in Europe is driven largely by concerns over climate change.
Photo
Apartment building - Solar water heater, Rhône-Alpes, France
References
Case study assignment
A municipality in France has hired you to determine the financial feasibility of installing a solar water heating (SWH) system on an existing residential apartment building.
Site information
The building is located in the town of Bourg-lès-Valence, in the Rhône-Alpes region, at a latitude of 45.7ºN. The nearest available location for weather data is Lyon/Bron. The 4-storey building has 21 apartments with a relatively low occupancy rate of 55%. The required hot water temperature is 60ºC. The existing conventional water heating system is a central natural gas-fired boiler with a seasonal efficiency of 70%.
The client has requested that the project use glazed solar collectors by the French manufacturer Techniques Solaires Appliquées (TSA), type ST3V. These collectors are reported to have a "tau alpha" coefficient of 0.70, a "Fr UL" coefficient of 5.00 (W/m²)/ºC and have an area of 2.31 m² each. For aesthetic reasons, the collectors should be tilted at 45º, facing due south.
For the greenhouse gas analysis assume that "Nuclear" is the base case electricity system.
Financial information
The glazed solar collectors cost €300/m².
The following values should be used for the financial analysis: 5% inflation rate, 3.5% fuel cost escalation rate, 9% discount rate and a project life of 25 years. The price of natural gas is €0.168/m³ and the price of electricity is €0.119/kWh. The project is eligible for a government grant totalling 32% of total initial cost.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from the analysis. If the project's Internal Rate of Return (IRR) is below 10%, determine how much higher the cost of natural gas would have to rise for the project to yield a 10% IRR.
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
- The cost of the solar water heating (SWH) system is relatively high compared to the norm. This is largely attributed to the fact that the installation is a retrofit to a large existing building and therefore required a significant amount of customized engineering and installation effort. Furthermore, the installation is a technology demonstration project aimed at establishing the effectiveness of SWH for apartment blocks. As such, the project costs and financial analysis results are not necessarily representative of typical commercial projects.
- The ratio of storage capacity to collector area was set to 58 L/m² so as to correspond to a storage capacity of approximately 2,000 L.
- One can use the "Goal Seek" function on the RETScreen Toolbar to determine what the cost of natural gas would have to rise to for the project to yield an Internal Rate of Return (IRR) of 10%.
Real project
Results
In 1996, l'Office départemental de l'habitat, a local public housing agency, installed a solar water heating (SWH) system on an existing 21-unit residential apartment building, the Résidence moulin des prés, in Bourg-lès-Valence, France. The retrofit was implemented as part of the European Union's (EU) SUNERGIE Program and EU grants covered 32% of the total project cost.
System description
The SWH system consists of 15 flat plate collectors of type ST3V manufactured by Techniques Solaires Appliquées (TSA). The total collector area is 34.7 m². The collectors are tilted at an angle of 45º from the horizontal and are connected to a 2,000 L hot water storage tank. Auxiliary water heating is provided by the existing natural gas water heating system.
Lessons learned
- A SWH system can be successfully retrofitted to an existing multi-unit residential building.
- More site-specific engineering work is required and costs are generally higher for retrofitting a SWH system to an existing building than for implementing a SWH system in a new construction project, where it can be integrated at the design stage.
- Given the relatively low cost of natural gas at the site (which is the fuel used by existing water heating system) the SWH system cannot be justified on financial grounds alone.
- The desire to demonstrate the technical feasibility and environmental benefits of a SWH system can be more important than financial considerations.
The big picture
SWH is a mature, well-developed technology and numerous manufacturers of high quality SWH products exist in many countries. A SWH system can typically displace 30-50% of the domestic water heating energy use in most latitudes, including much of northern Europe. SWH systems are often financially attractive when they displace high-cost energy sources in high load applications. In regions where the price of competing conventional fuels (e.g. natural gas) is low however, environmental concerns and government support programs tend to be the more important drivers for SWH installations.
Throughout the 1990's in France, the installation rate for SWH systems has been low relative to some of the other European countries. By 2001 however, the annual installation rate had increased drastically to about 18,000 m² of collector area. The French government's new Plan soleil aims for 550,000 m² of solar thermal collector installations by 2006. In neighbouring Germany, with longer-standing government incentives, some 900,000 m² of collector area was installed in 2001. The unprecedented growth of the SWH market in Europe is driven largely by concerns over climate change.
Photo
Apartment building - Solar water heater, Rhône-Alpes, France
References
- Canadian Solar Industries Association, Newsletter, March/April 2002.
- Madomercandy, Remeche, "Personal communication," IT Power India Ltd., 2002.
- Parthan, Binu K., "Personal communication," IT Power India Ltd., 2003.
- Tecsol S.A., Website: http://www.tecsol.fr.
