Energy efficiency measures - Residential - Passive solar heating / Japan
Case study assignment
You work for a manufacturer of pre-fabricated housing in Canada that is interested in expanding into the Japanese marketplace. You are asked by management to prepare a study that will quantify the energy savings and financial benefit, from the purchasers perspective, of using high performance windows in an energy efficient house design that your company would like to market in Japan.
Site information
The market area you are considering is in Kagoshima, Japan. Kagoshima is on the southern island of Kyushu and has significant heating and cooling loads. Typically, new homes in Japan are built using single pane, aluminium windows. Your company normally specifies double-glazed, low-e, argon filled windows with vinyl frames. The pre-fabricated home you are considering has two large casement windows in the front (1,700 Width x 2,000 Height mm) and a second-floor patio door (1,300 W x 2,000 H mm) over the main entrance. The remaining windows in the home are casements (700 H x 1,200 H mm) and are laid out in the Table.
Case study assignment
You work for a manufacturer of pre-fabricated housing in Canada that is interested in expanding into the Japanese marketplace. You are asked by management to prepare a study that will quantify the energy savings and financial benefit, from the purchasers perspective, of using high performance windows in an energy efficient house design that your company would like to market in Japan.
Site information
The market area you are considering is in Kagoshima, Japan. Kagoshima is on the southern island of Kyushu and has significant heating and cooling loads. Typically, new homes in Japan are built using single pane, aluminium windows. Your company normally specifies double-glazed, low-e, argon filled windows with vinyl frames. The pre-fabricated home you are considering has two large casement windows in the front (1,700 Width x 2,000 Height mm) and a second-floor patio door (1,300 W x 2,000 H mm) over the main entrance. The remaining windows in the home are casements (700 H x 1,200 H mm) and are laid out in the Table.
The 2-story, 129 m² home includes an oil furnace (75% efficient) for heat and has central air-conditioning. It is built with a relatively low mass level and medium insulation level. Internal gains are about ½ of typical homes.
Financial information
Typical financial figures are provided for your analysis. The costs of conventional windows (in Canadian dollars) are as follows: $760 for each of the two large casements on the front of the house, $1,130 for the patio door and $325 for each of the remaining windows. The cost premium for the high performance windows (including shipping) is roughly 30%.
Assume that 80% of the purchase price of the home will be mortgaged by the buyers at an interest rate of 8% over 20 years. Energy prices are expected to rise at an annual rate of 2.5% while general inflation is expected to be 3%. The discount rate should be 9%. The windows are expected to last for at least 30 years. The cost of oil in Japan is $0.799/L, and electricity is $0.390/kWh.
Prepare a RETScreen study that will quantify the energy savings of high performance windows relative to typical Japanese construction practices. Document 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
The Super E™ House Program was initiated by the Canadian government in 1998 to introduce Canadian energy efficiency and quality construction practices to the Japanese market. Over 50 Super E homes have been built in Japan to date. High performance windows are a key feature of every Super E home and can provide significant financial and comfort benefits in the wide range of climates found in Japan.
System description
The Super E House in Kagoshima employs double-glazed, low-e, argon filled windows with vinyl frames imported from Canada. Conventional practice for new Japanese housing typically calls for single pane, aluminium windows. The high performance windows reduce heat loss in the winter and heat gain in the summer, cut down air leakage around the window frames and counteract potential condensation and mildew problems.
The 2-story home has roughly a square footprint, representing a space efficient design required for the small building plots available in Japan. The Super-E home has central heating and air-conditioning, as well an Energy Recovery Ventilator (ERV) to provide mechanical ventilation. The latter is a requirement due to the air tightness of the design. The central mechanical systems are considerably different from what is typically installed in most Japanese homes. Japanese homeowners generally only heat or cool rooms that are in use, employing small room air-conditioners or heat pumps. In some cases portable kerosene heaters are used and transported from room to room as required.
Lessons learned
The big picture
Japan's significant demand for housing, combined with the high cost of land, labour and materials, has led to a shortage of affordable housing. At the same time, the high cost of energy has created a demand for more energy efficient homes.
Natural Resources Canada (NRCan), a Canadian government department, initially developed the Super E House Program to provide comfortable, energy efficient homes for the Japanese market. The program also helps the Canadian housing and housing products industries develop a potentially large new market in Japan. Since the program's launch in 1998, more than 30 Japanese companies have partnered with 10 Canadian companies to build houses throughout Japan. Based on its success in Japan, the Super E House Program has recently been expanded to the United Kingdom.
Photo
House - Passive solar heating, Kagoshima, Japan
References
Financial information
Typical financial figures are provided for your analysis. The costs of conventional windows (in Canadian dollars) are as follows: $760 for each of the two large casements on the front of the house, $1,130 for the patio door and $325 for each of the remaining windows. The cost premium for the high performance windows (including shipping) is roughly 30%.
Assume that 80% of the purchase price of the home will be mortgaged by the buyers at an interest rate of 8% over 20 years. Energy prices are expected to rise at an annual rate of 2.5% while general inflation is expected to be 3%. The discount rate should be 9%. The windows are expected to last for at least 30 years. The cost of oil in Japan is $0.799/L, and electricity is $0.390/kWh.
Prepare a RETScreen study that will quantify the energy savings of high performance windows relative to typical Japanese construction practices. Document any assumptions that you are required to make and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
- The assignment asks the user to evaluate the window energy savings potential. It is assumed that the windows will be installed in a pre-fabricated Low-e Home in Japan.
- At this feasibility study stage, no specific building position or orientation has yet been selected (only the general city/climate region is known). The assignment directs the user to determine the energy/cost saving potential of a "generic" Super E house. Any orientation (building north) would therefore be acceptable. The user is encouraged to investigate the sensitivity of the analysis to different building orientations.
- The cost analysis is performed in Canadian dollars ($) since the proposed high performance windows are to be manufactured in Canada. The "Second currency" feature of RETScreen can be used to display the costs in Japanese Yen (¥). The latter is for documentation and presentation purposes only.
Real project
Results
The Super E™ House Program was initiated by the Canadian government in 1998 to introduce Canadian energy efficiency and quality construction practices to the Japanese market. Over 50 Super E homes have been built in Japan to date. High performance windows are a key feature of every Super E home and can provide significant financial and comfort benefits in the wide range of climates found in Japan.
System description
The Super E House in Kagoshima employs double-glazed, low-e, argon filled windows with vinyl frames imported from Canada. Conventional practice for new Japanese housing typically calls for single pane, aluminium windows. The high performance windows reduce heat loss in the winter and heat gain in the summer, cut down air leakage around the window frames and counteract potential condensation and mildew problems.
The 2-story home has roughly a square footprint, representing a space efficient design required for the small building plots available in Japan. The Super-E home has central heating and air-conditioning, as well an Energy Recovery Ventilator (ERV) to provide mechanical ventilation. The latter is a requirement due to the air tightness of the design. The central mechanical systems are considerably different from what is typically installed in most Japanese homes. Japanese homeowners generally only heat or cool rooms that are in use, employing small room air-conditioners or heat pumps. In some cases portable kerosene heaters are used and transported from room to room as required.
Lessons learned
- High performance windows are particularly cost effective in new construction and in markets with high costs for heating and cooling fuels.
- The relatively conservative heating and cooling practices employed in Japanese homes mean that the energy savings of Super E homes are often lower than what would be expected under North American occupancy conditions.
- Super E homes are often sold not only based on their energy savings, but also on the comfort of their indoor environment.
- A Super E home, where all rooms are heated, can typically be operated with the same fuel costs as a normal Japanese home that utilizes room-by-room space heating and cooling.
The big picture
Japan's significant demand for housing, combined with the high cost of land, labour and materials, has led to a shortage of affordable housing. At the same time, the high cost of energy has created a demand for more energy efficient homes.
Natural Resources Canada (NRCan), a Canadian government department, initially developed the Super E House Program to provide comfortable, energy efficient homes for the Japanese market. The program also helps the Canadian housing and housing products industries develop a potentially large new market in Japan. Since the program's launch in 1998, more than 30 Japanese companies have partnered with 10 Canadian companies to build houses throughout Japan. Based on its success in Japan, the Super E House Program has recently been expanded to the United Kingdom.
Photo
House - Passive solar heating, Kagoshima, Japan
References
- CANMET Energy Technology Centre (CETC) - Ottawa Buildings Group, Evaluation of Cooling and Heating Loads in Japanese Housing, Report by Enermodal Engineering Ltd., 1998.
- CETC-Ottawa Website: http://buildingsgroup.nrcan.gc.ca/projects/Super_e.html.
- Kemp, Steve, "Personal communication," Enermodal Engineering Ltd., 2002.
- Sinha, Robin, "Personal communication," CETC-Ottawa Buildings Group, March 2002.
