Energy efficiency measures - Residential - Passive solar heating / Canada (Hamilton)
Case study assignment
You have been asked to provide input on the design of a new condominium building. The goal of the project is to bring higher-quality design and construction to the speculative condominium market in order to offer lower operating costs and better overall building performance. The use of high-performance windows has been proposed. The developer would like an energy and financial analysis of how upgrading the windows from standard double-glazed windows would affect a typical north-facing unit and a typical south-facing unit.
Site information
The building will be located near Hamilton, Ontario, Canada, not far from Toronto. It will be long and narrow with the long side facing 30o west of south. The main building structure will be concrete, with above average insulation. A typical unit will have a floor area of approximately 114 m² and 3 operable windows with a combined area of 11.9 m². It will be heated using natural gas space heating with an expected seasonal efficiency of 78%. It will be cooled with high-efficiency air-conditioning. A balcony heavily shades one of the windows on the south side during the summer. The building is still in the design stage, and the heating and cooling plant size has not yet been determined.
The builder ordinarily uses double-glazed windows with thermally broken aluminum frames. Typical specifications for the windows are U = 3.4 W/(m²-oC) and solar heat gain coefficient (SHGC) of 0.55. High-performance windows, with a low-e coating, argon gas fill, insulating edge spacer and better insulating frames, have U = 1.55 W/(m²-oC) and SHGC of 0.31.
Financial information
Typical financial figures for the analysis are provided by the client (inflation rate of 2%, debt ratio of 80%, fuel cost escalation rate of 3%, debt interest rate of 9%, discount rate of 9%, a debt term of 20 years, a project life of 30 years, tax rate of 25%). Windows can be depreciated, for income tax purposes, using a straight-line method over 30 years. Financing will be provided by the client. The retail price of electricity is $0.085/kWh and the monthly demand charge is $6/kW. Natural gas costs $0.20/m³. Standard double-glazed windows cost approximately $200/m² and high-performance windows can be purchased for an additional $50/m².
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
Results
The condominium at 77 Governors Road in Dundas, Ontario (near Hamilton, Ontario, Canada) brings higher-quality construction to the speculative condominium market in order to offer lower operating costs and better overall building performance. The owner and developer, Urban Horse Developments, intends to show the benefits of a more sustainable approach to multi-unit residential design, and to develop solutions for the building envelope problems that are common in many multi-unit residential buildings. Environmental, mechanical and electrical consultant Enermodal Engineering Limited assisted in evaluating the optimum design of the building envelope and designed superior-quality building ancillary systems to meet the energy use requirements of the Natural Resources Canada C2000/Canadian Mortgage and Housing Corporation Ideas Challenge.
High-performance windows are a key feature of the building design. The windows offer improved thermal comfort and substantial heating and cooling savings. Additional savings were realized in this case because building mechanical systems were down-sized according to loads defined by the improved envelope. Perimeter heating was eliminated, saving the cost of convectors and associated piping. The savings in heating and cooling systems were estimated to be $250 per suite. The payback associated with upgrading the windows is 5 years.
System description
High performance windows are the major distinguishing component of the building envelope. Fiberglass frames, insulating spacers, and low-e double glazing with argon fill give an overall U-value of 1.61 W/(m²-°C) - about the best window performance possible without going to triple glazing. Together with higher wall insulation, the windows ensure that interior surfaces are warm enough that perimeter heating is not required in winter.
Lessons learned
Apartment buildings have traditionally used very basic, low-performing windows. This project has shown that high-performance windows can be a key component in improving the performance, quality and comfort of multi-unit residential buildings.
Photo
Condominium - Multi-unit housing - Passive solar heating, Ontario, Canada
References
Case study assignment
You have been asked to provide input on the design of a new condominium building. The goal of the project is to bring higher-quality design and construction to the speculative condominium market in order to offer lower operating costs and better overall building performance. The use of high-performance windows has been proposed. The developer would like an energy and financial analysis of how upgrading the windows from standard double-glazed windows would affect a typical north-facing unit and a typical south-facing unit.
Site information
The building will be located near Hamilton, Ontario, Canada, not far from Toronto. It will be long and narrow with the long side facing 30o west of south. The main building structure will be concrete, with above average insulation. A typical unit will have a floor area of approximately 114 m² and 3 operable windows with a combined area of 11.9 m². It will be heated using natural gas space heating with an expected seasonal efficiency of 78%. It will be cooled with high-efficiency air-conditioning. A balcony heavily shades one of the windows on the south side during the summer. The building is still in the design stage, and the heating and cooling plant size has not yet been determined.
The builder ordinarily uses double-glazed windows with thermally broken aluminum frames. Typical specifications for the windows are U = 3.4 W/(m²-oC) and solar heat gain coefficient (SHGC) of 0.55. High-performance windows, with a low-e coating, argon gas fill, insulating edge spacer and better insulating frames, have U = 1.55 W/(m²-oC) and SHGC of 0.31.
Financial information
Typical financial figures for the analysis are provided by the client (inflation rate of 2%, debt ratio of 80%, fuel cost escalation rate of 3%, debt interest rate of 9%, discount rate of 9%, a debt term of 20 years, a project life of 30 years, tax rate of 25%). Windows can be depreciated, for income tax purposes, using a straight-line method over 30 years. Financing will be provided by the client. The retail price of electricity is $0.085/kWh and the monthly demand charge is $6/kW. Natural gas costs $0.20/m³. Standard double-glazed windows cost approximately $200/m² and high-performance windows can be purchased for an additional $50/m².
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
- The high financial returns on the windows are in large part attributable to the reductions in heating and cooling plant that they permit. In a retrofit situation, where the size of the heating and cooling plant was not reduced, the returns would be much lower. The payback period for the north-facing unit would be considerably longer than that for the south-facing unit.
- The incremental electricity load reduction has been calculated by dividing the peak cooling load reduction by the air-conditioner's seasonal COP. The unit cost is the monthly electrical demand charge multiplied by 3 months - the part of the year during which air-conditioning loads will be significant.
Results
The condominium at 77 Governors Road in Dundas, Ontario (near Hamilton, Ontario, Canada) brings higher-quality construction to the speculative condominium market in order to offer lower operating costs and better overall building performance. The owner and developer, Urban Horse Developments, intends to show the benefits of a more sustainable approach to multi-unit residential design, and to develop solutions for the building envelope problems that are common in many multi-unit residential buildings. Environmental, mechanical and electrical consultant Enermodal Engineering Limited assisted in evaluating the optimum design of the building envelope and designed superior-quality building ancillary systems to meet the energy use requirements of the Natural Resources Canada C2000/Canadian Mortgage and Housing Corporation Ideas Challenge.
High-performance windows are a key feature of the building design. The windows offer improved thermal comfort and substantial heating and cooling savings. Additional savings were realized in this case because building mechanical systems were down-sized according to loads defined by the improved envelope. Perimeter heating was eliminated, saving the cost of convectors and associated piping. The savings in heating and cooling systems were estimated to be $250 per suite. The payback associated with upgrading the windows is 5 years.
System description
High performance windows are the major distinguishing component of the building envelope. Fiberglass frames, insulating spacers, and low-e double glazing with argon fill give an overall U-value of 1.61 W/(m²-°C) - about the best window performance possible without going to triple glazing. Together with higher wall insulation, the windows ensure that interior surfaces are warm enough that perimeter heating is not required in winter.
Lessons learned
- High-performance windows can significantly reduce heating and cooling costs in apartments.
- Perimeter heating can be avoided with high-performance windows.
- Savings in mechanical systems costs by using high-performance windows pay for a large fraction of the incremental cost of these windows.
Apartment buildings have traditionally used very basic, low-performing windows. This project has shown that high-performance windows can be a key component in improving the performance, quality and comfort of multi-unit residential buildings.
Photo
Condominium - Multi-unit housing - Passive solar heating, Ontario, Canada
References
- Carpenter, Stephen, "Personal communication," Enermodal Engineering Limited, 2000.
- Commercial Building Incentive Program Case Studies, Website: http://www.cbip.nrcan.gc.ca.
