Energy efficiency measures - Residential - Passive solar heating / Canada (Toronto)
Case study assignment
You are an architect designing a home that will consume significantly less energy, water and construction materials than a conventional house. You wish to analyse the financial viability of a passive solar design approach. Specifically, you are considering upgrading the standard double-glazed windows to a high-performance type and moving all the windows that would be installed on the back (north) side of the house to the front.
Site information
The home will be located in Waterloo, Ontario, Canada, near Toronto, and have a floor area of 224 m². The front of the building will face 25o east of south. The wood-framed house will be well insulated, heated by a natural gas system with a seasonal efficiency of 80%, and cooled by a standard air-conditioner.
From the house concept drawings, you retrieve the schedule for windows in the table. Standard windows for this type of installation are double-glazed with aluminium frames (with a thermal break). From an ASHRAE (American Society of Heating, Refrigerating, and Air-conditioning Engineers) Fundamentals handbook, you estimate that casement windows of this type have a U- value of 3.42 W/(m²-oC) and a solar heat gain coefficient (SHGC) of 0.66; the corresponding specifications for fixed windows are 3.22 W/(m²-oC) and SHGC of 0.68. The glazing itself has a U-value of 2.73 W/(m²-oC) and a SHGC of 0.75.
You are considering replacing these with double-glazed units from Accurate Dorwin, with fibreglass insulated frames, low-e coating, and argon fill. The yard at the south of the house will have a garden with numerous trees and shrubs, providing shading of up to 40% in the summer. You decide to plant only deciduous plants, which provide much less shade during the winter. The other building orientations are not as shaded as the front.
Case study assignment
You are an architect designing a home that will consume significantly less energy, water and construction materials than a conventional house. You wish to analyse the financial viability of a passive solar design approach. Specifically, you are considering upgrading the standard double-glazed windows to a high-performance type and moving all the windows that would be installed on the back (north) side of the house to the front.
Site information
The home will be located in Waterloo, Ontario, Canada, near Toronto, and have a floor area of 224 m². The front of the building will face 25o east of south. The wood-framed house will be well insulated, heated by a natural gas system with a seasonal efficiency of 80%, and cooled by a standard air-conditioner.
From the house concept drawings, you retrieve the schedule for windows in the table. Standard windows for this type of installation are double-glazed with aluminium frames (with a thermal break). From an ASHRAE (American Society of Heating, Refrigerating, and Air-conditioning Engineers) Fundamentals handbook, you estimate that casement windows of this type have a U- value of 3.42 W/(m²-oC) and a solar heat gain coefficient (SHGC) of 0.66; the corresponding specifications for fixed windows are 3.22 W/(m²-oC) and SHGC of 0.68. The glazing itself has a U-value of 2.73 W/(m²-oC) and a SHGC of 0.75.
You are considering replacing these with double-glazed units from Accurate Dorwin, with fibreglass insulated frames, low-e coating, and argon fill. The yard at the south of the house will have a garden with numerous trees and shrubs, providing shading of up to 40% in the summer. You decide to plant only deciduous plants, which provide much less shade during the winter. The other building orientations are not as shaded as the front.
Financial information
Typical financial figures for the analysis are: inflation rate of 2%, debt ratio of 90%, fuel cost escalation rate of 3%, debt interest rate of 9%, discount rate of 9%, debt term of 25 years, and a project life of 30 years. The retail price of electricity is $0.085/kWh with no demand charges. The price of natural gas is $0.20/m³.
The standard glazing units are priced at $312/m² for casement windows and $208/m² for fixed windows. You estimate that the price of the high performance windows will be about 20% higher. The installation cost is estimated at $100/m² regardless of window type.
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
In the summer of 1991, CANMET, the main research and technology development arm of Natural Resources Canada, challenged the building industry to design and build houses that promoted energy efficiency and environmental responsibility. The Kitchener-Waterloo Home Builders Association and Enermodal Engineering Limited answered that challenge - and the result was the Waterloo Region Green Home.
The home is designed to consume significantly less energy, water and construction materials than a conventional house. The home is comfortable, has good air quality, and saves the homeowner between $1,200 and $2,000 per year in energy and water costs.
Monitoring shows that it is one of the most energy efficient houses in North America. The annual heating bill is about $100.
System description
The windows and glass inserts for doors were selected for their high solar heat gain and low heat loss. They are triple-glazed with two low-emissivity coatings, low conductivity edge spacers and argon gas fill. The window frames are foam-filled fibreglass. The chosen window has the best energy rating of all windows registered in the Ontario Hydro high-performance Window Incentive Program.
Windows are located such that heat gains are maximised in winter and minimised in summer, and are sized to avoid house overheating. The high-performance windows meant that perimeter heating was not needed. Ductwork and heating registers were located in the centre of the house, saving on the material and labour costs.
Lessons learned
The Green Home successfully demonstrated that very low energy housing could be built even in the cold Canadian climate. Passive solar heating was a key part of the building design and provided 50% of space heating load.
Photo
The Waterloo Region Green Home, Waterloo, Ontario, Canada
References
Typical financial figures for the analysis are: inflation rate of 2%, debt ratio of 90%, fuel cost escalation rate of 3%, debt interest rate of 9%, discount rate of 9%, debt term of 25 years, and a project life of 30 years. The retail price of electricity is $0.085/kWh with no demand charges. The price of natural gas is $0.20/m³.
The standard glazing units are priced at $312/m² for casement windows and $208/m² for fixed windows. You estimate that the price of the high performance windows will be about 20% higher. The installation cost is estimated at $100/m² regardless of window type.
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 $300/kW cooling system credit is due to reduced air-conditionner equipment size; it is quite possible that the same size air-conditioner would be used in both cases.
Results
In the summer of 1991, CANMET, the main research and technology development arm of Natural Resources Canada, challenged the building industry to design and build houses that promoted energy efficiency and environmental responsibility. The Kitchener-Waterloo Home Builders Association and Enermodal Engineering Limited answered that challenge - and the result was the Waterloo Region Green Home.
The home is designed to consume significantly less energy, water and construction materials than a conventional house. The home is comfortable, has good air quality, and saves the homeowner between $1,200 and $2,000 per year in energy and water costs.
Monitoring shows that it is one of the most energy efficient houses in North America. The annual heating bill is about $100.
System description
The windows and glass inserts for doors were selected for their high solar heat gain and low heat loss. They are triple-glazed with two low-emissivity coatings, low conductivity edge spacers and argon gas fill. The window frames are foam-filled fibreglass. The chosen window has the best energy rating of all windows registered in the Ontario Hydro high-performance Window Incentive Program.
Windows are located such that heat gains are maximised in winter and minimised in summer, and are sized to avoid house overheating. The high-performance windows meant that perimeter heating was not needed. Ductwork and heating registers were located in the centre of the house, saving on the material and labour costs.
Lessons learned
- Passive solar heating can significantly reduce space-heating costs even in cold climates.
- Perimeter heating is not required in houses with high-performance windows.
- Proper window selection, orientation and shading contribute significantly to reducing or eliminating space cooling loads.
The Green Home successfully demonstrated that very low energy housing could be built even in the cold Canadian climate. Passive solar heating was a key part of the building design and provided 50% of space heating load.
Photo
The Waterloo Region Green Home, Waterloo, Ontario, Canada
References
- Carpenter, Stephen, "Personal communication," Enermodal Engineering Limited, 2000.
- Grady, Wayne, Green Home, Camden House Publishing, Camden East, Ontario, 1995.
- Natural Resources Canada, Design and Performance of the Waterloo Region Green Home, report prepared by Enermodal Engineering Ltd., 1996.
