---
title: "Energy Efficient Windows Doors New Homes | AVANORTH"
canonical_url: "https://avanorth.ca/blog/energy-efficient-windows-doors-new-homes"
last_updated: "2026-03-10T07:33:39.872Z"
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description: "Energy-efficient windows and doors guide: performance metrics, glazing technologies, frame materials, installation practices, and Ontario code requirements."
"og:description": "Energy-efficient windows and doors guide: performance metrics, glazing technologies, frame materials, installation practices, and Ontario code requirements."
"og:title": "Energy Efficient Windows Doors New Homes"
"twitter:description": "Energy-efficient windows and doors guide: performance metrics, glazing technologies, frame materials, installation practices, and Ontario code requirements."
"twitter:title": "Energy Efficient Windows Doors New Homes"
---
AVANORTH Home
**Residential Trends**·April 8, 2026· 4 min read
# **Energy-Efficient Windows and Doors for New Homes**
Windows and doors are the weakest thermal links in the building envelope. Choosing high-performance products with proper installation is essential for meeting Ontario energy codes and reducing heating costs in Canadian homes.
**AVANORTH Team**
AVANORTH Construction
In a typical Canadian home, windows and doors account for 25% to 35% of total heat loss. Even the best window has a thermal resistance far lower than the surrounding wall. The Ontario Building Code requires increasingly better window performance as part of Canada's path to net-zero energy buildings. Selecting the right windows and doors, and installing them correctly, is one of the most impactful decisions in new home construction.
---
## Understanding Window Performance Metrics
| Metric | What It Measures | Better Performance |
| --- | --- | --- |
| U-factor (W/m2K) | Rate of heat transfer through the window | Lower is better (less heat loss) |
| R-value | Thermal resistance (1/U-factor) | Higher is better |
| Solar Heat Gain Coefficient (SHGC) | Fraction of solar radiation admitted | Depends on orientation (see below) |
| Visible Transmittance (VT) | Fraction of visible light admitted | Higher = more natural light |
| Air Leakage (L/s/m2) | Rate of air infiltration through closed window | Lower is better |
| Energy Rating (ER) | Canadian metric combining U-factor, SHGC, air leakage | Higher is better (positive = net energy gain) |
> **The ER Number:** The Energy Rating is unique to Canada and is the most useful single number for comparing windows. An ER of 34 or higher is required by the Ontario Building Code (OBC SB-12). An ER of 40+ is recommended for high-performance homes. Windows with a positive ER gain more energy from the sun than they lose through conduction and air leakage on the south face.
---
## Window Technologies
### Glazing
| Configuration | Typical U-factor | Typical ER | Notes |
| --- | --- | --- | --- |
| Double-pane, clear | 2.8 | 15-20 | Below code minimum, not acceptable for new homes |
| Double-pane, Low-E, argon | 1.6-1.8 | 29-34 | Minimum code compliant (barely) |
| Triple-pane, Low-E, argon | 1.0-1.2 | 34-42 | Code standard for high-performance homes |
| Triple-pane, dual Low-E, krypton | 0.7-0.9 | 42-50 | Premium performance, passive house suitable |
| Quad-pane or vacuum-insulated | 0.5-0.7 | 45-55 | Ultra-premium, limited availability |
### Low-E Coatings Explained
Low-emissivity (Low-E) coatings are microscopically thin metallic layers applied to glass surfaces. They reflect long-wave infrared radiation (heat) while allowing visible light to pass. The position of the coating determines the function:
- **Surface 2 (inner face of outer pane):** High Solar Gain Low-E. Allows solar heat in while reflecting interior heat back inside. Best for south-facing windows in heating climates (Canada).
- **Surface 3 (outer face of inner pane):** Low Solar Gain Low-E. Blocks solar heat while reflecting interior heat back. Best for west-facing windows where summer overheating is a concern.
---
## Frame Materials
| Material | Thermal Performance | Durability | Cost | Maintenance |
| --- | --- | --- | --- | --- |
| Vinyl (PVC) | Good (multi-chamber insulated) | 25-40 years | Lowest | Minimal |
| Fibreglass | Very good (low conductivity) | 40-50+ years | Moderate | Minimal |
| Wood | Good (natural insulator) | 30-50 years (maintained) | Higher | Regular (stain/paint) |
| Aluminum (thermally broken) | Fair (thermal break critical) | 40-60 years | Higher | Minimal |
| Wood-clad (vinyl or aluminum exterior) | Good | 40-50 years | Highest | Interior only |
---
## Installation Best Practices
The best window in the world will fail if installed poorly. Window installation in new construction must address three functions:
1. **Air barrier continuity:** The window must be sealed to the building's air barrier (typically the interior vapour barrier or sheathing membrane) with flexible tapes, membranes, or sealant. No gaps allowed.
2. **Water management:** The window must be integrated into the water-resistive barrier (WRB/housewrap) with proper flashing. Water that reaches the window must be directed outward, not into the wall cavity.
3. **Thermal bridge management:** The window must be positioned in the wall to minimize thermal bridging. In a 2x6 wall, the window is typically set at the outer edge of the rough opening, with insulation wrapped into the jamb.
### Flashing Sequence (Critical)
1. Sill pan flashing (angled to exterior, with end dams)
2. Window set in sill sealant
3. Jamb flashing (overlaps sill flashing)
4. Head flashing (overlaps jamb flashing)
5. WRB/housewrap overlaps head flashing
> **The Shingle Principle:** All flashing must overlap like shingles: upper pieces over lower pieces so water always flows outward and downward. If any piece laps the wrong way, water will enter the wall.
---
## Ontario Code Requirements (OBC SB-12 2024)
- **Minimum ER:** 34 for all windows (prescriptive path)
- **Maximum window area:** 22% of above-grade wall area (prescriptive path, more allowed with performance trade-offs)
- **Doors:** Insulated steel or fibreglass, ER 21 minimum for opaque, ER 25 for doors with glazing
- **Installation:** Must maintain air barrier and water-resistive barrier continuity
> **AVANORTH Practice:** We specify triple-pane, Low-E, argon-filled windows with an ER of 38+ on all new homes. We use fibreglass or premium vinyl frames with multi-chamber construction. Every window is installed with a complete air seal, proper flashing, and thermal break at the rough opening. The difference in heating cost between a code-minimum window and a high-performance window pays for the upgrade within a few years in Ontario's climate.
#windows #energy-efficiency #building-envelope
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