Question 1

What is a U-factor in windows?

Accepted Answer

U-factor measures how well a window prevents heat from escaping. Lower is better. U-0.30 means the window loses less heat than U-0.40. Required minimums vary by climate zone: Zone 3 (hot climates) allows U-0.40, Zone 5 (cold) requires U-0.32, Zone 7 (very cold) requires U-0.27 or lower. Triple-pane windows achieve U-0.15 to U-0.20. For every 0.10 reduction in U-factor, you can expect 10-15% reduction in heat loss.

Question 2

What is SHGC (Solar Heat Gain Coefficient)?

Accepted Answer

SHGC measures how much solar heat passes through a window on a scale of 0 to 1. Lower SHGC = less heat. Hot climates (IECC Zone 1-3) require SHGC 0.25 or lower to reduce AC costs by 15-25%. Cold climates benefit from higher SHGC (0.40-0.60) on south-facing windows for passive solar heating in winter. Low-E coatings control SHGC while maintaining visible light transmission.

Question 3

What does Low-E glass do?

Accepted Answer

Low-E (low-emissivity) glass has a microscopic metallic coating that reflects heat while allowing light through. In winter, it reflects heat back into your home. In summer, it blocks solar heat from entering. Types: Low-E2 (passive, for cold climates) and Low-E3 (solar control, for hot climates). Reduces energy loss by 30-50% versus clear glass. Required in most US climate zones under IECC 2018 and newer energy codes.

Question 4

Should I choose double-pane or triple-pane windows?

Accepted Answer

Choose based on climate zone: Zones 1-4 (mild to mixed): Double-pane Low-E sufficient with U-factors of 0.28-0.32. Zones 5-6 (cold): Triple-pane recommended for 20-30% additional energy savings with U-factors of 0.15-0.22. Zone 7 (very cold): Triple-pane often required by code. Payback period: 7-12 years in cold climates with 5,000+ heating degree days, 15+ years in mild climates. Triple-pane adds 30-50% to initial cost but dramatically cuts heating bills in cold regions.

Question 5

How much does window replacement cost?

Accepted Answer

Window replacement costs $380-$1,200 per window including professional installation. Single-pane glass replacement alone: $170-$450. Double-pane glass: $330-$820. Triple-pane: $600-$1,400. Cost factors include window size, frame material (vinyl cheapest at $300-700, wood mid-range at $500-1,000, fiberglass premium at $700-1,400), energy ratings (Low-E coating adds $50-100, argon fill adds $30-50), and local climate zone requirements.

Question 6

How long do window seals last?

Accepted Answer

Quality window seals last 15-25 years. Failure signs include condensation between panes, foggy or cloudy glass, moisture beads, and reduced insulation performance. Failure causes: UV exposure, temperature cycling, poor installation, cheap spacer systems. Climate affects lifespan: Hot-dry climates (Las Vegas, Phoenix) see 12-18 years, cold climates (Fargo, Anchorage) get 15-20 years, marine climates (Seattle) see 10-15 years due to moisture exposure. Quality brands like Andersen, Pella, and Marvin offer 20+ year warranties on seal failure.

Question 7

What are IECC climate zones?

Accepted Answer

IECC (International Energy Conservation Code) climate zones determine minimum window energy requirements. Zone 1-2 (Hot): Florida, South Texas, Hawaii - requires SHGC ≤0.25. Zone 3 (Warm): Southern US, Las Vegas - requires U-0.40, SHGC ≤0.25. Zone 4 (Mixed): Mid-Atlantic, Pacific Northwest - requires U-0.32. Zone 5 (Cold): Denver, Boise, Salt Lake City - requires U-0.32. Zone 6 (Very Cold): Montana, Wyoming, northern states - requires U-0.30. Zone 7-8 (Extremely Cold): Fargo, Duluth, Alaska - requires U-0.27 or lower. Stricter zones require better insulation to meet code.

Question 8

Do I need permits for window replacement?

Accepted Answer

Most states require building permits for window replacement to ensure energy code compliance and safety. States with strict enforcement: Washington, Oregon, California, Vermont, Massachusetts. States with moderate requirements: Idaho, Montana, Colorado, Utah (permits required, enforcement varies by jurisdiction). Permits ensure proper U-factor compliance, egress window codes for bedrooms, structural integrity, and moisture barrier installation. Licensed installers typically handle permits ($50-$200 fee). DIY replacement requires separate permit application and inspections. Permit violations can affect home resale and insurance claims.

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