{"id":3302,"date":"2026-05-14T10:41:45","date_gmt":"2026-05-14T10:41:45","guid":{"rendered":"https:\/\/www.gohomeguide.com\/?p=3302"},"modified":"2026-05-14T10:42:13","modified_gmt":"2026-05-14T10:42:13","slug":"window-ratings","status":"publish","type":"post","link":"https:\/\/www.gohomeguide.com\/ja\/\u30a6\u30a3\u30f3\u30c9\u30a6\u8a55\u4fa1\/","title":{"rendered":"\u7a93\u306e\u6027\u80fd\u8a55\u4fa1\u306b\u3064\u3044\u3066\u89e3\u8aac\u3057\u3001\u52b9\u7387\u6027\u3092\u5411\u4e0a\u3055\u305b\u307e\u3059"},"content":{"rendered":"\t\t
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Understanding the Most Important Window Ratings<\/h2>

Window ratings help you compare how well a window performs in real-life conditions. They measure insulation, sunlight control, airflow, moisture resistance, and even noise reduction. Understanding these numbers makes it much easier to choose windows that improve comfort, lower energy bills, and match your local climate.<\/p>

Rating<\/th>What It Measures<\/th>Lower or Higher Better<\/th>Ideal Range<\/th><\/tr><\/thead>
U-Factor<\/td>Heat transfer and insulation performance<\/td>Lower is better<\/td>About 0.20\u20130.30 for strong efficiency<\/td><\/tr>
SHGC<\/td>How much solar heat enters through glass<\/td>Lower for hot climates; higher for cold climates<\/td>0.25\u20130.40 for hot areas; 0.40+ for cold areas<\/td><\/tr>
VT<\/td>Amount of visible natural light entering indoors<\/td>Higher is better for daylight<\/td>0.40\u20130.70 for balanced light and comfort<\/td><\/tr>
Air Leakage<\/td>Unwanted air passing through window gaps<\/td>Lower is better<\/td>0.30 or lower<\/td><\/tr>
Condensation Resistance<\/td>Resistance to moisture and fogging on glass<\/td>Higher is better<\/td>50+ is good; 60+ is better<\/td><\/tr>
STC Rating<\/td>How well the window blocks outside noise<\/td>Higher is better<\/td>30+ for quieter homes; 35+ for noisy areas<\/td><\/tr><\/tbody><\/table><\/div>

U-Factor<\/h3>

U-factor measures how much heat passes through a window. In simple terms, it tells you how well the window keeps indoor heat from escaping during winter and blocks outdoor heat during summer.<\/p>

Lower U-factor numbers mean better insulation performance. A window with a low U-factor can help reduce heating and cooling costs while keeping indoor temperatures more stable throughout the year.<\/p>

Recommended ranges usually depend on climate:<\/p>