With windows and doors made from ALTERA profiles, the heat stays outside the building - thanks to their very good thermal insulation properties. That ensures not only a comfortable living climate, but also lower cooling bills from air conditioning and significantly reduce CO2 emissions.


To ensure that ALTERA window and door designs meet the most stringent energy codes in the United States, we have conducted numerous thermal engineering calculations. Our designs have been simulated using up to 20 different glazing, coating and spacer configurations.


The following chart summarizes the thermal performance of our designs.

Thermal ratings are highly dependent on glass configurations.


Request test reports before the start of any project.

  • U-factors (and R-values) measure the rate of heat transfer and tell how well the window or door insulates. U-factors (and R-values) generally range from 0.20 (R-5) to 1.20 (R-0.8). The lower the value, the better the window insulates.


  • SHGC (Solar Heat Gain Coefficient) measures the fraction of solar energy transmitted and tells how well the window or door blocks heat caused by sunlight. SHGC is measured on a scale of 0-1. The lower the value, the better a product is at blocking unwanted heat gain.


  • CRF (Condensation Resistance Factor) measures how well a product resists water build-up. CRF is scored on a scale of 1-100.  The higher the value, the less build-up the window allows.

Thermal image of ALTERA tilt-turn window demonstrates how effectively this design separates warmer air and cooler air in order to achieve optimal energy efficiency.

Contact Information

Address: 2260 Cordelia Road Fairfield, CA 94534


Phone: (707) 207 4850


Email: info@alterawindows.com

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