Glazing Type
Frame Material
Window Age
Overall Condition
Select any symptoms you have noticed.
Region
Sun Exposure
Noise Level
The DMV region is Climate Zone 4A (mixed-humid). ENERGY STAR recommends U-Factor 0.30 or below and SHGC 0.40 or below for this zone.
Energy Score
45/100
Grade D
Energy Loss
19%
Through windows
Potential Savings
14%
With upgrades
kWh Savings
4.8
Annual estimate
Below average. Your windows are a significant source of energy loss.
U-Factor (BTU/hr/ft2/F) (lower is better)
SHGC (Solar Heat Gain) (lower is better)
Current
Glass: Double pane
Frame: Vinyl
U-Factor: 0.51
SHGC: 0.56
Recommended
Glass: Double-pane Low-E with argon fill
Frame: Fiberglass
U-Factor: 0.27
SHGC: 0.25
ENERGY STAR certified windows for Climate Zone 4 (DC/VA/MD) must have a U-Factor of 0.30 or below and SHGC of 0.40 or below. These windows use advanced technologies including Low-E coatings, argon or krypton gas fills, warm-edge spacers, and insulating frame materials to minimize heat transfer while maximizing comfort.
Our licensed glass specialists perform on-site window energy assessments with thermal imaging throughout the DMV. We measure every window and provide a detailed efficiency report with upgrade options.
Window Science
The key metrics that determine how well your windows insulate and protect your home.
Measures how much heat passes through the window assembly. Lower numbers mean better insulation. For the DMV climate (Zone 4A), ENERGY STAR requires 0.30 or below. Single-pane windows typically rate around 1.10 -- nearly four times worse than the standard.
SHGC measures how much solar radiation passes through the glass. Lower SHGC means less heat gain from the sun. In the DMV, where summers are hot, a low SHGC (0.25-0.40) reduces cooling loads. Look for Low-E coatings that selectively block infrared heat while allowing visible light.
Low-emissivity (Low-E) coatings are microscopically thin metallic layers applied to glass that reflect infrared heat. They keep heat inside in winter and outside in summer. Modern Low-E glass blocks over 95% of UV radiation, protecting furnishings from fading.
The space between panes in double and triple-pane windows is filled with inert gases (argon or krypton) that insulate better than air. Argon is the standard choice; krypton provides even better insulation but is used in thinner gaps. Gas fills typically reduce U-Factor by 10-15%.
The spacer bar that separates glass panes creates a thermal bridge at the edge of the window. Warm-edge spacers (made from foam, silicone, or hybrid materials) reduce heat transfer at the perimeter, lowering condensation risk and improving edge-of-glass temperatures.
Aluminum frames conduct heat 1,000 times faster than wood or vinyl. Fiberglass frames offer the best thermal performance with excellent strength and dimensional stability. Vinyl is a cost-effective insulator. Wood provides natural insulation but requires exterior protection.
FAQ
This Window Energy Audit Tool is provided as a complimentary visualization and planning resource to help you explore design options and understand approximate configurations for your glass project. All dimensions, specifications, performance calculations, and visual representations displayed are estimates intended for planning purposes only and should not be used as final construction measurements or guaranteed performance values.
Accurate field measurements and assessments by a licensed glass technician are required before any fabrication, installation, or purchasing decisions. Site conditions, structural factors, building codes, and environmental variables can significantly affect final specifications and product selection.
Expert Glass Repair provides complimentary on-site assessments and professional consultations throughout the DC, Northern Virginia, and Maryland metro area. For precise specifications and a free estimate, contact our team at (703) 679-7741.
Energy Grade
D -- 45/100