BGE and Pepco both raised supply rates again this year. If your windows are original to a 1985 Rockville colonial or a 1990s Gaithersburg split-level, they're quietly costing you hundreds of dollars every season. Here's how to know if replacement makes sense, and what to actually buy.

5 signs your windows are due

  1. You can feel a draft with your hand on a cold day. That's air infiltration — and dollars leaving the building.
  2. Condensation between the glass panes. The seal has failed and the insulating gas is gone.
  3. Sashes that don't stay open or are painted shut.
  4. Visible rot on wooden sashes or frames.
  5. HVAC running constantly in extreme weather even though the system is properly sized and maintained.

The ratings that actually matter in Maryland

Look for the NFRC label on every window quote. The two numbers that drive performance in our climate:

  • U-factor (lower is better) — measures heat loss. Target 0.30 or lower for Maryland.
  • SHGC (Solar Heat Gain Coefficient) — measures heat coming in from sunlight. Target 0.25–0.40 for our mixed climate (you want some winter solar gain, but not summer overheat).

Both should meet ENERGY STAR Northern Climate Zone requirements, which is the standard we install to on every Andersen 400 Series and Pella project we run.

Realistic energy savings

The Department of Energy estimates 12–33% reduction in heating and cooling costs when replacing single-pane windows with ENERGY STAR doubles. Real-world numbers we see from clients in MoCo: $40–$120/month in summer cooling savings and noticeable comfort improvement — drafts gone, rooms more even, outside noise cut roughly in half.

Payback period

Be honest with yourself: a full-home window project rarely "pays back" in pure dollars within 10 years. The real ROI comes from a combination of: lower utility bills, increased home value (windows are a top-5 ROI remodel on Remodeling Magazine's Cost vs. Value), quieter rooms, and the simple fact that you stop overpaying every month for the rest of the time you live there.

When NOT to replace

If your windows are double-pane, under 15 years old, and the only issue is sticky operation or worn weatherstripping, a tune-up and storm-window add-on is the smarter play. We'll tell you that on-site instead of selling you something you don't need.