Stay Cool, Save Energy: 10 DIY Window Tips to Keep Your Home Cool This Summer

As temperatures rise, windows quickly become one of the biggest sources of unwanted heat gain in a home. The good news: a few simple, low-cost DIY strategies can make a noticeable difference in comfort and energy bills.

These DIY measures are a great starting point, especially for renters or households looking for low-cost solutions. For long-term impact, pairing these strategies with efficient window upgrades or whole-home weatherization can further reduce energy use and improve comfort year-round.

Here are practical, summer-ready tips: 

1. Seal the Leaks
   Even small gaps around windows can let hot air in and cool air out.

• Use weatherstripping or caulk to seal cracks and edges
• Check for drafts on hot afternoons when the temperature difference is greatest
• Focus on older windows where seals may have degraded

2. Add Reflective Window Film
   Window film is one of the most effective DIY upgrades for reducing heat gain.

• Reflects sunlight and blocks UV rays
• Helps keep indoor temperatures stable
• Easy to apply and relatively inexpensive

3. Use Thermal or Blackout Curtains
   Curtains aren’t just decorative—they’re powerful energy tools.

• Close curtains during peak sun hours (typically midday to late afternoon)
• Choose light-colored or reflective-backed options to deflect heat
• Blackout curtains can reduce heat gain by up to 30%

4. Install Temporary Exterior Shading
   Stopping the sun before it hits your window is even more effective.

• Hang shade cloths, bamboo shades, or even outdoor fabric
• Use removable hooks or tension rods for renter-friendly setups
• Prioritize south- and west-facing windows

5. Try DIY Window Inserts
   Create a barrier that reduces heat transfer.

• Use clear acrylic sheets or plastic shrink film kits
• These create an insulating air pocket similar to double-pane windows
• Especially helpful for single-pane or older windows

6. Use Reflective Hacks (Aluminum Foil or Cardboard)
   Not glamorous, but effective in a pinch.

• Place foil (shiny side out) behind blinds or curtains
• Reflects sunlight away from the home
• Best for short-term use during heat waves

7. Upgrade or Adjust Your Blinds
   The angle of your blinds matters.

• Tilt blinds upward to reflect sunlight toward the ceiling
• Consider swapping to reflective or “solar” blinds for better performance

8. Open Windows Strategically
   Timing is everything.

• Open windows early morning and late evening to bring in cooler air
• Close them before outdoor temperatures rise
• Create cross-ventilation by opening windows on opposite sides of your home

9. Add Window Awnings (DIY-Friendly Options)
   Awnings can reduce solar heat gain significantly.

• Install simple fabric or metal awnings above windows
• Even a small overhang can block high summer sun

10. Keep Windows Clean
    It sounds simple, but it helps.

• Dirt and debris can trap heat and reduce the effectiveness of reflective strategies
• Clean windows allow treatments like films and coatings to work better

Quick Tip for Impact

Start with the windows that get the most direct afternoon sun—typically west-facing. Improvements there will deliver the fastest and most noticeable results.