Korean winters can be surprisingly harsh. When cold air seeps in through the gaps around your windows, no amount of heating seems to warm the room properly. One of the most popular solutions in Korea is to stick bubble wrap (called “air-cap” or “bbokbboki”) directly onto your windows. It costs almost nothing and anyone can do it, so it is something we highly recommend to anyone spending their first winter in Korea.

When applied carefully, it is said to raise the indoor temperature by an average of 3 degrees Celsius or more. Save on heating bills and stay warm this winter!

Step-by-Step Overview

  1. 1. Measure your windows

    Use a tape measure to find the width and height of the windows you want to cover, and write the measurements down.

  2. 2. Buy the air-cap

    Purchase "insulation air-cap" (단열용 에어캡) from Daiso, a large supermarket, or online, in a size that matches your measurements.

  3. 3. Cut the air-cap

    Cut the air-cap to fit your window with scissors. It is fine to cut it a little larger than the window.

  4. 4. Clean the windows

    Wipe the glass and window frame thoroughly with a damp cloth, then let everything dry completely.

  5. 5. Spray water and apply the air-cap

    Spray water evenly over the glass with a spray bottle, then press the air-cap onto the glass with the bubble side facing the glass.

  6. 6. Seal the frame gaps

    Use leftover air-cap pieces or draft-excluder tape to seal any gaps in the window frame, improving the overall insulation.

Before You Buy: Measuring Your Windows

Measure your windows before heading to the shop.

  • Decide which windows you want to cover.
  • Use a tape measure to record the width and height of each window.
  • Having the measurements written down means you can buy exactly the right amount at the shop.

Applying air-cap will make the view through the window slightly blurry. If that bothers you, consider starting with windows you do not look out of very often, rather than main living-room windows.

Buying the Air-Cap

You can buy air-cap at the following places.

  • Daiso: Very affordable and easy to find. There is a Daiso in virtually every neighbourhood across Korea.
  • Local convenience stores and supermarkets: Many stock insulation air-cap during winter.
  • Large supermarkets (E-Mart, HomePlus, etc.): Offer a wider choice of thickness and size.
  • Naver Shopping and Coupang: Easy to order online; search for “창문 단열 에어캡” (window insulation air-cap) to see a wide range of products.

Things to check when buying:

  • Buy a size that matches the window measurements you wrote down.
  • Choose a product labelled “단열용” (insulation-grade) rather than ordinary packaging bubble wrap. Larger, thicker bubbles provide better insulation.

What You Will Need

Here is a list of everything required for the job.

ItemNotes
Air-cap (insulation bubble wrap)The roll or sheet you purchased
ScissorsFor cutting the air-cap to size
Tape measureFor accurate cutting
Spray bottleFor spraying water onto the glass; available cheaply at Daiso
WaterTo fill the spray bottle
Damp cloth (dish cloth or rag)For cleaning the glass and frame beforehand
Draft-excluder tape (optional)For sealing frame gaps; available at Daiso

How to Apply It

Step 1: Cut the Air-Cap

Cut the air-cap to the dimensions you measured. Cutting it slightly larger than the window is perfectly fine — you can trim the edges afterwards.

Step 2: Clean the Glass and Frame

Before spraying any water, wipe the glass and window frame with a damp cloth. Dust or grime will prevent the air-cap from sticking properly. Allow everything to dry fully before moving on.

Step 3: Spray Water onto the Glass

Spray water evenly over the surface of the glass using your spray bottle. The water acts as a natural adhesive, holding the air-cap in place without any glue.

Step 4: Apply the Air-Cap

Press the cut piece of air-cap onto the wet glass.

  • The bubble side (the side with raised bumps) must face the glass for maximum insulation effect.
  • Press carefully so that no gaps are left.
  • Smooth it from the centre outward to avoid popping the bubbles. Do not press too hard.

Step 5: Seal the Window Frame Gaps

After covering the glass, sealing any gaps in the window frame makes a big difference to the overall insulation. Window frame gaps are one of the main entry points for cold draughts. Push leftover pieces of air-cap into any gaps, or apply draft-excluder tape (외풍 차단 테이프) available from Daiso.

Important Things to Keep in Mind

  • Always ventilate your home. Good insulation reduces natural air circulation. Open your windows briefly once or twice a day to let fresh air in. If you skip ventilation, moisture can build up indoors, leading to condensation (water droplets forming on the glass) and mould growth.
  • When winter is over, the air-cap peels off easily. Simply pull it away slowly and gently.
  • If mould is already present around your window frame, remove it before applying the air-cap. For guidance on removing and preventing mould, see How to Remove and Prevent Mould in Winter.

Need Help?

If you run into any difficulty or have questions, please get in touch with MAP (Migrant Assistance Program — a support organisation for migrants in Korea). We are happy to help.