Shutters and blinds are your easiest insulation tool. When you close them at night, an insulating air layer forms in front of your window. This significantly reduces heat flow, and works immediately, without buying anything (if you already have shutters).
Step by step
Windows lose heat through two mechanisms: heat conduction through the glass and radiation from inside to outside. When a shutter is closed, an air gap (about 2–4 cm) forms between glass and shutter. This air is a poor heat conductor, it acts like an additional insulation layer. Plus, the shutter (especially with metallic backing) can reflect heat radiation. Together this improves U-value by 20–30%.
Source: Deutsche Energie-Agentur (dena), Closed shutter improves window insulation by up to 20%
Step by step
- Check your shutter operationTest your existing shutters: do they open and close smoothly? Are seals still intact or crumbling? If shutters are badly damaged, repairs or replacement before heating season are worth it.
- Establish a night routineCreate a habit: after sunset (around 5–6 PM in winter) close all shutters. This should become your norm, not an exception. Tip: set a phone alarm for 5:30 PM.
- Use morning ventilationEarly morning before you open the shutters, ventilate for 5–10 minutes with shutter closed. This removes condensation that forms at night before it creates mold conditions.
- Check seals regularlyOnce a year (summer) check your shutter guides: are brushes and seals still in place? Replace them if loose or worn. This improves insulation effect by 5%.
- Consider automatic controlIf you often forget to close shutters, a simple timer (around €30) or smart home system is worth it. It closes shutters automatically at a time you set.
Worked example
Before: 4-room old building, 8 windows with older shutters. Resident leaves shutters open day and night, forgets to close. Heating costs €2,100/year.
After: Consistently close all shutters at night starting fall. Shutters are 20 years old but functional. Heat loss at night reduced by 15%. Heating system saves 10–12% (about €210–250/year). Costs: €0 (already have them). Immediate effect.