1. Heat properly

The first step is to think about when and where heating is important, which means not always heating everywhere in the same way. Every extra degree of room temperature can mean a 6% increase in energy demand. 

Reducing the temperature in bedrooms during the day or in the rest of the home overnight means saving energy. That said, it's not economical to turn off the heating completely, as it leads walls to become unnecessarily cool, particularly in houses that haven't been refurbished. It also increases the likelihood of mold forming. 

What's helpful here are programmable thermostats that can be set to only heat rooms at certain times. They are also easy to install. 

Saving energy by bleeding radiators and closing doors

When heating one room at a higher temperature than another, keeping the doors between them closed will prevent the heat from the warmer space from escaping into the cooler one. 

In order for radiators to spread warmth throughout the entire room, they shouldn't be blocked by curtains or furniture. The latter should be positioned at least 30 centimeters (12 inches) away. Ideally, radiators should be visible and have nothing on top of them.

It's also important to bleed radiators. When air gets trapped inside them, they can't heat efficiently.

2. Adequate sealing to prevent heat escaping

In order to keep warm air inside a room or building for as long as possible, windows and doors should be airtight. For old window frames, it helps to seal them with strips of foam or rubber. This can lead to energy savings of up to 7%. 

To tell whether a window is airtight or not, hold a candle in front of it. If the flame flickers in a certain spot, it means air can escape.

Insulating window panes with plexiglass

Double-glazed windows insulate more effectively than their single-glazed counterparts, as there is a layer of air between the panes of glass. It's possible to turn a single-glazed window into a double-glazed one by adding a thin sheet of plexiglass.

The plexiglass should be cut so it is a little bigger than the window pane, then attached to the inside of the window frame with Velcro or tape. This creates an insulating interspace between the original pane and the plexiglass. 

Curtains, sun-blinds and shutters help against the cold  

Those who close their windows at night don't just keep prying eyes out, but also keep the warmth in. Curtains, blinds and shutters insulate the window surface. The thicker the material, the better the insulation.  

Thick curtains can also help keep the cold out when hung inside the doors to houses or apartments. It is also possible to add draft stoppers inside a door frame and on the floor.

3. Rooms should be aired, even in winter 

A lot of heat can get lost by not airing properly, while not airing at all can lead to mold.

In a four-person household, between six and 12 liters of water evaporate into the air every day. The higher the humidity and the lower the room temperature, the higher the risk for mold formation.

After a bath, a hot shower or cooking, it's advised to open the windows for five to 10 minutes as wide as possible in order for the humid air to move outside. It's also a good idea to properly air out bedrooms after getting up and to keep the heating turned off while airing.  

Experts recommend airing rooms two to four times a day for five minutes during the winter months and 10 minutes during transitions in and out of the cold period. That way the air that's already been used gets exchanged the fastest. 

Tilted windows consume a lot of energy

During the winter months, the general rule is not to keep windows tilted open all day, as this results in far greater energy loss than when only airing for short periods during the day.  

If windows are opened for five to 10 minutes, roughly 10 to 20% of heat gets lost, depending on the building. If they are tilted open for long periods of time, the percentage is a lot higher. 

Many new and refurbished houses have integrated ventilation systems with heat recovery that provide rooms with preheated fresh air. The energy is generated using the heat loss in the air already used. People who live in such buildings shouldn't air out their rooms during winter at all. The air circulation from the ventilation system is enough. 

4. Keeping our bodies warm

The main reason we heat our apartments is to prevent getting cold ourselves. Our body makes sure our inner organs and our brain are constantly kept at 36 to 37 degrees Celsius. If our body temperature drops, the blood supply to our skin decreases. That's why we often have cold feet in winter. 

Wearing suitable clothing can help keep us toasty. Contrary to heating, clothes do not add warmth from the outside but keep our own temperature close to our bodies.

Some materials are especially good for that. For instance wool. The reason is the structure of wool fiber, 85% of which is made from air. This air layer insulates and prevents our body heat from getting lost. 

Cozy warm — with rugs, socks and blankets 

Rugs also prevent our body from transmitting its heat to the cold floor. 

The best remedy for cold feet is warm socks and slippers. They cover the foot and insulate it from all sides. That's also how a blanket keeps our entire body warm at night — and it's so cozy.  

This article was originally published in German.