EnergyVille calculates in De Standaard how to save hundreds of euros on energy without catching a cold

The late autumn sun made sure we wouldn’t have to worry about turning on the radiator, but now time has come we should gradually start heating. Despite the falling prices, our energy consumption threatens to take a substantial bite of our monthly budget.

But good news: even with relatively small efforts, you can reduce your energy bill quite a bit. The profits from such savings depend on the individual situation says an analysis by Koen Vanthournout and Stijn Verbeke, researchers at EnergyVille/VITO, at the request of De Standaard.

Does it pay off to turn off the heating when you're not at home?

Keeping the temperature inside comfortable in the fall and winter, is the main chunk of energy consumption for anyone who does not live in an energy-neutral home. 80 to 85 percent of our consumption goes to heating.

Just bringing the kitchen and living space up to 21 degrees costs nearly 1,300 euros a year, according to calculations by EnergyVille/VITO and UAntwerpen, even in a very well-insulated row house. The residents of a poorly insulated villa annually pay almost 14,000 euros. This was calculated with the average price for energy, as calculated by the Flemish energy regulator Vreg.

Many families can save large sums of money on heating, even without losing much comfort during the “waking hours” at home. After all, it pays off to turn off the heating at night, and during the day when no one is home. For a poorly insulated row house heated with a modern gas boiler, this amounts to savings of almost 1,100 euros per year. In a very well-insulated villa, that adds up to over 900 euros. For all savings applies: ‘the more you already spend on energy today, the greater the savings from the same effort’.

It seems counter-intuitive, but it is useful to cool the house down and only reheat it when the residents benefit from it. Those costs are less than keeping the temperature up all night by continuously heating a little. After all, buildings lose heat when it’s colder outside, and that loss accelerates as the temperature difference between inside and outside increases. ‘If the heating is turned off at night and the temperature inside the house drops, the temperature difference between inside and outside reduces and less heat disappears to the outside’, explains Koen Vanthournout. ”In the morning, the heating then has to run more intensively for a short time to bring the room inside to a comfortable temperature again, but this requires less energy than keeping the temperature high all night.”

In general, says Stijn Verbeke, it is useful to turn off the heating in rooms where no one comes for hours. ‘For example, does the bathroom have to be warm all day, or is it sufficient if the heating is on for one hour in the morning and one hour in the evening? Same with the bedrooms. Keep them cool during the day and keep the doors closed on the non-heated rooms. Otherwise, you’re heating those rooms through the living space anyway.’

Attention: the temperature indoors better not drop below 14 to 15 degrees, because then the moisture from the air settles on furniture and walls and mold may appear. Another note: an underfloor heating system takes a long time to warm up rooms. The same applies for underfloor heating as these cannot quickly reheat a cooled-down living space as radiators do.

How much difference does one degree less in the living room make?

What the effective revenue is to lower the thermostat in the kitchen and living room depends greatly on how much energy is needed to keep those rooms warm. ‘In a well-insulated home, it is much easier to keep the temperature high,’ says EnergyVille researcher Stijn Verbeke. ‘In poorly insulated homes, more energy is lost and more additional heating must be used. Thus, lowering the thermostat has the most effect in poorly insulated homes.’

The same applies to the façade area: the larger, the more contact with the outside air, and therefore the more heat loss through the façade and the greater the cost to heat. To illustrate: in a well-insulated row house, one degree less creates an average revenue of 109 euros per year, in a poorly insulated one it is 591 euros. In a villa it is 644 (well-insulated) and 1,109 euros (poorly insulated), respectively.

Lowering the thermostat by one degree produces greater savings when the starting temperature is high (21 or 22 degrees) than when the thermostat is already a bit lower (19 or 18 degrees) and a further reduction is on the table. At the lower temperatures, there’s already less loss. ‘When the temperature in the living space is already lower, less is lost to the hallway or other unheated rooms,’ Verbeke explains. ‘Then lowering the thermostat further is still a saving, but it’s smaller per degree than if you start at a higher temperature.’

Of the options studied, with current prices a heat pump is the cheapest to heat the home, electric heating with accumulators is the most expensive. A fuel oil and modern gas boiler are in between.

Which energy savings will pay off big for you?

You like to shower lavishly? Long live the economy shower head

These are trends that work against each other, notes researcher Verbeke: homes are increasingly well insulated and, at the same time, more and more families who can afford it are opting for a rain shower or a shower with a back sprinkler. These encourage energy waste as a rain shower requires considerably more water to be heated.

In statistics: a rain shower consumes 20 liters of hot water per minute, while only 11 liters per minute will flow through a normal shower head. Through an economy shower head, it is only 6 liters per minute.

Switching to an economy showerhead – the cheapest models cost less than 20 euros – pays off. As an example, for a couple who shower 10 times a week for 8 minutes, switching from a rain shower to a low-consumption shower head will save them 560 euros per year.

But switching from a normal shower head to an economy shower head is also an investment that quickly pays for itself: it saves the same couple 200 euros. If those two people also take shorter showers, say 5 minutes instead of 8 minutes, they will consume 30,160 liters less hot water annually, which with current gas prices (and with a modern gas condensing boiler) means a total savings of over 293 euros.

Again, the energy source makes a big difference: those who heat their water with an electric water heater pay four times more with current energy prices than those who heat their water with a fuel oil boiler, which is currently the cheapest energy source.

More info?

The science editors of De Standaard had more up their sleeve and made a Podcast about it, which you can listen to on the website of De Standaard, Spotify or Apple Play.
(Disclaimer: Dutch only)