Sustainable home: water, a forgotten lever for domestic energy conservation?

Towards a more sustainable and “eco-efficient” habitat

Since 2006, the Energy Performance Diagnosis (EPD) has informed owners and tenants of the energy and climate performance of a home or building. To this end, the DPE evaluates its energy consumption and its impact in terms of greenhouse gas (GHG) emissions. Among the key criteria evaluated, we find the level of insulation, the type of heating and any cooling needs.

If the results (from A to G) offer a broad assessment of the energy performance of housing, they are far from providing an exhaustive vision of their environmental footprint, including the total energy consumed. Many other criteria, equipment or habits can considerably vary the actual energy consumption of a home.

This is particularly the case for water and its quality in the home. Indeed, water is present at all levels of housing (the French consume on average 149 liters of drinking water per day): general cold water, domestic hot water, drinking water, to supply the water circuits. heating or for other uses such as watering for example. So if preserving water resources is obviously essential, guaranteeing its quality also allows us to commit to energy sobriety.

Less energy-consuming and more durable equipment

At first glance, the link between water quality and housing energy consumption is not obvious. However, when we know that a layer of scale of 1 mm on household appliances or equipment dedicated to the production of hot water can lead to excess energy consumption of around 15%, we quickly realize that the quality of the Water should not be neglected.

In addition to excess energy consumption, water quality will considerably influence the performance of equipment and their lifespan. Indeed, better protected against scaling, corrosion, sludge or even abrasion, the installations consume less energy, but are also protected from premature wear. By being less prone to breakdowns, they are more durable: a benefit for the wallet (repair cost) but above all for the planet because we avoid significant waste.

Also bringing improved comfort to occupants, better water quality also limits the environmental impact of housing by reducing the use of cleaning products, detergents or even laundry products, and thus their transport and their effluent in the waste water, then treated in a wastewater treatment plant.

Domestic water quality and energy management: indirect but tangible gains

Eliminating limescale in the water is obviously one of the first reflexes to adopt to protect its habitat. However, taking care of water quality can also manifest itself in other areas of the house:

• filtering drinking water dedicated to consumption also represents substantial energy savings. Indeed, quality drinking water, directly from the tap, means an immediate reduction in CO2 emissions resulting from the manufacturing of water bottles and their transport. It is therefore estimated that a household consumes more than 2000 bottles of water per year - based on 1,5L of water consumed per day and per person, for 4 people.
• In the same way, the recovery of rainwater, drilling or drawing makes it possible to limit the use of drinking city water. In fact, we consider that 40% of the city water used in a home could be non-potable water: cleaning, watering, toilet supply, etc. Which represents an average of 50 m³ per year for a home of 4 people. In energy terms, the gains are not direct, but it would make it possible to better control the consumption of drinking water for domestic use.

In other words, if water is considered a resource to be preserved in a sustainable and eco-efficient house, the importance of its quality is often underestimated in improving the energy performance of buildings. However, from a macroscopic point of view, its participation in the energy and climate issues of today and tomorrow is far from negligible.

Tribune by Dominique Brun, Marketing and Communication Director of BWT France (LinkedIn).