New house vs. existing house: the energy consumption comparison

Regardless of the type of heating used, energy is a major expense for the vast majority of households. But what differences can be observed between a new house and an existing dwelling?

Domexpo wanted to find out, with supporting figures, through an exclusive study conducted by the AET Loriot office.

The study compares two detached houses of 100 m2 using electricity as their main energy source: a new, high-performance house, rated A in the Energy Performance Diagnosis (DPE), and an older house, rated D, which is much less efficient.

The objective is simple: to demonstrate, based on a collection of precise data, the difference in energy performance between these two types of construction.

Significant differences in consumption

The builders present at the Domexpo villages - villages of individual houses in Ile-de-France - are questioned daily by visitors on a crucial subject: the energy expenditure of their possible future house, in comparison, in particular, with a house bought in the old.

To provide a concrete answer to their concern, Domexpo conducted the investigation.

The results are unequivocal. The new house in the study, with its A-rated energy performance certificate (EPC), consumes 50 kWhEP/m²/year, compared to 220 kWhEP/m²/year for the older house with an EPC rating of D—more than four times as much. In terms of final energy (FE in the document), this represents 2.380 kWh for the new house and 10.476 kWh for the older house.

This considerable difference is directly visible on the invoices:

With standard usage, the annual energy bill is €697 in the new house, compared to €2.324 in the old house, representing an immediate saving of €1.627 per year.
For an energy-intensive household, the difference is even more marked: €860 for the new house versus €3.041 for the old house, i.e. €2.180 in savings per year[1].

In the long term, up to €90.020 in savings

Beyond annual savings, the study highlights cumulative savings over 25 years, based on a realistic assumption of a 4% annual increase in electricity prices. For standard usage in a new home, savings reach €67.032, while for an energy-intensive household, they amount to €90.020.

These data demonstrate, if any proof were needed, that energy performance is not just a simple technical or marketing argument: it constitutes a real lever to protect the purchasing power of families and anticipate the rise in energy costs, while improving daily living comfort.

A response to regulatory obligations

Since January 1, 2025, properties classified as G can no longer be rented. This ban will extend to properties classified as F from 2028, and then to properties classified as E from 2034.

In this context, the high-performance new home appears as a sustainable solution, both compliant with legal obligations and adapted to the needs of families, making it possible to limit the impact of future increases on the budget, while reducing the energy footprint of the dwelling.

Domexpo: comfort, savings and sustainability

The builders in Domexpo villages adhere to the highest environmental standards. Optimal comfort, sustainable energy efficiency, and long-term durability make these homes much more than just a real estate investment. They represent a responsible and protective choice for families, combining savings, comfort, and respect for the environment.

For Fabien Cuminal, President of Domexpo: "This study demonstrates that investing in a new, energy-efficient home is a tangible benefit for families. It provides long-term protection against rising energy prices while improving daily living comfort."

[1] These figures include the subscription and do not take into account additional uses such as an electric car or a swimming pool.

Illustrative image of the article via Depositphotos.com.