low-energy house

What Is a Low Energy House?


    – What is a low-energy house?

    – Maximum consumption target for a low-energy house

    – How to obtain the low-energy house qualification?

    – The interest of the low-energy house label

The low-energy house is a construction that meets the energy performance criteria of the low-energy building. The low-energy house qualification is obtained by studies, tests and measurements of the amount of energy required to live comfortably in the house, taking into account heating, cooling, ventilation, among others.

What is a low-energy house?

Initially, the low-energy label was launched as part of a study aimed at reducing the energy consumption of buildings and consequently limiting the level of greenhouse gas emissions from housing and real estate.

Subsequently, the low-energy house was defined to set a maximum consumption target for new residential buildings (apartment buildings and single-family homes) set at 50 kWhep/m²/year (kilowatt-hours of oil equivalent per m² of floor area per year).

The latest thermal regulations in force have made this objective of compliance with low-energy requirements to any new construction whose building permit was filed as from 2012.

Good to know: low-energy house applies to buildings that fall into class A of the energy label of the performance diagnosis.

Maximum consumption target for a low-energy house

low-energy house

The maximum consumption target of 50 kWhep/m²/year in primary energy is a base to be modulated according to:

    – the coefficient of a climatic zone (coefficient A), because the geographical position of the house on the territory influences its needs in heating and possibly in cooling (air conditioning);

    – the altitude coefficient (coefficient B) varies according to the altitude at which the house is located.

For each dwelling, the maximum primary energy consumption to receive the low-energy standards qualification of the building is measured according to the formula: 50 × (a + b).

The coefficient A can take 8 different values from 0.8 (hot regions) to 1.3 (cold regions). Thus, in hot regions, the limit of low-energy will be (50 × 0.8) = 40 kWhep/m²/year of maximum consumption in primary energy. In cold regions, it can reach (50 × 1.3) = 65 kWhep/m²/year.

The coefficient B is zero (0) for altitudes between sea level and 400 m; it will then be 0.1 up to 800 m altitudes, then 0.2 beyond 800 m.

How to qualify as a low-energy house?

The houses and apartments must meet the requirements of maximum primary energy consumption and pass the air permeability test of the construction carried out by the infiltrometry technique.

Primary energy consumption

The calculation of primary energy consumption considers the consumption of heating, cooling, ventilation, auxiliary equipment, production of domestic hot water and lighting.

The impact of the more or less green energy source used to calculate primary energy is essential. By convention, for 1 kWh of energy produced, the quantity of direct energy consumed is 0.6 kWh for wood and 2.58 kWh for electricity.

Blower door test

For the final blower door test, the value of the leakage rate through the envelope under a pressure difference of 4 Pa must be less than 0.6 m3/h.m² for a single-family house.

When is it required?

To obtain the low-energy label, you must act from the beginning of the project on all the levers of the entire construction of the house (shape, orientation, materials, insulation …) but also its equipment (heating, hot water, ventilation, lighting …) and the use of renewable energy (at least one device using renewable energy per single-family home built).

Note: the calculation of primary energy consumption and the final blower door test must be carried out by certified professionals, such as a design office or real estate diagnostician.

The interest of the low-energy house label

A low-energy house entitles you to benefits when you buy a new home, built to low-energy standards and even when you rent it.

In renovation, many energy renovation aids apply to insulation work. The eco-conditionality is met, and the work is carried out by companies or artisans recognized as environmental guarantors.

Read more:

Towards Sustainability | Building Your Home With Natural Materials

What Is an Energy-Saving House?


– What is an energy-saving house?

– Objectives of the energy-saving house

– Price of an energy-saving house

– Example of an energy-saving house: the passive house

An energy-saving house is environmentally friendly.

It consumes less energy and uses renewable energies that will sustainably balance your energy needs with the planet’s resources.

What is an energy-saving house?

The energy-saving house is an ecological house that must respect our environment.

Therefore, it will pollute as little as possible and reduce your energy needs as much as possible.

– To achieve this, you will take particular care in your home’s design (materials used) and its installations (water and heating).

– The energy-saving house can be ecological, green, bioclimatic, or even autonomous.

Objectives of the energy-saving house

The main objectives of the energy-saving house are to:

– reduce heating costs as much as possible by choosing a better orientation of the house;

– take special care to save energy through insulation;

– produce electricity (solar or wind power);

– saving water through rainwater recuperation or low-flow systems;

– managing waste as well as possible, such as selective sorting or composting.

Price of an energy-saving house

Compared to a conventional home, the energy-saving house represents an additional cost of 10 to 15%. However, this cost is amortized after a few years from the savings made on heating and electricity.

Example of an energy-saving house: the passive house

PassivHaus is a German label for energy performance in buildings. In the USA, the PHIUS+ association is responsible for certifying passive houses: these must meet the same criteria as those described by the PassivHaus label.

The passive house’s primary function is to reduce the energy input for heating, ventilation, and lighting through highly efficient building techniques.

It is, therefore, an environmentally friendly and energy-efficient home. Its location in the environment will therefore be of prime importance, both climatically and geographically.

Its low energy consumption is based on:

– the use of the passive heat of the sun;

– reinforced thermal insulation (walls, windows, etc.);

– not having thermal bridges, i.e. gaps in the insulation through which heat can escape;

– air-tightness and double-flow ventilation with heat recovery;

– the fitting of energy-saving appliances listed according to energy class.

Its advantages

The passive house has many benefits:

– The house does not need more than 15 kWh per m² per year for heating;

– its total primary energy consumption (heating, water, and appliances) must not exceed 120 kWh/m²/year;

– it also has excellent air-tightness.

It is essential to comply with specific standards to obtain the “passive house” label,

The house must be designed and optimized well in advance of construction to comply with the PassivHaus standard requirements. Two main techniques will enable you to meet the consumption targets set by this standard:


The energy losses of a Passive House can be significantly reduced, particularly by strengthening the insulation by using triple glazing. A heat recovery unit like a dual-flow CMV (controlled mechanical ventilation) system, must be installed to supply fresh air. The objective is to achieve ventilation energy less than or equal to 0.4 Wh/m3 of supply air.

Bioclimatic Architecture

Bioclimatic architecture is a technique used to increase solar gain received through the windows and bays and the south-facing aspect of the living room. The passive building also conserves the waste heat from electrical appliances.

A building of this type has far fewer humidity problems, ages better, offers greater comfort through a balance of temperatures while reducing energy costs and CO2 emissions. A fair calculation at all levels!

Furthermore, the incentive for building owners and developers has been introduced at the town planning level. You can read more on Passive House: An Ecological Concept.

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