Builder of individual houses for 50 years

throughout the south-west of France

5 secrets of building a low-energy house

what is a low energy house?

Table of contents

Building a low-energy house is the best response to environmental issues and energy increases. But we do not launch into such a project headlong. Building a low-energy house can be complex if you are not advised by the right professionals. Maisons SIC gives you the 5 secrets of a successful low-consumption home.


A clear construction site and a well-oriented building

Choosing the right construction site and properly orienting your building are crucial steps in creating a successful low-energy house.

An open area, sheltered from the prevailing winds and avoiding northern slopes, is ideal.

Orientation plays a major role, aiming to maximize southern exposure to fully benefit from solar heating. Glass surfaces, heated naturally by the sun, act as an energy-efficient radiator.

Bioclimatic design is at the heart of the low-consumption home. This approach takes advantage of the natural environment to optimize thermal comfort.

Large bay windows facing south capture solar heat, while reduced openings to the north and strategic use of vegetation minimize heat loss. The technical rooms, placed to the north, serve as thermal pads, thus contributing to the energy balance of the building.

The precise location of the building, taking into account sun masks and local regulations, is essential. Obstacle-free terrain to the south ensures optimal sunshine, crucial for energy efficiency. The layout and height of surrounding buildings, as well as the slope of the land, must be evaluated to prevent any future cast shadow.

It's there that SIC houses, a company with 50 years of experience in the construction of new houses in the southwest, becomes a valuable ally. Specialist in the construction of individual houses, Maisons SIC can provide sound advice on land selection and best construction practices to create a low-consumption home that meets expectations of comfort and energy efficiency.



Choosing the positioning of the rooms before building a low-consumption house

The choice of room positioning is crucial in the design of a low-energy house. This principle helps to maximize the energy efficiency and thermal comfort of the home.

Poorly heated rooms such as the garage, laundry room and toilets should be placed to the north. This provision limits heating needs.

Conversely, the main living spaces benefiting from direct sunlight, such as the living room, dining room and kitchen, must be located to the south. This promotes natural heat accumulation.

For bedrooms, East orientation is preferable. This prevents heat buildup at the end of the day, ensuring nighttime comfort. The vestibule, acting as an airlock, preserves interior heat, limiting thermal losses when the door is opened.

The interior design must also favor solar gain. South rooms should have few partitions, allowing the sun's rays to effectively warm the space. The walls at the back of these rooms, if possible made of materials with high thermal inertia and dark color, capture and store heat.

The layout of the house, beyond its orientation, must avoid cast shadows which could reduce solar gains. A precise analysis of the environment and potential shading is necessary to optimize the thermal performance of the low-consumption house.



Reinforced thermal insulation for optimal low-consumption house construction

State-of-the-art thermal insulation is essential for a low-energy home. This insulation goes well beyond the usual standards, with increased thicknesses on all surfaces: floors, walls and roof. The key lies in eliminating thermal bridges, those areas where insulation is broken, causing heat loss.

For walls, roofs, and floors, exceptional performance is required. We are considering up to 20 cm of insulation for the floor, 30 cm for the walls, and 40 cm for the roof.. This reinforced insulation considerably reduces heat loss, making it possible to keep the heating requirement below 15 kWh/m²/year, an ambitious objective compared to RT 2012 standards.

External insulation is favored to effectively treat thermal bridges and benefit from the thermal inertia of the supporting materials. This approach ensures a stable indoor temperature, contributing to year-round comfort.

Windows, often triple glazed, play a crucial role, with a Uw coefficient less than 0,8 W/m²K and a solar factor g greater than 50% to maximize solar gains.

Thermal insulation in a low-energy house is designed for maximum efficiency. It involves particular attention to construction details to guarantee airtightness and optimal insulation management. This rigor makes it possible to create homes that consume up to 90% less heating than traditional constructions, thanks to exceptional insulation and airtightness.



Strong airtightness and double flow VMC

how does a double flow VMC work?

source: wikipedia


Impeccable airtightness is crucial in the construction of a low-energy house, in order to control thermal losses due to unwanted air infiltration.

The blower door test is a method that allows this tightness to be measured. By pressurizing the house, it identifies precisely where the air leaks are. Low-consumption home standards require waterproofing approximately four times greater than that required by RT 2012, requiring exemplary expertise and coordination from craftsmen.

Double-flow Controlled Mechanical Ventilation (VMC) plays an essential role in this system. It recovers approximately 75% of the interior heat produced by occupants and equipment, to preheat the incoming air in winter. In summer, the process reverses, refreshing the incoming air with the coolness retained inside. This technology is essential to avoid uncontrolled heat loss and guarantee optimal comfort all year round.

Thermal bridges, sources of heat loss, are also minimized in a low-energy house. Thanks to the double flow VMC, the introduction of fresh air does not require drilling the windows, thus ensuring better sealing.

Although its cost is higher than a single flow VMC, double flow VMC is essential because it replaces traditional heating systems, while filtering and warming the air. This preheated and purified air not only ensures heating of the house but also contributes to a healthier indoor environment.



High-performance glazing and economical household appliances

low energy triple glazing for home

Low-energy homes incorporate high-performance glazing and appliances to maximize energy efficiency.

Windows, often equipped with triple glazing, play a crucial role. Their thermal transmission coefficient (Uw), including frames and glazing, must be less than 0,8 W/m²K, far exceeding the standard of 1,1 W/m²K for quality double glazing. The solar factor g, indicating the capacity to benefit from solar heat, is maintained above 50%, thus favoring passive solar gains.

The installation of these windows requires special attention, especially at the junction between the frame and the chassis, to guarantee optimal insulation. Although the initial cost of triple glazed joinery may be higher than double glazing, their impact on reducing heating and cooling needs justifies the investment. These choices make it possible to aim for the passive level, even without meeting all the technical criteria for official certification, thus offering flexibility in the approach to the construction of low-consumption houses.

At the same time, the use of energy class A household appliances is essential. These devices, designed to minimize energy consumption, help to significantly reduce annual energy costs, up to 90% lower compared to a standard home.

In addition to offering exemplary energy performance, these devices are part of a global ecological approach, in harmony with the use of renewable energies such as solar panels or rainwater harvesting, thus reinforcing the appeal and value of low-consumption homes.


The principles to follow when building a low-energy house

what is a low energy house?

The low-consumption house represents the pinnacle of energy efficiency in modern living. It stands out for its ability to minimize heating needs thanks to optimized design and insulation.

Here is an exploration of its foundations:

Maximization of solar radiation : By effectively capturing the sun's heat, the low-consumption house maintains a pleasant temperature. Surfaces like walls and floors absorb this heat, reducing the need for heating during cold periods.

Energy Efficiency : Thanks to its thoughtful orientation and advanced thermal insulation, the low-consumption house consumes up to 90% less heating energy than traditional construction. It is designed to take maximum advantage of solar input and eliminate thermal bridges, ensuring energy consumption reduced by 50% compared to current standards.


The essential principles for low energy construction include :

  • Use of passive solar : Orient the house towards the south to maximize the absorption of sunlight, without thermal bridges or cast shadow.
  • Optimal insulation : Outer casing with a U-value less than 0,15 W/(m²K), ensuring effective protection against heat and high compactness.

High-performance glazing and window frames, with a Uw value of less than 0,8 W/(m²K) and a solar factor (g) of around 50%.

  • Reinforced airtightness : Achieve an n50 value strictly lower than 0,6 air changes per hour to avoid heat loss.
  • Heat recovery : Exhaust air heat recovery system with a recovery rate greater than 75%.
  • Energy efficient devices : Use of highly efficient household appliances, energy class A, to reduce energy consumption.
  • Passive air heating : Optionally, use geothermal energy to ensure that the air temperature in winter remains above 5°C.


These principles guarantee that, whatever its location, a low-consumption house offers exceptional daily comfort, with minimized energy needs. The performance of these buildings is based on a global approach, from planning to construction, integrating the latest innovations for sustainable housing.


Low consumption house vs RT 2012

The site Thermal Advice. org carried out a comparison between a house compliant with RT 2012 and a low consumption/passive house. Although this approach may seem somewhat schematic, given that each project has its particularities, it still offers the possibility of distinguishing the two options in order to facilitate decision-making:

passive house RT 2020 2012


Continue reading

Other recent articles