A house with optimal comfort: how to maintain 23° all year round without heating

At a time when energy costs continue to rise, maintaining a comfortable indoor temperature without resorting to traditional heating systems has become an aspiration for many households. This quest for energy efficiency and sustainability has led to the emergence of innovative homes capable of stabilizing their temperature at 23 °C year-round, regardless of the external weather conditions. This article explores the methods, technologies, and advantages of such a habitat, inspired by the advanced solutions of the Passivhaus.

Current energy context and heating cost challenges

In 2025, French households are facing a notable increase in heating-related costs, a direct consequence of evolving energy prices. Natural gas, for example, experienced a 5.9% increase in bills between February and June 2025, primarily due to the end of the tariff shield and the rise in network maintenance costs. This situation places increased pressure on family budgets, making the search for alternative and more economical solutions necessary.

Furthermore, for electricity, although a 9% decrease in regulated rates has been announced, the increase in the excise duty on electricity from €21 to €33.7 per MWh on February 1, 2025 leads to an additional cost of approximately €100 per year for an average customer heated by electricity. This dual dynamic, both for decreases and increases in costs, complicates household energy expense management.

Since March 1, 2025, the VAT on the installation of gas boilers, including very high energy performance (THPE) models, has risen from 10% to 20%, significantly increasing the cost of such equipment. Meanwhile, the budget for MaPrimeRénov’ has been reduced to €3.4 billion, with a 30% decrease in subsidies for wood heating equipment. This reduction in financial aid now favors heat pumps as a more supported alternative.

These developments lead to an increase in energy expenditures for households, especially those using gas or electricity for heating. Additionally, the installation costs of new heating equipment are also on the rise, making investment in alternative solutions even more attractive.

In light of this economic reality, it becomes crucial to explore viable alternatives to maintain optimal thermal comfort without burdening the family budget. It is in this context that the idea of a house capable of maintaining a constant indoor temperature of 23°C year-round, without resorting to conventional heating systems, makes perfect sense.

Design principles of a passive house

The design of a passive house is based on fundamental principles aimed at optimizing energy efficiency and minimizing thermal losses. Unlike traditional homes that produce heat, the passive approach focuses on retaining existing heat and harnessing natural solar gains. These homes, often referred to as Passivhaus, are designed like true thermoses, preventing heat from escaping and maximizing thermal gains through smart architecture.

One of the key aspects of this design is high-performance insulation. The walls, floors, and roofs are equipped with high-quality insulating materials, such as rice straw and Biofib, which provide an effective barrier against fluctuations in outdoor temperature. For instance, the walls of a Passivhaus often exceed 50 cm in thickness, providing insulation that is twice as effective as that of a conventional house.

Controlled ventilation is also essential in this type of construction. Unlike traditional ventilation that allows warm air to escape, passive houses integrate heat recovery systems. These systems recycle the energy contained in the outgoing stale air to heat the incoming fresh air, thereby ensuring optimal air circulation without heat loss.

• Enhanced thermal insulation of walls and floors

• Use of ecological and sustainable materials

• Optimized orientation of openings to maximize solar gains

• Heat recovery ventilation systems

The passive design not only focuses on insulation; it also includes intelligent management of light and solar heat. Large south-facing windows capture maximum warmth in winter, while strategically placed solar protections prevent overheating in summer. This solar management is complemented by the integration of solar systems for hot water and electricity production, thus reducing dependence on external energy sources.

A prominent example of this approach is the La Poutinière house, located in Pont-de-Barret in the Drôme. Designed by Olivier Sidler, a former energy management engineer, this dwelling demonstrates that it is possible to maintain a stable indoor temperature of 23 °C year-round without resorting to traditional heating systems. This project shows that with careful planning and wise technical choices, a passive house can be both comfortable and economically accessible.

This holistic approach, centered on reducing thermal losses and optimizing energy inputs, makes the passive house an ideal solution for a sustainable habitat that respects the environment.

Technologies and materials for high-performance insulation

To achieve high-performance insulation, passive houses use innovative materials and advanced technologies. One of the most crucial elements is the thickness of the walls, often exceeding 50 cm, combined with insulating materials such as rice straw and Biofib. These natural materials offer exceptional thermal resistance while being eco-friendly and durable.

High-Performance Insulation consists of multiple layers, each serving a specific role. On the outside, insulating cladding protects against the elements while ensuring exemplary air tightness. On the inside, materials like Biofib, made from cotton, linen, and hemp, complement the insulation, creating a homogeneous thermal barrier.

Triple-glazed windows are another key element. These windows provide superior thermal insulation thanks to their multiple layers of glass and the air space between them, thus reducing heat loss through conduction and convection. Furthermore, the window frames are often made from insulating materials, such as wood or multi-layer PVC, to maximize energy efficiency.

The floor of a passive house is no exception. A concrete slab resting on 25 cm of polystyrene acts as an excellent insulator, preventing heat loss through the floor. This configuration ensures that the heat generated inside remains well-contained, contributing to maintaining a stable indoor temperature.

• Use of rice straw and Biofib for wall insulation

• Triple-glazed windows with insulating frames

• Concrete slabs with polystyrene insulation

• Weather-resistant exterior insulating panels

The materials used are not only chosen for their thermal performance but also for their durability and low environmental impact. By prioritizing eco-friendly solutions, passive houses reduce their carbon footprint while providing a healthy and comfortable living environment.

Additionally, the integration of technologies such as Thermor for thermal management and Solar Systems for hot water significantly minimizes overall energy consumption. These technological innovations are essential for achieving energy expense reduction goals without sacrificing occupant comfort.

The combination of these materials and technologies creates an optimal thermal envelope, preventing any heat loss and ensuring a uniformly pleasant indoor temperature in all seasons.

Optimization of ventilation and solar energy management

Optimizing ventilation is an essential component of passive house design. Unlike traditional ventilation systems, passive houses integrate controlled ventilation systems equipped with heat recovery devices. These systems ensure constant renewal of indoor air while minimizing thermal losses. By recovering heat from outgoing air, they warm the incoming air, thus reducing the need for additional heating.

Solar Systems also play a crucial role in maintaining indoor temperature. Large south-facing windows allow for maximum capture of solar rays in winter, providing natural warmth that significantly contributes to the thermal balance of the house. In summer, solar protections such as well-placed shutters or blinds prevent overheating, thus maintaining a comfortable indoor temperature without excessive air conditioning.

The integration of Solar Technologies goes beyond heat. Photovoltaic solar panels can be installed to generate electricity, thereby reducing dependence on external energy grids. This energy autonomy is reinforced by energy storage systems, allowing the use of electricity produced during the day for nighttime needs.

• Heat recovery systems for ventilation

• Photovoltaic solar panels for electricity

• Thermal barriers for temperature regulation

• Automated shutters for solar light management

Effective management of solar energy also involves precise orientation of the building. By maximizing solar gains in winter while limiting excessive gains in summer, architects manage to maintain a stable indoor temperature without resorting to energy-intensive heating or cooling systems. This optimization is made possible through careful planning and the use of advanced energy simulation software.

All these technologies converge towards an optimal EcoComfort, offering a superior quality of life while respecting sustainability commitments. This not only helps reduce energy costs but also lowers the ecological footprint of the habitat, thus responding to current environmental challenges.

Economic and environmental benefits of a sustainable habitat

Adopting a sustainable habitat like the Passivhaus offers numerous benefits both economically and environmentally. Economically, the drastic reduction in energy consumption translates into significant savings on heating and electricity bills. While the initial investment may be higher, often around €1,900/m² excluding taxes, the long-term savings more than compensate for this cost, with a return on investment estimated between 5 and 7 years.

Moreover, the decrease in energy expenses increases the financial resilience of households against fluctuations in energy prices. This budget stability is a major asset in an uncertain economic context, providing welcome peace of mind to homeowners.

Environmentally, passive houses contribute to reducing CO₂ emissions due to their low energy consumption. The use of eco-friendly and recyclable materials minimizes the environmental impact of construction, while the overall energy efficiency of the habitat reduces the demand for natural resources. This approach perfectly aligns with the objectives of energy transition and combating climate change, making passive houses a responsible and sustainable choice.

• 30-50% savings on energy bills

• Reduced carbon footprint of the habitat

• Increased property value

• Superior thermal comfort year-round

Additionally, the property value of passive houses is often higher than that of traditional houses. Buyers are increasingly sensitive to energy efficiency and sustainability, making these homes particularly attractive in the real estate market. This trend ensures good investment valuation, making the project even more profitable in the long run.

Investing in a sustainable home is also contributing to a more responsible and environmentally conscious society. Passive houses are often equipped with renewable energy production systems, such as heat pumps and solar systems, which reduce dependence on fossil fuels and promote a transition to cleaner energy sources. This energy independence enhances the energy security of households and participates in the fight against climate change.

In conclusion, adopting a sustainable habitat like the Passivhaus represents an effective and profitable solution to current energy challenges. It offers a unique combination of comfort, savings, and environmental respect, making each residence an active participant in the energy transition.

FAQ

• What are the main advantages of a passive house?

  A passive house offers high-performance insulation, optimized solar energy management, and controlled ventilation, resulting in high thermal comfort and minimal energy consumption.

• What is the average cost of a passive house compared to a traditional house?

  The initial cost may be slightly higher, around €1,900/m², but the savings on energy bills and real estate appreciation greatly compensate for this investment in the long term.

• Is it possible to convert an existing house into a passive house?

  Yes, several insulation and energy improvement techniques can be applied to transform a traditional house into a passive house, although this requires detailed analysis and specific work.

• What materials are used for the insulation of a passive house?

  Passive houses use materials such as rice straw, Biofib, polystyrene, and triple-glazed windows to ensure optimal thermal insulation.

• What is the lifespan of a passive house?

  With proper maintenance, a passive house can last as long as a traditional house while maintaining its energy performance over the long term.

Sources

• Maison La Poutinière in the Drôme

• Passive house without heating

• Heat in winter without heating

• Innovative house at 23°C year-round

• Innovation without heating

• House without heating thanks to the body heat of its occupants

• Living at 23°C without heating

• Construction of a house at 23°C

• House without spending on heating

• Live comfortably at 23 degrees

• Thermodynamic water heater and heating

• Impact of humidity on comfort

• Optimize your mixed boiler

• Advantages of a combined system

• Impact of humidity on comfort

• Thermodynamic water heater and heating

• Hot water production

• Safe heating solutions

• Living comfortably at 23 degrees year-round without resorting to heating, a realizable dream!