Introduction
The Passive House represents an innovative approach to housing construction that has attracted considerable interest due to its ability to maintain a comfortable indoor temperature without the use of traditional heating systems. This energy-efficient building model focuses on reducing heat loss and optimising passive solar gain, ensuring homes that require minimal active heating or cooling. We take a closer look at how passive houses work and the technologies used to achieve this extraordinary result.
Understanding passive house principles: The basic principle of passive houses is to create an extremely well insulated and sealed envelope around living spaces. These structures reduce air leakage and thermal bridges to a minimum, allowing heat to be retained during the cold months and a cool environment to be maintained during the warm months.
Passive houses must fulfil 3 main objectives in order to obtain certification:
Energy consumption for space heating - Less than 15 kWh per square meter per year.
Primary energy consumption - Less than 60 kWh per square meter per year.
Maximum air tightness - 0.6 air exchanges per hour at a pressure of 50 Pascal.
Insulation and reduction of thermal bridges: To ensure high levels of insulation, it is essential to use materials with a low U coefficient such as expanded polystyrene (EPS), extruded polystyrene (XPS), vacuum insulation panels (VIP) and mineral wool. These materials are installed uniformly on all exterior surfaces, including walls, roofs, floors and foundations. In addition, the designers pay special attention to the elimination of thermal bridges, ensuring the continuity of the insulation layers even in the joints between different structural elements such as windows, doors, balconies, etc.
High-performance windows and doors: Windows play an essential role in capturing free sunlight. Windows with triple glazing filled with argon gas or krypton offer superior insulation compared to traditional double glazing. In addition, thermally broken PVC, aluminium-clad wood or fibreglass window frames help prevent cold spots near glazed areas. High-quality doors also help maintain a constant interior temperature, sealing off unwanted draughts and reducing heat transfer.
Mechanical ventilation system with heat recovery (MVHR): Because passive houses have such compact envelopes, natural ventilation alone cannot ensure an adequate supply of fresh air. Mechanical ventilation systems equipped with heat recovery units (MVHR) effectively address this challenge. These systems extract stale air from damp rooms such as kitchens and bathrooms, while simultaneously introducing filtered fresh air into living spaces via separate ducts. During this process, up to 90 per cent of the waste heat contained in the extracted air can be transferred back into the incoming air stream via a cross-flow or rotary heat exchanger, thus pre-heating the air before it enters the living areas.
Minimal requirements for active heating: Due to the outstanding insulation properties and efficient use of passive solar gains, most passive houses require only a modest amount of auxiliary heat. Often, an underfloor heating system powered by a modest electric radiator or pellet stove is sufficient. Other designs may include radiant water panels connected to highly efficient heat pumps or district heating networks. In both cases, the total active heating demand is significantly lower than with conventional housing standards, leading to a significant reduction in CO2 emissions and operating costs.
Conclusion
Passive House represents a revolution in the building sector, focusing on optimising comfort, energy efficiency and environmental sustainability. Through intelligent design, careful choice of materials and innovative technologies, architects and engineers can realise homes that are able to maintain ideal conditions without excessive energy consumption. These strategies not only set new standards for affordability, health and climate resilience, but could also lead us towards a future where zero-emission buildings will be the norm rather than the exception.