Passivhaus – The five principals

Passivhaus general | The 5 principles | The science behind Passivhaus


In the sphere of Passivhaus construction, the element of airtightness is embraced not merely as a feature—it is deemed an essential component integral to the design’s efficiency and sustainability. Certified Passivhaus design principles are founded upon the rigorous incorporation of airtightness within the building’s anatomy. This treatise will expound upon the significance of airtightness within the Passivhaus framework, outline the methods by which it is secured, and discuss the extensive benefits that are bestowed upon a structure as a result.

The Significance of Airtightness in Passivhaus Design

Airtightness within a Passivhaus context is defined as the strategic restriction of involuntary air movement across the building envelope. It is dictated that air transfer into or out of the interior environment be mediated solely through controlled means. Determined via blower door tests, airtightness is measured in the number of air changes per hour at a pressure difference of 50 pascals (n50 value). An n50 value not exceeding 0.6 air changes per hour is mandated by the Passivhaus standard, a criterion that is significantly more exacting than those set forth by traditional building regulations.

Airtightness in Passivhaus Construction: Methods of Attainment

The journey to exceptional airtightness is characterized by precision and conscientious construction practices:

  1. Selection of Materials: Chosen are materials that function as effective air barriers and sealants, crafted specifically to maintain the airtight seal.
  2. Design Incorporation: Continuous air barrier systems are integrated into designs with rigorous attention to every seam, joint, and penetration.
  3. Detailing in Construction Plans: Detailed schematics for all components of the building envelope are produced, preemptively addressing areas typically prone to challenges, such as openings, service entries, and interfaces between varied building materials.
  4. Implementation of Construction: During construction, the preservation of the airtight layer is ensured, necessitating ongoing supervision and immediate remediation.
  5. Blower Door Testing: After construction, the blower door test not only serves as an indicator of airtightness but also as a means to detect and subsequently rectify any leaks.

Benefits Conferred by Airtightness in Buildings

A litany of advantages is conferred upon buildings through the incorporation of airtightness:

  1. Energy Efficiency: The prevention of unnecessary heat exchange in airtight structures leads to a reduction in the energy required for heating and cooling, thereby yielding lower energy costs and a diminution in environmental impact.
  2. Thermal Comfort: Stability in interior temperature is maintained, circumventing drafts and temperature disparities, thus ensuring consistent comfort.
  3. Moisture Management: By managing air exchange, the penetration of moisture-laden air into the building’s framework is prevented, avoiding the issues related to condensation and maintaining the condition of the building materials.
  4. Sound Insulation: A serenely quiet interior ambiance is afforded by the natural soundproofing characteristics of airtight construction.
  5. Indoor Air Quality Management: The precise regulation of air quality is facilitated through mechanical ventilation systems with heat recovery, ensuring a continuous supply of fresh air.
  6. Durability of Structure: The building’s longevity is enhanced as the uncontrolled movement of air and moisture, which could lead to material degradation, is prevented.

To sum up, airtightness is foundational to the Passivhaus ethos, ensuring energy efficiency, comfort for inhabitants, and the structural longevity of the built environment. The commitment to achieving airtightness in construction is an investment in enduring, sustainable architecture for the future. In the field of construction where excellence and foresight are of paramount importance, Passivhaus stands as an exemplar of advanced design and meticulous construction.

back to the top

Thermal bridges

Thermal bridges are specific areas or components in the building envelope that have higher thermal conductivity than the surrounding materials, causing an increased rate of heat transfer. In other words, they are the weak links in the thermal armor of a building. These bridges occur where insulation is interrupted by more conductive materials, such as steel or concrete, or where the building structure penetrates the insulation layer, like at junctions between walls and floors, windows, and doors.

Thermal bridging can lead to several problems in buildings:

  1. Increased Heat Loss: This is the primary concern, as thermal bridges can significantly increase the amount of heat that escapes from a building, making it less energy efficient.
  2. Condensation Risks: When warm, moist indoor air comes into contact with the colder surface at a thermal bridge, it can lead to condensation, which in turn may cause mold growth and material degradation.
  3. Reduced Comfort: Localized cold spots can occur around thermal bridges, leading to discomfort for the occupants.

The Passivhaus approach to dealing with thermal bridges is both rigorous and methodical. It aims to reduce or eliminate thermal bridges to the greatest extent possible, for several reasons:

  • To minimize energy losses: A Passivhaus building aims to have a very low heating demand, typically not more than 15 kWh/(m²yr), and reducing thermal bridging is crucial to achieve this.
  • To prevent condensation: By keeping the internal surface temperatures of the building fabric close to room temperature, the risk of condensation and subsequent mold growth is minimized.
  • To ensure occupant comfort: By eliminating cold spots, Passivhaus ensures that the interior of the building is uniformly comfortable.

Here’s how Passivhaus designers and builders address thermal bridges:

  1. Design Stage: Thermal bridges are identified and addressed during the design process using detailed thermal modeling. Tools like the Passive House Planning Package (PHPP) and thermal bridge software are used to calculate the impact of potential thermal bridges and design them out of the building.
  2. Material Selection: Materials with lower thermal conductivity are chosen, especially at junctions of building components. For instance, insulating material may be used continuously across junctions between walls, roofs, and floors.
  3. Construction Techniques: Passivhaus builders use construction techniques that avoid or minimize the creation of thermal bridges. This might include the use of thermal break materials that are inserted between conductive materials to reduce heat flow.
  4. Quality Assurance: During construction, care is taken to ensure that the design’s intentions are correctly executed on-site. After construction, thermal imaging cameras can be used to check for unexpected thermal bridges, and corrective actions can be taken if necessary.
  5. Continuous Insulation: A key strategy is to provide continuous insulation across all components of the building envelope. This means that the insulating layer is uninterrupted by thermal bridges at all points, creating a complete thermal barrier.
  6. Details and Junctions: Special attention is given to designing and constructing details and junctions, such as balcony connections, window installations, and service penetrations, to minimize heat loss.

By focusing on the elimination of thermal bridges, the Passivhaus standard ensures that the buildings designed under its principles are not only highly energy-efficient but also provide high levels of comfort and longevity due to the reduction of problems related to moisture and temperature variability.

back to the top

Thermal insulation

In the domain of sustainable architecture, the thermal insulation of a Passivhaus building is accorded paramount importance, underpinning the building’s energy efficiency and occupant comfort. This article aims to elucidate the fundamental role played by thermal insulation in the Passivhaus standard, describe how it is meticulously integrated into the building fabric, and enumerate the benefits that are derived from its application.

The Role of Thermal Insulation in Passivhaus Design

In Passivhaus buildings, thermal insulation is utilized as a critical component for minimizing energy loss. The importance of this component cannot be overstated; it is thermal insulation that ensures the minimal operational energy use for which Passivhaus buildings are renowned. The standard requires that insulation be applied in a continuous layer, enveloping the building to create a warm, protective shell. By doing so, the thermal bridge-free construction is achieved, and the passage of heat through the building envelope is greatly reduced.

Integration of Thermal Insulation in Passivhaus Construction

The integration of thermal insulation in Passivhaus construction is approached with great care and precision:

  1. Selection of Insulation Materials: Insulation materials with a low thermal conductivity are chosen to provide maximum resistance to heat flow.
  2. Application in Design: The placement of insulation is considered at the design stage to ensure continuity and to avoid thermal bridges.
  3. Installation Procedures: Insulation is installed meticulously, with attention to detail to maintain the integrity of the insulated envelope.
  4. Verification of Insulation Performance: The effectiveness of the insulation is measured through thermal imaging and other diagnostic techniques, which identify potential areas of heat loss.

The Benefits Derived from Thermal Insulation in Passivhaus Buildings

The inclusion of superior thermal insulation in Passivhaus buildings offers a host of advantages:

  1. Reduction in Energy Consumption: Heat loss is minimized, leading to a significant decrease in the energy required for heating and cooling the building.
  2. Enhanced Comfort Levels: A stable internal temperature is maintained throughout the year, contributing to a comfortable living and working environment.
  3. Economical Energy Bills: The demand for energy being substantially lowered results in markedly reduced utility costs.
  4. Environmental Impact: A decrease in energy consumption translates directly to a reduction in greenhouse gas emissions, reflecting a commitment to environmental sustainability.
  5. Improved Sound Insulation: Additionally, the thick layers of insulation inherently provide sound dampening properties, contributing to a quieter indoor experience.
  6. Elevated Property Value: Buildings adhering to the Passivhaus standard often enjoy an increase in market value due to their advanced features and reduced operating costs.

In conclusion, the meticulous integration of thermal insulation is not just a feature of Passivhaus design but a fundamental cornerstone that ensures the building’s superior performance. The adoption of such insulation strategies is a testament to the commitment to creating structures that are not only efficient and comfortable but also sustainable and forward-thinking. The attention to thermal insulation detail in Passivhaus construction is reflective of an overarching ethos that values precision, durability, and stewardship of the environment.

back to the top


In the lexicon of Passivhaus design, the role of high-performance windows is lauded for its critical contribution to energy conservation and comfort. This discourse will elucidate the essential nature of window design in Passivhaus standards, describe the meticulous process through which high-performance windows are selected and installed, and delineate the myriad benefits they bestow upon a structure.

The Role of Windows in Passivhaus Construction

In Passivhaus buildings, windows are engineered not merely as portals to the outside world but as key elements in maintaining thermal efficiency. It is through the careful selection of windows that heat gain and loss are mitigated, a process critical to the energy balance of a Passivhaus. Triple-glazing, low-emissivity coatings, and the use of inert gas fills are among the specifications required to meet the stringent Passivhaus criteria.

Selection and Installation of High-Performance Windows in Passivhaus Design

The selection and installation of windows in a Passivhaus are governed by strict performance requirements:

  1. Window Specifications: High-performance windows, characterized by exceptional thermal properties, are prescribed to minimize heat transfer.
  2. Frame Design and Material: The frames of these windows are as crucial as the glazing, being required to provide excellent thermal insulation and structural integrity.
  3. Precision Placement: The positioning of windows is carefully planned to exploit passive solar heat gain while minimizing heat loss.
  4. Sealing and Insulation: The installation of windows includes meticulous sealing and insulation to ensure the absence of thermal bridges and air leakage.
  5. Verification of Window Performance: Post-installation, the performance of windows is verified through various testing methods, including thermographic inspections.

Benefits Afforded by High-Performance Windows in Passivhaus Buildings

The integration of high-performance windows into Passivhaus buildings imparts numerous advantages:

  1. Optimized Energy Efficiency: Enhanced glazing and frame design significantly reduce energy requirements for heating and cooling.
  2. Elevated Interior Comfort: Windows play a vital role in maintaining stable indoor temperatures and reducing cold spots and drafts.
  3. Enhanced Daylight Utilization: Carefully positioned windows allow for optimal natural light, reducing the reliance on artificial lighting.
  4. Sound Insulation: High-performance windows inherently provide superior sound insulation, contributing to a quieter and more serene indoor environment.
  5. Lowered Operational Costs: The reduction in energy demand directly correlates to a decrease in energy costs for the occupants.
  6. Augmented Property Value: Given their energy-saving features and the comfort they provide, these windows often enhance the overall value of the property.

In sum, windows in the context of Passivhaus design are far from conventional. They are pivotal components, embodying the synergy between form and function, aesthetics, and performance. The rigorous standards to which these windows are crafted and installed reflect an unwavering commitment to building homes and structures that are as energy-efficient and comfortable as they are environmentally responsible. As such, high-performance windows remain integral to the Passivhaus philosophy, harmonizing the built environment with the natural world.

Follow this link to find out more about the certified Passivhaus windows

back to the top

Heat recovery ventilation

Within the scope of Passivhaus construction, the deployment of heat recovery ventilators (HRVs) is considered a cornerstone in achieving remarkable energy efficiency and providing superior indoor air quality. The purpose of this article is to detail the critical role that HRVs play in the Passivhaus standard, to outline the process by which they are integrated into the building’s systems, and to highlight the multiple benefits derived from their usage.

The Role of Heat Recovery Ventilators in Passivhaus Buildings

In Passivhaus buildings, the HRV system is relied upon as a pivotal feature that significantly reduces the need for conventional heating and cooling. The recovery of heat from exhaust air is seen as an essential function of maintaining the building’s thermal balance while ensuring the constant introduction of fresh air. By means of a heat exchanger, the HRV system conserves energy that would otherwise be lost, affirming the building’s adherence to the principles of sustainable design.

Integration of Heat Recovery Ventilators in Passivhaus Design

The incorporation of HRVs in Passivhaus buildings is performed with stringent adherence to efficiency and performance standards:

  1. Selection of HRV Systems: Systems with a high heat recovery rate and low power consumption are selected to optimize energy savings.
  2. Strategic Placement: The HRV system is strategically installed to ensure optimal distribution of conditioned air throughout the building.
  3. Detailed Planning and Installation: A meticulous approach to the planning and installation of ductwork is taken to maximize air distribution efficiency and minimize thermal losses.
  4. Performance Testing: Upon installation, the HRV systems are rigorously tested to confirm their performance aligns with the stringent Passivhaus criteria.

Benefits Accrued from the Use of HRVs in Passivhaus Buildings

The integration of HRVs in Passivhaus construction confers numerous benefits:

  1. Energy Conservation: The HRV’s capacity to reclaim heat significantly curtails energy demand for temperature regulation, underscoring the building’s energy conservation profile.
  2. Consistent Indoor Comfort: An equilibrium between fresh air supply and heat retention is maintained, enhancing the comfort levels within the building.
  3. Reduction in Utility Expenses: The HRV’s efficiency in heat recovery translates to lower heating and cooling costs, thus reducing overall utility expenses.
  4. Sustainability: By optimizing energy use and reducing dependency on non-renewable energy sources, the HRV system contributes to the building’s sustainable footprint.
  5. Improved Air Quality: The continuous exchange of indoor air with filtered outdoor air provided by the HRV system improves the building’s indoor air quality.
  6. Enhanced Building Value: The advanced technological integration of HRVs potentially raises the market value of Passivhaus properties due to their recognized efficiency and sustainability.

To encapsulate, heat recovery ventilators are not merely adjuncts to the Passivhaus design; they are intrinsic to its very essence, ensuring that energy efficiency and occupant wellbeing are maintained at the highest levels. The meticulous selection, installation, and operation of HRVs within Passivhaus buildings exemplify the uncompromising commitment to environmental stewardship, economic responsibility, and the creation of healthful living spaces. Through the adoption of these systems, Passivhaus continues to set benchmarks for sustainable construction, redefining the standards for the built environment of the future.

back to the top