Passive House Insulation

Passive House Insulation

In the quest to create energy-efficient, sustainable, and comfortable living spaces, Passive House Insulation has emerged as a key solution for architects, builders, developers, and homeowners alike. The concept of a passive house or passivhaus, as it is known in the UK, revolves around reducing energy consumption and carbon footprint while ensuring the highest levels of comfort for the occupants.
In this guide, we will explore the concept of Passive House (Passivhaus) in the UK, the insulation standards, and the benefits of using spray foam insulation for your Passive House project.
Passive house insulation

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What is a Passive House (Passivhaus) UK?

A passive house, or passivhaus, is a voluntary standard of construction that aims to create buildings with minimal energy requirements for heating and cooling. The concept, which originated in Germany, has gained significant traction in the UK and around the world.
The fundamental idea behind a passive house is to minimise heat loss and maximise heat gains, resulting in a highly energy-efficient and comfortable living environment. This is achieved through rigorous insulation, airtightness, and the use of high-performance windows, among other key elements.

Passive House Insulation Standards

Passive house insulation standards are essential in achieving the energy-efficiency goals of a passivhaus. These standards define the required levels of insulation and airtightness to minimise heat loss and maintain a comfortable indoor temperature. Some of the key insulation standards for passive houses in the UK include:
  1. Passive house U-values: The U-value represents the rate of heat transfer through a building element, such as walls, floors, or roofs. Lower U-values indicate better insulation properties. For a passive house, the U-values should be as low as possible, typically between 0.10 and 0.15 W/m²K.
  1. Passivhaus airtightness: Airtightness is crucial in preventing uncontrolled air leakage and heat loss. Passive houses should have an airtightness level of 0.6 air changes per hour (ACH) at 50 Pascal pressure.
  1. Thermal bridge-free construction: Thermal bridges are areas where heat can bypass insulation, leading to increased heat loss. Passive house insulation standards require that all thermal bridges be eliminated or minimised to ensure optimal insulation performance.

Super Insulation Passive House

Super insulation is a term used to describe the extraordinary levels of insulation employed in passive houses. This concept involves the use of insulation materials with exceptional thermal performance, such as spray foam, to create an almost continuous layer of insulation throughout the building envelope. 

The result is a significant reduction in heat loss, leading to substantially lower energy consumption for heating and cooling.

Best Insulation for Passive House

Selecting the best insulation for a passive house is crucial to achieving the desired energy efficiency and comfort levels. While there are various insulation materials available, spray foam insulation stands out as a superior option for passive houses. Traditional insulation materials, such as fiberglass or cellulose, can leave gaps and voids, allowing air to escape and reducing the insulation’s effectiveness.
On the other hand, spray foam insulation expands up to 100 times its original size, filling every corner and cavity to create a tightly sealed building envelope. This unique property can deliver up to 50% greater energy savings compared to other insulation products, making it the ideal choice for passive house insulation.

Using Spray Foam for Passive House Insulation

Spray foam insulation is a versatile and high-performance insulation solution for passive houses. It can be applied to various building elements, such as walls, roofs, and floors, providing excellent thermal and airtightness performance. Some of the key benefits of using spray foam for passive house insulation include:
  1. Exceptional U-values: Spray foam insulation can achieve U-values that meet or surpass passive house requirements, ensuring optimal thermal performance.
  2. Enhanced airtightness: The seamless and gap-free nature of spray foam insulation creates an airtight building envelope, which is essential for passive house standards.
  3. Minimised thermal bridging: Spray foam insulation’s ability to expand and fill all cavities and voids helps eliminate or reduce thermal bridging, further contributing to energy efficiency.
  4. Moisture resistance: Unlike some traditional insulation materials, spray foam insulation is resistant to moisture, preventing issues like mould growth and structural damage.
  5. Long-lasting performance: Spray foam insulation is a durable and long-lasting solution, maintaining its thermal performance and airtightness over time, which is ideal for passive houses designed for sustainability and longevity.
  6. Adaptability: Spray foam insulation can be tailored to suit the specific requirements of a passive house project, including the desired U-values, thickness, and application method.

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The Importance of Ventilation in Passive House Design

While insulation is a critical aspect of Passive House design, it is essential not to overlook the importance of proper ventilation. Achieving optimal airtightness can lead to indoor air quality concerns if proper ventilation measures are not in place. To ensure a healthy living environment and maintain indoor air quality, Passive House buildings are equipped with Mechanical Ventilation with Heat Recovery (MVHR) systems.
MVHR systems work by extracting stale air from the building and bringing in fresh air from outside, while simultaneously recovering heat from the outgoing air to pre-warm the incoming air. This process not only maintains excellent indoor air quality but also contributes to the energy efficiency of the building by reducing the need for additional heating and cooling.

Cost and ROI of Passive House Insulation

As mentioned earlier, the costs of Passive House insulation can vary depending on several factors, such as the size of the area, the type of spray foam needed, building condition, location, environment, and special requirements. Although the initial investment in Passive House insulation may be higher compared to traditional insulation, the long-term benefits in terms of energy savings and reduced utility bills far outweigh the upfront costs.

To obtain an accurate estimate, it is important to arrange a pre-installation survey with a qualified installer like Spray Foam Tech. This assessment will help determine the appropriate insulation solution for your Passive House project and provide a detailed cost breakdown. 

Investing in high-quality insulation like spray foam for your Passive House project can result in substantial long-term savings and a quick return on investment.

Passive House Certification and Benefits

Passive House buildings can be certified by the Passivhaus Institut, which ensures that the building meets the stringent requirements of the Passivhaus standard.
Achieving Passive House certification not only serves as a testament to the building’s exceptional energy efficiency but also offers numerous benefits, including:
  1. Reduced Energy Consumption: Passive House buildings consume up to 90% less heating and cooling energy compared to conventional buildings, resulting in significant energy savings and lower utility bills.
  2. Enhanced Comfort: Due to the high insulation standards and airtightness, Passive House buildings maintain a consistent indoor temperature and comfortable living environment year-round.
  3. Improved Indoor Air Quality: With the inclusion of MVHR systems, Passive House buildings maintain excellent indoor air quality by continuously supplying fresh air and removing stale air.
  4. Reduced Carbon Footprint: By consuming less energy, Passive House buildings contribute to the reduction of greenhouse gas emissions, supporting global efforts to combat climate change.
  5. Increased Property Value: A Passive House certification can increase the property’s value, making it a wise investment for homeowners, developers, and builders.


Passive House Insulation is the cornerstone of creating energy-efficient, comfortable, and sustainable living spaces. The rigorous insulation standards, along with the emphasis on airtightness and thermal bridge-free construction, make passive houses an exemplary model for the future of building design. Spray foam insulation, with its exceptional thermal performance, airtightness, and adaptability, proves to be the ideal insulation solution for passive house projects.
At Spray Foam Tech, we understand the intricacies of passive house insulation requirements and are committed to providing the highest quality spray foam insulation solutions for architects, builders, developers, and homeowners. Our team of skilled professionals is ready to assist you in achieving the energy efficiency and comfort goals of your passive house project.
To arrange a pre-installation survey and discuss your insulation needs, get in touch with Spray Foam Tech today. Together, let’s create a more sustainable and energy-efficient future for our buildings and homes.
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