This is a Passivhaus Basics blog post that gives an overview of a specific aspect of the Passivhaus Standard.

The international Passivhaus Standard does not explicitly require mechanical ventilation. And yet almost every certified Passivhaus building includes a mechanical ventilation system with heat recovery.

What is mechanical ventilation with heat recovery (MVHR) and why is it needed in Passivhaus buildings?

Mechanical ventilation is familiar to most people. This leads to the assumption that a Passivhaus ventilation system is the same as other mechanical ventilation systems. It is not.

There are things that MVHR does not do. It is important to know what these are in order to understand the difference between Passivhaus MVHR and other types of ventilation.

And there are things that Passivhaus MVHR does do that other ventilation systems don’t, including ‘natural ventilation’. It is important to know what MVHR does do, as MVHR is vital to the consistent success of the passivhaus standard.

Mechanical ventilation with heat recovery (MVHR) is key to delivering the benefits the Passivhaus Standard promises – radical energy efficiency and exceptional comfort.

036 What is Mechanical Ventilation with Heat Recovery (MVHR)?
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This is a Passivhaus Basics blog post that gives an overview of a specific aspect of the Passivhaus Standard.

The Passivhaus Standard requires airtight construction. What does this mean?

Essentially it means a draught-free building envelope.

A clear airtightness strategy is required to achieve this. The airtight line needs to be continuous even when formed of different materials. And it needs to be joined up, even where there are penetrations.

Sometimes airtight construction gets confused with how a building is ventilated or with ‘breathing construction.’ This post clears up these particular confusions.

And why does the Passivhaus Standard require airtight construction?

Airtight construction is draught-free construction. It is an essential part of the Passivhaus Standard to protect the building envelope, to ensure radical energy efficiency and to provide exceptional comfort.

030 What is Airtight Construction
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A passivhaus home in almost all climates across the world will include a mechanical ventilation system with heat recovery (MVHR*). This kind of ventilation system is required for both energy efficiency and for comfort. However, to many people this is an intimidating and misunderstood aspect of passivhaus. As a result, there are various concerns and misconceptions about what a passivhaus ventilation system is and how you use it.

To address some of these issues I have enlisted the help of Zehnder, a global supplier of Passivhaus Certified ventilation systems. In this post, we explore the following aspects of a residential passivhaus ventilation system:

  1. How do I control the ventilation system?
  2. What day-to-day interaction do I need to have with the ventilation system?
  3. What is the boost function and when should I use it?
  4. When should I switch the ventilation system off?

Rupert Kazlauciunas, Senior Technical Advisor at Zehnder Group UK, very kindly provided answers to my questions

In a residential passivhaus, the ventilation system can be simple to use. It will save energy and money, while ensuring comfort and excellent indoor air quality.

029 Residential Passivhaus Ventilation System
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What is the fundamental purpose of a building?

Buildings serve several needs of society – primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical division of the human habitat (a place of comfort and safety) and the outside (a place that at times may be harsh and harmful).
Wikipedia

As you can see, comfort is fundamental to the purpose of a building. So why do we find it so hard to ensure our buildings are actually comfortable? Why does our ‘world-class’ architecture still fail to provide comfortable buildings to live, work, learn and play in? (Besides using far too much energy and emitting far too much CO2!)

The Passivhaus Standard is known as the world’s foremost building energy efficiency standard. And it is that, but it is also a comfort standard. After all, what is the point of a building being energy efficient (or low carbon for that matter) if it compromises the functionality and comfort of the people who use the building? Passivhaus buildings provide exemplary comfort for the occupants by maintaining a healthy comfortable temperature, by being quiet, by having fresh air and by being draught-free.

Comfort is a reason to Love Passivhaus!

019 Love Passivhaus Comfort
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I was first introduced to Passivhaus several year back when we decided to pursue it in the architect’s practice where I work. It seemed like the right step forward in so many ways. However, learning about the Passivhaus Standard and everything that is required for certification, presented many challenges. There were some technical challenges, but probably the biggest challenges were to the received wisdom that I held firmly onto at the time.

This somewhat tongue-in-cheek post explores some of those mindset challenges with the benefit of hindsight. It also explores some other mindset challenges that arise from delivering passivhaus architecture.

010 10 Things I hate About Passivhaus

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