Category: Passivhaus Basics

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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 a fabric first approach and a high-performance thermal envelope. Not only does the thermal envelope need to be high performance, it also needs to have an efficient surface area in relation to the size of the building. The thermal envelope is, after all, the main area through which a Passivhaus building can lose heat.

The Heat Loss Form Factor is one way of measuring the efficiency of the surface area of the thermal envelope.

The Heat Loss Form Factor is the ratio of thermal envelope surface area to the treated floor area (TFA). This is effectively the ratio of surface area that can lose heat (the thermal envelope) to the floor area that gets heated (TFA).

In other words, the Heat Loss Form Factor is a useful measure of the compactness of a building. And the more compact a building is, the easier it is to be energy efficient. Conversely, the less compact a building is, the more insulation will be required for the building to be energy efficient.

The Heat Loss Form Factor is a measure of compactness and an indication of how much insulation will be required to achieve the Passivhaus Standard.

Passivhaus Heat Loss Form Factor

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

In passivhaus design and construction, there are frequent references to the “building envelope” and the “thermal envelope.” Neither are exclusive to the Passivhaus Standard, but both are important aspects of the standard.

A building envelope is the physical separators between the conditioned and unconditioned environment of a building including the resistance to air, water, heat, light, and noise transfer. The three basic elements of a building envelope area weather barrier, air barrier, and thermal barrier. [Wikipedia]

In simple terms, this means that the building envelope is made up of the walls, floors, roofs (or ceilings), windows and doors that separate the inside from the outside. The passivhaus building envelope is also made up of these elements, but there are some key aspects that make the passivhaus building envelope distinct.

The passivhaus building envelope requires a high-performance thermal envelope, it must be continuous and it is key to the fabric first approach.

028 What is the Passivhaus Building Envelope
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This is a Passivhaus Basics blog post that gives an overview of the Passivhaus Standard. Want to watch a 2-minute overview first? Jump to the video at the bottom

The Passivhaus Standard is often referred to as “the world‘s leading standard in energy efficient design.” And usually a description of the standard includes details of the specific technical requirements. (If you are curious about the technical requirements, I cover the key elements in this post.)

The Passivhaus Standard is indeed an international, rigorous, scientific, performance standard for the design and construction of energy efficient buildings. It applies to all kinds of buildings, not just houses. However, the Passivhaus Standard is not just about the technical requirements of energy efficient design, it encompasses:

  • Comfort
  • Energy Efficiency, and
  • Quality Assurance

It is the combination of these three key aspects that make the Passivhaus Standard what it is.

What do Comfort, Energy Efficiency and Quality Assurance mean in practical terms for a house that is certified to the Passivhaus Standard?

026 What is the Passivhaus Standard
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