What is a Passivhaus?

What is a Passivhaus?

The Passivhaus standard, developed in Germany, is a low energy design standard.

It was developed in 1990, over 25 years ago and some estimates suggest there are well over 50,000 Passivhaus buildings around the world. 

Some of the key characteristics of a Passivhaus include:

•Excellent levels of thermal comfort

•Very low energy demands

•Provision of consistent fresh air throughout the building

•High levels of insulation

•Airtight design

•Low energy costs

The Passivhaus has rigorous design standards and can be certified to prove the building has been designed to the assured Passivhaus criteria. 

The Passivhaus design methods can be adopted for new build designs, both residential and commercial, and on retrofit buildings of all types. There is in depth guidance associated with the different types of Passivhaus build and different certifications according to new build or retrofit status. A Passivhaus can be built using virtually any construction method, from concrete and masonry to timber frame. 

What is Passivhaus certification?

Passivhaus certification is an independent process that ensures Passivhaus standard for complete buildings, building components and building designers and contractors. Certification can be seen as the formal assessment and approval of the quality of a project, or component. 

Certification of a building

Certification is carried out by the Passivhaus Institute or any other accredited certifier. The process is designed to ensure the high standards and performance of the Passivhaus has been achieved, from design through to completion. 

The certification is based on the calculations from the PHPP, along with supporting documentation such as plans, details, manufacturer/component information, air tightness testing, and commissioning information for the mechanical ventilation with heat recovery unit (MVHR). 

EnerPHit Standard

The EnerPHit standard applies to existing buildings that have been renovated to improve thermal comfort, energy efficiency and many of the other elements of the Passivhaus standard.

Certification of a building component

When designing a Passivhaus it can be extremely helpful to specify building components that have been certified by the Passivhaus Institute. This certification means that the component will be of a suitable standard for use in a Passivhaus, but will most likely have all of the technical information available that will need to be entered into the PHPP.

How Passivhaus works

 
There are five key principles of the Passivhaus design. 
 
Principles of Passivhaus

Thermal Insulation

A Passivhaus has a continuous well insulated thermal envelope that keeps the building warm during the winter months and keeps the heat out during the summer months.
 
 

Airtightness

The Passivhaus has a continuous airtight barrier that protects the building from heat losses and improves overall thermal comfort. 
 
 

Ventilation Strategy

With an airtight construction, it is important that the Passivhaus is consistently supplied with fresh air. This is performed by the mechanical ventilation and heat recovery (MVHR) system that supplies fresh air to the rooms virtually at room temperature by recovering heat from the exhaust air.
 
 

Passivhaus Windows

The windows in a Passivhaus are high performance triple glazed with insulated window frames. These high performing windows ensure a warm, draught free building in winter and allow the building to benefit from winter solar heat gains. 
 
 

Thermal Bridge Free

A Passivhaus aims to be thermal bridge free, or minimise any occurrence of thermal bridges. This prevents potential building damage, lowers heat demand, and improves overall building performance.  
 
 
The Passivhaus Planning Package (PHPP) is a design tool that enables architects and designers achieve the Passivhaus standard. The PHPP is a spreadsheet programme that is filled in by the architect/designer during the design process in order to test out various design strategies and decisions, resulting in accurate data of the potential overall performance of the building.  

Passivhaus U-values

 
U-value requirements (dependent on form factor and other conditions, prescribed by PHPP):
 
Passivhaus Floor u-value: Starting at 0.15 W/m2K
 
Passivhaus External Wall u-value: Starting at 0.12 W/m2K
 
Passivhaus Roof u-value: Starting at 0.10 W/m2K
 
 
[UK Regs – Domestic New Build]
Floor: 0.13 W/m2K
External Wall: 0.18 W/m2K
Roof: 0.13 W/m2K
 

Passivhaus Details

 
The Passivhaus standard can be achieved using many different types of building methods. The decision on construction system will determine the basis for construction detailing and requirements for the project. There are advantages and disadvantages to all types of construction, the aim is to find a balance between constructional needs and the intention of the design.
If you would like to learn more about the Passivhaus and gain access to construction details for 6 different types of construction, with over 40 details in 2d and 3d check out the Understanding Passivhaus book – a simple guide to Passivhaus design and detailing.
 
Passivhaus is the fastest growing energy performance standard in the world. 
 
Whether you are an architect, student, construction professional or have an interest in the Passivhaus method, this book will serve as a great introduction to Passivhaus detailing and design. 

Passivhaus Construction

One of our readers Tim Maisey [https://www.tmcgproductions.com/architecture-portfolio] has very kindly shared some images of a Passivhaus under construction. 

My favourite Tools and Resources

I have curated a list of some of the tools and resources I would strongly recommend for anyone studying or working in Architecture.