Year: 2015

Posted on
by

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)?
Continue reading →

Posted on
by

Passivhaus seems to be in the industry news every week. More and more projects are appearing all across the world.

It is often stated that the International Passivhaus Standard is the fastest growing building energy performance standard in the world. The first Passivhaus building was completed in 1991 and only 25 years later it is estimated there are now 50,000 Passivhaus buildings. This is exponential growth!

And yet Passivhaus can still be a divisive subject. There are still many excuses given for not doing Passivhaus – by architects and designers, by builders and by clients.

It is true; there are real reasons for not doing Passivhaus in some circumstances. However, in most cases the reasons are based on misunderstandings, myths and mindsets.

This post looks at 5 excuses and why they simply don’t hold water. Or rather, why they aren’t airtight!

5 Excuses for not doing Passivhaus
Continue reading →

Posted on
by

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

Thermal bridges (sometimes referred to as “cold bridges”) in the building envelope have a measurable impact on energy efficiency and thermal comfort. The impact can be relatively low on buildings that are not very well insulated. However, with buildings that are well insulated and energy efficient, the relative impact of thermal bridging is significant.

Building regulations and codes are now starting to recognise this and in some places, it is required or recommended that thermal bridging be minimised.

The Passivhaus Standard recognises the importance of thermal bridges and the significant impact they can have on the high-performance Passivhaus building envelope. The Passivhaus Standard requires a continuous thermal envelope: this means thermal bridge free construction.

This blog post answers the following questions:

  • What is a thermal bridge?
  • What are the different types of thermal bridges?
  • Why are thermal bridges a problem?
  • What is thermal bridge free construction?

The Passivhaus Standard requires thermal bridge free construction to ensure a robust high-quality building envelope that delivers radical energy efficiency and exceptional comfort.

What is Thermal Bridge Free Construction
Continue reading →

Posted on
by

This blog post is a review of “American Passive House Developments” published in 2012. It is the third book of Passive House case studies from the US that author Mary James has published.

The previous two books explained the Passive House approach, detailing nine pioneering U.S. case studies (2008) and showcased ten Passive House projects from a wide range of climates across the U.S. (2010).

This third book, “American Passive House Developments”, explores how the passive house movement in the U.S. has scaled up and expanded beyond the single-family residential sector. It contains seven case studies, covering large multifamily, mixed-use, and commercial buildings.

These are important case studies. These projects are the forbearers to the explosion of Passive House current happening in the U.S., including the Passive House residential high-rise for Cornell University. As Mary James points out in the Introduction:

[The clients] have been willing to be innovative, are concerned about the future, and know that they will own their buildings for multiple decades—and be paying the electric bills. The fact that these projects were built at a small cost premium, if any, over conventional construction made the commitment to PH [Passive House] a choice 
with very clear-cut benefits.

“American Passive House Developments” is an excellent guide to a selection of seminal Passive House buildings in the U.S.

Passive House Case Studies from the US
Continue reading →

Posted on
by

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

Continue reading →