Timber frames in Passive Houses

What is a passive house? Passive house construction and technology was born around 20 years ago in Germany. The concept is actually very simple, but it remains a revolutionary idea throughout many cities in Europe. A majority of houses and commercial units in European cities were built using traditional construction methods. Unfortunately, many of these buildings waste a significant percentage of energy and can also have inadequate insulation.

Passive houses have a great deal to offer, and people’s interest in them has been gathering momentum in recent years. The ‘Passive House Standard’ is part of the European Union’s efforts to reach its ambitious 20-20-20 sustainability targets:

  • Reducing the emissions of green house gasses by 20%
  • Increasing the share of renewable energy consumption by 20%
  • Improving energy efficiency by 20%
  • To achieve all of this by the year 2020

Passive houses and insulation

The design and construction of passive houses focuses on insulation. Buildings account for around 40% of the world’s energy consumption. Until recently, they have been inadequately insulated and ‘leaking’ energy. If we are to meet sustainability and climate protection targets, everyone can agree that we need to start building more energy and resource efficient buildings.

This doesn’t involve expensive materials either. On the contrary, a majority of the materials used for passive houses are actually conventional building materials. Concretes, bricks, polystyrene and timber can all be used, but the key difference lies in the design. It’s not so much what you use, it’s all about how you use it.

Passive houses also give occupants an economic advantage. The energy efficient design drastically cuts heating bills. EU climate targets mean that stricter rules on sustainability will be imposed over the coming decades. Buildings that are built to a high energy efficiency standard will have a greater market value.

Are passive houses expensive?

The Passive House institute defines a passive house as “a building that is truly energy efficient, comfortable and affordable at the same time.”

The idea of passive houses is to reduce or eradicate the need for conventional heat sources. Instead, they use the sun or ‘solar gain’, alongside sustainable heat sources such as heat recovery. This is then combined with highly efficient insulation. This is where the timber frame comes in to play.

Timber frames and building envelopes

The ‘building envelope’ in a passive house separates the indoor climate from the outdoor climate. Generally, the building envelope consists of a timber frame structure, which supports the wall, roof and floor insulation panels and high energy performance doors and windows. This can be thought of as a ‘thermal envelope’. In addition to retaining energy from the sun, it also captures the heat given off from white goods and lighting. So, nothing gets wasted in terms of energy!

The building envelope is designed and constructed with ‘airtightness’ in mind. Air from a moist room can penetrate into the structure of a building if it is not sufficiently airtight. This can then cause condensation and damage. Airtightness is important in all climates. Room moisture can be a problem in colder locations, where internal heating is required. In warmer, more humid climates, moisture can infiltrate a building from the outside. So, the design of a passive house depends upon the environment in which it is built. Airtight design and construction are essential if you want to create good quality, permanent structures that will stand the test of time.

The building envelope keeps heat in, but it can also keep the interior cool. Other design elements help ensure that the building is kept at a pleasant ambient temperature all year round. They remain warm during the winter months because of the energy efficiency design. However, passive cooling techniques are also used, such as strategic shading.

A constant stream of fresh air can be supplied through a ventilation system, which cuts out draughts. The efficient heat recovery systems often used in passive houses ensure that heat is contained, whilst exhaust air is re-used.

Local, sustainable timber frames

Timber frames from local, sustainable sources add to the environmental credentials of a passive house. As the European Union moves towards a more sustainable future, we are seeing an increasing number of passive housing projects. Sustainability can also be thought of in an economic sense. Using timber that is produced within the EU protects our climate, but it also contributes towards creating sustainable jobs for local economies. So, passive housing can have a positive impact upon communities.

The 17th International Passive House Conference, organised by the Passive House Institute, took place on the 19th and 20th of April (2013) in Frankfurt, Germany. Over 100 experts gathered together during a series of lectures, to highlight how passive houses can offer a practical solution for buildings in all climates. In fact, the Passive House Standard makes “Nearly Zero Energy Buildings” possible, which has far reaching implications for worldwide energy efficiency building legislation. The International Passive House Conference attracted passive house experts from over 50 countries, including large delegations from Mexico and China.

People often think of passive houses in terms of new, residential builds like the ones availble here. However, the conference also covered retrofitting. Experts emphasised the fact that passive house principles can also be applied to schools, offices and other buildings.

In essence, this is a new way of building that effectively addresses the issues of energy transition and climate change. Construction is now about more than just the built environment. We also need to consider how it affects life on Earth. Experts at the International Passive House Conference outlined the responsibilities of the construction industry. Even if the necessary steps aren’t a legal requirement just yet, those involved must start thinking about how they can produce “Nearly Zero Energy Buildings”.

A Passive House Institute “Certified Passive House Tradesperson” qualification is already available. It is gaining popularity at the international level, as energy efficient construction gathers momentum.

Can we expect passive houses to become commonplace in Europe over the next few decades? It’s highly likely that we will.