A passive revolution?

Existing buildings consume between 40 percent and 50 percent of all energy used. Could the German concept of "Passivhaus" be the solution to ensure that housing becomes sustainable?

Time to be passive

From the spark that lit prehistoric man’s first fire to the flaming forges of the industrial revolution; from the wheels that drove agriculture across the world to the robots transforming the way we work and live; and from the stylus scrawled across papyrus to the 2.5 quintillion bytes of data transmitted across the Internet every single day – ours is a species that has always innovated.Through trial and error, our scientists, entrepreneurs and leaders strive forward, seeking new ways to improve our society. Advances in medicine, sanitation and dietary knowledge have extended life expectancy from just 25 years in Roman times to over 80 in many developed nations today. Such progress across the many fields of human endeavour is not only inevitable but for the most part highly desirable.

If there is one way in which human social progress has come at a cost, however, it is environmentally. And yet, in the face of climate change and mass extinction, innovation too holds the answer, from clean energy generation to green technology and sustainable development. As always when it comes to innovation, what starts as a barely recognised concept when fully realised by society has the power to change the world. And in the field of design, one such concept is about to make a big difference.

"That’s the way we are going. Essentially, everything will be Passivhaus it is just a question of how long it will take us to get there."

Asif Din, sustainability director at global architecture and design firm Perkins & Will

Passive is not normally a word you would associate with innovation. But the German concept of Passivhaus is seen by some as the future of sustainable housing. Indeed, many would argue the passive home standard has set a new bar for architects and designers creating environmentally friendly buildings. However, despite the idea being around since the 1990s, the number of completed passive homes, so called because they need little heating or cooling, remains small. To date, only around 60,000 are in use worldwide, mostly in European countries.

Leaking heat like sieves

So, what is Passivhaus exactly and is the business model scalable? Literally "passive house" in English, the concept refers to buildings created to rigorous energy efficient design standards so that they maintain an almost constant temperature. Unlike carbon neutral buildings, which aim to offset energy use through energy efficiency and clean energy generation, Passivhaus buildings aim not to use as much energy in the first place by being sealed against the elements. 

Most buildings leak heat like a sieve. It is no wonder then that that the built environment is responsible for almost 40% of energy consumption in the European Union. Passivhaus relies on innovative design to keep buildings at optimal temperatures and save energy. The buildings use superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings. They can therefore easily be powered by renewable energy sources such as solar panels and heat pumps. Passivhaus buildings also use a heat recovery ventilation system which supplies a constant supply of fresh heated or cooled air. The heat in the warm air being extracted is recovered and used to warm the fresh air coming into the building.

European turning passive

Investors are taking the concept more seriously as the property sector is under immense pressure to produce more environmentally friendly buildings. Several of the world’s biggest cities have agreed to make all buildings carbon-neutral by 2050 as part of the 2015 Paris Climate Agreement. A closer look at European housing markets shows that Passivhaus could eventually transform the way we think about our homes. There are only currently 30,000 built Passivhaus buildings in Europe, of which some 1,600 are certified, according to the International Passive House Association. But more sophisticated methods of offsite construction could change this. To date, the majority of Passivhaus buildings have been completed in Germany in places such as Hanover, Heidelberg and Frankfurt. The city of Heidelberg made the Passivhaus standard mandatory for its entire Bahnstadt development, making it one of the largest Passivhaus sites in the world. Established on the site of a former freight yard, the Bahnstadt area will eventually provide housing for 5,500 people as well as office space for 7,000.

Elsewhere in Europe, the world’s tallest Passivhaus is based in the Bolueta neighbourhood in Bilbao, Spain. At 289 feet (88m) and 32 storeys, it is the world's tallest building certified under the standard in 2018. Brussels now has over one million square metres of passive buildings. In 2015, Passivhaus became part of the official construction regulation, making it the reference standard for all new builds and deep retrofits. Other notable European Passivhaus buildings include the Raiffeisen Tower in Vienna, and the retrofitted tower block in Bugginger Strasse in Freiburg, Germany, the first high-rise building in the world to achieve the Passivhaus standard.

The concept is also gaining popularity in the UK. A sustainability head at a global asset manager said his firm was mulling launching a residential Passivhaus-focused fund in the UK. “We are learning how to apply the Passivhaus concept in Germany to the UK setting. We all have global environmental commitments. We can’t carry on business as usual if we are to hit longer term targets. The regulations are pushing us that way and our investors expect it.”

They pointed out that Passivhaus would lead to significant cost-savings, both for themselves as the landlord and the tenant. “Charging an all-in rent allows us to create more energy efficient buildings and get the benefit of using less energy. All the supply will come through us. The tenant will get the benefit of economies of scale and we will get the benefit of operational efficiency.” UK councils are also exploring ways of ramping up Passivhaus construction, both to save energy and costs. The City of York Council plans to build more than 600 Passivhaus homes during the next five years with heating bills of just £60 a year for residents, according to reports. Exeter City Council has already developed more than 100 Passivhaus homes. 

Pre-empting regulations

Against a backdrop of rising demand, UK architecture practices are looking at ramping up their production of Passivhaus buildings. Chris Morgan of Scotland’s John Gilbert Architects said his firm had been granted a Knowledge Transfer Partnership, allowing it to explore how to modularise the Passivhaus design process. The KTP scheme is designed to help businesses in the UK to innovate and grow by linking them with an academic. Morgan said: “We have hundreds of Passivhaus buildings on our books and we are working on developing and improving a modular process which should make our processes more cost effective.”

Asif Din, sustainability director at global architecture and design firm Perkins & Will said that going forward, Passivhaus will become much more commonplace. “That’s the way we are going. Essentially, everything will be Passivhaus it is just a question of how long it will take us to get there.”

So while we all recognise the innovations of the past, it is important to consider the ideas that are still evolving that could eventually shape our society for years to come. In the property sector, Passivhaus looks set to do just that and ultimately play an important role in reducing global carbon emissions.