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The outlook for Passivhaus

Passivhaus is an energy-efficient building standard that has been around for over 25 years and is becoming increasingly popular in our sustainable era. Passivhaus buildings don't require any form of heating other than supply-air heating via their ventilation systems, and are built to the exacting standards developed by the Passivhaus Institute in Germany.

Passivhaus buildings use very little energy for heating or cooling, yet provide high levels of occupant comfort. The strict standards of construction and design of Passivhaus buildings are maintained via an exhaustive system of quality assurance. Achieving Passivhaus standards within the UK means that buildings need:

- extremely high levels of insulation
- an airtight fabric for the building
- very high performance windows which feature an insulated frame
- use of 'thermal bridge free' methodology for construction
- mechanical ventilation systems which feature high efficiency heat recovery
- design which uses the Passivhaus Planning Package

Passivhaus projects need to be certified by registered Passivhaus certifiers if they wish to achieve the required levels of quality assurance, although non certified Passivhaus projects will still be able to claim Passivhaus status as long as they meet all required standards. A Passivhaus building achieves 75% cuts to space heating requirements.

The Royal Institute of British Architects (RIBA) annual regional awards shortlist has recently been published and three Passivhaus projects have made the list. These are The Deerings, a detached home in Harpenden, Hope View House in Worcestershire, and the Kellog College Hub, which is a development for Oxford University providing informal, relaxation areas for staff and students.

To date the uptake of Passivhaus design within the UK housing market has been slow, but Government targets for achieving an 80% reduction in carbon and the successful performance of existing Passivhaus structures are creating greater interest in this form of architecture. It's also possible to apply Passivhaus standards to retrofits of buildings to achieve the same levels of carbon savings. A recent summit led by the Urban Land Institute (ULI) has highlighted some of the successes and challenges facing Passivhaus developers.

Findings of the Passivhaus summit

The roundtable summit convened by ULI was attended by a variety of UK councils and organisations with experience of building Passivhaus designs, and all of them cited their reasons for use of Passivhaus were due to considerations of the built environment and the long term benefits for investment and occupiers. All the organisations highlighted that lack of industry knowledge and skills, coupled with a lack of available materials and planning limitations were challenges to their projects. The present planning environment does not recognise the non-conventional insulations, ventilation or heating used within Passivhaus architecture, so it can take added time to gain building approvals.

Benefits of Passivhaus

Some of the benefits offered by Passivhaus include:

- cuts to maintenance costs, as there are no heating appliances to consider
- improvements to the quality of indoor air
- higher quality of accommodation
- long term reductions to carbon
- benefits to health and comfort
- better sound quality

At present, evidence of the full range of benefits offered by Passivhaus is limited and hard to measure, due to the fact that most buildings are fairly recent.

Limitations and challenges of Passivhaus

Lack of market knowledge of the Passivhaus methodology is a challenge for any developer. Further challenges include supply chain limitations and the scale of developments. The small scale of most UK developments makes it difficult to address issues in upskilling workers in the construction industry or handling inefficiencies in supply chains. One recent Passivhaus development saw just 4% of the scheme's homes taking up a total 40% of the build time. However, once the learning curve for building these homes had been achieved the remainder of the properties took far less building time. Building costs for Passivhaus are currently higher than those for traditional buildings, but, it was recognised that this could change when larger scale developments and whole life costs are considered.

It is understood that Passivhaus is not a well recognised methodology and a good deal of marketing needs to be conducted to raise its profile within the construction industry and amongst consumers.

UK examples of Passivhaus

Some of the Passivhaus developments in the UK include:

- Norwich Council's 227 unit development of social housing and privately rented properties which was completed in May 2017.
- Future Home, a development in Elephant Park, London from Lendlease which will provide 15 Passivhaus terraced dwellings.
- Bridges Sustainable Property Fund developed their first Passivhaus care home in 2010 and the lessons learnt from Juniper House in Brackley have encouraged them to embark on a second scheme in Bristol.
- Wilkinson Primary School in Wolverhampton which was the winner of the 2015 Passivhaus Award.
- Brookway and Bennett Square in Exeter https://www.alsecco.co.uk/_images/_downloads/passivhaus-scheme-exeter.pdf, where Alsecco provided the external wall insulation system.

International examples of Passivhaus developments

There are a wide range of Passivhaus buildings around the globe, some of these are:

- the world's first Passivhaus hospital which is currently being constructed in the district of Hoechst in Frankfurt.
- the Raiffeisen Tower in Vienna, the first high rise Passivhaus building
- a 26-storey high rise student accommodation in New York, which is home to 350 students
- the Bolueta building in Bilbao, Spain
- 1400 Alberni in Vancouver, Canada which is the tallest Passivhaus building in the world.

At this moment, China is taking the lead in the construction of Passivhaus projects and will be the venue for the next Passivhaus Conference to be held in 2019.

The outlook for Passivhaus is good, both in the UK and globally, as more and more developers form the opinion that the construction and provision of homes and buildings featuring greater levels of energy efficiency will prove beneficial to society. The additional benefits to occupants' health and happiness, and carbon reductions are long lasting and provide more persuasive reasons to retrofit properties and develop new Passivhaus structures.

The Passivhaus Trust provides more information on the sustainability and benefits of Passivhaus construction in the UK and is an independent non profit making organisation which provides support and leadership on the adoption of Passivhaus methodologies.