Passivhaus Affiliate

Passivhaus Masterclass aims high

The Saint-Gobain Innovation Centre on Great Portland Street played host at the end of April to a fascinating day of presentations and workshop exercises exploring the details and possibilities of Passivhaus in high-rise buildings.

Tomás O’Leary and Jessica Grove-Smith, two superstars of the international Passivhaus world, travelled in from the Passive House Academy in Ireland and the Passivhaus Institut in Darmstadt respectively to give this masterclass its first outing. The whole programme, which they developed between them by long-range webinar collaboration, was packed with detail and engagingly presented.

Tomas O'Leary and Jessica Grove-Smith

Aiming high

Tall buildings have an advantage out of the starting blocks when aiming for Passivhaus certification because of their basic form: the low ratio of surface area to volume minimises the opportunities for heat loss. But by contrast, the opportunities for heat loss from the tiniest construction details are multiplied in accordance with the sheer scale of the build. Cornell Tower, for example, contains just short of 8km of window spacer bars, and 5.9km of window thermal connections.

Tomas O'LearyTomás O'Leary

Case studies – The House at Cornell Tech New York, and Bolueta Passivhaus Tower Bilbao

The House at Cornell Tech was one of two case studies guiding the overview that began the day. This tower for Cornell Tech is a 26 storey, 87m high student housing block in New York. The second exemplar was the Bolueta building in Bilbao, 172 apartments in a low energy district destined for a mix of sale and social rent. Both were completed and certified within the last year, with Cornell Tower holding the prize for the tallest Passivhaus in the world only briefly, before Bolueta pipped it by 2 storeys - and only 1 metre.

House at Cornell TechBolueta Passivhausleft: The House at Cornell Tech; right: Bolueta Passivhaus

While close in height, these two towers took interestingly different strategies to handle the challenges particular to high rise: should the ventilation be centralised or decentralised? Should the airtightness layer enclose the whole building, or wrap individual units, necessitating each unit to be tested individually?

Jessica Grove-SmithJessica Grove-Smith

Both faced interesting and sometimes unexpected difficulties, whether to do with meeting Passivhaus standard - welding prefab panels on the Cornell Tower was found to melt the airtightness membranes! - or not… located on an island, this building needed all its materials and equipment to be shipped in on barges. For Bolueta, we heard about the size of the task of calculating shading for every window individually. But this should soon become easier - Jessica was able to give us some advance news of the next iteration of DesignPH, currently in the works, which is incorporating in-built shading calculations to enable PHPP autofill.

 

Participants working together at the Passivhaus Trust High Rise MasterclassParticipants working together

Getting involved

The afternoon saw attendees taking active participation in proceedings, as they worked together to solve a choice of a building envelope or a ventilation problem on a sample project.

Contributions from the audience were stimulating throughout, with, for example, a participant from ATTMA pointing out the challenges to airtightness testing that are introduced by the subtle but significant changes in air pressure found at different storeys in a high-rise.

The day offered plenty of opportunities for participants to share their wide range of experiences and knowledge, with discussions continuing after the official close of the day in a local pub.

 

The High Rise Passivhaus masterclass was very useful.  Large buildings tend towards a good form factor and it was surprising just how high some of the U-values can be in high-rise Passivhaus.  Clearly the challenge was around airtightness with robust simple replicable details and efficient large scale systems.  The solutions used in the contrasting New York and Bilbao case studies were well explained by the trainers."

Mischa Hewitt, Earthwise 

 

Jessica Grove-SmithJessica Grove-Smith

Challenges remain

Challenges remain, not least in shifting the viewpoint of developers and clients to embrace the possibility of the Passivhaus standard for tall buildings.

The trend for cliffs of glass in high rise doesn’t make things easy, with one audience member having had the experience of a developer being put off the Passivhaus route because of the design restrictions it seems to impose. But Jessica Grove-Smith, later in the afternoon, gave two examples of fully glazed Passivhaus design, one complete, and one proven to be feasible in a detailed study (not published). So while difficult, and a brake on robustness, 100% glazing is proven to be possible.

If resisting the temptation to go all out with the windows, as another audience member pointed out, constraints can be an exciting stimulus, architecturally speaking! And it can be cost effective to reduce glazing – which is often the most expensive part of façade – as in Cornell Tower, where the window to wall ratio is less than a quarter.

 

Coming up next

And that brings us to the next Passivhaus Trust MASTERCLASS: Design Optimisation on 27 June, now taking bookings. Find out how optimisation can integrate cost efficiency with energy performance and design freedom, with Sally Godber of WARM: Low Energy Building Practice and Nick Grant of Elemental Solutions.

More information and booking details here.

 

Further information

MASTERCLASS: Design Optimisation

A selection of images can be viewed on the PHT flickr account. All image credits © Passivhaus Trust

22nd May 2018


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