Practical Considerations for Managing a Passivhaus Project

Gordon Shewan
With the UK Government legislating targets to achieve “Net Zero” by 2050 and devolved administrations setting even more challenging targets, local authorities and the public sector are exploring ways in which they will achieve this.

As outlined in the previous article of this series, Faithful+Gould’s Daniel Lockwood explored how using the Passivhaus Standard can help greatly reduce carbon emissions throughout the life of an asset. This article explores the practical consideration for managing a Passivhaus project.    

Appointing the Correct Team  

Although Passivhaus has been around for many years, there is a relatively low number of precedent projects in Scotland, particularly in the non-domestic setting. This means that the pool of consultant’s with Passivhaus experience for public sector clients to draw from may be limited.

This could lead to a desire to appoint practices from South of the Border. Especially as working remotely has become less of an issue following the experience of the Covid-19 lockdown. Getting the design quality is essential in Passivhaus and consultant’s without live experience should consider partnering with other practices which may be further afield but can contribute their specialist knowledge.

In order to show their commitment to Passivhaus in the long term, public sector clients will need to share the workload and “up-skill” the local market and not confine the workload to the small pool of consultants which can demonstrate Passivhaus experience. In practical terms this may be a project led by an architect well versed in Passivhaus who can impart their knowledge on the rest of the team who can then go on to deliver their own.   

Developing the Programme

When preparing programmes, benchmarking against previous projects is often the most suitable method. However, the nuances of Passivhaus means that additional time should be built in for specific tasks during the design and construction phase. For example, the Passivhaus certifier will require time at strategic points during the design phase to provide an initial check of the Passivhaus Planning Package (PHPP), drawings and specification to giving feedback on the likelihood of certification and any problems and risk areas. The earlier the certifier becomes involved in the project the greater chance that certification will be met first time around.

They will also require time to carry out full design assessment and thus create a PHPP which is suitable for certification prior to starting on site. Dynamic simulation modelling normally carried out in the by the M&E consultant in the later stages of pre-construction is also best pulled forward to happen sooner in order to support decision making by the Architect on design to achieve Passivhaus.

Timescales for construction should also be lengthened to take account of the emphasis on quality of workmanship to ensure things like airtightness, comprehensive testing and commissioning of the M&E systems and final Passivhaus strategy are working correctly in order to achieve certification – input from contractors will help to de-risk timescales early in the project.

Procurement and Tendering

When considering a procurement and tendering strategy it is worth noting that there will not be many contractors who will be able to demonstrate experience of delivering Passivhaus projects in Scotland. To keep competition and ‘upskill’ the industry, it is important that this should not preclude these contractors from tendering.

Many tier one contractors have realised that the principles of Passivhaus will likely form a major part in the construction of new buildings in the future. Tier ones are in the process of upskilling their design managers and site staff by completing certified Passivhaus designer and tradesperson training offered by the Passivhaus Trust, and often taking lessons learned from their counterparts down South. Difficulty comes with how to impart this knowledge on the subcontractors and tradespersons who will construct these buildings and avoid them pricing for unnecessary risk due to a lack of understanding.

For these reasons, and until the body of experience grows, consideration should be given to early contractor involvement during the pre-construction phase to allow for greater engagement with the supply chain. This will help set the expectations for quality of workmanship and offer the designers a forum to engage with subcontractors to explain some of the complex airtightness and thermal bridging detailing and afford the opportunity for subcontractors to offer their own solutions.

Setting the Budget

Based on recently completed non-domestic Passivhaus projects in the UK the additional capital cost can vary between 0-15% of an equivalent standard construction building however we should hope that as the supply chain become more familiar with the key principles of Passivhaus this will reduce to nil. In any case the increase in initial capital expenditure must be considered in conjunction with greatly reduced energy costs over the lifespan of the building. This topic will be explored further in the final article in this series.

Quality in Construction

Consideration should also be given to the level of on-site resource from supervisory roles such as the Clerk of Works or Technical Advisors. Providing a sensible resource to inspect the wall fabric, airtightness barriers and junction details etc. ensuring these are all being be constructed to the required standard prior to testing will prove invaluable. This also aligns to the industry wide agenda on improving quality.

Conclusion

Managing projects which are not “the norm” can prove challenging, however Passivhaus need not be complicated. Being conscious of where the project team may lack experience and supplementing this where necessary can prove invaluable. Allowing enough time to interrogate and simplify the design will also prove beneficial in the long run.

Faithful+Gould’s Edinburgh Project Management and Commercial Teams are currently delivering several Passivhaus schools projects. Presently in the design phase the team have enjoyed getting to grips with the nuances of Passivhaus, are gaining invaluable knowledge and experience which can be shared on future projects as our client’s collectively work towards a more sustainable built environment.

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