Diary Entry No.22 - Certification and Completion

Today the Crawfordsburn passive house certification became official as we received the documentation from MosArt! The dwelling is now a certified Passivhaus building. We previously discussed the extensive checklist of data we had to provide to the Passivhaus Institut for certification, including details of all the junctions, Therm modelling, photographic evidence, product certificates proving U-values and performance, detailed MVHR specification, documentation of airtightness and so on. The certifiers also needed to double-check which materials we actually used in the end to insure this hadn’t changed as the construction progressed.

The following photographs illustrate the official Passivhaus plaque which is now installed on the front elevation of the dwelling and the MosArt certificate.

The plaque proving it is a Certified Passive House

The plaque proving it is a Certified Passive House

The Passive House Certification certificate

The Passive House Certification certificate

Achieving the requirements

We were surprised by how easy, with careful planning and considered construction, it has been to achieve the Passivhaus criteria. We achieved the airtightness requirement on the second attempt with a few days spent taping and adjusting window and door components to meet the second test; our final figure was 0.585 air changes per hour (the criteria states 0.6 air changes per hour). Again we overachieved with the space heating requirement with 14kWh/m2/annum (the criteria states 15kWh/m2/annum).

Since completion we all agree that the requirements for Passivhaus construction are more substantial than those for traditional construction but they all make sense. We cannot find any disadvantages of Passivhaus except for perhaps the initial cost but as we discussed this is more than regained as a result of the minimal utility bills.


It has been a welcome outcome that we have remained on budget throughout the build. In total the only extras incurred were £300 of unforeseen works. Admittedly there were other additions  but these were made on request of the clients and were not part of the original tender price.

As the Passivhaus approach is a very new design and building technique in Northern Ireland we put a lot of time and effort into pre build research. The costs for the research stage were considerable and have been mostly absorbed by Paul McAlister Architects as we viewed this project as a learning process for our practice as well.

Overall success and the team

The success of the Crawfordsburn passive house is all down to the collective team. Particularly the construction professionals on site as they have made it happen and really took on board what standards needed to be achieved and why. It was essential that those on site knew every facet of the build and had an understanding, for example, of why it was so important to be careful to avoid puncturing the airtightness barrier.

The connection between trades and design knowledge at every stage of the build was critical and the main contractor Kevin Mulligan (Baylands Construction Ltd) recognised this from the very beginning. The relationship amongst the entire team has been vital; it all comes down to a good working partnership. Our clients Paddy and Helen have been brilliant, staying involved and following every stage of the design and build with great interest.

It is apparent that the Passivhaus approach translates into high quality design and construction. This is why we feel the Passivhaus certification is so important for quality assurance; it allows us to identify buildings which have truly strived to achieve the required criteria.

We, at Paul McAlister Architects, actively involve ourselves within the world of sustainable architecture.  We regularly attend lectures in order to maintain our knowledge; we attended the Eco Show at Earls Court last year and spoke with Dr Wolfgang Feist, founder of the Passivhaus Institut in Germany.

Coupled with extensive experience our practice is also a member of the Passivhaus Buildings Trust, a new organisation established by the AECB, committed to assisting with the delivery of buildings that perform as intended. The practice is also accredited with the ISO 14001:2008, a standard focused on environmental management systems.

We try our best to play a part in promoting Passivhaus design throughout the UK and Ireland.

For us, it has been an honour to be involved in such an innovative build project; we have enjoyed not only the practice of the design and construction but also the experience of writing the Passivhaus diaries.

We hope that this will not be the end of our diaries as we have recently received funding to measure the energy usage of the passive house now that it is occupied. This will determine and record whether it does indeed perform as predicted by the PHPP software.

South elevation

South elevation