Passivhaus for contractors: Building services and sequencing!
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December 8, 2016

Passivhaus for contractors: Building services and sequencing!

Building services in passivhaus: ventilation, controls and indoor air quality

Indoor air quality, which should be exceptionally good in Passivhaus buildings, will be spoilt if ductwork, mechanical ventilation with heat recovery (MVHR) and control systems are not adequately protected during their storage and installation. It is essential that all ductwork, MVHR units, attenuators, filters and control systems are stored in a dry, dust free environment. For this
reason it is advisable to ensure that open ends of ductwork and MVHR spigots are kept completely sealed until they are fully installed. Any dust or dirt entering the ductwork or MVHR systems will need to be removed before commissioning and it is far easier and less costly to avoid this situation altogether.

Sequencing and forward planning: for air tightness and thermal bridge free junctions

As with any construction programme, implementing the Passivhaus standard on-site requires that jobs are sequenced correctly. Passivhaus however has some specific requirements in order to achieve the required level of air tightness and thermal bridge free junctions. Ensuring an airtightness of 0.6 ac/h @n50 requires a continuous air barrier. An airtight construction of this standard cannot be achieved through last minute attention to detail and expanding foam alone!

Sequencing is about forward planning – so that complex and interdependent tasks are scheduled in the most efficient manner and materials are delivered to site when needed. The sequencing of a Passivhaus build requires a detailed understanding of the assembly process as well as critical stages in the build. A series of briefing meetings between the designers and contractors will be needed to ensure that the correct sequencing of key stages is clearly understood at the outset. The clerk of works and site manager should be present during these briefings. Project
management charts should highlight critical stages in the project sequencing, including any special ordering or preparatory requirements.

Tool box talks and site briefings should be scheduled prior to critical stages in the build programme. Detailed production drawings annotating any special sequencing and fixing procedures should be displayed on-site so that site operatives are able to verify detailed installation procedures.

Excerpt from “Passivhaus primer: Contractor’s guide. So you’ve been asked to build a Passivhaus?” by BRE.

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