Zehnder takes part in Manchester residential building refurb

The refurbishment of 32 flats and 6 bungalows at Erneley Close, Longsight, Manchester was part of Eastlands Homes’ £180 million decent homes programme and is the UK’s first large-scale Passive House retrofit. The objective was to achieve the PassivHaus EnerPHit Standard of low carbon energy efficiency.

The main problem encountered was leakage into the party walls and onwards to other maisonettes, the roof and underfloor voids. The volumes of air travelling through the party walls was far in excess of original expectations mainly due to the very poor build quality of the brickwork and the use throughout of paramount partitioning, which again was a source of major air leakage into the party walls.

Multiple means were used to address the issues including external parging, airtight taping, airtight foam, stitch drilling, spray foaming and airtight and fireproof composite sealing of vertical and horizontal service ducts through party and communal walls.

Ongoing tests and training were carried out under the supervision of a trained Air Tightness Champion. There was also an issue with the size of the glazing in both blocks that needed to be reduced. If left in their original sizes, it may have caused an overheating issue on the south facing elevations.

Designing the MVHR systems to fit into the maisonettes initially proved challenging for the team. Green Building Store’s MVHR department worked with Passivhaus mechanical & electrical expert Alan Clarke to design a system to fit the space available.

The Zehnder ComfoAir 160 unit was chosen because of its compact form and performance characteristics, which enabled it to be located on the bathroom wall behind the bath. Green Building Store and Alan Clarke carefully designed and attenuated the system to ensure that the system operates quietly and with maximum efficiency.

To ensure extra quality control, Green Building Store’s MVHR Technical Manager Andrew Farr gave a toolbox talk to ventilation installers on the project and he and Steve Clarke (Services Engineer at Green Building Store) commissioned the units after installation.

Phil Summers from R-Gen Developments said:

“As a developer it was vital we installed the most technically effective MVHR given the constraints of working within an existing building. Each flat now has a great internal air quality with residents amazed at how quiet the MVHR system actually is in performance.”