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Passivhaus Retrofit Admiral's Hard in Plymouth, Devon, UK

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Conversion of a first floor flat into an EnerPHit office, and extensive retrofit of the whole building, which includes  a ground floor shop. 

Situated on the Stonehouse peninsula, by the banks of the River Tamar, Number 3 Admirals Hard was built in the 1960s and comprises a shop on the ground floor and WARM's office, originally a flat, on the first floor. The extensive retrofit works included external wall insulation, cavity wall fill, floor insulation (between the office and the shop), roof insulation at rafter level, high levels of air tightness and high-performance triple-glazed windows, as well as a self-balancing MVHR system.


The first floor is EnerPHit certified. The shop has triple glazed windows and external insulation, but requires floor insulation and ventilation which will be installed at the next break in the lease. In terms of energy demand , the project reached a staggering Primary Energy Demand: 115 kWh/m2a and Space Heating Demand: 16 kWh/m2a. In terms of airtightness, the initial airtightness test failed to give a result as the standard domestic air testing fan was unable to reach 50 Pascals. The air testing equipment remain on site and tests were carried out each week.  This way there was a closely monitoring progress and were able identify leaks as they went along. This was one of the biggest successes of the project.


The team implemented an improvement in the heating balance by simplifying the window design & slight reductions in the extent of glazing: this was possible because the team chose to use the occasion of MVHR installation as a way to reduce as many openings as possible.


There were interesting approaches also with the building works. The team worked closely with the builders to ensure they understood everything necessary to achieve the target. 


The building is semi-detached, with the neighbouring property slightly offset which lead to some complicated detailing around the party wall. A layer of internal insulation was added on the party wall, which was thicker where it was adjacent to the neighbours unheated attic space.


Designers also decided to insulate at roof level to give an attic for storage and possible expansion, but more importantly, to give enough space for a decent MVHR installation, always a problem on retrofits.


Further Information here.

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