Farm Annexe, Passivhaus Design, Axminster, Devon

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Project Description

Contemporary House Concept Design using Passivhaus Standards. Axminster, Devon.

Following a visit to see us at the Grand Designs Exhibition in London, our client approached WDA to design a new replacement contemporary dwelling on their site in rural Devon. The driving concept for the project focuses on a high-performance construction, utilising principles of Passivhaus design

The house is designed to be simple in form and efficient with space. A key principle of Passivhaus design is to minimise a building’s surface area as this can achieve good energy efficiency (larger building envelope = larger heat loss). It is orientated with an east-west axis so the principle façade maximises the benefit from solar gain throughout the day. To avoid this elevation overheating during the summer months, a first floor balcony projects beyond the building line to provide solar shading to the internal spaces. The balcony structure is thermally separated from the warm building envelope to avoid any cold bridging between external and internal structures.

The roof overhangs the first floor balcony to provide solar shading to the bedroom spaces, along with sliding louvre screens on the principal elevation which occupants can adjust as the sun moves across the house throughout the day.    

Mechanical ventilation and heat recovery systems (MVHR) are also an important part of the building design so early consideration and allowance needs to be given to efficient service routes to make sure the building functions as efficiently as possible (generally higher than 75%). 

Facing materials for the build will utilise local vernacular materials such as flint for the ground floor walls with vertical hit and miss timber cladding completing the light weight first floor construction.