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Lime Tree Passivhaus

Location: Swaffham, Norfolk
Completion Status: Completed July 2015 Occupancy: Occupied since August 2015
Architect: Parsons + Whittley Architects Consultant: Passivhaus Consultant: Parsons + Whittley Architects, Mechanical: Alan Clarke, Engineer: Plandescil Consulting Engineers, Certifier: Mead Energy & Architectural Design Ltd
Contractor: Grocott & Murfitt Ltd Client: Private
Certification: August 2015 Certifier: MEAD
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Lime Tree Passivhaus, Parsons + Whittley. UK Passivhaus Awards 2016

Lime Tree Passivhaus is a small retirement bungalow on a garden plot for private clients. The design is a response to a number of key constraints including the tight site and the presence of a protected Lime tree. The curved form of the dwelling, centred around the Lime tree, allows the building to make the best use of the site and positions the tree as the central focus for both the building and the garden. The tree also serves to provide summer shading to the SW elevation ensuring an additional control against overheating. The curved monopitch roof contains an extra wide gutter and leaf protection to ensure that leaf fall doesn’t become a problem. 

The tall ‘exterior’ of the curve is constructed in brick to match the context of the adjacent development and to provide a strong shelter to the private side of the building, which in turn is clad in vertical larch timber boarding to reflect the arboreal nature of the garden. The curve finishes with a south facing gable fully glazed to illuminate the sitting room with large overhangs and flank walls to offer protection against overheating.

The building is constructed off a reinforced concrete raft supported on mini piles, carefully threaded past remaining archaeology, to support a traditional cavity wall construction and radial ‘I’ beam timber rafters. The insulation is provided by blown EPS platinum beads in both the walls and the roof, whilst the floor has 200mm of PIR insulation supporting a floating finish.

Constructed by Grocott and Murfitt, a first time Passivhaus contractor the construction went without a hitch thanks to their positive and proactive approach. Direct and sub contract labour trained as certified tradespersons and good communication with all of the construction team ensured a successful outcome first time.

Further Information

Parsons + Whittley Architects

Project Factfile 

Summary Card

UK Passivhaus Awards 2016 Presentation coming soon

Podcast: Building a home in your garden for your retirement – with Robert Young

UK Passivhaus Awards 2016 - Rural Finalist logoBack to 2016 UK Passivhaus Awards Shortlist


As a small garden plot, the presence of a protected lime tree was a significant constraint on the

available space, which drove the eventual arc-shaped plan of the building.


Recognising that the protected tree could provide shade in the summer but allow sunlight through in

winter; the opportunity for a large south-facing glazed wall for the sitting room and the client’s

request for a low energy building for their retirement, all led to the early adoption of the Passivhaus



However the site wasn’t finished with us yet. Archaeology and ground conditions combined to

require a difficult mini-piled raft, designed to avoid both archaeology and the root protection zone.

The raft solution presented further design challenges in respect of thermal bridge avoidance.


A construction based on aerated concrete blocks in a cavity wall construction ensured that no

significant new skills were necessary. The roof was constructed using timber I beams in a radial

pattern and the wall plate facetted and joined to avoid the need for curved beams and lintels. The

walls and roof void were filled with blown EPS beads to ensure a continuous insulation placement

with no gaps.


A lack of alternative fuels led to the use of an Air Source Heat Pump and radiators.

External finishes include a ‘soft’ side of timber cladding on the south and west facing the lime tree

and a ‘hard’ side consisting of a robust brickwork external wall on the north and east, emphasising

the protective nature of the proposal.


As a first time Passivhaus build for the main contractor, he arranged specialist training and

tradesperson courses for all operatives and sub-contractors. Good planning and close attention to

detail, along with a collaborative approach throughout the construction meant that this complex and

complicated project was completed on time and within budget.