The Tree House is a customisable house-type, adaptable to the customer’s choice of three, four or five bedrooms – including a ‘bunkhouse’ option. It also offers a choice of relationships with the site’s lakeside, including a main living space set right on the water’s edge and a summerhouse with a shady courtyard garden-room. The design is buildable at a cost of £1,400/m2, producing a 190m2, 3-bed option for £280,000.
The design is conceived as a tree with many trunks, with twigs supporting a green canopy at roof level with shingle ‘leaf’ cladding. The rustic tree-trunk columns support the roof and floors and connect the interior to the outside by echoing both courtyard planting and external structure. The house is accessed from the roadside by a generous deck, leading you to a covered entrance that opens into the main, double-height living space via an energy-saving lobby. Two tree trunk columns rise dramatically to the ceiling as – bathed in daylight from the full-height lake-side glazing – you ascend the staircase to the first-floor kitchen and dining area, sharing the views out across the courtyard garden to the lake. A left turn takes you to a wing with guest and children’s bedrooms. A second flight of stairs will take you up to the master suite with bedroom, bathroom and private sitting space opening onto a roof terrace.
Access to the bedrooms is from an outside covered gallery with an external stair which can allow children and guests to come and go without passing through the main house. There is a certain drama in going outside on the way to bed! The bedroom wing encloses the garden whilst allowing glimpses of the waterside from the ‘public’ side of the house. The garden room between the family room and the summerhouse has trees planted on-grid which echo the structural features of the building and form part of the home’s passive design strategy – in summer, they provide shading to the glazed lakeside frontage of the building, whilst allowing sun through bare branches to contribute to the heating of the building in winter.
The optional summerhouse can be fully opened on both sides to allow views from the shady garden retreat to the lake. In winter, a log-burner makes a cosy place to be right by the water’s edge, whilst also offering an extra sleeping space when required. The access deck running through from the main entrance becomes a pontoon, allowing easy access for boats which can be stored in the ground level store of the main-building. The store room also contains a wood-pellet boiler, pellet hopper, hot water cylinder and mechanical ventilation equipment with easy access for maintenance and fuel delivery.
The passivhaus ‘fabric first’ design methodology results in a building that automatically moderates internal comfort and energy demands. The design has been optimised to maximise useful solar gain, but also includes features that prevent overheating in summer, such as trees, shading and blinds in the right places, and the windows and doors can be opened in summer to provide natural ventilation during the day and secure ventilation at night. The house has a large amount of insulation and has been detailed to eliminate thermal bridging and be easy to build to high levels of airtightness. The tree trunk structural frame is independent of the envelope of the building and non-structural external walls, windows and internal partitions are planned on a modular grid and can be arranged at will.