Chalky Talkie
September 18, 2015
As part of West Dorset EcoHomes Open House Event last weekend my parents opened Chalk Wall House to members of the public. Well over 50 people attended and we conducted tours of the house and described to people the process of building the rammed earth (Chalk) walls with material excavated from the site. This was all part of a strategy to make the building built both 'out of site' and out of sight. A strategic approach to planning constraints leading to an innovative technological solution yielding practical, economic and spatial benefits. We worked on the project with the brilliant Integral Engineering Design from Bath and testing at the University of Bath by Professor Peter Walker.
The 2 different types of construction we used were talked about from within the courtyard garden. The South and East facing inner courtyard is constructed from a lighter weight, highly insulated timber frame and clad with Cedar Shingles to reflect the beach hedge that separates the new house from the former residence beyond. All of the timber and plywood shuttering used to make the formwork for the rammed chalk was recycled to form the external wall, floor and roof structures. The glu-laminated beams are organised on a 2.40m / 8ft grid to minimise cutting of sheet materials and wastage. Only 1 small skip was used for the entire build.
Inside, lots of people were keen to hear about the heating strategy and technologies used in the house. A Windhager FireWin wood pellet boiler provides heating and hot water for the house - this is a highly efficient wood gasification boiler producing very little ash and fed by a 10kg bag of pellets per day (approximately). The government currently run a Renewable Heat Incentive (RHI) grant which means the pellets are effectively free for several years. An 8Kw system supplies the underfloor heating to the Ground floor, whilst small radiators to the upper level prevent all the heat from the ground floating up into the double height living space by creating a cushion of warm air at the upper level. Solar thermal panels on the roof provide nearly all of the hot water requirements between April and September. An MVHR - Mechanical Ventilation with Heat Recovery system provides pre-warmed fresh air to all of the living and bedroom spaces, whilst it extracts from all of the warm wet areas (kitchen, bathrooms etc). This is essential in an airtight house, though is often turned off during the summer so long as the windows are all open!
