Broadacres
A dwelling designed on principles of breathable structure and passive ventilation.
Hemp in practice: hemp lime walls
The brief was for a replacement home on this stunning rural plot. The home was to be highly sustainable, cheap to run and should capture the stunning views to the North of the site.
The result is a highly contemporary and sustainable building of two sides. On approach the building seems modest in scale, you are greeted by a low veranda with balcony above and zinc clad roofs that rise away from you. This side of the dwelling protects from the sun while allowing transition in and out of the dwelling along the southern elevation. However, from the north, the building is far more prominent. It presents high white rendered walls and large glazed panels to the landscape. This side of the dwelling is all about capturing those northerly views.
The dwelling is efficiently heated with a Ground Source Heat Pump, and ventilated in a passive manner using stack ventilation and Earth Pipes. Passive stack vents are located in all wet rooms, the kitchen and utility and run vertically up and out through the roof. The natural draw created ensures that air is extracted from these spaces. This negative air pressure draws in air from the internal inlets. Inlets are located in all other habitable spaces ensuring a movement of air from habitable spaces to wet spaces and as such promoting moisture and smell removal from the dwelling. The inlets draw in air through earth pipes. These earth pipes run 1.5m underground to an inlet chamber 30m from the dwelling. During the airs’ passage through the earth pipes it gains the natural stable temperature of the earth at this depth (11deg). This ensures that air being brought in during the summer is gently cooled while air brought in during the winter is warmed, reducing the resulting demand on heating and cooling systems.
The building envelope is fully breathable and made completely of natural materials. An untreated timber frame is encased in a thick wall of hemp-lime. The hemp-lime provides racking strength, insulation and thermal mass. This is rendered externally and plastered internally with lime. The result is an air tight but fully breathable building envelope. The walls allow the natural movement of water vapour through them from inside to out, avoiding the problem of internal moisture build-up in modern construction. The thermal mass also help regulate temperature variations. As such the result is a heathy and comfortable living space.
In addition all materials, including the paints, have zero VOCs and the house is designed with lifetime home principles
