Regenerative Design, Integrated Permaculture Landscape and Passivhaus Principles in Devon
The project at Sherwood is an integrated Permaculture design for a new build Passivhaus Certified building with an integrated landscape design that provides the Client with their energy, food, water and shelter in a way that works with and enhances the natural environment.
The design demonstrates how people can be designed into the ecology of a site so that they become part of the biological systems that make the site function. When humans are able to intentionally participate as part of nature, actively co-evolving the whole system, we call this Regenerative Design.
Landscape Design Strategies
The landscape design has been based around Permaculture zoning, reflecting the frequency of use and placing design elements in the landscape so that they maximise beneficial relationships.
Key integrated landscape strategies include:
Zone 0 – new build healthy building designed to Passivhaus standards – see over
Zone 1 – the landscape immediately around the building features:
- inside outside spaces include conservatory for solar gain and planting and
- covered areas for outside use when weather protection is needed
- sun terrace from house for amenity use and access to gardens
- kitchen garden terrace including raised bed herbs, salad and vegetables
- terrace fruit and dwarf rootstock espalier fruiting trees, some with movable cloches
- terrace aquaculture ponds – taking key point surface water from adjacent land, rainwater overspill from the rain water collection system and grey water system; used as irrigation for terraces; reflects sunlight into house
- detached garage and poly-tunnel and potting shed for extended season planting and seedlings for site
Zone 2 / 3 – the main areas for fruit and nut production including:
- edible forest garden
- bark pit and reed bed system for harvesting nutrients for growing green manure
- large aquaculture pond – edible aquatic species and natural swimming pool fed from terrace aquaculture ponds
- access way to other zones and for moving harvested produce
Zone 4 – less intensive use areas including:
- wildlife pond – large body of water to link reed bed system and aquaculture system
- woodland edge planting including edible fungi areas
- woodland coppicing along ex railway track for systematic fuel and craft materials harvesting and running track!
Zone 5 – wildlife area where human interference is reduced to a minimum and learning from observation is possible e.g. natural regeneration.
Building design strategies - Zone 0 Passivhaus
The new two storey building replaces an existing single storey construction, the quality of which was beyond refurbishment. The new building has been design to be a Passivhaus certified low energy building. The building will be dug into the south facing slope with a curved turf roof so as to maximise solar gains and blend into the immediate surroundings. The design features a double heighted living space, forming a tower.
Whilst contemporary in its design, the materials and detailing used reflect local traditions. Natural materials have been specified throughout such as timber shingles, a green roof construction, timber windows and doors, untreated timber cladding and stone facing for the external material of the new building.
Key Zone 0 strategies include:
Building Biology - healthy building design to Building Biology principles featuring: non toxic materials used throughout, design out dust mite habitats, minimise Electo-Magnetic Radiation through wiring specification and design (radial wiring with EMR dampening switching), high levels of air quality, thermal comfort and daylight levels, potable water filtration and cleaning system.
Passivhaus - low energy design to Passivhaus Certified standards resulting in high thermal comfort levels, minimal CO2 emissions and greatly reduced energy consumption.
Renewable Energy - the remaining C02 emissions are to be offset by onsite renewable technology to make this home zero carbon.
Zone 0 design features include:
Contemporary - a contemporary dwelling that merges with its surrounding landscape and at the same time maximises natural day light and views.
Thermal Mass - inclusion of thermal mass is provided in the load bearing ground floor construction using solid internal walls and floor slabs. Thermal mass reduces internal temperature fluctuations and helps reduce energy use.
Super Insulation - walls to achieve high insulation levels and a U value no greater than 0.15W/m²K. An insulated roof construction achieves a U value no greater than 0.10W/m²K and an insulated floor construction also achieves no greater than 0.10W/m²K. All windows and doors are to be high performance with timber frames achieving a minimum U value of 0.85W/m²K. In combination, these high insulation values minimise heat loss through the building fabric and significantly reduce energy use.
Minimal Thermal Bridging - ensuring continuity of the insulation around the building through careful design, reduces heat loss and energy use and also prevents mould growth by eliminating cold spots.
Mechanical Ventilation with High Efficiency Heat Recovery – minimising ventilation heat losses through controlled ventilation, ensuring better indoor air quality and reduced heating requirements by retaining energy from exhaust air.
High Levels of Air Tightness – draught-proofing and sealing all parts of the construction beyond best practice levels aims to achieve 0.6 air changes per hour and further reduces heat loss, therefore further reducing energy use.
Daylight Design – is maximised in all spaces and habitable rooms where possible to reduce reliance on artificial light and utilize solar gain, which supplements internal heating levels and again reduces energy use.
Low Water Use Strategies – using flow regulators, low flush WCs, aerated taps and low water use showers, significantly reduces mains water use and costs.
Low Carbon Technologies and Onsite Renewables – Solar hot water panels in combination with photovoltaic panels will provide energy efficient hot water and are sized to offset the buildings’ entire carbon emissions.
Rainwater Collection – these systems recycle rainwater for garden usage efficient appliances – energy efficient lighting controls further reduce energy use.
This holistic passive design strategy allows the units to be designed without a conventional heating system. At the same time it will avoid overheating in summer and aims to have a minimal environmental impact.
The integrated landscape and building design approach demonstrated at Sherwood is a powerful model for how humans should be designed into their settlements to create a Permanent Culture.