Mana – Grown by nature, growing nature

The house that didn’t cost the Earth.

Design

Our design goals are: 

• To construct a house to live in that is integrated into the land around us where we grow our fresh foods.

• Design and operational simplicity means less effort to create and less effort to run.

• A house that is made almost entirely with natural zero carbon materials and which could be biodegraded or recycled at the end of its life.

• A zero waste system which is eventually off grid and where outputs like humanure, urine and used waters are used as resources for growing food and biodiversity.

The food we grow will come into the house and the waste will become a resource through composting. The roof is used for collecting water and generating electricity and the water will afterwards go into the gardens to build soil. The grey water from the house will be used in a WET System which will water and feed our crops as well as process the nutrients and provide a harvest, so firstly no waste and secondly multiple yields from one design element. Similarly the compost toilet processes our human outputs rendering them harmless, feeds the soil and avoids any water usage.

There will be no concrete by using rubble in trenches as foundations, a timber frame, hempcrete walls, solar heating, compost toilet (and later we intend to build a tree bog) and a green roof. In phase 2 we intend to install a wind generator to balance out the energy sources through the year. Sun is more plentiful in summer and wind is more plentiful in winter. Some of the newer designs of wind turbine will prove more reliable and less hazardous for birds. A Spanish firm is developing a wind generator without turbines and hopefully battery technology will improve to allow us to store charge.

Most houses use foundations that are dug into the ground and filled with rubble and concrete to support the house. This takes a long time and is very harmful to the environment. With rubble trench foundations the process involves no concrete and only uses natural stone with low embodied carbon and takes just a few days. 

Most houses still use bricks or concrete blocks which damage the Earth and need a lot of labour. Even most passivhauses need extra layers of sealing and breathing sheets on inside and out to ensure they are air tight but breathe at the same time. With hempcrete only hempcrete is needed to provide breathability and humidity control whilst providing no thermal bridges or air flows. Plus hempcrete locks up more carbon than was used to grow it and get it into the walls of the house and it also continues to absorb carbon even after that. When sprayed on, hemp walls produce a good seal for air tightness and easily eliminate thermal bridges without needing additional detailing and sealing tapes

Our green roof will visually integrate the side of the house which is facing the road into its green backdrop as well as helping to regulate the temperature of the house and absorb roughly half the rainfall that lands on it, preventing flood surges into the land. Plus the water that does flow off the roof will be captured in a pond and used for irrigation and at some point in the future we will use it to supply the house with drinking water to take us off grid.

Windows and door will be triple glazed.

The floor will be suspended and insulated with hemp or wood wool batts and the same materials will be used in the roof. We will have an earthen floor in the living area to make a more natural, soft and warm surface to walk on and we will use wooden floors in the bedroom and study plus stone floors in the larder to maintain a cool environment. We don’t use a freezer but keep food cool the old fashioned way.

Energy wise we will have a solar pv array on the green roof and a battery which can be topped up overnight at a cheap rate and discharged at peak grid times in the late afternoon and at a higher export rate that provides a profit for us and a better balance on the grid. We intend to use an integrated air source heat pump and hot water tank to provide the small amount of heat necessary for space heating and hot water.

The materials used in the floors and walls provide a natural environment which if experienced feels like a very healthy place to be. The sound quality is exceptional, the air humidity is regulated naturally and the feel is soft and welcoming.

You can hear us talk about the design on the Green Open Doors webinar we did last month.