Natural Eco-friendly buildings

A natural building should minimise the use of imported products, and unnatural and energy intensive materials. Where possible materials should be from the local area and ideally from the construction site itself.

Our concept above demonstrates an 'earth sheltered', 'zero carbon' home. Built into a sloping site, with windows to just one South facing side to utilise a full days sunlight. Utilising straw bale walls to the front and inside, rammed earth walls to the rear, and timber roof with earth on top. The focus is on low impact, low cost, and easy to build, and using as many local and natural materials as possible.

A carbon zero house must be 100% self sufficient in terms of energy consumption. They must also address issues such as water consumption, waste, lighting, sound, washing and drying, building fabric, security, construction, ecology and pollution.

'Zero Carbon' is a woolly term. A carbon zero building can use any energy intensive material from anywhere in the world, using masses of CO2 in both manufacture and transport. By reducing carbon intensive materials, and 'buying local' this can be eased. Sadly it is often unavoidable, due to lack of availability in the UK, time and cost restrictions. Ideally, to be truely carbon zero, a building needs to be carbon positive; ie produce more energy than it uses, to counteract the energy costs of building.

By 2016, all new buildings in the UK will have to be built to code 6 of the Code for Sustainable Homes (link). A Code 6 house aims to be as self sufficient, and highly efficient as possible in terms of energy, water, waste, lighting, sound, washing and drying, building fabric, security, construction, ecology and pollution.

Natural and recycled eco-building materials

Walls

Straw bales. Cheap, quick, versatile and high insulating. Usually lime rendered.

Cob. A mix of clay and straw. Usually mixed with the feet and hand made, the walls can be made in any shape.

Rammed Earth. A mixture of soils is tightly packed in fine layers usually by hand, in-between temporary wall panels. The panels are then removed leaving a strong natural wall.

Wood. Locally sourced hard and softwoods.

Recycled used tyres. Rammed with earth to form a strong walling system. Ideal for curved walls.

Earth-bags. A bag fill with earth and stacked like a brick.

Stone. One of the most trusted, solid and long lasting materials.

Recycled bricks. New bricks use vast amount of energy to create them, use recycled if possible.

Roofs

Earth sheltering. Best used with permeable soils, an earth sheltered roof is highly energy efficient, fire resistant and sound absorbing. Water must be well drained.

Shingle tiles. Pleasing to the eye, surprisingly durable.

Wood. Locally sourced hard and softwoods.

Insulation

Cork.

Wool.

Rammed earth.

Straw.

Other

Cordwood.

Technologies

Wind turbines. Suitable for open and consistently windy areas. Only a small percentage of the UK are in a suitable location for it to be viable to have one fitted.

Solar Panels and Photovolatic Panels.

Rainwater collection system. Store rainwater for reuse for flushing toilets, watering the garden, and washing the car.

Straw Bale Walls

The Benefits of using Straw Bale

• Highly insulating. At 500mm thick straw is a highly efficient insulator, resulting in lower carbon emissions and low heating bills.

• Low cost. At around £2.50 a bale, a wall is very cheap compared with a traditional brick and block wall with expensive insulation. Straw is virtually an all-in-one wall and insulation for a fraction of the price.

• Eco-friendly. Straw is a renewable source which can be sourced very locally, meaning a low carbon impact.

• Easy and quick to construct. With a bit of basic building construction knowledge and some common sense almost anyone can build with straw bales, and their large and lightweight nature means they can be stacked up very quickly.

• Straw can be easily cut to form many numbers of designs, from curved walls, chamfered window openings, or wall cutouts. Covered in lime mortar, it is generally considered aeasthetically pleasing.

• Lightweight. Aa lightweight straw bale wall need shallower foundations than a heavier brick/block wall, saving further time and money.

• Good sound proofing. 500mm thick straw bales absorb sound very efficiently!

• Good fire resistance. Straw bales are tilely packed and so very dense, meaning they burn very slowly, and once covered with lime mortar are highly fire resistant.

• By-product. Straw is a by-product, mostly of wheat and barley in the UK, so on a smaller scale it is not taking anything away from the food chain.

Why isn't Straw Bale more widely used?

The material

• Longevity within the UK weather not fully trusted or proven. Though it has been used succesfully in the US for many decades, convincing UK authorities, builders, home owners, and the general public of the benefits of straw bale will take far longer.

• Potential problems with vermin & damp if not properly constructed.

• Many people hold myths about straw bale fire resistance, and its longterm durability (think 'three little pigs'). People like to stick to the tried and tested methods they are familiar with.

• As straw bale is not a standard method of construction architects and builders maybe wary of, or not even consider specifying it.

• Banks may not give mortgage to an 'unconventional' construction method.

• Planning and building control may not give consent to an 'unconventional' and unfamiliar construction.

• Much like the bio-fuels debate (where straw is also used), there is an argument that if straw bale was a major construction material then many thousands of hectares of land would need to be used to grow the crops, potentially taking away from other crops, and increasing prices.

Value

• The final value of a finished straw bale house maybe lower than a standard built house. As there are so few straw bale houses being built there is little precedence of their value and so an uncertain resale value will put off building for investment.

• The high cost of land suitable for building on tends to determine what gets built on it and a building of less value is a less attractive prospect, on an expensive bit of land.

• Typically someone with a large budget building their own house is likely to build something more prestigious using expensive materials.

• Straw is particularly suited to those on a lower budget, who need to save money on materials and skilled labour. Sadly, few people on a lower budget are able to buy the land in the first place. The abundance of comparitively cheap land and relaxed planning and building control laws in the USA has certainly helped straw bale be more succesful there.