ProVillage


ECO-BUILDING – PART 6: DESIGN REQUIREMENTS FOR STRAW BALE

Design Styles

Before the final decision is made, many variables have to be considered before that final design, such as weather conditions. If there is a lot of rain in the location – either seasonally or throughout the year – a home designed for a place which gets little or no rain may not be the appropriate option for the design. The style and details of the design is important for the efficiency of the home, so this should be considered thoroughly and with time. This is a process which should not be rushed and the characteristics of the property should also be taken into consideration.

Visiting and evaluating the site and property

It can be considered vital to understand the property before and during the design-process. If there are no hurries in the design, one has the opportunity to study how the land interacts during the year. One could discover later on during the project that the location is a wind tunnel for most of the year or that some other place would have suited better in terms of solar power and ventilation.

All this is found out through experience.

Water considerations

Pay attention to how the water flows on the property. Study if there are any bodies of water which are influential to the planning and find out how they behave. What is the situation of the ground water? – and if you are not connected to the network of the city, what are the possibilities of building a well?

Some points to consider are also the leach field for the septic system, and where and how the grey and black water is treated.

The well for drinking water must be situated a safe distance away from these and it might be best to keep the well uphill from the drain field where waste water is drained to. These are one of the reasons why topographic knowledge of the topography is essential in the planning.

In addition, a possible field should be close enough to minimize costs.

Solar trackingsolar panelo and sun

The sun is vital for an efficient home. It is possible to harness the suns energy for electric and heating needs. How does the sun behave towards the land during the different times of the year? These points affect the size and need for the roof overhangs of the building and the placing of solar panels. Further investigating comes in regarding the trees, prevailing winds and the sloping of the land.

Other aspects on design

When you know your land and the positioning of your house, it is time to start designing. Pay attention to window placement and size, since these affect the heating costs. Straw bales are ideal for sound proofing and for insulation, so this information with additional info on light and ventilation creates balanced results.

It is more economical to design with the land: taking in mind to topography, water wind, the possibilities with solar issues and flora. It is also more beneficial to take into consideration to have the home as a part of the landscape.

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ECO-BUILDING – PART 3: Strawbales are outstanding as insulation!

The construction of strawbale homes has grown enormously around the world. The reason for this is the cost-effectiveness of the building material, and that the normal supporting structures and the clay-plastered straw bales replace many other materials, such as tile or wood cladding, wind-proof boards, insulation, plastics and decorative boards.

A large straw bale house - Wikipedia

Even large houses, such as exhibition halls of thousands of square meters, are being built using straw bales.

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From our three separate ’ProVillage’ -documents you can get a relatively clear idea about our project:

The documents can be found both in Finnish and in English.

Downloading might take some time, because the files have an approximate of 130 images.

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Wikipedia-Matawa_straw_bale_library

Here a library has been constructed using straw bales.  The wall support structures have been crafted for the windows. After this the walls have been plastered with a clay and sand mixture to leave it to a distinctive light colour.

straw-bale-house-window-installetion

The supporting structures are made in the same fashion as in the usual building of a house. Here a window-area has been prepared for the application of the external render.The window benches and the window frames are connected firmly together to the supporting structure. In the meantime, the ‘packages’ of straw are tightened and ‘barbered’ to a uniform surface.

Straw-bale-house-under-construction

The window benches and the window frames are connected firmly together to the supporting structure. In the meantime, the ‘packages’ of straw are tightened and ‘barbered’ to a uniform surface.

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The insulation capability of a straw bale structure

The Finnish thermal insulation requirements will tighten remarkably by the year 2010.

”The U-value (or U-factor), more correctly called the overall heat transfer coefficient, describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The usual standard is at a temperature gradient of 24 C°, at 50% humidity with no wind (a smaller U-value is better). U is the inverse of R with SI units of W/(m²•K)”

Source:  http://en.wikipedia.org/wiki/U-value#U-value

The U-value (previously known as the K-value) in part C3 of the collection of building regulations. —– The U-value is to indicate the thermal insulation of various structures in a construction.

The smaller the U-value, the better the insulative capabilities of the material.

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PASSIVE HOUSE:

“The term passive house (Passivhaus in German) refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in buildings. It results in ultra-low energy buildings that require little energy for space heating or cooling”

Source: http://en.wikipedia.org/wiki/Passive_house

All or nearly all of the heat energy needed  is obtained from solar energy and the heat generated from the living in the house.

A passive house does not have an actual heating system. The outer shell of the house has to be well insulated and tight.

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The pictures above and below have been taken from a guide book which is published by Amazonails, which also can be downloaded in PDF-format from:

http://www.amazonails.org.uk/UserFiles/files/strawbaleguide.pdf

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The following is a table of summary:

The tightening demands on external insulation of various building materials

building regs

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The situation is such that if one was to use 45 cm of mineral wool on a wall, that would also fall into the requirements of a passive house, but at the same time would be very expensive.

So it can be deducted that in reality strawbales are the best and most cheapest insulation material, falling greatly below the norms with its values even under tightened circumstances.

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Here you can find a lot of literature in English on the topic:

http://www.amazonails.org.uk/?contentId=59

Pictures :  http://www.StrawBale.com and http://www.LearnStrawBale.com

An information package can also be found there which can be distributed freely.

Videos can be seen here => http://www.StrawBale.com/videos


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