BuildingEnergy Systems

Passive Houses vs. Strawbale Buildings in the Czech Republic

The housing industry has slowly developed itself for a century or so in the cheap oil economy, and is now well-rooted and developed in the market and minds. As subsequent use of constructed buildings normally spans over long time intervals, it is historically a conservative area of the economy, and the field shows a great reluctance to change. This is true at each of its levels (producers, retailers, designers, consumers, etc.). This is especially true when changing means questioning the commonly accepted buildings practices, techniques and materials. In consequence, it is still oriented around cheap and easy to use products with little concern about the wider environmental impacts inherent with the longevity of its products.

Residential housing is also an area that well exemplifies the three dimensions of sustainability:

At an economic level, buying a house is, for most people — ‘consumers’ — the most important (expensive) consumption act of their life, with mortgages of 40 years getting more and more common, even reaching the markets of Eastern Europe: During the years between 2004-07, mortgages accounted for a 40% year-to-year growth in the Czech Republic, in a financial market which is only 12 years old (Sadil 2007, Kovacova 2005). In 2007, household expenditures related to housing accounted for 22.3% and 26.5% of the total family budget in countries such as Netherlands and France, for an average income (ILO Bureau of Statistics), clearly demonstrating the necessity for many home-buyers to prioritize economy when choosing their new home.

The social aspects are numerous. Maybe most significant is that houses, with their long lifetime, would last in average at least over two generations, perhaps up to three or four. In this perspective, the act of building is no longer personal. Indoor environment and health issues are also very important topics, and viewed more broadly, the urban planning and design largely influence community development and social interactions.

Looking at the environmental impact (the processing and transport of materials requires an increasingly amount of energy and natural resources), construction is responsible for large amounts of waste generation and typically includes many hazardous materials: In the UK 90 million tons of construction and demolition waste is generated annually. The construction industry produces three times the waste produced by all UK households combined. Construction and demolition is responsible for creating 21% of the hazardous waste in the UK (UK Environmental Agency 2007). This figure represents all construction; these numbers would be smaller for residential construction, but the data could not be found (neither could equivalent data for the Czech Republic). The usage stage traditionally requires significant amounts of energy, due to poorly insulated houses or energy demanding appliances, etc. The statistical figures show that buildings would account for 40% of energy consumption in the EU (EU Sustainable Energy Week 2007). The residential sector accounts for 26% of that amount (ibid.). In the UK alone the figures are shocking: About 10% of national energy consumption is used in the production and transport of construction products and materials, and the energy consumed in building services accounts for about half of the UK’s emissions of carbon dioxide (UK Environmental Agency 2007). George Monbiot details that the UK’s residential buildings account for 31% of national energy consumption, of which 82% is used for space and water heating. (Monbiot 2006, 65).

Life Cycle

There is a consensus in life cycle thinking that states that for active products, such as houses, the usage stage accounts for most of the environmental load, mainly through energy consumption. LCA energy oriented studies, also called Life Cycle Energy (LCE) (LCE studies refer to life cycle inventory studies that have considered only the energy contents and consumption of the products) have been conducted over recent years on typical residential housing, and most of them arrive at the same conclusion: The usage stage would contribute for most of the life-cycle energy, from 78% to 96% of the energy load (Suzuki and Oka 1998, 39; Aldarberth et al. 2001, 1; Blanchard & Reppe 1998, 18; Lin 2003, 411). However, parallel studies have been conducted on energy efficient houses. It has been stated that the use stage only accounts for up to 40-60% in energy efficient houses, significantly increasing the share of embodied energy. (Tormark 2001, 429; Yohanis 1999, 77).

The importance of these studies is that it clarifies the fact that the majority of modern houses built in accordance with ‘Passive House’ requirements, in reality do not save energy when viewed in a 50 year lifecycle from ‘Cradle-to-Grave’, as the construction techniques become too complex, high in embodied energy materials and rich in toxic materials, which prevents recycling. (Gonthier-Gignac and Jensen, 2009, 54).

Company Perspective


Austrian residential house based on the BBB
concept. (Photo from www.baubiologie.at)

The residential housing market demonstrates clear trends towards implementing more sustainable buildings. Increasingly terminology such as "green houses", "green architecture", "eco-houses" and none the least ‘low energy houses’ are used and thus tend to spread into consumers’ minds, and hence to building companies. However, few standards have been clearly established, and the most common measure of sustainability considered in the residential housing labels is energy efficiency during the usage stage.

Reducing the above mentioned 26% of energy/year for the EU usage stage is important of course, but such an approach neglects many other environmental issues, which can be seen if the house is examined from a life cycle perspective. The reason is simple: energy savings can easily be translated into economic units, a language well understood by the consumer and market players. On the other hand, environmental impact concerns may be either perceived as too theoretical via LCA or marginal, and most likely not felt as applicable to the business.

Big Bale Building (BBB)

The technique of building with small straw bales was developed in the late 19th century (with the appearance of baling machines), and significant developments occurred at the end of the 20th century. Recent new development includes the approach of using the newer rectangular big bales [BB] (about 1m x 0.7m x 2.2m (King 2003, 12)).

Once the technique of classical straw bale building had been developed, and the agriculture sector increasingly switched to only producing straw bales of large dimensions, the step towards BBB was predictable. The BB lent themselves towards the original ‘Nebraska-style’ building, also called “Load-bearing construction”, where the unsupported bale walls are topped with a bond beam dimensioned to hold an additional story, or simply the roof. The Big Bales allow for fast-mechanized construction of the exterior walls, and as the bales can be rendered directly, the wall system constitutes a complete wall with inner and outer skin, along with insulation. The large dimensions of the bales also have drawbacks: It imposes more limits in design, encourages mechanization to the weight, which again is a challenge to the logistics of the construction site. (Rijven 2007). Naturally it also requires that the homeowner can accept such thick walls, walls that in effect only had to be 35 cm thick to create the necessary insulation to fulfill Northern European building norms (Andersen & Møller-Anderson, 2004, 42).

As the wall raising becomes a matter of a couple of days of mechanized process, with a roof that may be crane lifted onto the building pre-constructed, and rendering done (predominantly) with mechanization, the labor costs becomes considerably reduced when compared to conventional brick construction (Keller 2007).

As local availability of materials (straw) is common, long distance transport and high energy demanding production is reduced. The environmental impact is limited; in essence straw-bales constitute an inexpensive by-product from grain construction. They are typically utilized for large-scale husbandry, biomass heating or to be returned to the fields as a fertilizer. We estimate that for the next many years it is unlikely that the amount of bales used in the construction industry would constitute a measurable subtraction from total bale production. In effect it is fully possible to construct a BBB as a biodegradable house, all depending on the overall design and choice of additional material within the building. (Wimmer et al 2004). If the BB gets rendered with an earth plaster they are completely degradable, (apart from the plastic straps). This ensures a CO2 neutral material, which may be CO2 positive as it replaces other materials with a high-embodied CO2 consumption. (Rowan, 2007). The interior qualities of such a house also adds to the requirements of a passive house building, as computer simulations based on embedded moisture sensors, has found that a Straw bale wall rendered with 3cm earthen plaster is able to regulate the atmospheric moisture content without degrading. A straw-bale wall rendered with an earthen plaster is neutral and improves the indoor environment through its ability to regulate interior moisture (Wihan 2007 /Minke 2006, 14).

Strawbale building in the Czech Republic

Strawbale building in the Czech Republic is in its starting phase. About 25 houses have been built, ranging from intricate architectural designs with budgets of 8-10 million Czech Korunas (US$470,000 – $585,000), to the more humble owner-built structures as small as 70m2.

Noticeably, the language isolation of many Czech architects, combined with a cultural predisposition not to confront administrative bodies, have led to a series of non-effective approaches to straw bale building, in effect building two conventional walls, and having the straw bales between them. This is not very effective, financially or environmentally. Increasingly straw bales are being utilized in houses aiming to reach passive house standards, unfortunately these technical parameters do not vouch for any sustainability of the building or end of life of the building, typically causing the building to become unsustainable due to the hi-tech approach. Significantly it also creates buildings that can become defunct in a future without reliable power supplies, as the buildings rely on re-circulation units and other automated electrical equipment.

PermaLot gained the first building permit in the Czech Republic, in 2005, for the internationally-conventional approach of building with straw bales; simply bales with 3 cm of earth plaster and no additional walls (however not load-bearing as the project changed an existing barn with load-bearing rock columns into a family house). The intention of the building is to use it as an inhabited demonstration house for the Olomouc region, demonstrating that it’s possible to attain a desirable modern standard of living in a sustainable built house out of predominant local materials. So far more than 1000 people has visited the The Natural House during the construction phase.

As of time of writing, no load-bearing straw bale houses, nor ‘Big Bale Buildings’ have been constructed in the Czech Republic as residential houses.

The concept of BBB has been introduced by PermaLot during June 2009 at the Prague fairgrounds, in the book ‘Prirodni Stavitelstvi’, by Doc. Ing. Josef Chybik CSc, and in the recent publication “Stavby ze slamenych baliku” by Ing. Arch Jan Marton. This last book is published by Ekodum o.s., of which Max Vittrup Jensen was one of the founders; PermaLot center of Natural Building is officially the Eastern training place of Ekodum o.s.

European Straw Bale Gathering

The biggest international straw bale building event in Europe is the biannual “European Straw Bale Gathering” (ESBG). The next is set for 23-27 August, 2011.

It is a 3-4 day event, which gathers between 130 to 200 architects, engineers and commercial- as well as owner-builders to share the latest developments regarding research, building techniques, specialized machinery etc. in a friendly atmosphere. The latest ESBG was in 2009, in Belgium, and prior to the event a national promotion of natural building was arranged which attracted around 3000 people during the one day fair. That event also included a well-attended meeting by important regional and national stakeholders and decision makers from Belgium. A film was produced about the ESBG, it is available here:

3 Comments

  1. Thank you for this interesting read! I’ve just been searching information about the zice of big bales for my upgrading of my document in material ecology and insulation, but could not find it. But now I found it in your article, and just added the information. For Scandinavian readers interested in material ecology: https://permaliv.blogspot.com/2011/03/isolasjon.html

    I’ve heard they have put up some houses from big bales in Denmark, self carrying walls with no framework.

    People not loving thick walls have not understood the true value of pattern 197: https://vasarhelyi.eu/books/A_pattern_language_book/apl197/apl197.htm

  2. Ok then Construction of a home using Big Bales I agrea on all that is in this Docment, But my prblem is that Hear in Hungary the development of a property is tyed down with to much red type
    First only one company is allowed to construct StrawBale Homes
    Big Bale home is better all round than the small Bale the smal Bale requres to much Timber Frame to kepp the walls in Place
    I wish to build hear in Hungary using Big Bales but this is far from easy
    Fist thay that is the Goverment Departments have forgoten there owen housing was Earth Wall Construction right up to the late 1950
    The goverment neads to look back to gain the facts that all of these properts are now ending there Life Span and there will be in the near futer a vast amount of Homes falling in to dis repair and take a closer look at re newbale buildings
    Big Bale are the Ansear I my self have spent meny years put to gether ever thing to take the Dream in-to realty
    Ok the End of this execet one Good Point when using Big Bale eather in the field on on Site re Band the Bales using Plastic strap with a braking stran of 3000kg b/strain this will ensure the bales will never break open in the life time of the Building
    I have meny points to add to this but for now Good Big Bale Buiding

  3. Stuart; I’m sorry that you didn’t take part in our EU funded ‘Big-Bale-Building-Basics’ workshop in September, however the chairman, Titus, of the Hungarian straw bale association did, so you can ask him if has any means to make your dream come through; he’s an Architect doing a .PhD
    It may also help you to know that an Austrian firm has recently done pressure testing of big bales…

    Good luck,
    Max

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