This introduction to my university project: Environmental Impacts of Passive Houses; A comparative analysis of life cycle estimated costs and environmental impacts of two different approaches to 'Passive House' construction" was partly published in Britsky Listy in Czech and all of the below text is available in Czech language here. The conclusion of the study is here, and the whole study, incl. cost analysis of a BBB house and all the Life cycle screening values, can be downloaded here
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...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 construction use stage spans over generally long time intervals, it is historically a conservative area of the economy, and the field shows a great reluctance to change, 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 to the size longevity of its products.
Residential housing is also an area that well exemplifies the three dimensions of sustainability:
At an economical 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 C.R, in a financial market which only is 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 wider, 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, are responsible for large amounts of waste generation and typically includes many hazardous materials: In UK 90 million ton 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 equal data for Czech Republic). The use stage traditionally requires significant amount of energy, due to poorly insulated houses or energy demanding appliances etc. The statistical figures tell that the buildings would account for 40% of energy consumption in the EU (EU Sustainable Energy Week 2007). The residential sector accounts of 26 % of that amount (ibid.). In 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 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 use stage is bearing the most important environmental load, mainly through the 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 the last years on typical residential housing, and most of them arrive at the same conclusion: The use 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 majority of the modern houses build in accordance with ‘Passive House’ requirements, in actuality does 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 in composite forms which prevents recycling. (Gonthier-Gignac and Jensen, 2009, 54).
Company perspective
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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, 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 use stage.
Reducing the above mentioned 26% of energy/year for EU during use stage is important of course, but such approach neglects many other environmental issues, which may be viewed if the house is seen 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 impacts 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 at the late 19th century, (with the appearance of the baling machines) and with significant developments happening at the end of the 20th century, Recent new development includes the approach of using the newer rectangular big bales [BB] (about 1 m x 0.7 m x 2.2m. (King 2003, 12).
Once the technique of classical straw bale building had been developed, and the agriculture sector increasingly switches to only producing straw bales of large dimensions, the step towards BBB was predictable. The BB lend 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) mechanized, the labor costs becomes reduced considerably as compared to conventional brick construction (Keller 2007).
Add to this the common local availability, thus limiting long distance transport, or high energy demanding production, further savings and environmental impact is limited; in essence the straw-bales constitutes 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 construction industry constitute a measurable reduction of the 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 house also adds to the requirements of a passive house building, as computer simulation based on embedded moisture sensors, has found that a Straw bale wall rendered with 3 cm 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 Czech Republic:
Strawbale building in Czech Republic is in a starting phaze. About 25 houses has been built, ranging from intricate architect designs with budgets of 8-10 mio czk, to the more humble owner-build structures down to 70m2. Noticeable the language isolation of many Czech architects, combined with a cultural predisposition to not confront the administrative bodies, have led to a series of non-effective approaches to straw bale building, in effect building 2 conventional walls, and having the straw bales between them. In general not very effective approaches, neither in financial nor environmental measures. Increasingly straw bales are being utilized in houses aiming to reach the passive house standards, unfortunately these technical parameters does 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 to building. Significantly it also creates buildings that become defunct in case of a future without reliable power supply, as the buildings rely on re-cuberation units and other automatized electrical equipment.
PermaLot o.s. gained the first building permit in C.R. in 2005 for the conventional approach of building with straw bales internationally; simply bales with 3 cm of earth plaster, 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 phaze.
As of writing, no load-bearing straw bale houses, nor ‘Big Bale Buildings’ have been constructed in C.R. 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).
It is a 3-4 day event, which gathers between 130 to 200 architects, engineers, 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, in 2009 was 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
PermaLot in Czech Republic has been elected to host the ESBG 2011
