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This is usually the type of building that are considered alternative today, have their heredity in structures that humans have been constructing for centuries. The reason why these building techniques are gaining popularity in modern times is twofold. First, the old building techniques are far more eco-friendly than the majority structures we used to seeing; second, these structures are simple enough in nature that they can built cheaply and can be built without the aid of a lot of the heavy and expensive equipment which is normally related with most new construction.
Currently words such as green, sustainable and alternative get used often in the construction industry, which make its pretty confusing and difficult to tell if any one particular method or material fall under one or many of these heading. The report will help identify, green alternative building method and materials which are less damaging to the environment than a similar practice used in conventional lumber-framed construction. The need to find alternative practices will encompass any building technique that can be done repeatedly without changing the environment in any noticeable way.
The Importance of Finding alternative Materials
As the world population continues to grow at an alarming rate, people are realizing that planet cannot sustain such continuous and exponential growth. With land being increasable limited and we are continually diminishing our natural resource such are timber, with majority of it being used to build homes. It is evident that we cannot continue to use our natural material at this rate to build our homes. With the awareness of these natural materials become increasing limited, has made the construction industry rethink their way and start to think more about sustainable construction. Using alternative material for 8building homes is much more environmental sustainable than conventional homes building. Depending on the type and amount of sustainable materials used, these types of alternative material can reduce the carbon footprint which is produce in building homes.
According to the Worldwatch Institute, an independent organization that analyzes critical global issues, one-fourth of the world's wood and one-sixth of its fresh water are used in building construction. This situation will only become worse as the world's population and more people continue to migrate toward cities. The greater demands also will add pressure on increasingly scarce essential resources, especially water.
The environment has now become issues and with it being heightened news, the Governments and individuals have seem to take notice and now taking to make a change because we cannot continuing abusing the environment, this is not an option anymore.
The chart below shows the proportion of CO2 emissions in the UK from buildings in use, the construction process (mainly due to the CO2 from the manufacture of building materials) and from all other sectors including industry, transport, agriculture etc. Buildings in use contribute about half of our CO2 emissions (and consume about half of our energy use).
Figure 1 - CO2 emissions
The next chart shows where these emissions come from and with over half of our energy use and CO2 emissions from building use come from heating our buildings.
Figure two - Energy Waste.
The UK government have stated that England must take action now, in order to make vast improvement to energy efficiency in both new and existing buildings. The government have set many ambitious goals, an example of one: they anticipate dramatic energy reductions to achieve its goal that all new homes in England will be carbon-neutral by 2016. World Business Council for Sustainable Development (2007)
There are three main approaches to energy neutrality:
Cut buildings' energy demand by, for example, using equipment that is more energy efficient
Produce energy locally from renewable and otherwise wasted energy resources
Share energy - create buildings that can generate surplus energy and feed it into an intelligent grid infrastructure.
Efficiency gains in buildings are likely to provide the greatest energy reductions and in many cases will be the most economic option. A study by McKinsey estimated that demand reduction measures with no net cost could almost halve expected growth in global electricity demand. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report estimates that by 2020 CO2 emissions from building energy used can be reduced by 29% at no net cost World Business Council for Sustainable Development (2007) and a cost curve for greenhouse gas reduction, McKinsey Quarterly 2007 Number 1.
Fox and Murrell (1989) state the fundamental ecology principle of renewable material, such as wood is sustainable source and are renewable however, for materials like metal, plastic, gravel and sand, stone-based materials such as cement, concrete and plaster, have been used cannot be used again, their consumption if the earth itself. (Berge, 1992) The extraction of certain raw material can be very destructive effects especially to the water table and wildlife habitats. Over usage of these materials can affect the availabilities of in the near future, cause environmental degradation, and contribute to global warming.
Impact of the Construction
The industry has a major impact on the environment, it affect are not only on the resources it consumes but also the waste it produces. The construction industry is accountable for producing a whole variety of different wastes, the amount and type of which depends on factors such as the stage of construction, type of construction work and practices on site. In Great Britain, over 90% of non-energy minerals is extracted and are used to supply the construction industry with materials. Furthermore, every year more than 70 million tonnes of construction and demolition waste has been produced in England and Wales
The key is alternative basic materials because they have historically driven innovation in every industry, and could spur significant advances in today's housing. In order to gain acceptance, however, basic alternative materials must offer more benefits than the traditional materials or methods they replace. They must reduce costs, increase design flexibility, enhance sustainability, perform multiple functions, have superior performance characteristics, or meet a market niche. Another potential driver for adopting alternative basic materials is a shortage of existing natural materials or concerns about their long-term sustainability. Martín(2005) states that in recent years, there has been a shortages of core natural resources; including lumber, steel, and gypsum, and this has driven construction costs higher. This volatility of supply and price motivates the industry to look for more sustainable solutions. Sustainability and resource shortages, in fact, will help to drive innovations in the future.
The objective of alternative basic materials is to develop new materials that spur innovation by serving multiple functions, increasing cost-effectiveness and efficiency, and using more sustainable materials. In many cases, these technologies form building systems that enable other Concept Home principles such as integrated functions, floor plan flexibility, and improved production processes.
Alternative basic materials consist of core technologies that manufacturers can use to create products or systems and composite systems that builders can purchase and use to build homes. Martín(2005)
Before considering the use of alternative materials, and before implementing into homes,
practical issues must be considered, (Berge, 1992) say to be realistic to imagine a technology that functions in line holistic ideas, none-mainstream approach but also providing humanity with an acceptable material standard of living, basically Berge is trying to say there just be a balance between the Eco approach and what consumer want.
Government Schemes and Regulation
After The Stern Review (2006) which advised that the implications of climate change couldn't be avoided any longer and urgent action was required, the government took notice and started implementing changes to building regulations. In 2007, the Government introduced the Code for Sustainable Homes to help improve the energy efficiency and sustainability of houses, by setting target for all new houses to achieve a carbon rate of zero by 2016. This is a level 6 in the Code for Sustainable.
Currently, the standards of the code are not mandatory for private house builders but there are intentions to incorporate them into the Building Regulations over the next couple years, starting with changes to Part L in 2010.
CAN I ADD MORE
Constructing environmental friendly house
To construct an environmental friendly houses are to focus on reducing the environmental impact of both its construction and its ongoing operation. This is achievable at the design phase by selecting the correct material and the process.
Environmental friendly houses and sustainable construction offer an exciting future for building houses. With the prospect of living in an environmentally efficient house that can generate its own power. Also reducing waste and running costs, safe in the knowledge that your house is not effecting but instead helping the environment. This is a positive step for a sustainable future.
It is well documented the impacts that human activity has had on our planet and with the Office for Climate Change 2010, attributing 27% of the UK's total carbon emissions to household heating and electricity, house construction is an area where we can make a huge difference.
During the development and construction stages of house being built, a ecological assessment should be carried out that reduces its impact. Also the see if it is feasible to create new habitats in the form of green or living roofs.
Houses are constructed using a vast range of products and materials from a range of sources. For each one the industry must need to consider:
The sustainability of the raw materials used.
The lifespan of the material.
Its performance characteristics as part of the building fabric.
The energy use and waste generated from:
The acquisition of raw materials.
The possibility for re-use or recyclability at the end of life.
Luckily, a lot of the legwork has been done for you on this one, with resources such as the BRE's Green Guide, which provides environmental ratings for building materials and components.
Material specific organisations like the Forest Stewardship Council (FSC) only certify timber taken from responsibly managed sources.
You can find suppliers who use environmental management systems (EMS) to maximise the environmental efficiency of their businesses. EMS accreditation can be awarded through British Standards (BS) and the International Organisation for Standardisation (ISO).
Alternative building systems improve on standard brick construction through their use of high performance materials and accurate construction techniques. Although many alternative systems involve the construction of buildings in-situ, in the same way that brick buildings are built, there are also many that are turning to off-site construction techniques to improve accuracy.
Another benefit of off-site construction
Alternative Natural Construction: Building Systems
Alternative building systems improve on standard brick construction through their use of high performance materials and accurate construction techniques. Although many alternative systems involve the construction of buildings in-situ, in the same way that brick buildings are built, there are also many that are turning to off-site construction techniques to improve accuracy.
Another benefit of off-site construction is that it can drastically reduce waste - by up to 90% over traditional building methods.
Mud brick is a building material, which consists of clay-loam soil puddle with water, sometimes containing straw. The ideal soil requires clay content and the straw can be added to reduce drying and cracking. However, almost any soil can be adapted to make mud bricks; making it one of the most flexible and convenient building methods. It is most popular due to its simplicity, which is easily grasped by the layperson with limited experience, time or resources. If the design and construction are good, the building will last indefinitely.
Mud brick has several advantages over conventional fired clay or concrete masonry. The advantages include:
Low in embodied energy
Utilisation of natural resources and minimal use of manufactured products
Good sound absorption characteristics
High thermal mass
A claimed ability to "breath"
Suited to a wide range of soils
Easily manufactured and worked
Flexibility in design/colour/surface finishes
Insulation properties similar to those of concrete or brickwork
Mud brick building is very labour intensive
Texts and magazines suggest it is possible to make 100 bricks per day per person, although that level of productivity comes with experience and fitness! Thousands of bricks are required for most dwellings.
Only two or three courses of bricks can be laid at one time, because the courses need to dry out before more are added on top, to prevent the wall slumping or warping.
The technique requires a lot of water, which can be a problem in dry areas.
Although it is possible to make bricks in wet weather, a large undercover area is needed.
Mud brick building is very labour intensive and quite tiring (the most exhausting part is mixing the soil and water).
(BBC - h2g2, 2003)
Wood is a very low carbon and sustainable material, it is important that the wood is ethically sourced and treated. There are types of wooden construction systems, they are:
timber framing - which is constructed completely on-site
Structural Insulated Panels (SIP)- they are manufactured off-site and assemble on-site.
Timber framing is a cost effective method of construction which is available , they can be used for buildings up to around seven stories high and can be highly insulated: level 4 or 5 of the Code for Sustainable Homes should be achievable.
The drawbacks of timber farming are that construction time to build the walls to the specification at the suppliers. With the possibilities of dry rot or wood worm if the timber is not treated properly in the first place. Which mean that only certified companies can be used.
SIPs, this method usages large sheets of plywood or chipboard (more or less) to sandwich to provide a stern insulting core, with these structurally sound panels then joined together to construct the building. SIPs are more expensive, are slightly less flexible in the buildings they produce, but are generally extremely well insulated and airtight: level 6 of the Code for Sustainable Homes is achievable.
The drawback of wood-clad panels is that they do not provide any thermal mass as part of their composition. Frechette (2009) http://www.greenhomebuilding.com/sip.htm, stats that when SIP it will burn, it has been demonstrated that they remain structurally sound for a lengthy period during a fire and do not emit fumes any more hazardous than those of wood products. Another possible concern is with insects or rodents nesting in the insulation since this can be an ideal habitat for them. One last concern is that a well-constructed SIP structure is practically hermetically sealed, which means that the walls are not breathable; for this reason they require some sort of mechanical ventilation system for healthful habitation.
Straw bale Construction
Brian Waite from straw bale house design states that the UK alone produces 4 million tons of surplus straw every year - enough for 250,000 homes. Straw must have the lowest embodied energy of any building material and is probably the cheapest and most sustainable. Straw-bales have an insulation "U" value much better than required by the building regulations as well as excellent sound deadening properties which, together, give a living space an ambience that has to be experienced to be appreciated.
Contrary to common perception straw-bales in a building, is not a fire risk, is not a vermin risk and are not short-term, but would compost back into the earth if and when required to do so. Straw in bales is so tightly bound that it doesn't contain enough air to support combustion, just add a (carbon neutral) "breathing" lime render/plaster and any fire regulation requirement is easily met. There is no nutritional value in straw and so it does not attract vermin, it is only voids that vermin like, so proper attention to detail is the only precaution needed. Lime rendered straw-bales "breath" so evening out fluctuations of humidity thereby creating a healthier environment.
Straw bale construction is the use of compressed blocks (bales) of straw, either as fill for a wall cavity (non-load bearing) or as a structural component of a wall (load bearing.) In each case, the interior and exterior sides of the bale wall are covered (by stucco, plaster, clay, or another treatment.)
The drawback of straw is that it requires special measures must be taken to provide nailing surfaces, since straw bales do not hold nails as well as wood and anchored to the foundations. The external weatherproof cladding will need to be good, as bales will rot badly if they get damp If straw bales are not available within a few hundred miles of your construction site, the cost of shipping them, along with the potential pollution from the transportation, must be taken into account.
Views of the industry Straw bales may be plastered inside and out to provide thermal mass and, like standard construction, the walls must be protected from moisture
Straw bale can be more resistant to termites and vermin than stick construction, but (as with any type of construction), elimination of cracks and holes is key
Rammed earth walls (aka pies) are constructed by the compacting (ramming) of moistened subsoil into place between temporary formwork panels. When dried, the result is a dense, hard monolithic wall.
Rammed earth is an ancient form of construction, usually associated with arid areas. There remain plentiful examples of the form around the world - evidence that rammed earth is a successful and durable way of building. A few historical rammed earth buildings are to be found in the UK.
Rammed earth construction is once again gaining in popularity for home builders looking for eco-friendly options. With rammed earth, you're using the dirt under your feet (or from a local quarry) to build a house. This is certainly a "green" practice since it usually makes use of local materials (local dirt!) and you don't need lumber, quarried stone, brick, etc. to be transported from long distances.
Rammed earth construction has its pros and cons of course. Let's take a look at the positives and negatives.
A properly sited and designed rammed earth home is ideal for passive solar strategies, so it can be great for an off-the-grid house. The thick, dense walls absorb the warmth from the sun all day and slowly release the heat into the interior of the house at night. This helps keep heating bills low in the winter, and these homes tend to stay cool in the summer as well.
Dirt is an easy-to-acquire material and while there are some requirements (not all dirt is going to have the right mix of sand and clay), you ought to be able to get it locally, so this tends to be an eco-friendly building material.
Soil selection needs to be done carefully, and if you are able to use dirt from the building site, you'll end up with some big holes you need to figure out how to work into the landscape. Though it might seem that a house made out of dirt would be cheap, rammed earth construction actually tends to cost 5 to 15% more than conventional construction (due to the labour-intensive process of creating the rammed earth forms).
It's difficult to impossible to create rounded or sculpturally shaped walls the way you can with other materials. Homes made with rammed earth construction are going to be boxy in nature.
Constructing a rammed earth house in the UK would probably require extra insulation, (it's typical to add foam insulation to exterior walls and then cover it up with stucco) as rammed earth method is not suitable for colder climates
Another mud-hut style of building, but there are occupied cob houses around the UK that are anything up to 500 years old. Not bad for a mud hut.
Cob houses are built from a mixture of earth, clay, sand and straw. The ingredients are mixed together with a little water until they form a paste-like substance. The paste is then slapped onto a stone foundation to form walls that are often around two foot thick, then more and more slapped on to form a monolithic structural building. The slap is usually built up in layers about 18 inches high to avoid slumping.
The great thing about cob houses is that they can be built into more or less any shape you care to dream up: curves, vaults, domes etc. This can result in some pretty funky buildings. The drawback is that it is very labour intensive and the walls can take up to a year to fully set.
Cob is a Cheap, sustainable and eco-friendly method of construction using local materials. This is as load-bearing method of construction and needs no framework. A cob house uses 60 per cent less timber than a stud frame building. a cob house typically uses 20 per cent less energy.
Cob house are naturally energy-efficient to cool and heat, provided the builder takes care to insulate the ceiling, and attend to solar positioning advantages. Straw bales embedded into north walls make this truer. Heat tends to pass out through north facing walls. Straw bales tend to keep this heat in, better that only earth, which is more porous for air passage.
Contractor do not like working with Cob material as it is time consuming and labour-intensive. It makes the need for community obvious, while demonstrating our inherent unified power. Cob has to "breathe" - to dry out naturally after becoming wet. It used to be that the exterior walls were either left bare or lime rendered (which is expensive these days). Excessive moisture can give you a probleme, as the material needs some moisture (3-5% is considered good - much higher than that and you might have rising damp). Cob generally exceeds the minimum u-values for a house.
Cost & benefits compared below
Traditional brick & block
Well known, flexible, popular, robust, durable.
Materials not eco-friendly, high waste, often poor performance.
Sustainable, cheap, fairly rapid, well known, good performance.
Poor image, needs good planning.
Sustainable, excellent performance, rapid, can be fairly cheap.
Poorly understood, few contractors, inflexible, needs good planning.
Very sustainable, good performance, can be very cheap.
Misunderstood and could have low sale value, limited lifespan, needs very good planning.
Very sustainable, durable, good performance.
Misunderstood and could have low sale value, needs insulating, easily water damaged, long build time.
Very sustainable, durable, good performance, very flexible.
Misunderstood, needs insulating, easily water damaged, long build time.
Traditional Building Method and Materials used
The majority of new homes in England and Wales are built using traditional masonry construction. With most people in the construction industry are familiar with this method. This method has many advantages, such as a deep historical and psychological attachment to masonry construction, which has contributes to its persistence use as the main house building method in the UK. A national survey by MORI found that 61% of respondents would prefer to buy a newly built property of traditional block construction.
Most building systems in England and Wales use a timber frame for the skeleton of the house , this is the core of most traditional method of construction, however manufacturing developments have moved many of these methods into the categorization of modern methods of construction discussed below. This is currently second most popular technique for new home construction in the UK and, according to the UK Timber Frame Association, is the fastest growing method of construction in the UK. Traditionally used in North America and Scandinavia, as those areas are rich in timber resources, it comes with some good environmental credentials.
Before considering what type of alternative method or material to use, we need to understand how current building methods and materials are being used. Below is a basic method
Once the excavation and installation of the foundations is completed, the bricklayers erect cavity walls that consist of an inner and outer skin.
The inner skin is the main structural element, which supports internal floors and the roof structure. It is constructed using concrete blocks laid on beds of sand and cement mortar.
The outer skin of the house is the first line of defence against the elements and provides the aesthetic element to the structure. This is constructed usually with brick, stone or block work, this can produces a number of finishes. The two skins are connected by steel wall ties and separated by a cavity that is partially or fully filled with insulation.
Internal floors, they are constructed using timber joists, composite timber beams, or one of many precast concrete systems which are available. The roof is usually traditional cut timber or prefabricated truss construction.
With environment and health issues, concrete are non-toxic stains and sealants can be used. They are Manufacturer of Portland cement contributes between 5-8% of carbon dioxide emissions and greenhouse gases, which means concrete is non-green material. It under goes a chemical process of limestone, it creates the same amount of carbon dioxide in weight, but concrete can be grounded and recycled for use in roads and pavements (Holistic Interior Designs,2007)
Concrete is often used in the construction and constructing home and is there a need to find an alternative material to replace concrete. Traditional concrete contains material such as stone or other material with similar properties. Concrete is made from gravel, sand, cement and water through a chemical process, the concrete is next, poured into slabs for worktops and panels - creating a stone like appearance. The traditional use for concrete are use walls, floors, fireplace surrounds, worktops, panels, wall finishes, concrete furniture, sinks and basins. It offers an exceptionally high lifespan - up to 3 times that of alternate building materials
The use of concrete has many advantages, Farrell (2009) summaries the advantages and disadvantages of concrete: which are stated below
Fire, moisture, insect, rot and rust resistant,
Can be poured into form Absorbs and retains heat very well,
Concrete is water resistant and will not warp, rust or rot.
Concrete homes are less affected by flooding or by leaks from tanks or water pipes. Concrete walls between adjoining properties offer high levels of security and peace of mind to property owners.
Which are Poor insulation properties
Concrete May Not Offer Pleasant Aesthetic
Embodied Energy of concrete manufacture creates very high levels of carbon emission.
Origin Extraction of the raw materials in very large quantities has a negative impact on the local surrounding environments.
Transportation of raw materials over long distances accounts for further release of carbon dioxide levels into the atmosphere
There are now more environmentally friendly alternatives to traditional concrete on the market, made with hemp or carbon neutral concrete. Traditional concrete should be the last choice. Which will be explain later chapter.
Are Bricks Green or Not?
(Proefrock, 2007) asks what is brick made of, which is just clay and water and that is it, there are no complex chemicals, no exotic compounds, no imported components. Brick are effectively just a manufactured clay stone with a special shape. It breaks down into earth since it comes from earth. (Proefrock, 2007) Clay mining is comparatively benign, compared to ore mining for metals, which requires far more material to be extracted and processed to produce the finished product. Clay is not a resource that is in short supply, which makes it a more attractive material to use, as well. The main reason brick is not an even greener building material is that it takes a lot of energy to make a brick. However, the extra energy is relative. (Proefrock, 2007)
Finding alternative Insulation
sustainablebuild.co.uk (2010) state: insulation is a key component of sustainable building design. A well insulated home reduces energy bills by keeping warm in the winter and cools in the summer, and this in turn cuts down carbon emissions linked to global climate change.
In regard to energy efficiency, investing in high levels of insulation materials when constructing houses is a cost-effective method of saving energy, rather than investing in expensive heating technologies. It is important to choose the correct type materials in the context of whole building design.
Insulation materials are used in roofs, walls and floors. Alternative methods that have solid walls structures from cob and adobe cannot be insulated, Cob and Adobe already offers good thermal mass to compensate. Houses that construction with Timber frame require wall insulation in the form of batts (pre-cut sections that are designed to fit between stud walls), rolls or boards. Other types of construction methods such as brick or concrete insulate with spray foam, loose fill or rolls.
Insulation materials work by resisting heat flow, measured by an R-value (the higher the R-value, the greater the insulation). This R-value varies according to material type, density and thickness, and is affected by thermal bridging, unwanted heat flow that occurs at joists, studs and rafter beams. sustainablebuild.co.uk (2010)
Conventional/ traditional Insulation
This method of using insulation materials are made from petrochemicals and include: fibreglass, mineral wool, polystyrene, polyurethane foam, and multi-foils. Conventional insulation materials have functions which allow them to absorb or slow down both convective and conductive heat transfer to provide insulation properties.
These materials are commonly used when constructing homes, as they are inexpensive to buy and install, but there is an assumption within the construction industry that their performance ability is higher than the natural alternatives.
Fact about traditional Insulation
that almost all conventional insulation materials contain a wide range of chemical fire retardants, adhesives and other additives, and the embodied energy in the manufacturing process is very high.
They are not as effective in providing insulation from radiant heat transfer. During the winter, 50-75% of heat loss through the ceiling or roof and 65-80% of heat loss through walls is by radiant heat transfer. While in the summer, up to 93% of heat gain is by radiant heat transfer. Worse still, traditional forms of insulation are virtually transparent to radiant energy and are also badly affected by changes in humidity or moisture levels. For instance, a 1% to 1.5% change in the moisture content of fibreglass insulation will result in a 36% decrease in performance.
Natural Insulation Materials
The green alternative to synthetic insulation is natural insulation. There are many different types available, including:
This material usually needs to be treated with chemicals to prevent mite infestation and reduce fire risk, although some natural builders use it untreated with success. It has very low embodied energy (unless it is imported) and performs exceptionally well as an insulation material. Thermal fleece is the most common commercial brand available.
Flax and Hemp
Natural plant fibres that are available in batts and rolls, and typically contain borates that act as a fungicide, insecticide and fire retardant. Potato starch is added to flax as a binder. Both materials have low embodied energy and are often combined in the same product. Examples include Isonat and Flax 100.
A recycled product made from newsprint and other cellulose fibre. It is one of the most favoured materials of natural builders because it can be blown into cavity walls, floors and roofs; used as a loose fill; and is also available in quilts, boards and batts. Like hemp and flax it contains borate as an additive. Products include: Warmcell and Ecocel.
Made from wood chips that have been compressed into boards or batts using water or natural resins as a binder. It has very low embodied energy and uses by-products from the forestry industry. Examples include: Pavatex, Thermowall and Homatherm.
Expanded Clay Aggregate
These are small fired clay pellets that expand at very high temperatures to become lightweight, porous and weight-bearing. They can be used in foundations as both an insulator and aggregate. They have excellent thermal insulation properties, but high embodied energy.
Insulating for a Better Environment
Natural insulation products have many advantages over conventional materials. They are low impact, made from renewable, organic resources and have low embodied energy. They can be reused and recycled, and are fully biodegradable. They are non-toxic, allergen-free and can be safely handled and installed. They also allow for a buildings to breathe by regulating humidity through their absorbent properties, and reducing problems of condensation. This keeps the indoor environment comfortable and protects any timber structures from rot.
Unfortunately, natural insulation materials are currently up to four times more expensive than conventional materials, which can be prohibitive to builders, architects and developers. But the environmental and health benefits of natural insulation materials far outweigh their costs, and growing consumer demand combined with government regulation, and rising oil prices will inevitably drive prices down. Despite the high price, natural insulation is an energy-efficient, healthy and sustainable choice for a better indoor and outdoor environment.
Natutal alternative to insulation
How natural materials can actually improve energy efficiency of buildings
Natural materials tend to be much more complex than highly processed materials, and have different qualities. If used correctly they can considerably enhance building performance. For example in comparing natural fibre insulation with synthetic and mineral/ glass based insulations the following can be asserted:
Natural fibres are on the whole much stronger than glass and rock fibres. Much conventional fibre insulation collapses and degrades over a few years (note that loft insulation which is now a damp squib). If buildings are to last over 100 years then we need insulation to last at least as long, particularly in areas where it is difficult to replace or renew. Natural fibres are known to last this long in the correct environments. As regards gas blown insulations, there remains a significant question as to whether these gases will remain for the life of the building. In many people's opinion only air based insulation is guaranteed. And as regards multi-foil insulation, there are major concerns about the claims made by the manufacturers.
Thermal performance with moisture: natural fibres absorb and desorb moisture hygroscopically, unlike synthetic fibres. Far from reducing their overall thermal resistance this has been shown to improve performance in comparison with conventional materials
2. In one study comparing flax insulation with mineral wool insulation with a similar designed thermal performance over a bathroom, the thermal resistance of the flax insulation fluctuated more than the mineral wool, but overall had about 10% better resistance.
Specific heat capacity: most natural fibres have a specific heat capacity of about 2000J/kgK, compared with 800J/kgK for mineral wool, and 1400J/kgK for plastic insulations. When combined with the higher density of most natural insulations this means that the thermal mass of natural insulations is considerably higher than conventional insulations for the same thermal resistance. This means that they give far better thermal storage and overheating protection both of which are increasingly important in energy efficiency strategies, particularly in light weight structures.
The multi-functionality of bonafide natural insulation products extends also to their acoustic performance, which again is far superior to synthetic fibres and plastic insulants, thus making them highly cost effective in designs where thermal resistance, overheating control and acoustic insulation are all required. Add in their breathable qualities and the products become cheap.
The Self Build Guide: Straw bale
Alternative manufactured material
Steel framed houses are a rarity in the UK. Nobody seems to know quite why, because in
the USA and Australia they are very common. Steel framed housing did enjoy a spell of
popularity in the UK in the 1940s, but today houses built in this way are estimated to
embrace less than one per cent of the UK housing stock. However, there are some signs
of a revival. A handful of small manufacturers produce systems of this sort and are
aiming them at the self-build market. They would appear to have a great deal to
Basically steel framing, like timber framing, is a form of part-prefabrication. Today's
steel frames for houses are a latticework of lightweight C-sectioned galvanized steel, to
which sheathing board and insulation is applied to the outside before the whole is
usually finished off with a render.
Steel framing of this sort is infinitely cheaper than the massive I- and C-beam systems
we see in the shells of new commercial developments and factory units. This sort of
frame is only considered necessary for a house when there are extremely large spans
Page 11 of 11
Advantages of Steel Frame
Lightweight steel frame is faster to erect than timber frame, fireproof, and highly
accurate as it is factory-produced and transported to the site in sections. As it is strong
it allows for large internal open plan spaces. It also appears to compare very favourably
in price with what is generally recognised as the cheapest means of building - dual
skinned blockwork. Some systems allow for the sections to be produced and assembled
on site. Insulation is easily installed: some systems have walls with a U-value of 0.7 and
houses built in this fashion are easy to extend and modify.
Disadvantages of Steel Frame
The main one appears to be public perception. Despite the fact that thousands of homes
have been built in this way in other countries British people somehow seem to think it is
both expensive and in some way difficult to achieve. Neither is true.
The other obvious disadvantage is sound transmission. Steel framed houses are
potentially poor from the point of view of sound transmission. In the case of airborne
sound this can be overcome by packing the frame with quilting. In social housing with
party walls, impact sound, which is transmitted through the floors, can present more of
a problem. However in individual self-builds, where the floors are of timber or
chipboard, this is less of a problem as the noisy elements can be isolated and dealt with
One company experienced in steel frame construction that is now turning its sights to
the self-build market is Cressey Engineering. They claim to be able to build a complete
150m2 house in 12 weeks at a cost of around £550/m2 all in.
Another young company, Bristol-based Metek Building Systems uses steel rolling
machinery that can be transported onto site to convert steel coils into cold-rolled steel
frames for fast track buildings. In the housing field this has so far only been used for
social housing but the company is also now looking at the self-build market. Managing
director Dr Alan Rogan quotes a price of £30/m2 for finished wall frames. The company
can also supply full insulation and a choice of a brick slip or rendered walls. They do not
generally supply roofing systems. "There are no real disadvantages with this system," Dr
Rogan says. "We can offer bespoke frames extremely quickly - sometimes within
Permanently Insulated Formwork (PIFs)
The idea behind PIFs is that you start with a delivery of hollow interlocking polystyrene
blocks, rather like giant light pieces of Lego, and stack them up into the shape you
require. You then pour concrete into them - occasionally reinforced with steel and they
remain in place permanently as insulation. The difference with PIFs is that with
conventional poured concrete you remove the formwork after the material has set. The
polystyrene can be rendered on the outside, though many self-builders prefer to add a
brick skin. The system is so easy to use that it is ideal for DIYers.
Alternative Method and Materials
Eco homes and sustainable construction offer an exciting future for house building and the homes we live in. Who doesn't love the idea of living in an environmentally efficient home, generating your own power, reducing waste and running costs, safe in the knowledge that you are doing something to help the environment? It's a step towards the good life.
On the whole, self builders have been more enthusiastic about embracing sustainable development and eco homes than commercial house builders who, understandably, have been reluctant to invest until public opinion, economics or government regulation motivate them to do so.
Disadvantages of green building or alternative material Brick are prefecly fine to use. Companies have started to make greener bricks
While choosing to build green--or eco-friendly--has many advantages, there are disadvantages that need to be considered. Considerations such as cost, funding, material availability and location restrictions must be taken into account when choosing to build green.
The first--and perhaps most prohibitive--disadvantage to green building is the upfront cost. Eco-friendly building materials are often difficult to find in many areas of the United States, which can cause the prices to be much higher than standard building materials.
Besides the initial cost of green building, finding a lender who offers loans for building that is non-traditional may be difficult. Depending on the area of the country, there may be few, if any, lenders available. In addition, certain restrictions may be applied by a lender that a homeowner or builder may find too difficult to follow.
Availability of Materials
While homeowners who live close to larger cities may have no difficulty finding green building materials, the selection may be scarce in other areas. Many materials may require special ordering, which could increase the cost. In addition, some materials may only be available through Internet orders, which will include a cost for shipping and handling.
The location may play a large role in making green building not feasible. Areas of the country that are more humid or moist may preclude certain styles of green building, such as straw bale construction. Local restrictions and codes may also not allow use of certain materials or building styles.
Since some green building projects encourage the use of recycled and found materials, time may become a disadvantage. Finding the needed materials may take extra time that the builder and/or homeowner doesn't have for the project.
Comparing the Methods
Each house construction method has its own advantages and due to the complex nature of the processes involved and the unique requirements of different projects it is very difficult to directly compare them in terms of cost, time and sustainability.
When assessing the environmental impact of a system, the whole lifecycle of the products involved needs to be considered including acquisition of raw materials, transportation, processing, manufacture, waste generation, operating efficiency, specification, lifespan and recyclability at the end of its life.
Time comparisons also require further investigation and although site times may be reduced by offsite prefabrication, lead and manufacture times must also be considered to give accurate schedule predictions.
To compare costs accurately, the best way is to build up a set of costs for each method and compare them directly for your specific project. Have a look at our Money section for tips and techniques.
Making a Choice
Follow the links from this page to more information on the various house construction methods. Weigh up the pros and cons and compare them to what you want from your self-build home.
You should also check your position in relation to mortgage lenders, insurers,warranty providers and building control before proceeding too far with your plans. Most of the modern methods are gaining acceptance and shouldn't be a problem but now is the time check.
Despite many methods laying claim to being the 'future of construction', there is no definitive solution to choosing one of the house construction methods, it really comes down to feasibility and which one suits your personal requirements the best.
Now you're a step closer to choosing your build method, have a look through the rest of The Self Build Guide for information on other aspects of building your own home including buying land,design, project management and all things financial.