Friday, 27 August 2010

Insulation is the key to Energy Efficiency

Energy efficiency which embraces a range of strategies, from basic draughtproofing to using energy-efficient appliances and heating systems, is key to eco-design. Of these strategies one of the most critical is insulation. The colder the climate, the more imporant it is for a house to be well insulated. Heat is lost primarily through walls, windows, the roof and the basement. Just by insulating walls and the loft space, heat loss could be reduced by half.
 Materials vary widely in their ability to conduct heat, with metals, for example, being very efficient heat conductors and hence poor insulators, and light porous materials, like wool, very poor heat conductors and consequently good insulators. Air is also a very poor heat conductor which is why materials that are honeycombed with air pockets are good insulators. Increasing the thickness of a material also increases its insulating properties.
  How well a structual element, such as a roof or wall, performs as an insulator is expressed as its U-value, a figure that is derived according to a formula that takes into account the thermal conductivity of each of the components that makes up that element. For example, in the case of a standard cavity wall, the calculation is based on the conductivity of the exterior brick, the airspace, the insulating material, the interior brickwork, and the plaster or other finish. The lower the U-value, the higher the degree of insulation provided.
 The standard way of insulating is to line roof spaces and walls and fill cavities with a baulky insulation product. This may be made of a number of different materials, including cellulose, mineral wool, glass fibre and extruded polystyrene, some of which are more environmentally friendly than others. In most cases, grond and basement floors also need insulation, as dowater tanks and pipes. Heat loss can also be reduced by using a highly reflective material, such as foil , to bounce the heat across a void or cavity instead of the heat being absorbed by a wall - a conventional example is placing foil behind a radiator on an external wall so that heat is directed back into the room.

Friday, 20 August 2010


In all parts of the developed world, construction is highly controlled. Building codes and regulations, regularly updated to ever more exating standards, specify the materials and methods that are regarded as suitable for safe construction, particularly in terms of fire resistance and stability.In response to such legislation, the construction industry has typically reacted by enhancing the performance of structural elements: one example of this is the treating of lumber with chemicals to promote fire- and moisture-resistance. However, for anyone who is concerned about the environment, treating wood with potentially toxic chemicals to overcome such innate disadvantages is unacceptable.

Timber and timber-frame
Timber construction, which is very common for domestic building worldwide, makes good ecological sense. Wood is a renewable resource and has low embodied energy; timber-frame structures are lightweight , easy to insulate to a high degree of effectiveness and can be readily converted, altered, added on to and remodelled. For builders, timber-frame construction is also both cost-and labour-effective. And because timber construction is relatively lightweight, foundations can be minimal, hence some post-and-beam timber-frame structures rest quite simply on individual concrete pads,rather than on slabs, which means less disruption to the site.
Although timber-frame construction, disguised behind masonary or brick cladding, is very common in housing developements, all-timber  construction is much more the exception in Britain and northern Europe today, because of the perceived risk of fire and the propensity of timber to rot when exposed to moisture. In some areas, timber structures is only permitted for structures of one or two storeys.Over the last 30 years (in Britain) timber has been exhaustively tested for its fire performance than any other material. Such studies have revealed that in the sizes used in construction , timber is slow to ignite,and once ignited burns very slowly. Treated with borax, a naturally occuring salt, timber meets British building regulations for fire-resistance and spread of flame.
 Green oak is the best timber for construction and is also affordable. Whitewoods and redwoods should be avoided if possible. Parts of the structure that might be more at risk from fire or vermin attack can be treated locally with borax paste squeezed into drill holes. Borax can also be applied externally provided it is subsequently stained over. An eco choice for external timber treatent is a non-toxic organic wood stain.
Because of their relatively low thermal mass, timber buildings do not store heat very well but can heat up quickly, while buildings with high thermal mass, which heat up slowly and lose heat slowly, require more energy to reach the desired level of warmth. But the low thermal mass of the timber building need not necessarily be a disadvantage. Such a building can be an ideal solution for modern working families: the heating can be left off during the day when family members are out at work and switched on in the evening to more or less immediate effort.
 Timber also has a role to play in hybrid types of construction. Good energy efficiency can be achieved when the basic structure is a lightweight timber frame, external walls are well-insulated timber and internal walls are made of high-mass materials such as concrete block or brick.

Wednesday, 18 August 2010

Eco Design

Eco-friendly design is not just a question of choosing between good and bad alternatives, but involves complex equations that take into account both the broader picture and the longer view. While 'ecological', 'environmentally friendly', 'sustainable', 'green', 'natural' and 'organic' appear to be interchangeable concepts, they can imply quite different solutions. The fluidity of these terms has resulted in many interpretations by architects, designers and ecologists, and not a little controversy.
  Broadly, ecological design is design that makes use of resources that come from the earth in such a way that they can be returned to the earth without causing harm, in a cycle that echoes the natural system of living things. 'Sustainability', a related but not exactly equivalent concept, implies using resources, including land and energy, with maximum efficiency, at a rate that does not compromise the needs of future generations. While 'green' has become a blanket term for a rangeof environmentally friendly approaches, 'natural' and to some extent 'organic are even less precise, particularly since such terminology has been increasingly  appropriated by companies seeking to 'greenwash' their products. In design terms, 'natural' and 'organic' have also been used to describe buildings that echo the colours and forms of the natural world which is not the same as designing to protect the natural environment.

The benefits of natural design
Theres no getting away from the fact that eco design is fundamentally altruistic; it's investing in a future one won't necessary live to see, on behalf of generations to come. But alturism, on the whole is not a strong motivator. We live in a 'here' and 'now' society and have grown accustomed to more or less instant gratification of our needs and desires.
  Some builders of eco homes did not deliberately set out to design and construct on ecological grounds; they simply arrived at that point by opting for the most cost and labour-efficient options.
In general, however, it is important to be aware that eco design does not necessarily save money in the first instance, nor cost less. While it seeks to reduce the use of materials, which can result in considerable savings for new-build projects, in some cases there may actually be a greater use of materials.While many eco homes cost next to nothing to heat and power and some actually earn income by exporting home-produced energy to national grids, at the same time, there are higher start-up costs associated with energy-efficient elements such as high-performance glass or solar technology, and the payback period for these can be as long as ten to twenty years. The economic picture, however, is not a static one; with increased demand, it is likely that many eco-products or technologies may cost less in the future, as is already happening in the case of photovoltaics.
  If the economic arguments in favour of eco design are not clear cut, one of the most immediately obvious benefits is improved personal health. Many modern materials and finishes commonly used in construction contain a huge number of chemicals and additives with a proven track record of causing illness. Chief among the culprits are volatile organic compounds (VOCs), a large class of chemicals that includes formaldehyde, organo-chlorines and phenols, which readily release vapours at room temperature or below. VOCs are present in carpets, underlays, paints, varnishes, vinyl flooring, insulating materials, seals and adhesives, household cleaners and air freshners among other products. Health problems associated with VOCs range from skin rashes, nausea, asthma and other breathing problems to chronic fatgue and dizzyness. Designing and decorating with natural, untreated materials will help remove the threat caused by such toxins from the home.
  Less tangibly but no less satisfying, eco design encourages an innate feeling of well-being and comfort. Natural light, fresh air and greater reliance on passive heating and cooling create environments in tune with biological rhythms - houses that feel like a third skin. Materials that connect with the land offer a quality of rootedness that gives a house a true sense of place as well as providing unforeseen sensual delights, such as the velvety sound quality of a straw-bale house, for example.
  Eco design promotes a better style of life in the fullest sense of the term.