Archived Entries
March 2009
Hemp and The Construction Industry: Will it ever break the mould?
When we think hemp, it is likely that an image of sandal wearing caftan clad teenager's springs to mind. However, think again; beyond this stereotypical image of a plant more associated with the psychedelic 1960's, hemp can contribute toward a healthy diet (Omega 3) and can be used as a cotton substitute in ecologically sound clothing and bedding. For the construction industry, it is a material that has been employed for many hundreds of years but has never quite made it as a mainstream construction material. The question that springs to mind is why should this be so?
A hemp crop can be grown without the use of herbicides or insecticides and can produce up to 4 tonnes of material per acre per year. Processing hemp results in two materials; hurds and fibres, both of which have properties that make them extremely useful in building construction.
Compressed hurds can be used in the creation of fibreboard, roofing tiles, insulation and bricks. Foundations can be made out of hemp hurds "hempcrete" when combined with lime, sand, plaster, some cement and water. A 6th Century hemp-reinforced bridge found in France is testimony to its stone-like strength and durability.
More recent examples of its use include 2 experimental homes built in Bury St Edmunds by the Suffolk Housing Society. Its purpose was to compare its energy efficiency and general performance against traditional materials. A subsequent report was issued by the Building Research Establishment in 2002 which compared the hemp houses against the traditional material built houses and its principal conclusions were:-
"Hemp houses have far less impact on the environment - they use less energy to build, create less waste and take less fuel to heat; albeit they cost about 10% more to build than a brick and block house".
Whilst hemp offers many qualities, it appears that it cannot compete with modern day materials on one key factor and that being cost. In a capitalist society, cost rules and until this is redressed, hemp will remain a fringe material better known for associations other than construction.
Radiators - It is all in the reflection
Did you know that as much as 25% of radiant heat from a radiator placed against an outside wall is lost to the wall behind it? A simple solution that can reclaim possibly 50% of this wasted heat is by applying a foil-face expanded polystyrene lining to the wall behind the radiator to reflect the heat back into the room. This can be bought at most D-I-Y stores and is available as rolls, sheets or tiles. In terms of application, the best time to do this is when you are decorating and the radiator can be removed from the wall. Fear not, it can also be done with the radiator in place.
The beauty of this task is that it can be done by anyone whose only skill requirement is patience!
- Turn off the radiator and measure it, making a note of the position of the brackets.
- Use a sharp trimming knife or scissors to cut the lining to size, so it is slightly smaller than the radiator all round. Cut narrow slots as needs be, to fit over the fixing brackets.
- Apply a heavy duty fungicidal wallpaper paste to the back of the material and then slide it behind the radiator.
- Smooth it onto the wall with either a radiator roller or a wooden batten.
- Allow the paste to dry before turning the radiator back on again.
- An alternative to using paste is double-side adhesive pads.
