Building Layout & Design: Passive Solar Design: Insulation.
Insulation slows down the rate at which heat naturally moves from a
warm to cooler environment. Insulation will reduce the daily temperature
fluctuations within the house. It is therefore an integral part of the
building envelope, either in the form of bulk insulation or reflective
insulation.
Bulk Insulation
The products 'R-value' is the effectiveness of the fibre to resist to
the passage of heat. The insulating material works through a combination
of the fibre itself and the air pockets trapped within it, both of which
resist heat conduction. Bulk insulation is essential in cool climates
where heat can easily escape the building envelope through the floor,
walls and ceiling.
R-Value of Insulating Materials
|
Material
|
R - Value
|
|
Sheep's wool
|
2.1-2.7
|
|
Fibreglass
|
2.0
|
| Air-Cell |
2.4 - 2.7 |
|
Rock wool
|
2.5
|
|
Cellulose fibre
|
2.3
|
|
Polyester
|
2.3
|
|
Extruded polystyrene
|
3.5
|
|
Expanded polystyrene
|
2.6
|
|
Strawbale (rendered 450mm wide bale)
|
5.6
|
|
Aerated concrete
|
0.8
|
|
Insulated cladding
|
2.6-5.0
|
Reflective insulation
Reflective insulation works in conjunction with an adjacent air space.
Its efficiency depends on the amount of heat reflected so that it does
not enter the building envelope. It is therefore an ideal product in
hot climates. It reflects most of the heat (95-98%) on the warm side,
whilst the air pockets aids in preventing heat loss from cool side.
It is therefore more effective in preventing heat from entering the
building than from leaving.
Insulation in the Newton House
1.
Air-cell reflective foil will be inserted in the ceiling
and under the floorboards. The foil will reflect 98% of the heat from
entering the house in summer. It has the added value of air pockets
between layers of foil which slows the movement of hot air out of the
house in winter.
2. Straw bale will be used on all external walls, it has an R-value
of 5.6.
Links
http://www.air-cell.com.au
http://www.greenhouse.gov.au/yourhome/technical/fs16a.htm
http://www.leafbeater.com.au/
http://www.greenbuilder.com/sourcebook/Insulation.html
