Also know as PIR. Polyisocyanurate is essential a stronger more fire retardant development of Polyurethane. As may be expected it shares many of the characteristics of Polyurethane.

Description
Usually produced as a foam panel insulation, PIR foam panels coated with aluminium are used for the prefabrication of ducts and flues commonly used in heating and cooling systems.

Features

• Manufactured from petrochemicals so not sustainable and toxic when burnt.
• High embodied energy.
• Low k-value – excellent insulator.
• Moisture & fire resistant.

Performance
Usually installed as a foam, Polyisocyanurate has a thermal conductivity or K value of 0.023 W/m.K.
(Watts per meter Kelvin ~ a lower value is a better result)

Cost
Per meter costs are difficult to derive as Polyisocyanurate is usually supplied as an all-in service including installation. Typically, it will cost 4 to 5 times more than mainstream alternatives such as mineral wool with a total cost of £2-3,000 for an average UK home.

As the building progresses so some of the clean lines that I’m so fond of start to emerge. Below are some of my current favourite examples, more can be seen in my Picasa web album – (following a couple of technical hitches flickr seems to have abandoned me for the time being…)

They are to be found in many places and take many forms…

Of course, not all clean lines are new and ‘shiny’ they can also be old and organic.
	From Clean Lines

It’s not all old either. This picture shows the high-tech face of clean lines – solar panels and modern ‘heritage’ velux windows set against original welsh slate roof.
	From Clean Lines

This picture is a favourite of mine, with its sharp technical (clean) lines tempered by the decorative (but functional) oak beam. I’ve always been proud of the fact that the beams are both decorative and structural (they bear much of the weight of the first floor).
	From Clean Lines

Visit my Clean Lines photo album on Picasa>>
	Clean Lines

MyBarnConversion.com is not the natural place for philosophical discourse but the building of the hearth in the barn has changed the way I view the building. It seems that the central position of the hearth against the gable end wall and within the building, its associations with fire and the power that has on the human psyche all contrive to make the new hearth a catalyst in starting to view this as a house or even a home rather than merely a barn that is being converted into something else…

From MyBarnConversion 2009

The hearth transforms the barn from a building to a house, hopefully once the stove is in and a fire is burning in it that house will become a home. We’ll see…

Philosophical interlude over…

Often abbreviated to PU, Polyurethane is usually applied as a foam insulation sprayed onto the underside of roof rafters.

Description
A complex manufactured compound, polyurethane has traditionally been manufactured from petrochemicals and so has a few green credentials except for those gained from the energy it saves. Recent developments toward the use of polyols derived from vegetable oils to make polyurethane may yet redress this and shift this technology toward the green part of the insulation rainbow.

Features

• Manufactured from petrochemicals so not sustainable and toxic when burnt.
• High embodied energy.
• Low k-value.
• Moisture & fire resistant.
• Adds structural stability to a roof, seals small gaps etc. – Can be a viable alternative to a complete re-roof.

Performance
Polyurethane has a thermal conductivity or K value of 0.02 W/m.K.
(Watts per meter Kelvin ~ a lower value is a better result)

Cost
Per meter costs are difficult to derive as Polyurethane is usually supplied as an all-in service including installation. Typically, it will cost 4 to 5 times more than mainstream alternatives such as mineral wool with a total cost of £2-3,000 for an average UK home.

Reference:
For the science see the very thorough Wikipedia article: http://en.wikipedia.org/wiki/Polyurethane

As well as bitingly cold weather the New Year has seen some slow progress on the barn.

The hearth has now been installed ready for the chimney and stove and then eventually a joined together, operational heating and hot water system. I’m really looking forward to getting that up-and-running, it’s been so long in planning and commissioning and I’m ready to get it working.

We’ve installed a couple of small electrical 2Kw heaters, that even when turned down to 1.25Kw keep the building warm – all that insulation seems to be working and working well.

It’s been so cold and the gable end wall is still so damp as there is no proper heating that the cold weather has cracked some of the lime render and so will need patching up. Hopefully, a drier, heated wall in future years won’t be so prone to that problem.

Roll on February…