Diary Of An Eco-Builder

Oak bark sounds like the appropriate insulation for tree house, but we need something better

I've been dreaming of insulation for months, but last week we finally fitted the first pieces into Tree House. Grabbing the opportunity of a dry day between the storms, all hands were on deck - the roof deck - to build the thick layer of insulation between the roof's plywood sheathing and the plastic rainscreen that will support our solar power station. By the end of the day the job was done, and the roof was covered in a bright blue tarpaulin just in time for the next downpour.

Our super-insulated roof is not graced with any of the materials alluded to in my dream: hemp, sheep's wool, cork and recycled newspapers. These are all excellent insulants, but - although cork (the bark of the oak Quercus suber) would perhaps be the most fitting choice for Tree House - our roof and floor are in fact being packed with a synthetic product, Kingspan Insulation rigid phenolic boards (www.insulation.kingspan.com).

The key issue with all insulation is to select the most appropriate material for the task. Bark may be all that a tree needs to protect its living tissues from the extremes of the elements, but our "zero carbon" house needs something more substantial. We have chosen rigid phenolic boards for the roof simply because they keep the heat in (or out) better than any other material on the market.

The most important characteristic of any insulant is its thermal conductivity, so always check the value of this when making comparisons. The thermal conductivity of a material is the rate at which heat flows through it when the temperature on one side is greater than the other. This is standardised as the rate of energy flow (in watts) through one metre of material for one degree difference between inside and outside (in degrees Kelvin - the same scale as Centigrade, but starting at absolute zero). Typical values are 0.034 W/mK for mineral wool, 0.037 W/mK for sheep's wool and 0.022 W/mK for phenolic board. The lower the conductivity, the more effective the insulation.

Beyond this bottom line, there are lots of other issues to consider in choosing insulation, such as the size and shape of the space; moisture and fire risks; and the potential for poor installation to undermine effectiveness. For example, we will be spraying Warmcel 500 recycled newspaper (www.excelfibre.com) into our walls because the nooks and crannies of our "I beam" wall studs would not be adequately filled using only rigid boards.

Synthetic insulation materials have often been dismissed by eco-builders because of the blowing agents used in their manufacture. These were originally ozone-depleting CFCs, subsequently replaced by marginally less nasty HCFCs and HFCs. Happily, Kingspan Insulation now produces all its insulants using pentane, which has minimal impact on either the ozone layer or global warming, and any energy used in manufacture is rapidly off-set by its energy-saving performance once installed.

For advice about the insulation in your walls, wall cavities, floors, loft or roof, see the Energy Saving Trust website (www.est.org.uk) or phone 0845 727 7200.

In years to come, our super-insulated roof will keep us cool in hot summers as well as warm in cold winters, so we should sleep soundly beneath it. With any luck, my dreams will be more peaceful too, with all those giggling right-wing sheep long since chased into the wilderness.

Discover more property articles at Homes and Property
News
The guide, since withdrawn, used illustrations and text to help people understand the court process (Getty)
newsMinistry of Justice gets law 'terribly wrong' in its guide to courts
News
Bobbi Kristina Brown with her mother Whitney Houston in 2011
people
News
Starting the day with a three-egg omelette could make people more charitable, according to new research
scienceFeed someone a big omelette, and they may give twice as much, thanks to a compound in the eggs
News
Top Gun actor Val Kilmer lost his small claims court battle in Van Nuys with the landlord of his Malibu mansion to get back his deposit after wallpapering over the kitchen cabinets
people
PROMOTED VIDEO
News
The actress Geraldine McEwan was perhaps best known for playing Agatha Christie's detective, Miss Marple (Rex)
peopleShe won a Bafta in 1991 for her role in Oranges Are Not The Only Fruit
News
newsPatrick Cockburn was able to update his agenda-setting 'The Rise of Islamic State' while under attack in Baghdad
News
Robert Fraser, aka Groovy Bob
peopleA new show honours Robert Fraser, one of the era's forgotten players
Life and Style
Torsten Sherwood's Noook is a simple construction toy for creating mini-architecture
tech
Sport
David Silva celebrates with Sergio Aguero after equalising against Chelsea
footballChelsea 1 Manchester City 1
News
i100
Property search
Property search
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Online Media Sales Trainee

£15000 - £30000 per annum: Recruitment Genius: Now our rapidly expanding and A...

Recruitment Genius: Public House Manager / Management Couples

£15000 - £20000 per annum: Recruitment Genius: Are you passionate about great ...

Recruitment Genius: Production Planner

£20000 - £30000 per annum: Recruitment Genius: This fast growing reinforcing s...

Recruitment Genius: General Factory Operatives

£18000 - £35000 per annum: Recruitment Genius: This fast growing reinforcing s...

Day In a Page

As in 1942, Germany must show restraint over Greece

As in 1942, Germany must show restraint over Greece

Mussolini tried to warn his ally of the danger of bringing the country to its knees. So should we, says Patrick Cockburn
Britain's widening poverty gap should be causing outrage at the start of the election campaign

The short stroll that should be our walk of shame

Courting the global elite has failed to benefit Britain, as the vast disparity in wealth on display in the capital shows
Homeless Veterans appeal: The rise of the working poor: when having a job cannot prevent poverty

Homeless Veterans appeal

The rise of the working poor: when having a job cannot prevent poverty
Prince Charles the saviour of the nation? A new book highlights concerns about how political he will be when he eventually becomes king

Prince Charles the saviour of the nation?

A new book highlights concerns about how political he will be when he eventually becomes king
How books can defeat Isis: Patrick Cockburn was able to update his agenda-setting 'The Rise of Islamic State' while under attack in Baghdad

How books can defeat Isis

Patrick Cockburn was able to update his agenda-setting 'The Rise of Islamic State' while under attack in Baghdad
Judith Hackitt: The myths of elf 'n' safety

Judith Hackitt: The myths of elf 'n' safety

She may be in charge of minimising our risks of injury, but the chair of the Health and Safety Executive still wants children to be able to hurt themselves
The open loathing between Barack Obama and Benjamin Netanyahu just got worse

The open loathing between Obama and Netanyahu just got worse

The Israeli PM's relationship with the Obama has always been chilly, but going over the President's head on Iran will do him no favours, says Rupert Cornwell
French chefs get 'le huff' as nation slips down global cuisine rankings

French chefs get 'le huff' as nation slips down global cuisine rankings

Fury at British best restaurants survey sees French magazine produce a rival list
Star choreographer Matthew Bourne gives young carers a chance to perform at Sadler's Wells

Young carers to make dance debut

What happened when superstar choreographer Matthew Bourne encouraged 27 teenage carers to think about themselves for once?
Design Council's 70th anniversary: Four of the most intriguing prototypes from Ones to Watch

Design Council's 70th anniversary

Four of the most intriguing prototypes from Ones to Watch
Dame Harriet Walter: The actress on learning what it is to age, plastic surgery, and her unease at being honoured by the establishment

Dame Harriet Walter interview

The actress on learning what it is to age, plastic surgery, and her unease at being honoured by the establishment
Art should not be a slave to the ideas driving it

Art should not be a slave to the ideas driving it

Critics of Tom Stoppard's new play seem to agree that cerebral can never trump character, says DJ Taylor
Bill Granger recipes: Our chef's winter salads will make you feel energised through February

Bill Granger's winter salads

Salads aren't just a bit on the side, says our chef - their crunch, colour and natural goodness are perfect for a midwinter pick-me-up
England vs Wales: Cool head George Ford ready to put out dragon fire

George Ford: Cool head ready to put out dragon fire

No 10’s calmness under pressure will be key for England in Cardiff
Michael Calvin: Time for Old Firm to put aside bigotry and forge new links

Michael Calvin's Last Word

Time for Old Firm to put aside bigotry and forge new links