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Insulation Facts & Trivia

By: Dr Gareth Evans - Updated: 17 Apr 2015 | comments*Discuss
 
Insulation Insulating K-value U-value

Everyone knows that insulating your home is one of the single most useful things you can do to help you start saving energy.

Between lagging your pipes, looking after your loft and filling up your cavity walls, there’s hundreds of pounds – and tonnes of carbon – to be saved.

It’s a familiar old song, and everywhere you look, someone seems to be singing it!

If you think you’ve heard it all before, you’re probably right, but before you completely give up on seeing anything new about insulation, here’s a short collection of odd facts, quick snippets and useful trivia that you just might find interesting.

Odd Performance Facts

There are lots of performance facts bandied about, especially over how much you can save by installing proper insulation in your wall cavities or loft (around £120 and £150 a year respectively, in case you didn’t already know) but here are a few of the more unusual ones.

  • Swedish builders put three layers of insulation in lofts, each 100mm thick and separated by a layer of building paper. It improves the insulation effect by around 60% when the wind blows, since it traps air within the insulation and stops it from being forced out.
  • According to some estimates, as much as a quarter of the heat lost through the fabric of a typical house occurs as a result of cold bridging – losses around un-insulated areas such as where the walls meet the floors or roof, and around windows and external doors.
  • Around 300mm is the optimum depth for loft insulation; doubling the depth beyond this will not double the energy saving.
  • If every house in the UK was fully draught-proofed, the nation would save enough energy to easily heat all the homes in Belfast and Cardiff combined.

Making Comparisons

Comparing different kinds of insulation and building materials to try to see which one will be best for your needs can sometimes seem a bewildering problem. Here are a few straightforward facts to help you tell your K-values from your U-values – and why they matter!
  • A good insulator is a bad conductor of heat; it’s blindingly obvious when you think about it, but it’s worth saying all the same.
  • An insulator’s K-value is one of the ways commonly used to measure its “thermal conductivity.” It’s all about how much heat can travel through a piece of insulating material one-metre thick for every one degree C difference between outside and inside temperatures.
  • K-value units are W/m.K (Watts per metre per degree)
  • U-values are typically used to give an idea of the flow of heat energy through a whole building component – a wall, window or roof – rather than a single type of insulating material. They measure the amount of heat moving through the whole thing for every one square metre of its surface area.
  • U-value units are W/m2.K (Watts per square metre per degree).
  • For both K- and U- values, the lower the number, the better insulation you’ll get.
  • A good insulating material should have a K-value no higher than 0.04 W/m.k
  • A well-insulated outer wall should have a U-value of less than 0.2 W/m2.K and a window 1.0 W/m2.K or lower.

Staying Environmentally Friendly

Saving energy’s a great way to help the environment, of course, and fitting good insulation is a very good start – but not all insulating materials are as eco-friendly as others. Here’s our final few facts to help you stay green all the way.

  • There’s now a whole range of natural insulation materials available, including cellulose, flax, hemp, straw and sheep wool.
  • Some kinds of traditional materials have recycled content; some glass mineral wools are 55% recycled and so is 20% of certain types of rock wools.
  • “Blown” cellulose is made from recycled newspaper.
  • Studies suggest that natural insulating materials are more durable over time than their traditional counterparts – though you might have to wait for 100 years or so to be absolutely sure!

Go on, tell the truth; you hadn’t really heard all of that before – had you?

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Share Your Story, Join the Discussion or Seek Advice..
@Terry - I have included the Which information guide to different types of loft insulation here , which may help you make more of an informed decision.
EnergySavingCommunity - 17-Apr-15 @ 10:48 AM
I have about 6inches of insulation under my boarded loft. I do not want to increase it due to upheaval as I use the loft for storage. Is YBS Superquilt under the rafters going to give me adequate insulation or is it over the top? Thank you for your help.
Terry Davis - 17-Apr-15 @ 8:05 AM
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