Installer Directory
author

Written-by

Janet Richardson

calendar

Updated on

Nov 06, 2023

Read Time : 1 Minutes

Thermal Values of Insulation

What are U-Values, Lambda Values and R-Values and K-Values?

R-Value

An R–Value rating is given to insulation in order to measure its thermal resistance with the standard measurement given in square metre kelvin per watt. It measures the temperature variation over insulation and also the amount of heat transferred through the insulating material. The higher the calculated number value the more effective the insulating material will be at preventing heat transfer. The R-values primary measure is the insulation materials ability to prevent or reduce heat flow.

Thickness
λ

U-Value

Insulation can also be ranked using a U-value which calculates a materials insulating effectiveness in watts. A lower U value generally indicates that the material is a more effective insulator. U values are useful for calculating a building elements overall insulating effectiveness rather than just measuring the effectiveness of a specific material. U-Values are calculated as the reciprocal of the sum of R values, i.e.

1
Total sum of R values

  So the lower figure reached in calculation, the better the insulation value of the structure

COMPARE PRICES FROM LOCAL INSTALLERS

Compare prices from local companies fast & free

Enter your postcode to compare quotes from leading professionals. We promise to keep your information Safe & Secure. Privacy Policy

Lambda (λ) Value (thermal conductivity)

Lambda value λ(w/mK)  is a measure of the rate at which heat passes through a material. The units are watts per unit thickness per degree temperature difference across that unit thickness. Examples include Glass mineral wool Loft roll at 0.044w/mk, and Celotex GA4000 PIR board at 0.022w/mk. The lower the value, the better the insulating capacity of the product (for a given thickness).

K-Value

Another measure of the effectiveness of insulation is the K-value which is used to measure the ability of the insulation material to conduct heat. Specifically, it is the measure of the amount of heat, in BTUs per hour that will be transmitted through one square foot of material that is one inch thick to cause a temperature change of one degree Fahrenheit from one side of the material to the other. A lower K value would indicate that the material is a good insulator. Because the numbers will vary between different products the EU has a 90/90 rule which means that 90% of the insulating product will conform to the K value with a confidence level of 90%.

R-Value Blanket Insulation Rock Mineral Wool Loose Fill Insulation Rigid Foam
11 3" 3" 5" 3"
13 4" 4" 5½" 3½"
19 6" 5½" 8½" 5"
22 7" 6" 10" 5½"
30 9½" 8½" 13½" 7½"
38 12" 11" 17" 9½"
Insulation R-Value Heat Flow Reduction Improvement In Efficiency
R-8 90% -
R-12 93% 3%
R-16 95% 5%
R-20 96% 6%
R-32 97% 7%
Area of Home Attic: New Attic: Re Insulation Ceiling 2x4 Wall 2x6 Wall Floors Crawl Spaces Basement Walls Sound Control
Good R-30 R-19 R-19 R-13 R-19 R-13 R-13 R-11 3.5"
Better R-38 R-25 R-30 R-19 R-19 R-13 - - -
Best R-49 R-30 R-38 R-15 R-21 R-30 R-30 R-15 3.5"

Find a local installer

Welcome to the biggest directory of UK renewable energy companies

image

Related Information

Images

History of Insulation

Insulation is not a new thing, as you might expect. It was born out of our desire to keep warm and...

Images

How does Insulation work

Thermal insulation is a means to prevent heat loss or heat gain by creating a barrier between two a...

Images

Thermal Values of Insulation

What are U-Values, Lambda Values and R-Values and K-Values? R-Value An R–Value rating is give...

Images

Types of Insulation

What are the different types of insulation available? When insulating your home you have many di...

Find a local installer

Welcome to the biggest directory of UK renewable energy companies

Or

COMPARE PRICES FROM LOCAL INSTALLERS

Compare prices from local companies fast & free

Enter your postcode to compare quotes from leading professionals. We promise to keep your information Safe & Secure.

Privacy Policy
Contact

Contact Us

Answer these simple questions and we will find you the BEST prices.

What technology are you looking to install?

What do you require?

What happens now?
  1. We will give you a quick call to discuss your requirements.
  2. With your permission, we'll get three vetted companies to contact you.
  3. Compare quotes and select the best fit.
The Renewable Energy Hub provides expert advice for those looking to invest in renewables.

We've been doing so for over a decade. Fill in the form on the right and one of our experienced operators will give you a call to discuss your requirements and answer any questions you have.

We're ethically run and will only share your details with 1-3 of our REH approved installation companies with your express permission. Privacy Policy

Please enter your contact details

logo

Before you go...

Can we help you with anything?

Leave your details and we'll contact you to discuss your requirements

x

logo

quick and free price comparison for solar or heat pumps