Glossary, Notes, Disclaimer, Privacy


Air films sit against the outer and inner most surfaces of the system. These air films still provide a small insulating effect ie provide a small R value.

Air-spaces are cavity spaces between bricks or blockwork, the air between stud walls if there is no bulk insulation, the air around battens between plasterboard and a pre-cast panel wall, a free space between the roof and the ceiling, a free space under a floor etc. Note air-spaces filled with bulk insulation are not air-spaces. Also reflective air-spaces are air-spaces where there is a reflective surface (usually a foil) facing towards this air-space. A reflective air-space achieves a higher R value than a non reflective air-space. Non ventilated (still air) air-spaces achieve higher R values than ventilated air-spaces.

Emissivity is the value given to materials based on the ratio of heat emitted compared to a blackbody, on a scale of 0 to 1. A blackbody would have an emissivity of 1 and a perfect reflector would have a value of 0. So, more reflective items have a lower Emittance value. An alternative definition: emissivity is the relative ability of a materials surface to (absorb and) emit energy by radiation. Shiny surfaces cannot (absorb and) emit radiation significantly.

So there are high emissivity polyweave faces, low emissivity antiglare faces (usually on one side only) and very low emissivity bright/reflective faces

Reflectivity is inversely related to emissivity and when added together their total should equal 1 for an opaque material. Therefore, if asphalt has a thermal emissivity value of 0.90 its thermal reflectance value would be 0.10. This means that it absorbs and emits 90% of radiant thermal energy and reflects only 10%. Conversely, a low-e material such as aluminum foil has a thermal emissivity value of 0.03 and a thermal reflectance value of 0.97, meaning it reflects 97% of radiant thermal energy and emits only 3%. Low-emissivity building materials include window glass manufactured with metal-oxide coatings (low e glass) as well as housewrap materials, reflective thermal insulations and other forms of radiant thermal barriers.”

  • Emissivity of polyweave foil – bright face 0.03, polyweave face 0.87
  • Emissivity of antiglare foil – bright face 0.03, antiglare face 0.1
  • Emissivity of bubble or foam foils – bright face 0.03, antiglare face 0.1
Solar Absorptance values – from BCA vol2 – light coloured roofs with lower solar absorptance reduce the flow of heat from solar radiation better than dark coloured roofs Value
Slate (dark grey) 0.9
Red, green 0.75
Yellow, buff 0.6
Zinc aluminium – dull 0.55
Galvanised steel – dull 0.55
Light grey 0.45
Off white 0.35
Light cream 0.3

Sarking  or sisalation (reflective sheet) may change a tiled roof space from ventilated to unventilated. (1)
A thermal break (which prevents thermal bridging) may be provided by materials such as timber, expanded polystyrene strips, plywood or compressed bulk insulation. Reflective insulation alone is not suitable for use as a thermal break because it provides very little insulation effect in its own right – it requires an adjoining airspace to achieve its often quoted R values. (1)
The thermal performance of a roof may vary depending on the position of the insulation, the climatic conditions, the design of the house, and the way in which it is operated. Insulation installed under the roof rather than on the ceiling of a conditioned house with a large roof space will be less effective because of the aditional volume of roof airspace that would need to be heated or cooled.(1)


Insulation values are only accurate when insulation is installed correctly on site and all gap widths, materials, and reflective surfaces are facing airspaces etc per the descriptions below. Different temperatures, temperature differences between inside and outside, and ventilation (air velocities) affect airspace and airfilm R values. The age of materials and moisture levels in bulk insulation also affect R values. As such the total R values will be approximate and to be taken as a guide only. If in doubt we recommend additional insulation be installed to manufacturers recommendations.

Airspaces are spaces between two materials. Air films are a layer of air that sits against a surface plane.

The R value of an item, other than an airspace, air film or air cavity, may be increased in proportion to the increased thickness of the item.

Airspaces are either between parallel or non parallel surfaces ie where the ceiling is flat and the roof flat (or ceiling is cathedral and parallel to the roof), or when the ceiling is flat and the roof is pitched ie such as in an attic space.

The R value of a material (other than airspaces and airfilms) is not affected if it is horizontal or vertical. It is also not significantly affected by temperature.

The R value performance of bulk insulation batts is slightly affected by temperature, however the quoted average R value is used in this table for simplicity.

Where the R value of a material is known by us to age over time, the aged R value is provided in this table.

Where a cavity or airspace is filled for example by bulk insulation, the R value listed for the cavity does now not apply and cannot be included in the total R value for the wall.  (1)

The values provided in these tables are for the material itself only – not the material and air spaces or total system value.

*manufacturers nominal R value is provided.

Note for comparison R values of windows are calculated as the reciprocal of the U value ie 1/U value = R value. Typical R values for single glazed aluminium windows are R0.2 – R0.3 and R0.3 – R0.4 for double glazed windows.

Tiled roofs without sarking/sisalation or blanket under the tiles are considered ventilated roofs.

Suppliers wishing to include details of their products on this site should email certified material R values to the email address below.


Your access to the Low Impact Development (LID) Consulting online calculator is conditional upon your acceptance and compliance with this Disclaimer.  Your use of the website constitutes your acknowledgement that you have read and agreed to this Disclaimer.

These calculators are populated by data from the listed sources. Low Impact Development (LID) Consulting accepts no responsibility for the interpretation and/or use of this data (incl. correct and/or appropriate entry of data in the tables, or the figures in the tables). To the maximum extent allowable under the law of Australia, neither Low Impact Development (LID) Consulting, nor its employees, or agents shall be liable to you, or any third party for any loss, damage, claims or costs suffered by you or any third party whatsoever from your use of this website, or reliance on the data in these tables, calculators and software contained on it. The data is provided ‘as-is’ without any warranty, express or implied, and/or representations of any kind. Use of these calculators is entirely at your own risk. 

The raw figures are taken from the BCA, AIRAH Handbook 2007, ICANZ manual, AS/NZS 4959.1:2002 with interpolation as appropriate, or suppliers figures where indicated. Figures from independent sources were preferred, but when unavailable, suppliers figures have been used. This calculator has been prepared in consultation with RMIT’s Centre For Design. Low Impact Development (LID) Consulting accepts no responsibility for the ultimate accuracy of these figures and recommends values to be read to the closest 1 decimal place only as NCC/BCA “required R values” are.

Furthermore, The Centre for Design at RMIT University makes no claim as to the accuracy or authenticity of the data, and does not accept liability to any person for the information provided in or incorporated on this website by reference.

Privacy Policy

About us

  1. We are Low Impact Development (LID) Consulting Pty Ltd (ABN 25 104 732 872) of Level 1, 252 St Georges Rd, North Fitzroy, Australia 3068 (“LID”) and welcome to our privacy policy. This policy sets out how we handle your personal information if you register on this website.
  2. When we say ‘we’, ‘us’ or ‘LID’ it’s because that’s who we are and we own and run this website.
  3. If we say ‘policy’ we’re talking about this privacy policy. If we say ‘user terms’ we’re talking about the rules for using this website.

The type of personal information we collect, how we collect it, how we use it.

  1. We collect certain personal information about visitors and users of this website.
  2. The most common types of information we collect include things like: user-names, member names, email addresses, other contact details, occupation and web analytics data.
  3. We collect personal information directly when you provide it to us when registering for use of this website.

How we use personal information

We will use your personal information:

  1. To understand who users are to our database.
  2. To verify your identity when you sign in to our site
  3. Where this is necessary for purposes which are in our legitimate interests. These interests include:
    1. operating the Sites;
    2. providing you with services described on the Sites;
    3. verifying your identity when you sign in to any of our Sites;
    4. responding to support tickets, and helping facilitate the resolution of any disputes;
    5. updating you with operational news and information about our Sites and services e.g. to notify you about changes to our Sites, website disruptions or security updates;
    6. carrying out technical analysis to determine how to improve the Sites and services we provide;
    7. monitoring activity on the Sites, e.g. to identify potential fraudulent activity and to ensure compliance with the user terms that apply to the Sites;
    8. managing our relationship with you, e.g. by responding to your comments or queries submitted to us on the Sites or asking for your feedback or whether you want to participate in a survey;
    9. managing our legal and operational affairs (including, managing risks relating to content and fraud matters);
    10. training Envato staff about how to best serve our user community;
    11. improving our products and services.
    12. providing general administrative and performance functions and activities; and
    13. processing your job application to Envato.
  4. Where you give us consent:
    1. providing you with marketing information about products and services which we feel may interest you; and
    2. customising our services and websites, like advertising that appear on the Site – where this involves the use of cookies or similar technologies – in order to provide a more personalised experience.
  5. For purposes which are required by law.
  6. For the purpose of responding to requests by government, a court of law, or law enforcement authorities conducting an investigation.

When we disclose your personal information

We may disclose or allow access to personal information to the following recipients if working with this site:

  1. employees of LID;
  2. authors of any items or services made available to you;
  3. subcontractors and service providers who assist us in connection with the ways we use personal information (as set out above), in particular: website development providers or website hosting providers;
  4. regulators and government authorities in connection with our compliance procedures and obligations;
  5. a purchaser or prospective purchaser of all or part of our assets or our business, and their professional advisers, in connection with the purchase;
  6. a third party to respond to requests relating to a criminal investigation or alleged or suspected illegal activity;
  7. a third party, in order to enforce or defend our rights, or to address financial or reputational risks;
  8. a rights holder in relation to an allegation of intellectual property  infringement or any other infringement; and
  9. other recipients where we are authorised or required by law to do so.

Where we transfer and/or store your personal information

We are based in Australia so your data will be processed in Australia. Some of the recipients we have described in section 10 above, and to whom we disclose your personal information, are based outside Australia. We do this on the basis of your consent to this policy.

How we keep your personal information secure

We store personal information on secure servers that are managed by us and our service providers, and occasionally hard copy files that are kept in a secure location in Australia, Ireland and the US. Personal information that we store or transmit is protected by security and access controls, including username and password authentication, two-factor authentication, and data encryption where appropriate.

How you can access your personal information

You can access some of the personal information that we collect about you by logging in to your account. You also have the right to make a request to access other personal information we hold about you and to request corrections of any errors in that data. You can also close the account you have with us for any of our Sites at any time. To make an access or correction request, contact our privacy champion using the contact details at the end of this policy.

Marketing Choices regarding your personal information

  1. Where we have your consent to do so (e.g. if you have subscribed to one of our e-mail lists or have indicated that you are interested in receiving offers or information from us), we send you marketing communications by email about products and services that we feel may be of interest to you. You can ‘opt-out’ of such communications if you would prefer not to receive them in the future by using the “unsubscribe” facility provided in the communication itself.
  2. You also have choices about cookies, as described below. By modifying your browser preferences, you have the choice to accept all cookies, to be notified when a cookie is set, or to reject all cookies. If you choose to reject cookies some parts of our Sites may not work properly in your case.

Cookies (not the type you eat!) and web analytics

  1. For more general information on cookies, see
  2. When you visit this site, there’s certain information that’s recorded which is generally anonymous information and does not reveal your identity. If you’re logged into your account some of this information could be associated with your account. We’re talking about the following kinds of details:
    1. your IP address or proxy server IP address’;
    2. the domain name you requested;
    3. the name of your internet service provider is sometimes captured depending on the configuration of your ISP connection;
    4. the date and time of your visit to the website;
    5. the length of your session;
    6. the pages which you have accessed;
    7. the number of times you access our site within any month;
    8. the file URL you look at and information relating to it;
    9. the website which referred you to our Sites; and
    10. the operating system which your computer uses.
  3. Occasionally, we will use third party advertising companies to serve ads based on prior visits to our Sites.  For example, if you visit our Sites, you may later see an add for our products and services when you visit a different Site.

Information about children

If you are under 16 we ask that you do not use this site or give us your personal information (if you are a young tech wiz, please direct your nearest responsible adult to use the site for you!). If you are from 16 to 18 years, you can browse the site but you’ll need the supervision of a parent or guardian to become a registered user. It’s the responsibility of parents or guardians to monitor their children’s use of this site.

Information you make public or give to others

If you make your personal information available to other people, we can’t control or accept responsibility for the way they will use or manage that data. There are lots of ways that you can find yourself providing information to other people, like when you post a public message on a forum thread, share information via social media, or make contact with another user (such as a third party Author) whether via this site or directly via email. Before making your information publicly available or giving your information to anyone else, think carefully. If giving information to another user via this site, ask them how they will handle your information. If you’re sharing information via another website, check the privacy policy for that site to understand its information management practices as this privacy policy will not apply.

How long we keep your personal information

We retain your personal information for as long as is necessary to provide the services to you and others, and to comply with our legal obligations. If you no longer want us to use your personal information or to provide you with the services this site provides, you can request that we erase your personal information and close your account for this website. Please note that if you request the erasure of your personal information we will retain information from deleted accounts as necessary for our legitimate business interests, to comply with the law, prevent fraud, collect fees, resolve disputes, troubleshoot problems, assist with investigations, enforce the terms of service and take other actions permitted by law. The information we retain will be handled in accordance with this Privacy Policy.

When we need to update this policy

  1. We will need to change this policy from time to time in order to make sure it stays up to date with the latest legal requirements and any changes to our privacy management practices.
  2. When we do change the policy, we’ll make sure to notify you about such changes, where required. A copy of the latest version of this policy will always be available on this page.

How you can contact us

  1. If you have any questions about our privacy practices or the way in which we have been managing your personal information, please contact us in writing at our office address or
  2. We’re really glad you made it to the end of the privacy policy, because knowing this stuff is the best way to understand how your personal information is used and how to best manage it!

If you’re a user or visitor in the European Economic Area these rights also apply to you:

For the purposes of applicable EU data protection law (including the General Data Protection Regulation 2016/679 (the “GDPR”), we are a ‘data controller’ of your personal information.

How you can access your personal information

  1. You are also entitled to ask us to port your personal information (i.e. to transfer in a structured, commonly used and machine-readable format, to you), to erase it, or restrict its processing. You also have rights to object to some processing that is based on our legitimate interests, such as profiling that we perform for the purposes of direct marketing, and, where we have asked for your consent to process your data, to withdraw this consent as more fully described below.
  2. These rights are limited in some situations – for example, we can demonstrate that we have a legal requirement to process your personal information. In some instances, this means that we may retain some data even if you withdraw your consent.
  3. Where we require your personal information to comply with legal or contractual obligations, then provision of such data is mandatory: if such data is not provided, then we will not be able to manage our contractual relationship with you, or to meet obligations placed on us. In all other cases, provision of requested personal information is optional.
  4. If you have unresolved concerns you also have the right to complain to data protection authorities. The relevant data protection authority will be the data protection authority of the country: (i) of your habitual residence; (ii) of your place of work; or (iii) in which you consider the alleged infringement has occurred.

Both personal information and personal data have the same meaning in the context of this Privacy Policy.

LID Privacy Policy v1 – effective date 25 May 2018