Ecodesigner - good resource to understand U-values, etc

[Haneef Tayob]

Does any have a suggestion for good internet resource to understand U-values for different materials, combining, etc.
My physics 101 course was ages ago and I want to be able to use EcoDesigner to its maximum.

[Anonymous]

Try http://www.diydata.com/information/u_values/u_values.php for some general approximations.

The best source is usually the product manufacturer. Some will even do dew-point calculations gratis.

[Anonymous]

The U value depends on the material you use, its thickness and on the surface resistance of the air.

You can read about thermal transmittance here: http://en.wikipedia.org/wiki/Thermal_transmittance

About the U value in the link indicated bu Samovar, those elements have rather bad insulation performance.

Generally speaking, you want the lowest U value as possible (according to your budget).

For example, the best performing exterior wall listed in that page has a U value of 0,6 W/m2K. Here in Italy, it is not legal to build anything with such a low performance (current maximum allowed U value in my area is 0,24 for the vertical opaque envelope).

For passive design, the maximum U value is 0,15 for walls and roofs, and 0,80 for windows (Uw).

If you tell me more about what you need these values for, I may be able to help you more.

[Anonymous]

the Energy Saving Trust in the UK has some excellent scientifically researched advice.

Here's a link to their chart of different insulation types used in construction:

http://www.energysavingtrust.org.uk/Publications2/Housing-professionals/Insulation-and-ventilation/Insulation-materials-chart-thermal-properties-and-environmental-ratings

[Anonymous]

The chart published at the link above can be a starting point. However, if you want to get started on actual energy efficient design, those values are too general for any practical use in design.

[Anonymous]

Hi All

Just bought Ecodesigner and try to set it up. Can someone explain ho to set external/internal heat coefficient?

Thanks
Tom

[Anonymous]

you can find basic info about the R-value and U-value calculation on Wikipedia:
http://en.wikipedia.org/wiki/U-value#U-value

The internal/external heat transfer coefficients are two standard values (measured in lab, and their values are fixed and standardized) that show the contribution given by the internal/external air to the overall insulation value of your structure. These values depend on the geometry of your structure (whether it is a horizontal slab or a vertical wall, for example), and on the ventilation ratio of your external conditions.

Basically, the very first layer of air next to the surface of your wall/slab stays still, and helps insulating the structure.

For example, the standard R-values for a vertical structure are:

Internal: 0,13 Km2/W;

External: 0,04 Km2/W.

You can find other standard values in the wiki article above.

[Anonymous]

Thanks for big help it explain a lot but will comeback with questions if you don't mind?

Best Regards
Tom

[Anonymous]

I don't mind at all, I may just take sometime to answer.

[Anonymous]

I found and printed manual then I think I will be fine with basics but maybe anyone has sorted typical skims like for UK:

blockwork (100 or 140mm), cavity: wool insulation 90mm + 10mm void, brick or stone work 100mm

or for Central Europe:
autoclave blocks (24mm), EPS insulation (150mm)

or anywhere:
timber stud (140mm) with wool insulation in between + extra 50mm of foam
between counter battens

I have no problem with U value for them, found some on-line calculators but how to sort rest of parameters for them in Ecodesigner?

Maybe someone could send any open Archicad files to have a look I promise to send mines to anyone when done