Reflective Foil Insulation

Forum for DesignBuilder EnergyPlus simulation users to exchange views and questions. Posts regarding use of Detailed HVAC should go to the EnergyPlus HVAC forum

Moderator: DesignBuilder Support

clydea
Posts: 2

Reflective Foil Insulation

Postby clydea » Wed Mar 29, 2006 7:54 am

When is DB going to add reflective foil insulation? This is a common form of insulation (low cost and effective) used in warm to hot climates. The effective R-Value depends on emissivity of both surfaces, direction of heat flow (down, up, in, out and at an angle), position and thickness of adjacent air spaces and ventilation of these air spaces.
Andy Tindale
Posts: 2669
Location: Stroud

Postby Andy Tindale » Wed Mar 29, 2006 12:25 pm

You can set up a new material type which has the appropriate R-value including the effect of low emissivity surfaces. I do not have any such air gap resistance data - all the data I have is for high emissivity surfaces. Do you know a good source of standard air gap resistance data for various emissivity surfaces? I would be happy to include it in the DesignBuilder database.

Thanks
Andy
clydea
Posts: 2

Postby clydea » Wed Mar 29, 2006 11:59 pm

The best source of data on reflective foil insulation properties is from the Robinson, Powlich
and Dill data given in the ASHRAE Handbook of Fundamentals.
You can fit algorithms to the data and come up with the two-way R-Values for all combinations of emissivity, angle, air space thickness and whether ventilated or not.
Unfortunately, the data doesn't go past 90mm air space and extrapolation of data may be required for roof spaces.
Andy Tindale
Posts: 2669
Location: Stroud

Postby Andy Tindale » Fri Mar 31, 2006 5:41 pm

Thanks Clyde, I'll take a look at the ASHRAE fundamentals.

Andy
xyliu925
Posts: 23

Postby xyliu925 » Thu Sep 24, 2015 7:20 pm

Hi Andy

Has this issue been fixed in DB3.4? I mean can I pick a built-in material that has different R values in up and down direction.

Thanks

Return to “EnergyPlus General”

Who is online

Users browsing this forum: No registered users and 9 guests