Conceptual constructions

Hi all,

I am interested to know more about the assumptions made when you use a type of wall for example lightweight non insulated wall. I have been on the user's manual an found same values

Units R-value Unit density Heat capacity
IP ft²-hr ºF/Btu lbm/ft² Btu/(ft² •°F)
SI W/(m² • °K) kg/m²

J/(m² • °K)

Mass Exterior Wall

The following table shows IP values.

Conceptual Construction R-value Unit density Heat capacity
Lightweight Construction - High Insulation 25 23 5
Lightweight Construction - Typical Cold Climate Insulation 17 21 4
Lightweight Construction - Typical Mild Climate Insulation (default) 10 18 4
Lightweight Construction - Low Insulation 8 19 4
Lightweight Construction - No Insulation 3 18 4
High Mass Construction - High Insulation 17 115 23
High Mass Construction - Typical Cold Climate 15 110 22
High Mass Construction - Typical Mild Climate 11 110 22
High Mass Construction - No Insulation 1 110 22

However my question is in Europe we normally use W/m.k, kg/m3 and j/kg.k

I would like to know if anyone knows the thickness in which this walls are based so I can calculate the equivalent to Europe or if anyone knows the document in which this walls are based on

Also I have another question in HVAC, is any ideal HVAC system temp which it can be used in Vasari, the HVACs on Vasari are focus on USA and it would be good if for example I want to know which wall will be the most appropiate in certain area in Europe without have to know much about the Hvac system.



thanks Lilli

We have added metric values for conceptual constructions to our wiki help. You can find them at this link

thanks for your replay

Hi Fernando,

Thanks for writing in with your question. To convert an Imperial R-value into a Metric U-value, divide 1 by the R-value, then multiply the result by 5.682. Alternatively to convert a metric U-value to an Imperial R-value, multiply by 0.176, then divide 1 by the result. It’s not really to do with the thickness of the wall specifically but the thickness and conductivity of each layer (brick, insulation, block etc.) in the wall construction, plus a couple of other parameters. We are workign to get the metric values on our help wiki, I will send you a link when it's finished.

At this time the system choices in Vasari are fixed. The system you chose will impact energy performance based on how efficiently it services the heating / cooling load however if you are concerned with investigating wall insulation alone you may be better off focusing on the monthly heating load / monthly cooling load outputs. These are relatively independent of the system type.

Hope that helps,