Calculating the gains and losses from the envelope of a building is a large part of determining accurate heating and cooling loads. Doing so requires that each surface is cleanly defined and its thermal performance is captured. These two important steps occur in drawing.tool where models can either be imported or drawn natively and then assigned unique performance values per surface.

Performance values defined in drawing.tool

Currently wall (interior and exterior), window (interior and exterior) , roof, and floor (ground and interior) thermal performance can be assigned directly in drawing.tool. To assign performance utilize Assemblies which can be added or edited via the Assembly Builder. When an Assembly is assigned the corresponding performance values can be seen in the elements panel.

Default values

When geometry is first drawn or imported into the drawing.tool default assemblies for all surfaces will be assigned. These defaults are based on the energy code minimum as selected on the Project Page.

Assigned performance in loadmodeling.tool

All performance information is used in loadmodeling.tool for the envelope heat loss and gains calculations. Assigning the design intent envelope performance will provide accurate room loads based on the impact of each surface calculated by EnergyPlus whole building simulation engine. Using the Room Results page the % of total load coming from each surface type (window, wall, roof, etc.) can be reviewed helping to identify where higher performance will have the greatest impact on the design.


Q. How can I assign an exterior wall to Adiabatic?

A. Exterior walls can be defined as Adiabatic via the Interior Wall check box. Setting this to true will model the wall as adiabatic, no sun exposure, and no wind exposure

Q. How can I separate rooms without a wall and assembly?

A. Using Air Walls rooms can be split with an adiabatic surface which does not block daylight.

Q. How can I assign large doors, such as overhead doors?

A. To easily capture the additional heat transfer that large doors introduce to the project we recommend splitting the wall using the method in this gif. Once split a lower performing assembly that represents the overhead or other door type can be applied.

Shows intersecting a wall with a perpendicular wall
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