# How are the energy balance items calculated?

**URL:** <https://discourse.ladybug.tools/t/how-are-the-energy-balance-items-calculated/2235>\
**Category:** honeybee-legacy\
**Created:** [November 1, 2017, 5:27am UTC](https://discourse.ladybug.tools/t/how-are-the-energy-balance-items-calculated/2235 "2017-11-01T05:27:37Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![Grasshope](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/grasshope/32/4_2.png) [@Grasshope](https://discourse.ladybug.tools/u/Grasshope)\
**Post date:** [November 3, 2017, 10:14am UTC](https://discourse.ladybug.tools/t/how-are-the-energy-balance-items-calculated/2235/8 "2017-11-03T10:14:16Z")

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thank you very much, @SamueldeVries and @chris, for the detailed clarification.

Yes, the **mechanical ventilation energy** is calculated as the following as you explained:

> ( Zone Ideal Loads Zone Total Heating Energy  
> - Zone Ideal Loads Supply Air Total Heating Energy)  
> -  
> ( Zone Ideal Loads Zone Total Cooling Energy  
> - Zone Ideal Loads Supply Air Total Cooling Energy)

The updated excel sheet is attached for everybody’s reference.

May I also ask:

1. Is the item **opaque conduction** in the energy balance chart calculated from **Surface Average Face Conduction Heat Transfer Energy**?  
This is the only item that I’m unable to get the same value as that produced by the **Construct Energy Balance** component for some reason …

2. The **solar** item on the energy balance chart seems to be **solar gains through glazing surfaces**. What about the **solar gains through opaque surfaces** , and what is the output variable from which it is calculated?

Appreciate your advice.

 ![Image 61](https://discourse.ladybug.tools/uploads/default/original/2X/0/04a3dc79e73132976484910a7cc4a3c3fe46509c.png)

 ![Image 64](https://discourse.ladybug.tools/uploads/default/original/2X/2/2c38614bbfb47caff2b157e006a7067cffd4d2ca.png)

[EnergyPlus output variables \_v010.xlsx](https://discourse.ladybug.tools/uploads/default/original/2X/1/1ec18c695f25049b819e4a22d4ca69b6b79bdbdd.xlsx) (14.3 KB)

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