The following diagram illustrates the most common factors taken into account in building energy models:

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- Conduction through building fabric: walls, windows, loft, floor, thermal bridges. Calculated via material U-values or thermal conductivity.
- A Simple JavaScript model for calculating heat demand

- Metabolic (body heat)
- Lighting
- Appliances
- Cooking
- Hot water, including solar hot water
- Heating system

- Utilisation factors of gains
- Thermal mass

For examples of the following model types see the model examples page.

**Simple annual**
The simplest of all models, possible to get good insight into energy performance with the least amount of calculations, but not as accurate as more detailed models.

**Simple monthly**
A very common simple model type, used in SAP and PHPP, more accurate than the annual model and gives insight into seasonal factors throughout a year. Require's higher detail datasets.

**Simple daily**
As above but on a daily basis

**Dynamic simulations**
The simple model's use averaged annual, monthly datasets and so give outputs that are averages for a year/month. Dynamic simulations can give far greater detail and can be useful for finding out what happens in extremes of climate: hour-by-hour on a sunny day in June rather than the average for June.