Simulation of roof spaces within iCD
In iCD, when a building’s “Roof type” attribute is set to either Gable or Hipped, the building is modelled with a roof space on top of the last floor.
These roof-spaces are treated differently compared to other spaces defined in iCD.
- These spaces are not editable by the user and will therefore not appear when looking at space level attributes.
The example here below shows a 2-storey building with its roof space alongside the query tool. Only the ground floor and the first floor are available to the user for editing.
- These spaces are not accounted for in the total floor area calculation.
- For simulation, these spaces are considered:
- Un-occupied: no lighting, equipment or occupant loads are assigned to these spaces. This also means the space is not taken into account when calculating the total number of occupants in the building and the Domestic Hot Water loads associated with them.
- Unconditioned: no system provides heating or cooling to this space.
In addition to this, some building-level attributes can affect the construction assigned to the roof space:
- Loft insulation, this attribute adds insulation to the construction between the top-floor and the roof space. Note: this attribute does not affect the model for flat roof buildings.
- Roof insulation, this attribute adds insulation to the roof construction above the roof-space, if any. Note: this attribute adds insulation to the roof construction right above the last floor, if no roof space.
- Roof U-value, this attribute overwrites the U-value of the roof construction above the roof space.
In our iCD version 2024.0.0, we have improved how the thermal conditions of these roof spaces used are assigned for simulation so that the behaviour described above remains consistent no matter the template used or the simulation engine.
With this improvement simulation results may be different to previous iCD versions. If you would like to revert to previous iCD version simulation results, you can go to Extension > IES iCD > ‘Troubleshooting and license’ and untick ‘Force unconditioned roof spaces’ (see below).
