Adjacency

Construction tab in model data under Construction header

The adjacency of individual surfaces can be set to be either adjacent to ground or adiabatic.

The available options are:

• 1-Auto - the adjacency of the surface is determined automatically by DesignBuilder based on its position.  This is the default setting where external surfaces below the ground plane are considered to be adjacent to ground and external surfaces above the ground plane are considered to be adjacent to outside conditions.
  
• 2-Not adjacent to ground - the surface is not adjacent to ground even if it is situated on or below the ground plane.
• 3-Adjacent to ground - the surface is adjacent to ground even if it is above the ground plane or it is an internal surface.
• 4-Adiabatic - the surface is adiabatic.  This means that heat is not transferred across in its external surface.  Adiabatic surfaces are frequently used in thermal modelling to represent surfaces which are between two zones at similar conditions.  Note that thermal mass is still modelled in Adiabatic surfaces because heat can still be transferred into the mass through the internal surface. Adiabatic surfaces are often used for modelling the boundary between the actual building model and any adjacent buildings which are not to be modelled.

You can determine which surfaces are adiabatic or adjacent to ground by looking for the corresponding surface adjacency markers in the Edit Screen at zone and surface levels:

Tip: The recommended way to set ground and adiabatic adjacencies is to use ground or adiabatic component blocks. Or, if for any reason that isn't practical and you need to set multiple surface adjacencies you can use the Model data grid view.

Adiabatic surfaces

Adiabatic surfaces are modelled as being adjacent to the same conditions as the current zone and always use internal constructions:

• Adiabatic external floors use Internal floor construction.

• Adiabatic flat roofs use the reversed Internal floor construction.

• Adiabatic external wall surfaces use the Internal partition construction.

Note: All openings and sub-surfaces in adiabatic surfaces are ignored in EnergyPlus simulations

Exclude this surface area from total zone floor area?

When modelling situations such as offices space within large warehouse zones where the ceiling at the top of the offices is not usable floor area in the warehouse it may be useful to exclude the area of any unused floor surfaces from the floor area of the zone above. An example of this situation is shown on the Warehouse with Office page.

For internal floors such as the unused 'floor' on top of the office space you can check the surface level Exclude this surface area from total zone floor area? checkbox to ensure the floor is not used in the calculation of zone and building floor area and in the calculation of internal gains where defined per m2 or per ft2.

Note this surface setting should not be made for the floor of office zone itself, which of course is usable floor area, but for the 'floor' of the zone above (typically a warehouse or other large volume space) which is not usable floor area.

Another situation where this option can be used is where holes have been cut in a floor surface to remove it, so upper and lower zones can be merged. In this case, any small remaining border in the cut floor surface should ideally be removed from the floor area calculation for the combined zone.