Domestic Hot Water (DHW) is provided in DesignBuilder Detailed HVAC through DHW loops, Water heaters, Water outlet groups and Water outlet components.
DHW loops are added at the HVAC System level. On the demand side of the DHW sub loops, Water outlet groups can be added. However a default Water outlet group is provided with the initial DHW loop so in many cases you will not need to add a new Water outlet group. Instead simply navigate to the default Water outlet group and add one or more Water outlet components to define hot water consumption and any heat transfer to a building zone.
If you are working with the default 1-Simple HVAC Detailed HVAC Activity data model option then simply associate the zones to be connected on the Zones served tab of the dialog. In many cases this would be all occupied zones in the building. In this case the amount of DHW consumed is calculated as a function of the activity in the zone. For example, there is a demand assumed to arise from the occupants of an office for activities such as washing hands and washing up cups. This demand is associated with the office rather than the toilet or tea room. So the demand from each space needs to be assigned to a DHW system even if the DHW delivery (tap, shower etc) is not present in the space.
On the other hand, when using the 2-Detailed HVAC Detailed HVAC Activity data model option it would normally make more sense to model the actual water draw off rates in the rooms where hot water is consumed (toilet, tea room, shower room etc).
Tip: For consistency with Simple HVAC use the default 1-Simple HVAC Detailed HVAC Activity data model option then create a single DHW loop, use the default Water outlet group and Water outlet provided with the DHW loop and select all zones in the building on the Zones served tab of the Water outlet.
The DHW-related Detailed HVAC components are: