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Placing Thermostats in the Revit Model
January 14, 2011

Physical and Digital Environments
Figure 1: (Left) Two sample thermostats on the 5th floor. (Right) The same thermostats are placed in the Revit model.

In our previous blog we provided a brief overview of how to place custom sensors in a Revit model. Our goal was to create semantic links between physical sensors and their corresponding BIM sensors. In addition to our custom sensor network, our 210 King building is also equipped with thermostats that are distributed throughout the building as a means to report thermal values from various locations (Figure 1). Our building operator can remotely monitor these thermostats through our Building Control System (BCS) interface (Figure 2). The distribution scheme for these thermostats however is still based on the original design assumptions that consisted of large open areas. To meet the ongoing business needs, our building has gone through many retrofits and the existing distribution of thermostats do not provide a high resolution sample of thermal values within each environment. When combined with our custom sensor network we can achieve a rich environment for sampling various environmental data.

BCS Interface
Figure 2: BCS interface for monitoring thermostat values.

Similar to our custom sensor network, we need to create a semantic link between existing thermostats in our Revit model and data collected from our BCS. Each thermostat already has a unique ID within our BCS therefore we had to spend some time to acquire corresponding IDs from our BCS system. The following are some sample IDs from various data points in 210 King:

  • Tracer_Summit_BCU-1-Analog_Input-152-VAV-2-2-123
  • Tracer_Summit_BCU-1-Analog_Input-2-VAV-1-1-67
  • Tracer_Summit_BCU-1-Analog_Input-56-VAV-3-2-66

Before adding the semantic information, we placed all our existing thermostats inside our Revit model according to our HVAC drawings (Figure 3). We also tested selected sensors to make sure they correspond to data points found in BCS. To do this, we simply held a heating device against the selected thermostat while monitoring its value through our system (Figure 4).

VAV system as built drawing
Figure 3: VAV system as built drawing indicting each thermostat and its name.

Testing a thermostat
Figure 4: Testing a selected thermostat against values monitored through our BCS system.

For modeling purposes, we used a default thermostat family grouped under Electrical Fixtures. Moreover, to meet our future needs we had to incorporate some custom parameters to make sure thermostats will be recognized as IFC sensor objects when exported out of Revit (Figure 5).

Custom IFC Parameters
Figure 5: Adding custom IFC parameters to a default thermostat family.

Having placed all the thermostats in the Revit model, we cross referenced thermostats IDs collected from our BCS to our VAV system as built drawings to physically locate and properly name each individual thermostat. Figure 6 illustrates a sample thermostat family with an appropriate mark and label that correspond to data collected from the BCS.

Semantic link
Figure 6: Semantic link between a BIM thermostat and BCS data point.

Our building consists of many data points. Therefore, we have created a thermostat schedule to quickly identify thermostats according to their label or associated level (Figure 7).

Thermostat Schedule
Figure 7: Thermostat schedule.

In parallel to our HVAC, we have also been developing an electrical and plumbing Revit model based on the drawings provided by our facility manager. In our future blogs will provide an overview of our electrical and plumbing Revit model.

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