Traverse equipment chains

Use upstream and downstream fields to follow feeds relationships through your building.

Equipment chains

Buildings distribute conditioned air, hot water, and other media through chains of equipment:

HIU → AHU → VAV → Zone

The upstream and downstream fields let you follow these chains without knowing their depth.

Upstream: “What feeds this?”

Start from an endpoint (a zone or terminal unit) and trace back to the source.

From a zone

{
  zone(siteId: "your-site-id", name: "Library") {
    name
    upstream {
      name
      type
    }
  }
}

Result: TW01-LBR-RPC-01 → TW01-XX-AHU-001 → Tower East HIU System, the full supply chain.

From a piece of equipment

{
  equipment(siteId: "your-site-id", id: "TW01-LBR-RPC-01") {
    name
    upstream {
      name
      type
      points(is: "Temperature_Sensor") {
        type
        timeseriesId
      }
    }
  }
}

This finds the upstream equipment and their temperature sensors. It is useful for diagnosing whether a comfort problem is local or upstream.

Downstream: “What does this feed?”

Start from a source and find everything it feeds.

From an HIU

{
  equipment(siteId: "your-site-id", name: "Tower East HIU System") {
    name
    downstream {
      name
      type
    }
  }
}

Result: all AHUs, VAVs, and zones the HIU feeds. Useful for understanding the blast radius of an HIU failure.

From an AHU

{
  equipment(siteId: "your-site-id", id: "TE01-XX-AHU-001") {
    name
    downstream(is: "HVAC_Zone") {
      name
    }
  }
}

Returns every zone served by TE01-XX-AHU-001, regardless of how many VAVs are in between.

Combining traversal with type filters

Root cause analysis

A zone is too warm. Is the problem local (VAV) or upstream (AHU or HIU)?

{
  zone(siteId: "your-site-id", name: "Library") {
    points(is: "Zone_Air_Temperature_Sensor") {
      timeseriesId
    }
    upstream {
      name
      type
      points(is: "Temperature_Sensor") {
        type
        timeseriesId
      }
    }
  }
}

Check the response: if the zone temperature is 26°C but the AHU supply temperature is correct at 14°C, the VAV is the problem. If the supply temperature is also high, look further upstream.

Impact analysis

An HIU is going down for maintenance. What zones will be affected?

{
  equipment(siteId: "your-site-id", name: "Tower East HIU System") {
    downstream(is: "HVAC_Zone") {
      name
      points(is: "Zone_Air_Temperature_Sensor") {
        timeseriesId
      }
    }
  }
}

Traversal options

Limit depth

# Only direct feeds (1 hop)
upstream(maxDepth: 1) { ... }

# Up to 3 hops
upstream(maxDepth: 3) { ... }

Filter by medium

# Only hot water chain
upstream(medium: "HOT_WATER") { ... }

# Only air distribution chain
downstream(medium: "AIR") { ... }

Next steps

Fetch historical data

Query timeseries data for the points you discover.

Build an AI agent

Use traversal patterns in an AI agent for building diagnostics.