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Mechanical / HVACaka: programmable thermostataka: smart thermostataka: room temperature controller

Thermostat

In Plain English

A device that senses room temperature and turns heating or cooling on and off to maintain a desired setpoint.

Definition

A temperature-sensing control device that regulates a heating or cooling system to maintain a setpoint temperature in a space. Modern programmable and smart thermostats can adjust setpoints based on schedules, occupancy sensing, and remote control. In commercial buildings, thermostats may be integrated with the building automation system for centralized monitoring and control.

Why It Matters in Bidding

Thermostats are small line items but they carry outsized coordination risk in bidding because their controls scope often falls in a gray zone between the HVAC sub, the electrician, and the controls or BAS contractor. Unclear division of work in the spec leads to gaps, double-counting, or change orders after award.

Example

While reviewing an office TI bid, the HVAC estimator flags that the spec requires smart thermostats tied to the building automation system, so he confirms with the GC whether his scope includes the BAS integration wiring or only the thermostat furnish-and-install.

Related Terms

Building Automation SystemHVACVariable Air VolumeDamper

Frequently Asked Questions

Responsibility depends on the spec and trade division. Low-voltage thermostat wiring usually falls to the HVAC sub, while line-voltage feeds and conduit may belong to the electrician. Smart or BAS-integrated thermostats often involve a controls contractor, so estimators should confirm the split during bid review to prevent scope gaps.
Smart and BAS-integrated thermostats add cost for the device, network connectivity, programming, and commissioning beyond a basic programmable unit. They may also require coordination with the controls contractor and IT infrastructure. Estimators should price the integration labor and confirm who owns the commissioning scope rather than carrying only the hardware.
Thermostats are typically counted per zone, since each controlled area needs its own sensing point. The takeoff should match the mechanical zoning shown on plans, not just room count. Miscounting zones understates both device cost and the associated control wiring, which can compound into a meaningful shortfall on larger projects.

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