Connected Thermostats Demand Response

At a Glance

Status

active

Sector

residential

Applications

HVAC

RTF analysts developed per unit technical potential estimates for demand response impacts from connected thermostats. When demand response events are called, connected thermostats reduce the usage of heating and cooling systems by adjusting thermostat set points: upward during summer to reduce cooling load, and downward during winter to reduce heating load. Importantly, the demand impacts are not coming from the thermostat itself, but from the HVAC technology being controlled. Therefore, impacts are determined by individual household characteristics, such as heating/cooling system technologies, efficiencies, size, and shell, as well as event-specific conditions, such as weather, time of day, and the size of the thermostat setback.

RTF Decision

The analysis and methodology were presented to the RTF at the March 2019 meeting. Due to a robust discussion and time constraints, the RTF was unable to vote upon a proposal at the meeting. However, the following text and caveats was approved subsequently by a majority of voting members with a few expressed reservations:

Limitations

The RTF contract analysts recent work on connected thermostats demand response provides a good starting point for analyzing technical potential of these units, given the tools currently available to the RTF and the resource limitations. The RTF recognizes that while providing a good starting point, there are several limitations in this analysis and opportunities to enhance the work in the future. These include:

SEEM, as it currently exists today, is not the best tool for estimating demand response savings. Key limitations of the model include:

The model currently only allows two different temperature set points to be scheduled, which limits the ability to model nuances of a DR event, such as pre-conditioning
SEEM is an hourly model that does not have the granularity to model inter-hour dynamics.
For zonal systems, SEEM only has the ability to model the whole house, whereas DR programs may only target the main living area
Should the RTF do additional demand response in the future, it should explore alternative models and/or enhancements to SEEM
Additional analysis should update the equipment sizing to more accurately reflect the equipment anticipated for the house/climate need, rather than the regional average sizing used in the current analysis.
There are limitations to using a single extreme day from TMY weather files, without consideration of the prior few days weather.
While the current analysis breaks out different insulation quality levels, this may not be practical from a DR program perspective.
Current modeling does not sufficiently capture systems with backup propane or gas heat. This could be improved in future analysis.

Workbook

Latest Version

Residential Connected Thermostats Demand Response Workbook v1.0

Residential Connected Thermostats Demand Response Workbook v1.0

This workbook was approved at the March 2019 RTF meeting with a number of expressed reservations on the part of members. Those limitations and caveats are described above.

Date

Mar 19, 2019

Version number

1.0