JA5.1       Introduction

The Occupant Controlled Smart Thermostat (OCST) shall be self-certified by the manufacturer to the Energy Commission to meet the requirements described in this section. This document provides a high level technical specification for an OCST.  All OCSTs shall comply with the specifications set forth in this document or a specification approved by the Executive Director. This specification focuses on three interfaces that the Energy Commission has determined shall be supported by all OCSTs:


(a)        Communications Interface

(b)        User Display and Interface

(c)        HVAC System Interface


Sections within this document address each interface in terms of its hardware and software characteristics.  This specification is intended to compatible with NEMA Standards Publication DC 3-2008 – “Residential Controls – Electrical Wall-Mounted Thermostats” unless otherwise specified.


The Communications Interface is defined as a set of logical services that may be performed over a physical network interface connected to either an expansion port or an internal communications device. The communications interface is designed to permit a variety of intended uses for OCSTs including remote energy management services, to the extent that occupants voluntarily enable such services.  To the extent possible, this document strives to be compatible with related efforts underway (e.g. National Institute of Standards and Technology (NIST) Smart Grid Interoperability Panel (SGIP), Open Smart Grid, etc.).


The following elements are addressed in this document:


(a)  Support for the basic HVAC terminal interface specification

(b)  Support for an internal communications device or for an expansion port that will allow for the installation of a removable module to enable communications with the thermostat.

The following sections describe these and other elements of the specification in more detail.